Monday, November 4, 2013

ewe post-mortem

*please do not read on if you get woozy with descriptions of organs/anatomy/medical convo..

Did a very cool post-mortem today on a ewe with a 2 week history of inappetence, weight loss, down on several occasions and arthritis in its right fetlock joint (thank you G for letting me practice doing a necropsy on a sheep that was going to be euthanised anyway). She was already dead when we came, so I was spared having to exsanguinate a live animal (to drain the blood supply to the brain to render them unconscious), but I was taught and got to actually practice the technique, and he also gave me a tip to hyperextend the neck to reveal the spinal cord to be severed to ensure that the animal is really unconscious/dead after severing of the carotid. Also, make sure you have a really sharp knife so that this process can be done as quickly as possible and cause least stress to the animal. 

Anyway, the abdominal cavity was unremarkable besides some barber's pole (the spiral-y pattern on the worm) in the abomasum - she still had plenty of fat as she was well conditioned before she was sick. Looked for signs of Johne's disease as she was originally from a part of NSW that the bacteria likes (cut through the two leaves of greater omentum so that the abdominal organs weren't displaced and more easily identified), and could not find any. She was a young ewe anyway. Then we opened the thoracic cavity and immediately found that there was an adhesion from the R middle ventral lung lobe to the chest wall - still haemorrhagic and not fibrinous so probably not so old. The apex of the right caudodorsal lung lobe felt nodular, and contained purulent material in the airways when the lung parenchyma was sectioned. Another tip that I was taught was to ask the farmer to help cut the top of the ribs, and then use the rib cage as a board to inspect the organs. Then we inspected the heart, and everything externally was normal, but on opening of the heart, the tricuspid valve was extremely proliferative and cauliflower-like - she had endocarditis! 
Those cauliflower growths on the valves aren't normal. Contrasting red and green colours yo.

Not sure if the tricuspid valve is more commonly affected in sheep, like in cattle (unlike dogs/cats where the mitral valve is most commonly affected).The mitral valve was also infected, but less so. We also checked her mouth, as she was inappetent, and her tongue, pharynx and teeth (both incisors and cheek teeth) were normal. So she most likely died from the endocarditis, which could have spread causing the pleuropneumonia and septic arthritis (we were rushing for time so did not open up the fetlock joint).

*why am i posting such a long description of the necropsy? well at first i was just excited at all the findings, but then thought that i might as well write everything down so that i don't forget what I learnt, particularly the necropsy technique tips.

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