Pain management in the horse is an everyday part of the equine veterinarian’s practice. Therefore a good working knowledge of the various analgesic medications available is essential. However the need for knowledge of pain management goes beyond just the veterinarian, as it is also important that horse owners have a basic understanding of horse pain management. One of the most important things to understand about pain is that it is important. Pain is important because it is essentially a natural protective mechanism that serves to protect a portion of the body that has been injured.
When we are dealing with pain in the horse, it also becomes important to understand where the pain is originating from. The next major aspect to developing a plan for pain control in the horse stems directly from knowing where the pain is coming from, and that is to understand how long we may be treating this animal. Like other medications, pain medications, or analgesics, can cause certain negative side effects when used inappropriately. Additionally these negative side effects can be seen occasionally even when the medication has been used correctly.
There are several types of analgesics available for use in the horse. One of the first medications that are used in the sudden, or acute, situation is the class of drugs known as the alpha-2 agonists. Many horse owners would recognize this class by the drug names of Rompun or Dormosedan. These are the common sedatives that are used by veterinarians during various procedures. The analgesic effect of these drugs is short lived (45-90 minutes), but can be enough in situations such as during a colic examination. These drugs however cannot be used as long term analgesics because of their short duration of effect. A class of drug that is common combined with the alpha-2 agonist to increase the duration of effect and to increase the level of analgesia is the opioid class of drugs. The most commonly used drug in this class for large animals is butorphanol. Butorphanol is a very good analgesic; however the down side to its use is that it has a very short duration of effect lasting only 15-30 minutes after its administration. Thus like the alpha-2 class of drugs it is not a good medication for long term pain control.
The class of drugs used for analgesia that most owners are familiar with is the NSAID class, or the nonsteroidal anti-inflammatory class of drugs. In large animal this class includes phenylbutazone, flunixin meglumine (Banamine), ketoprofen, firocoxib (Equiox and Peroxicam), and meloxicam. The first four of these drugs are the ones that have been approved for use in the horse. Meloxicam is no longer used in horses since firocoxib was approved. All of these medications work in a very similar way to reduce pain and inflammation. Firocoxib is the drug that is a little different in its mechanism of action, and it is the difference that helps to make is less likely to have negative side effects during long term use. Some of the side effects that can occur with the used of the NSAID class of drugs would include stomach ulceration, colitis (inflammation of the colon), and kidney damage. This is why when using these medications long term, the veterinarian will usually try to find the smallest amount of medications needed to keep an animal comfortable.
In summary, there are a variety of drugs that can be used to treat pain in our large animal patients. The selection of which drug to use depends on what is causing the pain, how severe the pain is, and how long we may need to treat the animal. These factors are what may mean the difference between a successful pain management protocol, and having to deal with negative side effects from the drugs. Thus it becomes important that when putting an animal on a pain management protocol that you involve your veterinarian to help make a diagnosis for the cause of pain, and to help advise on what volumes of mediation to administer and how long to do so.
Dr. Mike Cissell
Board Certified Large Animal Surgeon
Prescott Animal Hospital Equine Center