Update on Proventricular Dilatation Disease and Bornavirus

Probably one of the most frightening and frustrating disease of parrot species is proventricular dilatation disease (or ‘PDD’). The disease goes by many names such as macaw wasting syndrome, myenteric ganglioneuritis, proventricular dilatation syndrome and more.

The bottom line is that the disease is characterized by a specific inflammatory pattern found around nerves that causes the target organ to fail.  If the affected nerves supply the proventiculus (stomach), food passes undigested and the bird wastes away and starves to death.  If nerves in the brain are affected, the bird may suffer from seizures and strange neurological abnormalities.  If the nerves to the eyes are affected, the bird can become blind. Wherever nerves can be found, they can be affected by this disease.  An affected bird may show only gastrointestinal or neurologic signs in addition to a combination of both.

Left untreated, the disease is often progressive until the bird succumbs.  Even if treated (usually with anti-inflammatories and autoimmune type drugs), some birds may have progressive disease or stable but persistent clinical signs.

Macaw affected with PDD passing whole food

While the disease has been studied for over two decades, it has only been since 2008 that avian bornavirus infection has been linked to PDD.  With the recent discovery of the avian bornavirus relationship to PDD, we have learned a lot (and created more questions).

Bornavirus is a RNA type virus and has previously been reported to cause, or is associated with, disease in rats, horses, primates, chickens, pigs, humans and now parrots and finches.   Avian bornavirus, as opposed to borna disease virus recognized in other animals, is now confirmed as at least one cause of PDD in parrots.  It is speculated, but not proven, that avian bornavirus triggers an autoimmune reaction whereby the bird’s immune system attacks it’s own nervous tissue.

At this time, there appear to be seven avian bornavirus genotypes that affect parrots species differently.  While most infections are of one genotype, recent research supports multiple genotype infection is possible. To make things more confusing, there is also a passeriforme bornavirus (and 3 distinct canary bornavirus genotypes) and a waterbird bornavirus.  Unless the ‘bornavirus’ test defines which genotype, all one can say is that ‘the bird is positive for avian bornavirus’.  More on testing below.

The general incidence of avian bornavirus infections in parrot populations is relatively high.  One study in which researchers screened 1400 birds found that 22.8% were positive for avian bornavirus.  Other estimates conducted non-scientifically at veterinary hospitals suggest up to 1/3 of pet parrots are positive for avian bornavirus.  At this point, no studies have clarified the incidence of each genotype within general parrot populations.

Until a recent presentation given in 2013, avian bornavirus infection and PDD were considered diseases of captive parrots.  Research by Enderlain, et al showed that 33% of tested free-ranging parrots (84 birds total, 7 different species) from Brazil were positive for avian bornavirus on PCR.   Members from all species, both sexes and different ages were positive.  Twenty two percent had specific anti-avian bornavirus antibodies (only genotype IV found in this group- see more on genotypes below).  Finally, 11 birds had histologic lesions consistent with PDD (of these, only 4 were avian bornavirus positive via PCR).  It is important to note that this information has not gone through peer review (and should not be used for reference material) but will hopefully be published soon.  This is the first time that we have support that both avian bornavirus and PDD are present in wild parrots and has implications as to the origins of the virus and disease.  As a note, avian bornaviruses have been found in free ranging Canada geese, North American Gulls and other non-parrot birds.

Transmission of avian bornavirus in parrots has been proven in the lab (by injecting virus directly into a bird’s bloodstream, brain, oral/nasal tissue, etc) but has not been completely worked out in a natural setting.  Recent research has even shown that developing embryos can carry the virus in multiple tissues supporting ‘vertical’ transmission (from mother to egg).   Collectively, these studies support a fecal-oral transmission.  However, with so many tissues potentially infected with virus, other means of viral shedding (not just through the droppings) are possible. Additionally, infected hens may pass the virus to their young.

The true means of transmission is still not clear.  While we know that bornavirus can be readily found in the crop and feces of infected birds, how it gets into susceptible birds and causes infection is not clear. Lab induced oral and nasal infection has not been successful in infecting susceptible birds.  Recent research published at a European conference in 2015 suggests that the infected hen passes the virus on the eggshell (not necessarily in the developing embryo).  Additionally, cleaning the eggshell and pulling the egg for artificial incubation may break the cycle.

Birds may become bornavirus positive in as little as 6 days after exposure.   Shedding of the virus (through feces) may occur in as little as 18 days after infection.  This supports the assumption that transmission occurs at least through a fecal-oral route.

Testing is generally directed at identifying the presence of the virus and/or antibodies against the virus.  Getting a positive avian bornavirus test (general PCR that checks for the presence of the virus) only means the bird is infected and not necessarily diseased.  Again, this test generally does not give genotype information but rather infection with a member of the avian bornavirus family. This type of test is more commonly performed and commercially available in the US.  Getting a positive antibody titer implies the bird’s immune system has recognized the infection and is attempting to fight the virus.  This type of test is more typically performed in research situations but can be found commercially outside of the US.

While it might seem intuitive that birds with high levels of antibodies against the virus could be protected against disease development, recent research suggests otherwise.  In fact, one study showed that parrots positive for the virus and with high antibody levels were at greatest risk of developing PDD (compared to those with low antibody titers).

We still don’t understand the factors that lead to infection with avian bornavirus and the development of disease.  It has long been suspected that birds housed in a closed building (as opposed to free standing cages outside) are at greatest risk of infection.  While this has not been proven scientifically, it seems logical since aerosolized fecal matter has the greatest chance to be inhaled by a naïve bird when sharing the same airspace with infected individuals. African grey with neuro PDD

Genotype of the avian bornavirus appears to be one major factor in PDD devlopment.  For example, we know that genotype II can cause disease more rapidly and severely in cockatiels than infection with genotype IV.  Also the presence of serum (blood test) antigangliosides antibodies (recognized autoimmune markers that seem to be correlated with nerve fiber injury) has been associated with the development of PDD in some parrots.  This s not a commercially available test at this time.  And, of course, some birds confirmed with PDD also test negative for serum antiganglioside antibodies (just to make things a little more confusing).

Diagnosis of PDD can only definitively be made by identifying the classic lesions in affected nerve tissue.  This of course means biopsying affected nerve tissue! Because the lesions can be randomly scattered or inaccessible (the brain and spinal cord) on a live bird, we are not always able to get a definitive diagnosis.  Our next best option is a presumptive diagnosis based on clinical signs (consistent with PDD) and supportive blood tests (positive avian bornavirus PCR and/or anti-viral antibodies).  As a note of caution, PDD clinical signs can mimic many diseases and a positive avian bornavirus blood test does NOT equal PDD!!!

Treatment options are limited generally to anti-inflammatories.  Only a few different drugs have been trialed to treat parrots with PDD.

