Cockatiel Disease

Q: I am a veterinary technician in Hawaii, and the available diagnostics for avian medicine are not what we were used to on the mainland. An aviary of cockatiels is dying of sudden respiratory distress. They are housed in outdoor flights and have a relatively good diet consisting of seeds, pellets, fruits, vegetables and clean water.
We have seen some white blood cell counts and they are relatively unremarkable except for a shift in the heterophil/lymphocyte ratio. We have done some Chlamydia testing through the state lab and results are all negative so far. Necropsies have revealed nothing that the state lab or our doctor can put their finger on. Any ideas about where to go next or what to do?
 

A: I love challenges, and it sounds like we have one here. I want a blood smear if you can send me one, and one should go to a good avian pathology lab like University of Georgia. There must be many blood-borne parasites there, such as Leucocytozooan and Hemoproteus. These require an insect vector, such as a mosquito, and I am sure you have plenty of those.

I also wonder about Sarcocytosis, a protozoal parasite that infects the lungs and muscle and can cause sudden death. Here, the disease is seen mostly in the southern states, although I have diagnosed it as far north as middle Indiana. It can be hard to see on histopath slides, and I have often had to seek two or three pathologists' opinions to get a correct answer. Sarcocystosis has a complicated life cycle involving a mammal, such as an opossum, an insect vector, such as a cockroach and often another host, such as a blackbird or grackle, as a reservoir host. I am not sure what fulfills the part of the opossum there, but I wonder if the mongoose plays a similar role.

Do an in-depth history with the owner, and find out what creatures frequent the outdoor aviary and surroundings. Are the birds on dirt, or is there a wire floor? Have you done fecal floats? You may find parasites causing hypoproteinemia. When protein gets low enough, there could be pulmonary edema or pleural effusion (fluid on the lungs).

With the next carcass presented, do a detailed necropsy and formalin fix on all tissues, and freeze a second battery of samples. If the histopath is not answering the questions, viral isolation can be attempted.