Equine Medicine

When I signed up for the advanced equine medicine elective I was expecting just a once a week lecture on something that involves horses. Maybe I'm biased, but I don't feel like we get a lot of information that relates to horses, it feels like a lot of small animal. But I'm sure the small animal lovers feel like we get too much large animal. We definitely get more equine than exotics, which is why I'm taking two exotic electives, but I'll save that for another post. 

Anyway, I expected the class to be just sitting in a classroom listening to, I don't know, common equine diseases or nutrition or something along those lines. Instead I was pleasantly surprised that for the majority of our class periods, we'll actually be spending them in the teaching hospital working on horses. And not just watching other people working on horses like all the intro to clinics classes, but actually working on them. Finally, some more hands on experience. 

Last week it was lameness exams, and this week it was jugular catheters and urinary bladder catheters. Lameness exams are extremely routine in equine practice, so even if you're just interested in horses you probably know what a lameness exam entails. Horses are always going lame, which just means they're not walking right for one reason or another. And if you're doing it in Oklahoma, you definitely want to be the one watching the horse and not the one jogging it in the 100 degree heat. But basically all a lameness exam entails is jogging the horse and trying to see which leg it's lame on. There are a couple tricks to help- the horses head will bob up on the lame leg if it's in the front, and the hip raises on the lame leg in the back. Sometimes the lameness is subtle, so you can use a flexion test to try and exacerbate the lameness and make it more obvious. For the flexion test, you have to isolate each joint and jog the horse after each joint flexion, otherwise it wouldn't help you narrow down which part of the leg was the cause of the lameness. If the lameness is coming from the joint you’ve just flexed, they will be noticeably more lame on the next job.

If the lameness is in the front legs, for the majority of the time the problem is going to be in the feet. Even if it looks like it’s coming from somewhere else, say, the shoulder, a lot of the time the horse is just trying to compensate. If the lameness is in the hind legs, and lot of the time the problem is in the hock joint (the equivalent of our ankle). If there is lameness in both the front and the hind limbs, look at which sides of the body they are on, and that can give you a clue as to which is the primary lameness and which one is compensatory. If the limbs are lame on the same side of the body, it’s more likely that the primary lameness is in the front limb. If the horse is lame on the diagonal, such as the right front and the left hind, it’s more likely that the primary lameness is in the hind limb. These don’t hold true for every case, but it’s always a good starting point.  And you just have to train your eyes to watch the entire horse as it moves to pick up the clues, as not all lameness are obvious. Most of the time a horse is completely sound while walking, and you might only pick it up intermittently while jogging/trotting.

That’s pretty standard procedure for horse care. If you own a horse, at some point it will be lame. So I was pretty excited to do a urinary bladder and jugular catheter, because that I don’t get to do every day. Not that I do a lameness exam every day either, but when I was shadowing vets I did quite a few of them, and I was always the one who got to jog the horse. I got a lot of exercise those summers.

Although something new that the school was doing that I like was using a sensor system during the lameness exam. The horse gets a little head mask with a sensor, a sensor around the ankle, and a sensor on top of the hips. Then when you jog the horse, it sends the information to a computer that tells you where the horse is lame after monitoring its movements. I’m not sure how well the system works, since this was the first time I’ve seen it used. But I do know one downfall is the sensors can’t tell a pacer from a trotter, which would reverse your lame leg if it was in the hind limbs, and it can’t tell if your jogging straight or in a curve, which would affect your lameness score. But those are pretty minor details.

To insert a urinary bladder catheter you have to use sterile technique, which means just cleaning off the vulva before sticking your catheter in. It’s always fun when, right after you’ve finished cleaning, your horse decides it has to go to the bathroom. Then you get to start all over. When you’re ready to go, you have to slide the catheter into the vulva and try to find the little slot leading to the urethra. It feels like a little knob, and if you poke it your finger should slide right in. I found it was easiest to stick my middle finger in, and then slide the catheter in under my finger a bit, before removing the finger and sliding the catheter in more. You don’t really have to go that deep at all- as opposed to all of the artificial inseminations I did where I was literally up to my shoulder in the mare, placing a urinary catheter really only puts you in up to your wrist. That’s a good check to make sure you’re not going to the wrong place. And then you just keep sliding the catheter in until urine comes out. You should pay attention to where you’re holding the other end of the catheter, or you may end up spraying urine all over your shoes or shooting it at the person standing next to you, which I almost did by accident.

For the jugular catheter, it’s the same theory as in dogs and cats except you get a bigger vein to hit. Unfortunately, that vein likes to fill very slowly in some horses, making it more difficult to see. You always want to insert the catheter in the jugular groove, where there is muscle underneath the jugular vein that helps protect the carotid artery. The very last thing you ever want to do is hit the carotid when you’re aiming for the jugular.

Horse skin is pretty thick, so you have to use a good jab to get the needle going in. Then once you get the flash (blood coming out of your catheter), you slowly advance the plastic, flimsy catheter off of the metal needle further into the jugular vein. And that’s all there is to it. Be prepared to get blood all over your hands though when doing this, just because a horse is pumping a lot of blood, and you don’t have anything to stop if from coming out when you don’t have anything hooked up to your catheter.

I love getting hands on experiences like this. First, because it’s always so much more interesting that sitting in a classroom just listening to the theory on how to do something. But it also stays in your brain better once you’ve actually done it. Because you could tell me what it feels like to insert a urinary catheter as many times as you want and how to do it, but until I can feel that little bump and slot for myself, I’m still going to struggle the first time I do it. So basically, I feel like I’m just eliminating a step and getting further ahead by doing so.

I can’t wait to see what else we’ll get the chance to do this semester.