March 3, 2019: ICHC and a Case Closed

I had a great moment at the conference yesterday I wanted to share with you all. In the attached picture, the left is a 3D printing of a normal alpaca’s healthy heart. The right is a picture that I took during a necropsy (autopsy or postmortem exam) of a patient two months ago.

The patient was a middle-aged male Huacaya who was acting sluggish, with vague symptoms. On my first examination of him, I listened to his heart and lungs and immediately realized he was in terminal congestive heart failure. This was surprising in a previously healthy adult. I sent baseline bloodwork to my colleagues at Cornell and was absolutely shocked at the results. It’s some of the most outstanding bloodwork I have ever seen – and I knew exactly what my diagnosis would be if this were any other species: lymphoma, a type of cancer that can be fairly aggressive. A call to some trusted colleagues confirmed my hunch. But what does this have to do with the heart? Is the cancer related to the sudden heart failure, or are the conditions independent?
I recommended humane euthanasia, but unfortunately the patient collapsed and passed away while I was on my way to the farm. The owner was kind enough to allow me to perform a thorough necropsy. It was easily the most fascinating necropsy I have performed, and we discovered many very significant findings. We left no stone unturned, and with every organ we explored, I found myself shaking my head and speechless. I’m off on a tangent, though, and this post is about the heart specifically.
Once I was able to extract the heart from the chest, I made a cross-section through the apex (the pointy bottom part) to observe the wall thicknesses of the ventricles (chambers). I immediately noticed that the walls of the left ventricle were so incredibly thickened that the inner chamber itself was almost nonexistant. In a normal heart, with every beat, the chamber walls squeeze the chamber itself shut, forceably ejecting blood from the chamber space and throughout the body. If the walls are so thick that there is no chamber space to squeeze, then the blood doesn’t have the momentum to be pumped out of the heart and throughout the body. Eventually, the poor pressure leads to a backup of blood that can go all the way backwards, back to the heart itself. This is the condition known as congestive heart failure.
Typically in alpacas, heart failure occurs because there is a congenital heart defect present from birth that eventually results in failure. But what happened here to cause the chamber walls to become more thick? My friend and colleague at Tri-State Veterinary Services, LLC had a theory – the cancer itself was so widespread that it infiltrated the walls of that chamber, laying down layer after layer of microscopic cancer cells, until the walls were so thickened that the heart lost function.

Fast forward to yesterday, when I had the opportunity to speak with a board certified cardiologist after her lecture during the 2019 International Camelid Health Conference. “This case bothers me,” I told her, “it keeps me up at night.” She reviewed the necropsy photos with me, listened to the case details, and confirmed Dr. Lisa‘s theory. She said that this is something that’s been recorded in cattle for some time, but this is the first incidence she has heard of in alpacas where lymphoma infiltrated the heart walls. She had brought these great 3D printed models of a regular heart with her, and I couldn’t help but put these two pictures side by side.

This conference has been incredible for a number of reasons, but I think this case really brings home what it’s like to work with species that is fairly unexplored. Doctors have to extrapolate from knowledge that has been gained after decades of studying other species. However, there are many pitfalls when you make decisions for one species based on information about another species. Do alpacas utilize our antibiotics the same way that say, a goat does? Does a cancer in alpacas progress the way that the same cancer does in a dairy cow? Do alpacas have the same insulin receptors as dogs? It’s exciting to be in a room with people who are exploring these questions for the first time, and reporting their findings to each other. Sometimes we are right, and sometimes we are very wrong, and we have to continue the journey into the soft and fluffy unknown.

 

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