Monday, March 24, 2008

Follow the Yellow Cat Road

Greetings all from the wonderful but stressful land that is veterinary school. I apologize for the absence (yet again), but as I'm sure is obvious, I've been outrageously busy and I'm a noob in regards to blogging. Since my last post, I have completed a few rotations such as soft tissue surgery, ophthalmology, and neurology, but I am now beginning my second round through internal medicine. I say second round because all small animal students are required to endure two medicine rotations and not because I failed the first time. As an aside of good news before I scribe another tale of veterinary medicine, I found out last month that I PASSED MY BOARDS!!!! (one), and I now have a job lined up back in not only my home state, but in my home town as well. While these are great things, the reality and potentiality of graduation and actually being a doctor have really set in.....and I have completely checked out mentally. This is not interfering in my dedication to the care of my patients by any means, but I can't stop thinking about my graduation date. My classmates even set up one of those countdown clocks in the hallway where all the senior students complete all their paperwork. So for the next 6 weeks, I am just in cruise control to say the least.

Now as promised from my last post, I would entail my first experiences dealing with "the yellow cat", and you get the added bonus of hearing how I received two yellow cats at once, actually to great benefit to my learning experience. By yellow, I mean that the cats' skin was actually yellow in color, and not that the cats were easily scared or timid. The proper term for this condition is called "icterus", though you may have heard the term "jaundiced" used in the past regarding people, particularly newborn babies, who have yellow skin. In animals, the reason why their skin turns yellow is due to liver dysfunction of some sort. When red blood cells are broken down and turned-over by the body in a normal fashion, they release hemoglobin (the oxygen-carrying molecule) into the bloodstream. It is the liver's job to remove this from the blood and convert it into a molecule called "bilirubin" which is then excreted into the bile via the gall bladder, then into the intestines, where it can be broken down and reprocessed. However, if the liver is not working or there is a "traffic jam" somewhere along that path, bilirubin builds up in the blood and actually turns the skin yellow. The actual discoloration of the skin itself is not bad, but what it reflects can be life-threatening.

In cats, if you see yellow skin, it is most likely due to one of two diseases. The first disease explanation will hopefully provide some advice to cat owners since it can easily be prevented. The first cat of the pair I saw was a relatively obese cat where the owners said that they noticed the cat's appetite declined over the past week, the cat appeared dull and depressed, and the skin became yellow. We worked up the cat's case by giving the cat IV fluids, offering it all sorts of delicious foods, and analyzing bloodwork, which showed there was liver comprimise. I had a suspicion from the beginning that this cat had a disease called hepatic lipidosis. When obese animals go for an extended period without eating, the body naturally reacts by mobilizing other body tissues to provide nutrition and energy. Proteins usually are processed first to an extent, but then the body starts using up it's fat stores which have to be processed by the liver cells. For whatever reason, the liver cells of cats cannot handle the load of fat that gets mobilized and they get easily overwhelmed, causing a "fatty-liver". This not only affects the health of the liver as the cells get swollen with fat, but a diffuse traffic-jam (as mentioned before) occurs.

Now what I wish to get across to all you cat owners, is that if you can prevent a fat cat from becoming anorexic, please do so. What I did not tell you about this cat is that it had a very stressful history. In recent months, the owners 1) added a new cat to the home, 2) had a child, 3) had construction going on in their home, and 4) recently went on vacation. Oh, and I forgot to mention the cat was blind for different reasons. Sounds like a recipe for stress to me, how about you? I want to emphasize that these owners did nothing wrong, nor were they aware of this possibly happening to their cat. Strangely enough, the way to treat these cats is to get them to eat and they generally have a good prognosis if they start eating on their own. Sadly, even though we placed a tube to place food directly in the cat's stomach, it crashed one night and we lost it :(. The owners thankfully consented to have a necropsy performed and I was correct; it had hepatic lipidosis.

The reason why I said getting two of these cats was a good learning experience was because the second cat had the other common cause of yellow skin in a cat. This one did not have a stressful history, but rather became acutely anorexic and just overall ill. Unfortunately for this cat, it had what is loosely called the "cholangiohepatitis complex" where the "traffic jam" in the gall bladder and its related ducts (aka the biliary system). There is always some inflammatory component in the biliary system in this disease, but the reason why is not always entirely understood. Also, when that bile backs up, it is also toxic to the liver so you get a hepatitis as well. Overall the incidence and prognosis of this disease is not studied well, but animals tend not to do well with this disease because it requires a long recovery and hospitalization time that many owners can't handle either emotionally or financially. Liver disease as a whole is very frustrating because there isn't much that we can do to help. The liver has a tremendous health reserve, so once they present in poor health with elevated liver blood values, it's bad news because it usually means 3/4 of their liver is shot. We applied all the right liver protecting medications and supportive care that is needed in these cases, but the owner did not want to see their cat suffering for so long and elected euthanasia.

I hope these stories did not bore you too excessively, nor do I hope they just made you depressed. I hope you got some important information out of them, namely make sure your cats keep eating and if they become yellow take them to a vet pronto. For my next post (which I'm hoping won't be long from now), I'll move onto my soft tissue surgery rotation which had some neat cases, but unfortunately mostly dealt with cancer. Till next time...