A recent (2013, non-peer reviewed) publication from Rossi, et al suggested that a combination of Mycobacterium tuberculosis extracts and a specific non-steroidal anti-inflammatory drug can be used to suppress nerve inflammation and clinical signs associated with PDD in parrots.  The treatment protocol is under patent protection and is still being investigated but may, in the near future, offer a more targeted treatment option for birds affected with PDD.

At this time, non-steroidal anti-inflammatories along with general nutritional support and management of secondary diseases appear to be our most readily available options.

What does this all mean???

  1. Avian bornavirus has been confirmed to cause PDD in parrots and both the virus and disease can be found in captive and wild populations.
  2. There are seven genotypes of avian bornavirus, all of which likely have different infective and disease causing capabilities.  Other genotypes of avian bornavirus can infect non-parrot birds.
  3. An infected bird may shed virus through multiple routes, thereby infecting the environment and other birds, long before it shows any clinical signs (if ever).
  4. General avian bornavirus (PCR) testing at least determines which birds carry the virus and can be used to isolate infected from non-infected birds.
  5. Diagnosis of PDD is still frustrating and challenging, but at least the identification of avian bornavirus and newly available tests can help.
  6. Treatment options are generally limited to supportive care and anti-inflammatories.
  7. Talk with you avian veterinarian about the latest options for preventing, diagnosing and treating PDD as our understanding of this disease is changing rapidly!

 

M. Scott Echols, DVM, Dipl ABVP (Avian Practice)

 

Kindly reviewed by:

Prof. Dr. Michael Lierz, MRCVS, DZooMed, DipECZM (WHM), DipECPVS

Giessen University, School of Veterinary Medicine

Giessen, Germany

About BirdDoctor

58 Responses to “Update on Proventricular Dilatation Disease and Bornavirus”

  1. Patricia Barth

    Hi Scott,

    In order not to make eyes roll on the Probreeder list with my conjecture that PDD can possibly be either/or due to exposure to chemicals, environmental toxins or mycotoxins from mold (explaining the fact that indoor birds are more prone to it). I am a toxic mold victim and have researched the topic for 16+ years. You might want to join the human “sickbuildings” list for more info on the subject or just ask me questions about it. I’ve suggested this to many researchers, but do not know how many have actually considered my thoughts and experience. All toxic mold victims have temporary brain lesions in one specific part of the brain (according to studies done at Mt. Sinai Hospital many years ago). Mycotoxins eat away at the myelin nerve sheaths and can cause neurological symptoms to some degree. There so far is no cure for it and treatments are questionable except for toxin binding elements. Milk thistle (silymarin) is one good no-side-effect element for damage control and toxin release. Would be very interesting to have some funding to do good testing (Real Time Lab in TX is the best) on birds that present with symptoms of PDD and test positive for avian borna virus. Feel free to tell me I’m far off in left field about this.

    BTW, I’ve never had a bird diagnosed with PDD or necropsied with it. Nor have I had any tested for the avian bornaviruses. My exposure was not at home, but in the workplace….ironically – United HealthCare!

    Reply
    • spotdvm

      Hi Pat,

      The link between avian bornavirus and PDD in parrots is real. What is not understood is how the disease develops once infection occurs. Given that so many birds test positive for avian bornavirus, there must be a certain set of conditions that take infection to disease. So environmental, dietary, toxic and other factors likely work alone or in combination to contribute to cause the actual disease. Demyelination, as you describe with mycotoxins, is not a feature of PDD. So if mycotoxins are a component, the lesions are very atypical of mycotoxicosis.

      Scott Echols, DVM, Dipl ABVP

      Reply
      • Patricia Barth

        Thanks for explaining it, Scott. I hope that the enigma of this self-attack or autoimmune attack will be eventually be brought to light in order to deal with it more effectively.

        Reply
    • Betty Clift

      here is my issue. Out of the blue my hand fed from birth 19 year old nanday conure develop feather picking , within 24 hours her chest was bare! I took her to the aviary vet. He charged us a bundled , kept her 24 hours on an iv and told us to stop smoking around her. (which we did) . He sent her home
      It is now 3 weeks later, she has not been picking when I am with her , which is most of the day. She never did change her eating or drinking habits though any of this. But today I awoke to find her whole chest completely BARE!
      I have a friend who does exotic bird rescue, I called him in a panic, he went over everything I had done past couple of days with the bird.
      The only thing different was I relocated her cage closer to the heater vent in a room where we do not smoke. He seemed to think perhaps she was stressed from relocated to be too warm. I now have her back where she was.
      But he also mentioned that she could have Borna Virus? I tried to look up pictures of that online but could not find any pictures. I found plenty of information data. But it does not fit the way she is acting. She is acting normal except for picking her chest. I have been misting her since I took her to the vet as he did suggest that I do that. For some reason , she has been shying away from her bath water since this all began. Any suggestions.
      From what I read Borna Virus is treatable but it also is terminal!
      Thank you. bettyclift@rocketmail.com please subject : borna virus

      Reply
      • spotdvm

        Betty,

        Sorry to hear that your nanday is having these problems. Sudden onset feather damaging after 19 years is not a typical presentation for anything specific. While I cannot comment on the medical care you have already received, a complete work up that includes a complete history, physical exam, blood work and radiographs (X-rays) would be the first place to start.

        Sudden onset feather damaging is not typical of avian borna virus infection or proventricular dilatation disease (PDD). Borna virus infection is not the problem but rather when infection progresses to PDD. The presence of borna virus (unfortunately) does not determine if a bird will develop PDD.

        You may also ask your veterinarian to consult with a specialist if the issue is not resolved.

        Sincerely,

        M. Scott Echols, DVM, Dipl ABVP (Avian Practice)

        Reply
  2. Keri

    Hi Scott
    I am very interested in any info. you have on ABV. Do you know how long the virus survives in the environment and what procedures should be taken when cleaning a house once a pdd bird has passed. And how long one should wait before adopting another bird? Any info. you have would be very much apprcitated.

    Reply
    • spotdvm

      Keri,

      These are excellent questions that have no specific answers at this time. To the best of my knowledge, no one has studied avian bornavirus survivability outside of the host. Closed or minimal airflow aviaries (such as with a closed building) and high viral load (from actively shedding infected birds probably mostly through feces) seems to increase the risk of infection. However, infection is sporadic even in the most unsanitary situations. General environmental cleaning, especially of bird droppings, is probably best. At this time, there is not enough information to give specific guidelines as to when new birds can be added to an infected environment. Until I see more data, I recommend that no birds are brought into a previously infected environment for 3-6 months after birds are removed and the area is cleaned (this is not based on any scientific proof!).

      Scott Echols, DVM, Dipl ABVP (Avian)

      Reply
  3. Keri

    When you say general environmental cleaning what do you mean? And what kind of cleaner do you recommend. I would prefer to know of something other than bleach. And I am not talking about an aviary. I am talking about a normal household.

