WHAT DO, OR SHOULD, VETERINARY SURGEONS USE TO TREAT PAIN ASSOCIATED WITH LAMINITIS? This was a topic for a panel discussion at last December’s convention of the American Association of Equine Practitioners.
The discussion facilitators were Dr Lori Bidwell, a certified veterinary acupuncturist at East West Equine Sports Medicine in Kentucky, and Dr Debra Sellon, director of Washington State University’s Veterinary Teaching Hospital.
A number of practitioners said they struggled with providing appropriate analgesia but drugs used commonly included: NSAIDs such as phenylbutazone; gabapentin; tramadol; acepromazine and acetaminophen.
Dr Bidwell commented on the value of lidocaine when treating horses in pain. It can be used as an IV bolus, topically by the patch formulation or as a continuous rate infusion and can be combined with morphine and ketamine in an infusion.
Ketamine bolus administration was also mentioned but some vets were unwilling to try it because of the risk of horses falling down. Dr Bidwell didn’t think the benefits of ketamine had been fully explored, and said she had used it to break the pain cycle and regain control over the patient’s discomfort.
She also encouraged practitioners to consider morphine as although it could potentially cause gastrointestinal stasis, it had a number of benefits.
Dr Sellon said that SC administration of butorphanol was another option.
The group discussed the practice of “stacking NSAIDs”, with more than one NSAID, such as phenylbutazone and rocoxib, administered at the same time. The panel was strongly opposed and believed that a safer approach was to attack pain using a combination of drugs with different mechanisms of action.
There was a mix of views over the role of corticosteroids with the facilitators divided in their opinion regarding the value of “BBD” in laminitic patients. Dr Bidwell said she would consider using it; Dr Sellon would not. Methadone, a μ-agonist, was considered an economical analgesic option and at an appropriate dose a good option for use in pregnant mares with laminitis.
The panel concluded that despite the newer analgesics available, NSAIDs, including phenylbutazone, remain the first-line option for pain management in equine practice.
Four main causes
Dr James Belknap, a professor at Ohio State University’s Department of Veterinary Clinical Sciences, has been researching laminitis for more than two decades, and believes that laminitis has four main causes.
First is the the classic carbohydrate overload, where a horse eats too much grain or overloads on sugary spring or autumn grass; second is a septic issue such as Potomac horse fever, a retained placenta, or an illness such as pneumonia; thirdly, laminitis could develop as a result of a supporting limb injury when the horse favours an injured limb, forcing all the weight to the non-injured limb, resulting in more of a vascular problem; and fourthly, the horse could have insulin resistance as a part of an endocrine condition such as Cushing’s disease or equine metabolic syndrome, which also impact the laminae.
With a septic horse, the laminitis episode tends to come on quickly and intensely, Dr Belknap says. With a horse that has endocrine issues, it’s usually a much more insidious disease, but either can become a longer-term process to treat and manage.
“There can be a lot of trial and error in treating cases of laminitis,” Dr Belknap says. “What worked on the last horse may not work on this one.”