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An Experience with PDD

"This is a horrid, insidious disease that can be in any aviary - no matter how clean, how good the husbandry, or how respected the breeder." - Jean Pattison

Jean Pattison began breeding birds in the mid 1980s. She lives in Florida, and all her birds are flighted outside.

She acquired a pair of male Blue Crown Conures right out of quarantine. A breeder referred by her former vet had a pair of hens who had lost their mates. The histopathology on the males had revealed no significant problems, so Jean purchased the hens and set them up in a breeding situation after quarantine.

After about four months, the hens laid eggs. The males developed an unusual appetite, consuming copious amounts of food. Jean assumed they were eating these vast amounts to help feed the hens in the nest. The chicks died in the shell, and shortly after both male Blue Crowns died.

Histopathologies showed nothing significant, except the birds were terribly thin - a type of wasting. This is a symptom common to many avian diseases.

Sometime later, Jean purchased 2 more male blue crowns, and in a short time the hens were on eggs again, and one of the males began to eat copious amounts of food again. Her vet suspected Chlamydia, and began to treat for it. In the meantime, the chicks again died in the shell.

After two weeks treating for Chlamydia, birds no longer shed the organism, so Jean knew housing them near other birds would not cause infection. Preparing for a Florida cold snap, she relocated the Blue Crowns (in new holding cages) and ten other birds to her garage.

Two weeks later, a grey became horribly ill and died. Another vet advised Jean to speak with Dr. Jack Gaskin, a researcher at the University of Florida. Dr. Gaskin suspected PDD, and the grey that had died confirmed it. Jean donated the remaining Conures to Dr. Gaskin.

Jean was raising a brother and sister pair of Senegals to pair with unrelated stock in future breeding. The hen became deathly ill, passing whole seed, vomiting, and losing weight. The only food she would eat was papaya. Medication seemed to turn around the situation - by all appearances and vet tests, she was once again a healthy bird.

With the return of warm weather, the birds were placed outside and separated. Jean placed the Senegals with her sister, who had no birds at the time. The Senegals were never exposed to a bird across the next decade. The hen died 9 years after her exposure to PDD, and her brother died one year after that. Both died of PDD.

Jean had also noticed a grey in a group of three pair showing signs of illness. The hen would drop her head over a perch and drool a clear liquid. Three months later, she became severely ill and died of PDD. The remaining five greys of that three pair died in rapid succession.

A single male grey, who had been unpaired and located quite a distance from the rest in the garage, developed very watery stools. He died two years after his exposure to PDD.

In the end, all 10 birds in the garage died of PDD, with the last one, the male Senegal, dying 10 years after the first exposure.

I believe in the research end of PDD. Research teams do not see birds in the very early stages of PDD, so little is known. Many lectures I attend provide details of the symptoms, but upon hearing them, I think to myself, any one would know that was PDD.

Note: The Blue Crown Conure hens were determined to be the super shedders, apparantly presenting no clinical signs. To Jean's knowledge, the hens lived for 5 years with no outward clinical signs. The hens infected and killed 4 mates each.

Early Signs of PDD

by Jean Pattison, AHN Advisory Board Member

Very early signs that I am aware of in PDD of the digestive tract are:

  • Very watery droppings. The fecal material is still well formed and urates are present. (my grey presented itself for a year with these symptoms before any others)

  • Voracious appetite, and this can be for months prior to other clinical signs.

  • Dead-in-shell chicks

  • Feather picking in the chest or crop area

As the disease advances there, I have observed whole seeds in the droppings, vomiting, and weight loss. Some of the birds may never develop any neurological signs.

Very early neurological signs of PDD show when a bird walking across cage wire "seems" to get a toe nail snagged. One would think, "Looks like I have a bird that needs a nail trim." This symptom, too, can last for many months to a year before other signs become visible.

Once the disease has progressed to readily visible body twitches, and balance problems, the birds usually are eating more food. These birds may never pass whole seed, but generally have watery droppings.

Most PDD birds seem to drink more water than normal.

Keep in mind these are not scientific studies, but my own personal experience in my aviary as well as many other breeders sharing their experiences with me over the last 15 years.

Please remember, any of these symptoms can also be symptoms of many other bird diseases, not just PDD.

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