    Reply
    • spotdvm

      Keri,

      General environmental cleaning means removing all solid wastes regularly (bird droppings, cage papers, etc) in and around the cage and providing clean water at all times. I am not a fan of chemical disinfectants (like bleach and others) especially for small scale and family pet arrangements. (For commercial and other large operations I do sometimes recommend chemical disinfectants for a variety of reasons and always tailored for each situation.) Also, I recommend general cleaning for the room where the bird spends most of its time: air filtration (if needed), regular sweeping for non-porous floors, vacuum cleaning for carpet and corners, and dust control (wiping counter tops, fan blades, shutters, etc).

      The frequency of all cleaning really depends on the bird and its immediate environment. For some this means cleaning every 1-2 days (smaller spaces). For most is means regular cleaning every 1-2 weeks. Some birds spend very little time in their cage and lots of time outside. These birds may have minimal mess in and around their cage requiring even less frequent cleaning.

      My favorite all-purpose cleaner is simply warm soapy water. Mechanically removing dust, debris, etc will significantly reduce the risk of airborne disease transmission.

      Thank you for the questions!

      M. Scott Echols, DVM, Dipl ABVP (Avian Practice)

      Reply
      • Keri

        Is this what you recommend for an area that had a pdd bird in it to prevent it from spreading to another bird that is not sick? The reason I ask is because I bought a bird that come to find out was sick with pdd. Luckily I had that bird quarantined upstairs and my other bird was downstairs. They never saw each other and I have done everything in trying to prevent this horrible virus from getting to my other bird. And since so little is known about ABV I have no idea if I have done everything to protect my bird that I have had for years. I have made myself sick over this whole fiasco. There is a lot more to this story but I am trying to make this somewhat brief. I only had the pdd bird for one week. I changed his papers twice during that time. Once he was put to sleep I cleaned the upstairs with a veterinary cleaner called f10 and had my couch and carpet up there professionally cleaned. So do you feel like my other bird should be okay or is there something more I should do? Any comments would be appreciated.

        Reply
        • spotdvm

          Keri,

          At this point, we just don’t know enough about how a bird contracts the ABV (in a natural setting) or how the bird goes from infection to disease to make concrete recommendations- very frustrating! However, limited exposure time (1 week is a short time span fortunately) and a limited viral load (we don’t know how much your sick bird was shedding but the cleaning you did should help to significantly reduce the risk plus the fact the birds were physicall separated helps a lot) will greatly reduce the risk that your other bird will contract ABV from your sick one. So overall, I think the risk of the sick bird exposing your healthy bird to ABV is low.

          Just to make matters more confusing, your first bird may already have ABV in its system from an event unrelated to this recent sick bird. So many birds have been ABV positive for years with no evidence of disease.

          The best things you did are A.) quarantine the new bird and B.) clean up after it left your house.

          M. Scott Echols, DVM, Dipl ABVP (Avian Practice)

          Reply
          • Keri

            I completely agree with you with how frustrating this virus is. I just wanted to let you know that yes they were separated but I only have one heat pump in my house that provides ac or heat for the whole house. I do not believe that it came on while the sick bird was here but I can’t swear to that. If it did it was only for the first 3 days because once I realized what was happening I turned the heat pump completely off. One good thing is there is no return vent upstairs only vents to blow air into the room not suck it out. So I don’t think I should have anything to worry about there either but I thought I would see what you thought. Once the sick bird was gone I changed the filter downstairs and sprayed the vents with the f10 disinfectant. It has been about 2.5 months since all of this happened and so far my bird I have had for years seems to be fine. Thank goodness. Thank you for the information. I have an avian vet here but since so little is known about the virus I have been looking anywhere to try to find more knowledge. I am so glad that I found you. I greatly appreciate you taking the time to answer my questions. Please let me know if you feel that I could have spread this virus around with my heat pump or not.

          • spotdvm

            There is no way to answer your last question. But overall, I think the risk is low.

  4. Keri

    Thank you so much for all of your help. You really are a special person. I hope you continue to update everyone on ABV and PDD. There are so many people waiting to hear how this virus works and how it spreads from bird to bird. It has taken too many wonderful birds from owners that are broken hearted over their loss. I sure do know that I lost a wonderful bird to this horrible diease and have been in fear for my other bird because of the difficulties of figuring out ABV. Once again thank you.

    Reply
  5. Layna Scheunemann

    What procedure do you recommend when bringing a bird into a home with existing birds, to help reduce the spread of disease?
    If a bird that is in the house was positive for ABV (asymptomatic) should that stop you from adding another bird?
    I have 8 birds so statistically 2 would be ABV positive. Do you recommend routine screening for ABV?

    Reply
    • spotdvm

      Layna,

      Your question is very good and one that one that I will turn back on you. The question for you is ‘what are your requirements before a bird can enter your home with your other birds?’. Please let me explain. This is the basic closed aviary principle- that being that all birds that enter your home must pass a series of tests or requirements before joining your other birds. These protocols are highly variable and depend on the species, type of operation (home up to commercial aviary to rescue/rehabilitation organization- all are going to have different entrance requirements), and in part by recommendations from your veterinarian. First let’s focus on general health and then we will get to ABV and PDD. A general home ‘entrance requirement’ may be something like the following: A. Birds come from trusted sources B. Birds are examined by an avian veterinarian and routine tests are run C. Specific disease testing may be run also (to check for psittacosis, herpes, beak and feather disease virus, etc) and then D. The bird is quarantined for 2 months before joining the flock.

      Closed aviary practices should reduce the incidence of most infectious diseases. However, it does not eliminate risk of any disease. Homes and facilities without any type of closed aviary protocols are at highest risk of infectious disease spread. Also places with a protocol that gets violated (in the example above, let’s say someone decides to accept a bird from a source with known infectious diseases in their birds) increase risks of infectious diseases.

      Now how about ABV??? While we have established a link between ABV and PDD, we do not understand how the process of infection to disease works. We also know that a bird can intermittently test negative (false negative) meaning that some screening will miss ABV infected birds. We also expect that roughly 1/3 of tested pet parrots will be ABV positive (many of which will never develop PDD). Put this all together and it makes for a testing nightmare.

      There are some aviaries (homes, business, etc) that say no ABV + birds shall enter. All of the resident birds are tested negative and any future candidates are denied entry if they test positive during the initial testing and quarantine period. Some with ABV + birds don’t bother testing (we never did before 2008!) and assume their flock is already exposed and are taking a wait and see approach. Some say, no more ABV+ birds even though they have birds that are positive in their current collection.

      The initial step to correlating ABV to PDD created at least one solution to the problem- ‘what causes PDD and is there a test available for the agent?’. It also has created a lot of problems in that we really don’t know what infection means for most birds.

