“Chronic pain likely affects most, if not all, geriatric horses,” stated Alex Bianco, DVM, MS, Dipl. ACVIM, clinical faculty in large animal internal medicine at the University of Minnesota. Bianco compiled the latest research in equine pain management and shared her findings at the 2021 Veterinary Meeting and Expo (VMX) in Orlando, Florida.
While it’s a common contributor to the horse owner’s decision to euthanize a senior equine companion, chronic pain is nonetheless poorly recognized by the average equestrian. “Identifying pain needs to be the role of the veterinarian,” Bianco said. “Research has demonstrated horse owners’ difficulty in doing so.”
She cited a 2020 Swiss study in which experienced horse owners declared 182 horses to be sound, when veterinarians had actually found that 100 of them were a grade 2 or higher out of 5 on the AAEP lameness scale. And lameness is a characteristic component of conditions associated with chronic pain, such as osteoarthritis and laminitis. Muller et al. (2018) also found that geriatric horses are less likely to receive lameness examinations than their nongeriatric counterparts. The bottom line: In many cases owners of geriatric horses won’t recognize a lameness themselves or ask their veterinarian for routine soundness examinations. This leaves their senior equines at risk of suffering from undiagnosed – and, therefore, unmanaged – chronic pain.
The study by Muller and colleagues also featured the reassuring fact that horse owners highly value their veterinarian’s opinion. Practitioners, therefore, can take steps to promote good pain management. Bianco described the following as options to consider when systemically addressing chronic pain in geriatric horses:
- Non-steroidal anti-inflammatory drugs (NSAIDs): Cost-effective and easy to administer, these are popular when managing pain associated with arthritis and laminitis, among other painful, chronic conditions. However, owners and veterinarians should consider their potential adverse effects – gastrointestinal ulceration and renal (kidney) damage – with long-term use.
- Opiates: These controlled substances are effective for treating multifactorial or idiopathic (having unknown cause) pain. Butorphanol (Torbugesic) is the only opiate labeled for horses. Cost and risk for human substance abuse make its long-term use difficult.
- Gabapentin: It targets neuropathic (nerve-related) pain, but its bioavailability (absorption rate) in horses is low. It’s sometimes used as part of multimodal therapy in conjunction with other medications.
- Acetaminophen/paracetamol: Tylenol has analgesic effects and appears to be as effective as Banamine (flunixin meglumine) in treating lameness. However, due to concerns about liver toxicity, more research needs to be done on the efficacy and safety of this over-the-counter drug for equine use.
- Ketamine: This drug can be given as a constant rate infusion, along with tramadol, to reduce laminitic pain. Both are controlled substances; their handling and usage must be done judiciously by a licensed veterinarian.
Bianco also outlined common local therapeutic options:
- Corticosteroids intra-articular injections: Joint injections provide rapid relief from pain and inflammation associated with osteoarthritis. However, their use is controversial due to possible long-term harmful effects on cartilage.
- Topical diclofenac (Surpass): This NSAID can be applied over painful, arthritic joints.
- Podiatry: Therapeutic shoeing is often implemented to relieve pain associated with podotrochlear syndrome or laminitis.
- Desmotomy/tenotomy/neurectomy: These surgical procedures that involve transecting a ligament, tendon, or nerve can eradicate the source of pain.
- Arthrodesis or facilitated ankylosis: Veterinarians generally perform surgical fusion of a joint as a last resort for pasture soundness.
With any treatment plan, Bianco emphasized the need for frequent veterinary reassessment of a chronically painful geriatric horse. Equally important is the ‘end-point’ discussion, which might include hospice care in advanced cases. “Quality vs. length of life must be evaluated,” she said. “The ideal life for our horses is the longest quality life.”