Pain Management for Horses

Pain management is an essential component of equine veterinary medicine, but it is often overlooked and underutilized. Defining the cause of the pain and preventing pain when possible in performance and working horses are ongoing concerns amongst horse owners and managers. Deep pain in horses is frequently more difficult to control than superficial pain, whilst pain can be caused by trauma, infection or inflammation, whether musculoskeletal or visceral in origin.1 Neurological pain is often the hardest to diagnose and treat, requiring long-term analgesics and a multimodal approach.2

Critical assessment of orthopedic pain is more routinely carried out, with various grading systems available, as well as recent advances in computer-generated assessments of lameness. The inherent problem in assessing pain is the non-verbal nature of horses as well as their inconsistent demonstration of pain.

Following recognition of pain in a horse, a treatment plan can be designed and built around the source of the pain, the animal involved and owner compliance. When designing the treatment plan for an equine patient, it is important to ascertain the severity of the pain as well as the type of pain, as this should alter treatment undertaken.

Nutrition and Diet

A horse’s nutrition and diet are essential in supportive treatment of pain and in the prevention thereof. Vitamin and mineral supplements, such as vitamin a acetate, pyridoxine hydrochloride (Vitamin B6), magnesium oxide, sodium sulfate, manganous oxide, folic acid, niacin, choline chloride, biotin, riboflavin, calcium pantothenate and essential amino acids often come highly recommended by equine veterinary practitioners.

Analgesia

Multimodal analgesia is often the most efficacious way to treat pain, but this should consist of first-line treatment using the appropriate equine products via the appropriate route. Non-steroidal anti-inflammatory drugs (NSAIDs) are the first-line therapy in the vast majority of cases. As the clear majority of pain in horses is associated with inflammation,2 the use of NSAIDs should play a pivotal role in its treatment.

NSAIDs are not without their risk though, and chronic use should also involve ongoing monitoring for signs of toxicity. Gastrointestinal ulceration and right dorsal colitis are the most frequently discussed side effects. Renal papillary necrosis is another uncommon side effect.

Isoxsuprine is a peripheral vasodilator that causes vascular smooth muscle relaxation predominantly through α-adrenoreceptor blockade. It has been used in veterinary medicine to increase peripheral blood flow in horses with vascular disorders of the lower limb. Isoxsuprine causes direct vascular smooth muscle relaxation primarily in skeletal muscle. While it stimulates beta-adrenergic receptors, it is believed that this action is not required for vasodilatation to occur. In horses with navicular disease, isoxsuprine raises distal limb temperatures significantly. Isoxsuprine relaxes uterine smooth muscle and may have positive inotropic and chronotropic effects on the heart. At high doses, isoxsuprine decreases blood viscosity and reduces platelet aggregation.3

Calcium Carbonate is an essential mineral for all mammals. The majority of the calcium (almost 99%) in a horse’s body is found in bones and teeth.2 However, calcium also has other important bodily functions. It plays a role in muscle contraction, cell membrane function, blood clotting, and some enzymes’ function, as well. As such, the body must regulate blood calcium concentrations carefully.1

The National Research Council’s Nutrient Requirements of Horses recommends that a mature idle horse weighing 500 kilograms (1,100 pounds) consume 20 grams of calcium daily. This requirement increases to 30 to 40 grams per day for the same horse in light to heavy exercise. Calcium requirements for pregnant mares (weighing 500 kilograms) only increase about mid-way through pregnancy to 28 grams per day and topping out at 36 grams per day towards the end of pregnancy.2

Sodium salicylate is a nonprescription salicylate. Its characteristics are similar to those of aspirin with one major exception: sodium salicylate is not acetylated. As such, it does not have a two-compartment half-life as does aspirin. The second major difference between aspirin and sodium salicylate is that aspirin acetylates and irreversibly blocks cyclooxgenase. Therefore, platelet aggregation is effectively inhibited for the life of the platelet with aspirin, whereas the antiplatelet adhesion effect is only temporary with the nonacetylated salicylates.3 Sodium salicylate is considered somewhat less effective in reducing pain when compared with aspirin. However, some horses who are hypersensitive to aspirin may tolerate sodium salicylate.

Phenylbutazone is a nonsteroidal anti-inflammatory agent (NSAID) that is used primarily for treating pain and inflammation in horses. It has analgesic, anti-inflammatory, antipyretic, and mild uricosuric properties. The mechanism of action is by the inhibition of cyclooxygenase, thereby reducing prostaglandin synthesis. Other pharmacologic actions may include reduced renal blood flow and decreased glomerular filtration rate, decreased platelet aggregation, and gastric mucosal damage. Following oral administration, phenylbutazone is absorbed from both the stomach and small intestine. The drug is distributed throughout the body with highest levels attained in the liver, heart, lungs, kidneys, and blood.3

Where to buy ABCI Powder 

Specially-formulated ABCI Powder by NexGen Pharmaceuticals is a supplement which, when mixed in horses' feed, aids in the symptoms of lameness, and is an excellent solution for ongoing pain management.

Each Scoop Contains: 

• ISOXSUPRINE 0.38 GM

• CALCIUM CARBONATE 2.35 GM

• SODIUM SALICYLATE 3.6 GM

• PHENYLBUTAZONE 1 GM

Please consult your veterinarian prior to beginning any treatment regimen.

FOR RX ONLY: A valid prescription from a licensed veterinarian is required for dispensing this medication.

1aaep.org.

2Merck Veterinary Manual.

3Plumb’s Veterinary Drugs.