      Back to your question…. you will ultimately have to decide what you feel is best for your flock and the incoming bird. You may decide to test all of your birds for ABV and isolate positives from negatives. Any new birds will then go with the appropriate group. You may also decide to not perform ABV testing. Regardless, I would have a ‘closed aviary program’ for your home to reduce risk of all infectious diseases. Additionally, keep up with the flood of information coming regarding ABV and PDD. Who knows, maybe next week we will have more specific guidelines.

      Scott Echols, DVM, Dipl ABVP (Avian Practice)

      Reply
  6. Hatty

    Hi Dr. Scott
    i have a question. could a vet diagnose a parrot with PDD as a Parrot with Lymphoma cancer? and treat the bird for over a year with chemotherapy and then the bird dies from PDD?
    thank you

    Reply
    • spotdvm

      Hatty,

      A bird can certainly have both cancer and PDD. It is more common for only one major disease to be present. Regardless, multiple diseases (such as PDD and cancer) can be present in the same bird.

      Scott Echols, DVM, Dipl ABVP (Avian Practice)

      Reply
      • Hatty

        Dr. Scott
        i actually wanted to know if the symptoms of PDD can be mistaken with Lymphoma? i saw in one of the articles about PDD that one of the symptoms can be elevated of the white blood cells. and therefor my parrot was treated with chemotherapy for the cancer but actually was suppose to be treated with anti inflammatory drugs.
        also statistically, do you know how long usually a parrot will die after showing signs of pdd. is 16 months impossible?
        thanks

        Reply
        • spotdvm

          Hatty,

          Lymphoma can present in many different forms- just like PDD. Unfortunately, there is no one set pattern that goes with lymphoma. An elevated W while blood count is not typical with PDD- but that too is possible. Yes a bird can have the clinical form of PDD for months to years and really depends on which nerves are affected and how severely.

          Scott Echols, DVM, Dipl ABVP (Avian Practice)

          Reply
  7. Valorie Nycum

    Hi Dr. Echols
    I just heard your Podcast on PDD. Best information I have received on this disease. Thank you and your team for getting the word out. My history with PDD begins when I lost a Hahns Macaw at one year old. I have a six year old Grey with ABV. Diagnosed in 2011. Both purchased from the same breeder. My Grey is showing the typical balance neurological issues as you described in the podcast. My Grey Bentley stopped eating a well balanced healthy diet. He will only eat a watered down oatmeal diet instead? I do add organic pellets to the oatmeal mixture. Of course the pellets have to be soft. He doesn’t like the mixture if I put to many pellets in it. Last year I took Bentley to his veterinarian when he was falling off his perch at night. He also was suffering from polyuria. Bentley’s veterinarian suspected he was in liver failure. He took some blood and discovered his SGOT was 501 CPK was 1008 and elevated chloride and cholesterol. We got him on Baytril and Silybin. He finished his course but I kept him on the silybin A year later his veterinarian cant believe he is still alive. His weight went from 457 to 522 since we added the Celebrex to his meal. After your podcast, I’m going to add the omega 3 to his diet as well. Your advise is priceless for all of us fighting against PDD.

    Reply
  8. Valorie Nycum

    Dr. Scott,
    My Grey, Bentley as PDD. I would like to know if there is anything that will help his balance? He seems to constantly be correcting himself by flapping his wings when he finds his balance compromised. He doesn’t move around his cage. He stays in one spot. I take him out in the sun several times a week. I put him in a tree that has different branch sizes in hopes of keeping his muscles working. He is already on Celebrex everyday and liquid Milk Thistle for his liver. Is there anything else I can do to help him?

    Reply
    • spotdvm

      Valorie,

      First I am sorry to hear that Bentley is suffering from PDD. It really is a terrible disease and unfortunately we have little to offer other than supportive therapy. As I indicated in the blog, there is some preliminary data suggesting that a novel approach to treating this disease with a combination of a tuberculosis extract and an anti-inflammatory may actually reverse lesions in some affected birds. The work is being conducted in Italy and we are still a ways away from an actual product that can be purchased and used for PDD affected birds.

      As for Bentley, your veterinarian can judge what is best for supportive care. If Bentley has liver disease it may certainly be complicating the problem and targeted therapy may be needed. The addition of omega-3 fatty acids may serve two roles: 1.) to non-specifically decrease inflammation (inflammation along nerves actual causes the symptoms of PDD) and to increase the efficiency of electrical transmission along nerves. Arrange the cage such that Bently can easily move around without risk of falling (or at least without risk of falling far) and such that food and water are readily accessible. Last, a little sun cannot hurt. If you can go outside with Bentley on nice days it may help to at least improve his mood.

      Sincerely,

      M. Scott Echols, DVM, Dipl ABVP (Avian Practice)

      Reply
  9. Pat

    Dear Dr. Scott,

    I have lost a couple of birds, both palm cockatoos, and their histo came back stating they had lesions consistent with PDD although neither bird died directly from PDD. I lost the first one 4 1/2 yearsd ago and since that time I feel like I must have set a record for having my birds tested for ABV. Earlier this week my vet submitted samples for testing for 2 more palm cockatoos of mine. The one that was positive last year is now negative and the one that was negative last year is now positive. Both of these palms have been on daily Celebrex for about 3 years now. I don’t understand how they go from negative to positive and back to negative again. Also, last year I had a pair of my Major Mitchells tested and both were ABV positive. Physical exams and blood panels make them appear to be quite healthy. The exception was the CK of one of the Mitchells was 2396 (lab reference range 500). Should I assume she already has PDD even though she looks great?

    Reply
    • spotdvm

      Pat,

      You are directly experiencing some of the frustrations with avian bornavirus testing (ABV) and proventricular dilatation disease (PDD) that we are all encountering. I again want to make it clear that a bird that is positive for ABV does not equal a bird having PDD. Some birds that are positive for ABV go on to develop PDD. At this point, we do not understand all of the risk factors that lead to infection with ABV or to development of PDD. Numerous studies have now shown that birds can test positive for ABV one day and then negative at the next testing. This means a bird can shed the virus intermittently and random testing may result in false negatives. Even in a collection where numerous ABV positive birds are kept, not all will ever test positive for the virus. On the same note, when birds in a collection are surrounded by PDD affected cagemates/housemates some will never test positive for ABV or develop PDD. So I would not assume your Major Mitchells cockatoo has PDD based on a positive ABV test or an elevated CK. Currently, the only means to diagnose PDD is to biopsy affected nerve tissue and see the lesions under a microscope. Yes, these limitations are very frustrating!

