There Are Always Surprises

In the lab, we conduct necropsies on all species, including companion animals (dogs, cats, small exotic mammals, reptiles); horses (racehorses, horses used for trail riding, barrel racing or other sports); wild animals; food and production animals (lots of poultry); animals used for research; animals kept in zoos or raised for display or exhibition; animals submitted by rescue organizations, animal shelters, or law enforcement that are involved in cruelty or abuse cases…the list goes on!

In the past couple of months, this is a cross section of cases I’ve worked up.

Chukar (a type of partridge) and quail raised for commercial hunting operations. One of each was submitted for necropsy. The birds were wasting and dying. I noted that the mucosal layer of the crop of both birds had thick rumpled folds. Histopathology identified crop worms (Capillaria spp.). That was the second time I’ve seen that pathology in quail.

A five-year-old blue and gold Macaw. Three weeks of listlessness, anorexia. Found dead in the cage. I noted that the proventriculus was dilated and flabby. Approximately 50% of the mucosal layer had been eroded off and the tissue was so thin it was transparent. Proventricular dilatational disease is a viral disease that affects psittacine birds. The virus causes neuropathy, most often in the nerves of the digestive system. It’s so common in macaws that it is informally called “macaw wasting disease.”

A dog that was found dead in the neighbor’s backyard. It was submitted by animal law enforcement officers from a nearby city. They suspected that the neighbor’s dog had killed it. I documented extensive lesions and trauma consistent with an attack by a larger animal. While we photograph nearly every necropsy case, legal cases like this one result in more extensive photo documentation.

A piglet that was part of a heart valve transplant research program. The piglet developed a persistent infection along the line of the surgical incision in the chest and body wall that was made when its main pulmonary valve was replaced with a valve from another piglet. Because it was on so many immunosuppressive drugs as part of the transplant protocol, antibiotic treatments could not effectively clear the infection. While not a legal case, the purpose of this necropsy was to document everything so these results could be factored into the research project.

A dozen, 15-day-old commercial broiler breeder pullets. Histomonas meleagridis is an amoeba that lives in the guts of cecal worms, a type of round worm with the formal name of Heterakis gallinarum. The worms are specialized to only live in that part of the chicken’s intestinal tract. Most chickens have a few cecal worms, and usually the amoeba isn’t a problem. But if the cecal worm burden gets too heavy, the amoebas can migrate out of the cecae and into tissues such as the liver where they cause severe systemic disease. The amoebas can also be shed in feces and can persist in the environment for quite a while. Fifteen days is too short for these birds to have developed a heavy burden of cecal worms (the worm life cycle is longer than that). Instead, the birds had to have picked up the amoebas directly from the litter. Where did the amoebas come from? From worms in the guts of previous flocks of birds run through that poultry house. In the US, litter is not cleaned out of poultry houses between every flock. As many as five or six flocks may be run through one house before all the litter is removed, the house is disinfected, and new litter put in.

Raccoons with distemper. Dogs with heartworm disease. Cats with feline hypertrophic cardiomyopathy. Rabbits with respiratory disease caused by Pasteurella. Cows with pneumonia and emphysema caused by eating perilla mint.

Veterinarians are expected to have knowledge of anatomy, physiology, and pathologies of many species, and how those vary with age, sex, and reproductive status. We also need to have some idea of husbandry and how the animals are used. The differentials for a 3 week old calf are quite different from those for a 5 year old cow who had her third calf earlier in the summer. And those differentials are a universe away from what I need to consider for a backyard laying hen or a kitten from a shelter.

Nothing is routine about being a veterinary pathologist. You have to pay attention because there are always surprises. It takes a lot of work to build and maintain a solid foundation of knowledge and expertise. And it’s not accomplished by one person working alone. I’m lucky to have reasonably sane colleagues and hard-working technicians. 

I like this job a lot. It opens a fascinating window into the pathology of so many different types of disease. It can sometimes be emotionally stressful for us, but it can be very satisfying to work up a case and get a definitive answer that can help a pet owner find some closure or help a farmer be more successful going forward.