Being a large animal vet means having patients that enter the food chain. Working on steers that will soon be steaks, and hogs that will soon be bacon, does not bother me, as I realize my job is to keep these animals healthy until they enter the food chain. A few of my colleagues in vet school were vegetarians and are, naturally, small animal vets. I’ve never met a vegetarian large animal vet. I myself am partial to chicken.

One aspect of food animal medicine is the concept of withdrawal times. This is a totally novel concept to the small animal practitioner and I didn’t know about it until my food animal courses in vet school. A withdrawal time is the time period required to withhold an animal from slaughter or throw out its milk after it has been treated with a medication. The purpose behind it is to keep that medication out of the human food chain.

Every drug approved for use by the FDA for food animal medicine has a withdrawal time. If you look at a bottle of such a medicine, you’ll see a warning label indicating how long you must wait to slaughter an animal after giving it this particular medication. These times are established before the drug is put on the market, based on the chemistry of the drug and how fast it is eliminated from the body. For example, flunixin meglumine (tradename Banamine), an NSAID used to reduce fever, has a meat withdrawal time of four days and a milk withdrawal time of 36 hours in cattle.

For many of my clients, observing withdrawal times is not critical in most cases, as the animal is usually young, of breeding stock, or in some other way not close to being slaughtered. The main exception is on dairy farms when the cows are milked twice daily. Observing milk withhold times is extremely important on a dairy farm since all milk goes into what is called a bulk tank and this is what is taken away by the milk truck to a larger processing plant. These bulk tanks are tested for drug residues and if any residue is found, the entire tank is dumped, which means not only that the farmer is in trouble legally but has also lost the income from that entire tank. So as you can see, withdrawal times are serious business.

Another instance where withdrawal times come into play is when an animal, usually a cow or pig, is sick enough to not warrant keeping in the herd. Here the owner must decide if it’s worth it to treat the animal and keep it a little longer (to get a little more weight on it) or not treat it and simply take it to slaughter without any medications. These decisions are always economical decisions, which is the way many food animal decisions are made.

In vet school we were always coming up with clever little slogans to put on club T-shirts and the like. One such slogan was, "We eat what we can’t treat." This may seem a bit crass to those unfamiliar with food animal science, and the comment was meant partially tongue-in-cheek, but this scenario does happen on the farm. What happens to the bull that’s too aggressive and keeps breaking fences? Hamburger. What happens to the sow that broke her leg and can’t get up to eat with the other hogs in the pen?  Bacon. This is the reality of the farm.  

So, do I actually eat what I can’t treat? Well, I can’t say that I’ve directly eaten one of my patients (that I’m aware of), but I did once eat a steer I knew named Bubba. It was a weird feeling. You don’t really think of your steak having a name. All I can say is, if you’re going to be a farmer, you’d better learn not to get attached to your animals — which is one of the many reasons why I’m not a farmer. If I had a cow, I’d surely name her Buttercup. And you just can’t eat a steak named Buttercup, can you?

Dr. Anna O’Brien

Image: Osage County Plates by Barbara Jakobson and Grant McClintock