      Sincerely,

      M. Scott Echols, DVM, Dipl ABVP (Avian Practice)

      Reply
      • Pat

        Last week my vet sent samples from yet another pair of my Major Mitchells for ABV testing. The results said that one bird was positive and the other negative but my vet told me that both birds are probably positive and the test just didn’t pick it up on the other bird. None of these birds are showing any signs of PDD. My questions is, would you recommend putting all the birds on Celebrex based on positive ABV tests alone?

        Reply
        • spotdvm

          Pat,

          Ultimately the decision to treat a bird is between you and your veterinarian. However, treating non-symptomatic birds does not seem to give any advantage. With our current knowledge, I would reserve treatment for clinically ill birds. All medications come with potential side effects.

          Sincerely,

          M. Scott Echols, DVM, Dipl ABVP (Avian Practice)

          Reply
  10. Jeannine Miesle

    I’d like to find out what the tests consist of identify anti-ganglioside antibodies in ABV/PDD- affected birds. Are they rt-PCR tests? Serology? Thank you.

    Reply
    • spotdvm

      Jeannine,

      Great, a technical question! A lot of the ABV tests specifically test for ABV RNA by real time PCR (rtPCR) (many tissues- blood, tissue swabs, etc). ABV-RNA has also been tested by reverse transcription combined with quantitative PCR (qPCR). ABV antibodies have been detected using immunofluorescence assay. ELISA and Western Blot have also been used to identify ABV antibodies.

      Specific to your question, ELISA and Dot blot have been used to detect anti-ganglioside antibodies in PDD- affected bird sera. Immuno-electron microscopy has also been used to detect antibody deposits (gold nanoparticle aggregates) in affected nerve tissue consistent with anti-ganglioside antibodies.

      I bring up the other tests simply because many different diagnostic approaches are being evaluated (likely more than what I have listed here). So we will probably see refined and/or additional testing methodology in the near future.

      Sincerely,

      M. Scott Echols, DVM, Dipl ABVP (Avian Practice)

      Reply
  11. Chris

    Hi, I currently have a baby macaw that is being handfed that came back positive for ABV. I was told he was swabbed and now that I said I don’t believe it is accurate now they tell me they sent blood too. I also called another place that told me the lab is known for false positives. I have been worried sick about what I should do. The baby macaw checks out great and all blood work was great with exception to ABV. I was told he could possibly test out negative in a couple months..huh? I am so confused as I have other birds to worry about. Do I retest? I can’t quarantine the macaw as I don’t own a mansion. Please help me. Thank you

    Reply
    • spotdvm

      Chris,

      In the recent words of one of my esteemed colleagues currently studying ABV and PDD ‘I am now more confused about this virus and disease than ever before’. I will not reveal the researcher’s name but the statement was given at the Association of Avian Veterinarians Annual Conference in August, 2013.

      You are experiencing the same confusion and concern over this test result that many others have expressed. The question for any test result is ‘what does it mean’. So what if the ‘value’ is high, low, positive or negative it all comes back to the interpretation. At this point in time, I don’t think we can say any more than your bird tested positive for avian borna virus(I assume it was not subtyped). With that information, I cannot say whether or not your bird will every develop PDD or be infectious to others.

      It is this exact situation that people question the value of randomly testing birds. I am not suggesting that one should or should not test for ABV but rather realize that we have many limitations when it comes to interpreting test values.

      Sincerely,

      M. Scott Echols, DVM, Dipl ABVP (Avian Practice)

      Reply
  12. Layna Scheunemann

    What is known about the ABV going from parents to eggs/babies? Is it in the egg or is it transferred thru feeding? If one or both parents are positive for ABV will all the offspring be positive as well?

    Reply
    • spotdvm

      Layna,

      At least one study has shown that parrot eggs coming from ABV infected aviaries can be infected with ABV. Whether or not the young chicks would have gone on to hatch (which would be required to complete this ‘vertical’ transmission cycle) is now known. So this study strongly supports that ABV can be successfully transmitted through the eggs. Given that ABV can be detected in crop samples supports that parents can transmit the virus through regular feeding. We don’t know the factors that determine whether or not an exposed bird will become infected with ABV or go on to develop PDD.

      Sincerely,

      M. Scott Echols, DVM, Dipl ABVP (Avian Practice)

      Reply
  13. Sandy Bredehoft,RN

    I have a 16y.o. Yellow front Amazon who has been continually sick with multi bacterial Infections one right after another x 2 yrs. Swithched vets and she has given vit A shots plus Booster which has helped him improve to 1 bacteria every 10 weeks. He has just now tested (+) ABV. This bird was very young when got and couldn’t fly yet. If he flies now his wings hurt and so do his legs from landing. I have vets that are trained as chiropractors for animals. An adjustment plus laser helps. I wonder if there is a common ground here. I have fibromyalgia with same muscle and nerve problems, no I don’t fly! But using my muscles cause same symptoms. I was put on Celebrex years ago which helped but it gave me other problems. I’m wondering if Neurontin would be a drug that would help the nerve issues from PDD and ABV. They know nothing about FM either and thinking now it may be a human strain. Think about this and read about FM I really think there is a correlation. I have a Bare Eyed Cockatoo that has half a liver and major nervousness . Always thought from liver but now maybe ABV, still testing (+) ABV. I give more nursing care to them than my human pts ! Pass this on to other researchers. I was a past pres to a bird club that gave lots of donations for PDD. Glad to see it helped.

    Reply
    • spotdvm

      Sandy,

      Thank you for sharing with us. A number of researchers have looked potential avian borna virus infection in people. The disease (meaning lesions that match) PDD has been identified in some mammals. In fact borna disease virus (related to but not the same as avian borna virus) has affected numerous mammal species. However, there is no known cross over between avian borna virus and humans.

      The lesions seen with PDD in birds are different than that seen with fibromyalgia in humans. However, both appear to have a neurologic base. So some drugs that affect inflammation along nerves may benefit birds with PDD and humans with fibromyalgia. This appears to be true of Celebrex.

      Gabapentin (Neurontin) has been used in birds with mixed results. In humans it is used to treat seizures and nerve related pain (and a few others). Gabapentin may have value in birds with PDD, however we have little information other than anecdotal reports.

      As the scientific community continues to work to better understand diseases such as PDD in birds and fibromyalgia in humans, we will likely find parallels that allow the human and veterinary community to share information. Sometimes that shared information leads to new discoveries! We just need to keep exploring ideas such as what you presented.

      Sincerely,

      M. Scott Echols, DVM, Dipl ABVP (Avian Practice)

      Reply
  14. Pat Pecora

    Dear Dr. Scott,
    A while back I posted here about losing two male palm cockatoos and that their histos came back with the words lesions consistent with PDD. Recently I was exchanging e-mails with someone who keeps a large number of birds including palm cockatoos. He wrote me the following———-The only other encouragement I can offer is that some will never get sick, Mostly hens, and you need to keep them individually for a few years if they lose a mate. For some reason, some hens will seroconvert the virus and never get ill, but they go through a stage where they are contagious and the mates will die over and over again till the hens convert.——–I have not read this before Is there documented evidence of this and if so can you explain it to me a bit more, please.

