An old injury, a strenuous workout or a lot of time standing (in a stall or a trailer) can create inflammation. There are a variety of options to choose from to decrease swelling and keep your horse comfortable. Choosing the right treatment starts with understanding how a horse’s tissues become irritated.
Inflammation occurs due to a complex cascade of chemical mediators that are released in response to irritation or injury in the tissues. One group of such potent mediators is known as prostaglandins. Many medications (as anti-prostaglandins) target prostaglandins to control the inflammatory response. In particular, the enzyme cyclooxygenase (COX) that is important in the production of prostaglandins is inhibited by many of the drugs used to defeat inflammation and pain.
Unfortunately, some of the prostaglandins are important to normal housekeeping within the body, as for example, prostaglandin E is responsible for its protective role to the lining of the intestines and kidneys. Many drugs used to target inflammation bind to the COX enzymes, thereby also exerting adverse effects by nullifying the important actions of the good prostaglandins. With that in mind, it is important to use anti-inflammatory medications judiciously and under advisement from your veterinarian.
Non-steroidal Anti-inflammatory Drugs (NSAIDs)
NSAIDs are commonly used medications, which you might recognize as phenylbutazone (bute), flunixin meglumine (Banamine), ketoprofen (Ketofen), firocoxib (Equioxx), as some examples. All but firocoxib affect both COX-1 and COX-2 pathways of inflammation and thereby diminish the good prostaglandins. This is the reason why NSAIDs that target both pathways are also known for their potentially toxic effects of gastric ulcers, right dorsal colonic ulcers and kidney disease.
Firocoxib mostly targets COX-2 pathways—those most associated with injury—and tends to bypass the good prostaglandins to some extent, although not entirely.
One example of a non-steroidal anti-inflammatory drug that is used topically is diclofenac sodium or Surpass. It is recommended that this cream be rubbed into the local area 2-4 times per day to provide local anti-inflammatory relief.
The action of corticosteroids to inhibit enzymes and mediators of inflammation occurs closer to the origin along the biochemical pathway than what occurs with NSAIDs. This makes “steroids” a very powerful tool to control inflammation through their potency in blocking COX-2 prostaglandins, although steroids do have an effect on COX-1 pathways, as well.
Time to Effect
Most of these anti-inflammatory medications take 2-4 hours to begin to exert their effects, with peak effects in 6-9 hours, and waning after 12 hours. The rate at which anti-inflammatory results are seen is dependent on how the medication is given—oral versus injectable—and which medication is used. Which tissue is involved will determine which drug choice your veterinarian will recommend for inflammation control.