Aspirin, acetylsalicylic acid, has enjoyed a resurgence in popularity in human medicine. Most recently, it’s being looked at as a colon-cancer preventative of sorts, as it appears to reduce colon polyps.
However, its biggest boon to modern medicine appears to be its ability at very low doses to effectively block any increased tendency of the platelets to form clots in small or spasmed blood vessels and thus help protect from heart attacks and strokes.??Aspirin can be used in horses to a similar advantage in therapy for laminitis or navicular disease, both of which are believed to have a component of vascular blockage.
Aspirin is also a potent and effective anti-inflammatory agent in horses, every bit as effective as phenylbutazone.??However, its effect in the horse only lasts half as long as bute. To maintain good blood levels, you need to dose about four times a day, although therapeutic benefits in terms of pain relief can often be maintained with dosing twice a day.
As you know, you don’t need a prescription to purchase aspirin, however, you should know what you’re treating. We don’t recommend giving it without knowing what’s wrong with your horse.
The recommended dose of aspirin for horses is usually about 7.5 to 15 grams, once or twice a day.?? The most economical form of aspirin you can purchase is “livestock” aspirin, which comes in large boluses of 240 grains each.??
A gram is 65 mg, so these contain 15.6 grams.?? The boluses are scored down the center, and one will give you a day’s worth of aspirin at about 7.5 grams/dose.??Fifty of these livestock aspirins cost $10 to $12, for a daily cost of about 24??, making the price great. Aspirin??for livestock can also be purchased in a granular form that resembles sugar.
The major drawback to aspirin use, besides the extra dosing, is that like any other non-steroidal anti-inflammatory drug (NSAID), it has the potential to cause ulcers.??It’s often said that aspirin is not as risky as bute in this regard, but we found no studies to confirm this. To be safe, we think it’s best to presume the risk is the same. Studies in other species comparing plain aspirin, buffered aspirin and enteric-coated aspirin showed the same ulcer risk with plain or buffered aspirin but less for enteric-coated.
As with bute, the risk of ulceration increases with the dose, so if you’re using aspirin for anti-clotting effects rather than pain relief, you may be able to cut the dose in half, thereby decreasing ulcer risk.
Aspirin isn’t the greatest-tasting stuff, but it beats bute in the palatability department, with most horses eating a dose mixed into their grain more readily than bute.