    Reply
    • spotdvm

      Pat,

      While most birds that are bornavirus positive never get PDD, the statement ‘For some reason, some hens will seroconvert the virus and never get ill, but they go through a stage where they are contagious and the mates will die over and over again till the hens convert’ has not been proven exactly as written. There are plenty of accounts of male and female parrots being bornavirus positive, shedding virus long term and never showing signs of illness. So it is not limited to hens. Plus, these birds can intermittently shed virus. One day they are positive and the next negative only to be positive again at a later date. Males can do the same. We don’t yet know why some birds remain carriers or why some get sick. Isolating a known bornavirus positive bird (with a history of a mate dying of PDD) for a few years does not guarantee that the same bird will or will not shed virus later in life.

      Scott Echols, DVM, Dipl ABVP (Avian Practice)

      Reply
  15. Michelle Ashkin

    Please tell me if you have heard of using St, John’s Wart for PDD. I have read that it might be helpful in supporting the nervous system.

    Thank you.

    Reply
    • spotdvm

      Michelle,

      At this time, there is no proof that St John’s wort has any effect on birds with PDD. That does not mean it is not helpful, but no one has critically studied its use in birds.

      M. Scott Echols, DVM, Dipl ABVP (Avian Practice)

      Reply
  16. Michelle Ashkin

    Also, what foods are the most easily digested? You didn’t mention the kinds of food on your podcast. Our little Nanday Conure has been diagnosed with this PDD. He eats heartily, but still is not gaining weight. He ats a combo of fresh fruits, grains, salmon, yogurt, walnuts, the best birdy cereals, whole grain breads – but won’t touch green leaf vegetables. We are sprinkliing his food with probiotics, some say we should use ‘proenzyme’ to sort of ‘predigest’ the food a bit, but we haven’t done that yet. What is the most easily digestible food for our little Luke? We are desperate to keep him alive and well. And he is on Celebrex.
    Thank you
    Michelle

    Reply
    • spotdvm

      Michelle,

      The true digestibility of foods has not been evaluated in just about every bird except for poultry species. So at this time there is no means to accurately tell you which foods are most digestible for your Nanday.

      However, there are some things you can do to improve the digestibilty of foods and make certain food recommendations. First, whole grains (spelt, oat groats, quinoa, wheatberry, etc) can be cooked to make them more digestible. I would recommend against sugary foods and most simple carbohydrates as they tend to ferment in a slow gut as is common with PDD. Those sugary/simple carbohydrate foods include most yogurts (high in added sugar), birdy cereals, whole grain breads, some fruits (especially citrus, bananas and dried fruits), pasta, rice, white potatoes, etc.

      Medical digestive enzymes (especially those that contain cellulase) can be helpful to ‘predigest’ food for some birds and other animals with poor pancreatic function, malabsorption, maldigestion or other intestinal problems.

      Probiotics can be helpful when they are used for the appropriate species. From published research, we know that probiotics do not cross species very well. In other words, a chicken probiotic would not work for a cockatiel. Likewise human probiotics seem to have no proven benefit with birds of any species. So until we get species specific probiotics, I think the research will continue to show that these products do not work. I am well aware of the anecdotal reports but the research says differently.

      Another consideration is supplementing the diet with semi-elemental foods (such as Lafeber Critical Care products). These products can be used to provide readily digestible protein, fats and carbohydrates and is something I commonly use in birds with PDD.

      I hope this helps with your Nanday.

      Sincerely,

      M. Scott Echols, DVM, Dipl ABVP (Avian Practice)

      Reply
  17. Daniel Thorne

    My blue and gold macaw has been on celecoxib for 9 years. He has been tested and does not have the pdd virus any more. He is being slowly taken off the meds. Is there any chance of reinfection , and have you known of any other birds recovering from pdd,

    Reply
    • spotdvm

      Daniel,

      First I would like to clarify that the presence of avian bornavirus (ABV) does NOT equal psittacine proventricular dilatation (PDD). We do know that ABV can lead to PDD. However, there are other non-ABV things that can also induce PDD in birds. While the research surveys vary, roughly 30% of captive parrots have ABV. All that means is that a lot of birds have been exposed to ABV. Only a fraction of those birds ever develop PDD. We still do not know how or why PDD develops.

      To answer your question ‘is there any chance of reinfection?’ I really don’t know. There are several types (at least 7 fairly commonly encountered) of ABV. We are learning that the different types of ABV cause disease in some parrot species but not others. In the US, the general tests for ABV do not differentiate between the types. So for example, without special testing we could not say that your bird was positive for ABV 2, ABV 4, etc. Without that knowledge, we really cannot say whether or not your bird had a type that is considered higher risk (of developing PDD) for blue and gold macaws.

      We also don’t understand how birds ‘clear’ themselves of ABV- if they do. A negative ABV test does not indicate the infection is gone but rather that it could not be detected. Some birds are ‘intermittent shedders’ meaning at times they test negative in between a series of positive tests. That is they intermittently shed the virus (usually in the stool, sometimes in the blood).

      As you can see, there are a lot of very important holes to fill in. Both ABV and PDD continue to be very frustrating diseases with more questions than answers. However, I encourage everyone involved to keep asking the questions so that researchers are pressed to find answers!

      Sincerely,

      M. Scott Echols, DVM Dipl ABVP (Avian Practice)

      Reply
  18. Pat Pecora

    Dear Dr. Echols,

    I was just reading through the posts and your responses and this in the above post caught my attention–“We are learning that the different types of ABV cause disease in some parrot species but not others.” —A few months ago I lost a third palm cockatoo to PDD. I have genotype 5. Dr. Tizard has sequenced the DNA from my birds. He told me that he has only seen genotype 5 once before here in the US. When I talked to my vet about this she said there is probably a lot more of genotype 5 but since most tests don’t include genotyping, that no one knows how much. I have a male eclectus who is now showing signs of PDD and my vet has put on Celebrex. Is there anything you can tell me that is specific to genotype 5?

    Reply
    • BirdDoctor

      Pat,

      First I am sorry to hear about your palm cockatoos succumbing to PDD. This is truly a terrible disease. With as much as we have learned about the relationship between bornavirus and PDD, we still have far more questions than answers. You are correct that because we don’t typically get genotypes of bornavirus here in the US (rather ‘bornavirus positive’ or ‘bornavirus negative’) we really don’t know the incidence of the various genetic forms of bornavirus in the pet populations. In fact, we still don’t know how a bird goes from bornavirus infection to PDD (the actual disease). So at this time, we really know very little about bornavirus genotype 5. I attended an avian conference this year in Europe and there were no major advances to report on bornavirus or PDD. We have another conference coming up soon and we will likely discuss this virus and disease further.

