MSU Equine Summer Fellowship Blog: Follow the Fellows...: A Field Necropsy

Hello again! This past week we had a case that turned into an amazing learning opportunity. We were called out to evaluate a pony that had a history of founder. When we arrived, you could tell from a distance that the pony was having trouble breathing.

This is what we found on our physical exam:

Heart Rate: 80 beats per minute
Respiratory Rate: 100 breaths per minute
Mucous Membranes: Brick red with a toxic line
Capillary Refill Time: Prolonged
Digital Pulses: Within normal limits
Abdomen: Extremely distended

The pony did not act sore on his feet. When we lifted his feet, he was not reluctant to put weight on the opposite front foot. A lot of horses with founder would be resistant to this due to how painful their front feet can get. Additionally, he was not standing in a way that would shift weight off of his front feet. We were unable to do rectal palpation due to his size.

Unfortunately, due to the pony's poor condition and old age, the owner elected to humanely euthanize the pony. However, she agreed to let me ultrasound and then necropsy the pony for learning purposes. It was extremely kind for her to allow me to do this.

The ultrasound yielded some additional information. When scanning the lungs, we saw "comet tails." This suggests that there is some level of disturbance on the outside pleural surface of the lungs. Dr. Sarah Varnell was concerned that there may be fluid in the thoracic cavity as well because of the scan, which could have been contributing to his labored breathing. We did see some nodules on the spleen and there was decreased motility of the small intestines. We weren't able to do the best abdominal scan, because we only had a tendon ultrasound probe on the truck. But we did the best that we could with what we had!

It was great to get the opportunity to match the ultrasound findings to the necropsy findings. When we opened him up, immediately we noticed that the ventral colon was extremely distended. The vasculature of the intestines and stomach was also incredibly distended. The lymphatics of the mesentery were also so engorged that we initially thought that the abdomen had parasites in it! At the hilus of the mesentery, the blood vessels and lymphatics were so distended that when you reached your hand into the abdomen, they felt like ropes. There was indeed fluid sitting around the lungs and hemorrhagic fluid in the abdomen as well. The small intestines were abnormally colored. There were in fact nodules on the spleen and also on the kidney. The liver lobes were rounded. Although there was a lipoma, it was not of any concern for intestinal strangulation.

While we did not come up with a definitive diagnosis because no samples were sent off for histopathology, Dr. Varnell was suspicious of lymphoma given the pony's age and necropsy findings. This case was truly incredible. To get to work up a horse, perform ultrasound diagnostics, and then compare those findings to the necropsy is an experience I will never forget. I am very humbled to have had this opportunity and that the owner values student education so much.

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