      M. Scott Echols, DVM, Dipl ABVP (Avian Practice)

      Reply
  19. Vrami Bird

    Dr. Echols, in a post on June 3rd you mention that “other, non ABV things can cause PDD. Could you elaborate on that ? I found that in humans with Irritable Bowel Disease, lymphoplasmacytic infiltrations are found in the enteric ganglia. I am not aware of a link between IBD and a virus. What other agents are found or suspected to trigger the infiltration in parrot’s nerve ganglia, a process, which I understand is agreed to be an auto immune response.
    Thnk you

    Reply
    • BirdDoctor

      Vrami Bird,

      First I would like to distinguish between ‘other things’ (non avian borna virus- ABV) that cause PDD and that mimic PDD.

      PDD is defined by a collection of specific microscopic findings (specific inflammatory histologic changes in nerves). PDD is not definitively diagnosed by clinical signs- no matter how classic they may be. PDD is also not definitively diagnosed by the presence of ABV positive lab tests even if clinical signs are present.

      At current time, anti-ganglioside antibodies have been shown to induce PDD in parrots without the presence of ABV. It has been shown experimentally. However, it is still not clear exactly how this is occurring, transmitted, etc.

      Several diseases mimic PDD. Certain infectious diseases (West Nile Virus), toxins (lead, botulism), cardiovascular diseases (atherosclerosis and diminished blood flow), gastrointestinal disorders (especially proventricular [stomach] ulcers) and more can (short to long term depending on the disease) mimic PDD.

      It is important to understand the complexity of PDD and other diseases. As we learn more about individual diseases, we are better able to discern them from each other. With relatively new and poorly understood diseases definitive diagnosis is far more challenging.

      Sincerely,

      M. Scott Echols, DVM, Dipl ABVP (Avian Practice)

      Reply
  20. Lucy

    Hi Dr Scott,

    I have a question about a necropsy of a Jenday conure. I know that there isnt alot of info on PDD to have a true confirmation of diagnosis so to speak but this is the necropsy report..Does this report say my bird died of PDD or had the symptoms of PDD…Is there other avian diseases that mimic PDD and could be mistaken for it?
    Necropsy below:”Diagnosis: Histologic lesions consistent with Proventricular dilatation disease (PDD)Final Diagnosis CommentGross lesions were suggestive of proventricular dilatation disease (PDD) and histopathology confirms the diagnosis. This disease is also known as Macaw wasting disease. The disease is caused by avian bornavirus.””Gross Examination CommentsThe gross appearance of the proventriculus is troubling. Additional histologic evaluation is required to determine the significance of it’s gross appearance. Ancillary tests and histopathology are pending. Photographs taken during necropsy are attached to the report in LIMS.HistopathologyBrain – There are scattered lymphoplasmacytic perivascular cuffs in the cerebrum and brain stem. Similar infiltrates are found in the choroid plexus. The cerebellum is normal.Ventriculus – There are severe infiltrates of mononuclear cells, lymphocytes, plasma cells, and lesser numbers of macrophages within the muscular wall of the ventriculus. These infiltrates multifocally efface the muscle, surround blood vessels, and efface ganglia.Crop – There are lymphoplasmacytic perivascular infiltrates in the wall of the crop.”

    Reply
    • BirdDoctor

      Lucy,

      While I cannot tell if your bird died from PDD or if its clinical signs were consistent with the disease, the histopathology report does support the diagnosis that (at least) your bird had proventricular dilation disease. Some birds do have PDD but it is not the cause of death. This is a situation where it would be best to work with your veterinarian to determined if the histopathology report matches the clinical signs and what, if any, steps should be taken for other birds that might be present in your household. I am sorry for your loss.

      Sincerely,

      M. Scott Echols, DVM, Dipl ABVP (Avian Practice)

      Reply
  21. Sharon

    Hello, i hope this is still an active site. One of my African greys has recently tested positive for PDD . He ( dna tested male as a chick , yet following endoscopy 5 weeks ago was found to be female) He initially went quiet at the end of May this year, stopped talking and dropped 30 to 40 gr in weight in a short period. After 4 days of being ‘ off color’ i took him to my most local avian vet. Blood tests revealed a low calcium level.
    My Grey is 12 yrs old, started snipping feathers at 15 months and continued this until earlier this year when out of the blue he regrew all flight feathers and tail feathers. For the first time in 10 years he was able to fly which he did with a vengeance.
    The calcium deficiency we presumed to be due to this sudden surge of feather growth and he was treated with zolcal d . For a few days he seemed better but then deteriorated again. Within 2 weeks he was back at the vets, this time x rays and endoscopy were performed, also repeat bloods.
    Calcium levels were back to normal range, i cannot remember exactly but there were slight issues with red /white counts but nothing to signify a problem. X rays showed everything including the proventricular to be normal. Endoscopy also showed normal other than he was actually a she. The crop however couldnt be seen clearly due to a large amount of saliva being present. Incase of pain due to something not picked up on ( we originally thought perhaps a mild crop burn after ‘stealing ‘ a hot chip off my plate 2 weeks earlier) he was started on a low dose of metacam once daily. Again for a few days he seemed to be recovering, good days outweighed the bad days.
    Still not right he returned to the vets2 weeks later after i discovered a grittines to his droppings. He had repeat x rays, bloods and scoping. This time the x rays revealed a hugely distended proventriculus . Swabs and crop biopsy were taken. The crop biopsy tested positive for PDD.
    He was put on a higher dose of metacam, and i started im on various herbal remedies, including olive leaf extract, maitake, digestive enzymes, spirulina, and bee pollen.
    Three weeks ago he weighed in at 332gr, today he weighs 374 grs. We started him on celebrex last saturday evening after 24 hours clear of metacam, and he had a very restless night. The next morning he was rushed back to the vets as during the early hours he had picked at the biopsy wound and reopened it into the crop.
    Whether it was the lack of pain meds for 24 hrs or the celebrex that caused him to pick at the wound we are unsure but just incase he was put back on to the metacam and celebrex was discontinued for now.
    He eats fairly normally, dropping are slightly sloppy but relatively normal in color and larts, there are only the occasional partially digested seeds present, and of course he large weight gain.
    As olive leaf extract is a diuretic he is not retaining fluid, and what he eats is passing through the digestive system . The only real issue at the moment, a few years ago he lost the tip of a toe plus nail. This toe has recently developed a sore spot which is causing him to flinch every few seconds which in turn disturbs his sleep. Aloe vera gel helps for short spells, but have yet to try other products to help with this.
    What i would like to know is have you seen this sudden progression of PDD before, space of 2 weeks from clear x ray to showing massively distended proV.? Also the considerable weight gain? Before illness his average weight was between 364 gr and 370 gr so his weight loss wasnt even massive , maximum of 35 grs which he has regained.
    Also could you perhaps suggest something which will help with the toe?
    Thankyou.

    Reply
    • BirdDoctor

      Sharon,

      Thank you for the history on your grey. As a quick note, I cannot effectively make diagnoses or recommend treatments without seeing the patient.

      To answer your questions about the rapid changes in weight and proventricular size, yes there can be significant fluctuations in both especially during the early course of PDD. We more commonly expect to see a consistent weight loss and large proventiculus. However, this disease can present in a large variety of ways. And yes, a bird can seemingly be normal one day and sick with clinical signs of PDD in less than two weeks. We also sometimes biopsy tissue that is positive for PDD however there are no clinical signs. Just to add to the confusion! It is a difficult disease and I am sorry to hear that your bird is affected.

      Sincerely,

      M. Scott Echols, DVM, Dipl ABVP (Avian Practice)

      Reply
  22. Lori Meyer

    My beloved African Grey just tested positive, and I’m devastated. He has been stabilized with Metacam, Reglan and Tribrissen. I’m concerned about the side effects of these drugs. I would like to add milk thistle and omega 3 to his diet. What ate the best forms and doses that I should give him? I so appreciate your help.

    Reply
    • BirdDoctor

      Lori,

      Can you please clarify what your African grey has tested positive for?

      To answer your question, you will need to consult with your avian veterinarian for the appropriate dose of milk thistle and omega-3’s. Regarding the best forms, make sure that you get pharmaceutical grade supplements. Recent reports (consumerlab.com and research articles) have suggested that up to 90% of milk thistle products do not contains the labeled amount. Even more troubling are the reports of toxic components being found in omega fatty acid supplements. The label should state the following “follows USP guidelines for potency, uniformity and disintegration”. If the product does not, you are taking a gamble as to its contents.

      Sincerely,

      M. Scott Echols, DVM, Dipl ABVP (Avian Practice)

      Reply
  23. Annmarie Pottrell

    Thank you for this updated report. I’m in the UK and there is next to nothing about it over here.
    My 30 year old Cockateil was diagnosed with PPD in June 🙁

    She went off her food then started passing full seeds in very runny poops and sleeping most of the time. After many tests ruling all other things out the vet mentioned PPD and said it was tricky to test for due to the shedding but it’s better to try then risk knocking her out for x-rays and camera to see if a tumour as less likely a tumour.

    A few days later I got the dreaded phone call saying it’s PDD :/

    Will her age of been the main reason she got it? I’ve had her since I was a little girl when I rescued her, she’s been with me since all way through schools, collage, marriage etc.

    She’s lost almost 50g in weight but now been holding steady for a month and half on a soft food diet (crushed nutra pelletes mixed with soaked eggfood by EMP and probiotics (potent brew) ) with critical care if she drops below a certain weight.

    The only thing I’ve noticed is I have to clean her out much more due to her having runny poos but they turn funny quicker so if my migraines last more than 2 days the cage looks and smells bad :/

    Is there anything else that can prevent this that won’t harm her or is it a nasty side effect of PPD?

    Also will I pass it on to any chickens at the local rescue (currently just cuddled the guinea pigs but would love to help with the hens)

    Thank you!

    Reply
    • BirdDoctor

      Annmarie,

      First, I am sorry to hear that your cockatiel is having problems. These situations are always difficult, especially when we don’t know exactly what the problem is or how best to treat it.

      I do want to clarify that there is no means to diagnose PDD other than with a biopsy of affected tissue. There is no blood test for PDD. There is a blood test for avian borna virus which does NOT equal PDD. Recent reports suggest that 30-50% of the captive parrot population (in the US) is positive for avian borna virus. Only a small percentage of avian borna virus positive birds develop PDD.

      To make things more frustrating, no one has been able to induce PDD naturally in any study. Let me explain. All of the studies of adult birds that were exposed to avian borna virus (and that subsequently developed PDD) were injected with the virus. Since we presume that wild birds are not injecting each other with hypodermic needles full of avian borna virus, this really is not a natural means to get infected with the virus or develop PDD. However, under these unnatural conditions, avian borna virus can cause PDD in parrots. The bottom line is that we don’t know how avian borna virus is transmitted between adult birds (although it is suspected via aerosolization of the virus). Nor do we know if, how or why birds naturally infected with bornavirus develop PDD. We only know that unnaturally experimentally infected avian borna virus birds can develop PDD.

      There a far more diseases that cause birds to pass whole seeds in their droppings other than PDD. Of the birds I see passing whole food in their droppings, very few have confirmed PDD. Other causes including atherosclerosis (blood vessel plaques cut off blood flow to portions of the intestines- most common in my experience), foreign body ingestion, intestinal or coelomic (abdominal) cancer or infections, intestinal parasites, spinal damage (often related to osteoporosis) and others are often more frequently seen (and proven) causes of these clinical signs. However, PDD is still possible.

      You probably don’t want to hear this, however, additional diagnostics may be needed to help determine if some of these other potential causes are present. Of course, I cannot make a diagnosis through the internet and your avian veterinarian is best suited to make a diagnosis and treatment plan.

      At this time, we have not been worried about pet parrots transmitting avian borna virus to backyard chickens. However, I would not allow an avian borna virus bird to live with chickens (meaning sharing the same place0 given that we don’t really understand natural transmission or disease.

      Sincerely,

      M. Scott Echols, DVM, Dipl ABVP (Avian Practice)

      Reply
  24. Ursula Berg

    Good Day, Dr. Echols:
    A prospective customer would like to purchase a Macaw baby from us, however her Scarlet Macaw died one week ago. PDD is suspected. I was told the bird was 22 years young and came from a store where it was not given proper care. The last weigh was 649 grams. X-Rays showed gas in the stomach I was told.

    I am hesitant to sell her a baby Macaw as I am not certain what the cause of death actually was. Prospective customer cleaned the house completely including carpet cleaning, etc.

    Have we learned a little more about the waiting period before a new bird is added? Thanks for your time.

    Reply
    • BirdDoctor

      Ursula,

      With the history you describe, anything is possible as the cause of death of the scarlet macaw. It is always frustrating trying to determine if a household is free of infectious disease- especially when a bird died and no definitive cause of death is available. Gas seen in the stomach on radiographs (X-rays) can come from many causes with the most common resulting from stressed birds breathing hard and gulping air. Unfortunately this finding is non-specific.

      If there are no other birds in the household, the chance of any infectious disease (especially of those found in macaws) persisting in the environment is minimal. To be safe, I would recommend new toys, bowls, etc. If the cage is thoroughly cleaned (use bleach if you want to be certain) there should be little to no risk of passing on an infectious organism to a new bird.

      Sincerely,

      M. Scott Echols, DVM, Dipl ABVP (Avian Practice)

      Reply

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