Chronic Pain Management in Geriatric Pets

Philip R Judge BVSc MVS PG Cert Vet Stud MACVSc (Vet Emergency and Critical Care; Medicine of Dogs)

Introduction

As veterinary medicine extends the lifespan of dogs and cats, the prevalence of age-related chronic pain, particularly from osteoarthritis (OA), has increased. Managing pain in geriatric patients requires a multimodal approach that accounts for comorbidities, altered pharmacokinetics, and diminished organ function. The goal is to optimize comfort and quality of life through a combination of pharmaceutical and non-pharmaceutical therapies, with the caregiver as an active team member.

1. Pharmaceutical Cornerstones and Cautions

Nonsteroidal Anti-inflammatory Drugs (NSAIDs): NSAIDs remain a cornerstone of chronic pain management but require caution in geriatrics due to increased risk of gastrointestinal, renal, and hepatic adverse effects.

• Key Principles:
  • Screening: Baseline laboratory monitoring (renal/hepatic function) is essential before initiation, with rechecks at 2-3 weeks and periodically thereafter.
  • Dosing: Base dosage on lean body mass and use the lowest effective dose, though evidence for risk reduction with underdosing is lacking.
  • Contraindications: Avoid concurrent use of other NSAIDs, corticosteroids, or certain herbal supplements (e.g., ginkgo, ginseng). Use extreme caution in patients that are hypovolaemic, dehydrated or have renal, hepatic, or cardiac dysfunction.
  • Grapiprant: An EP4 receptor antagonist (piprant) that bypasses COX inhibition. It offers a potentially safer alternative for patients intolerant to traditional NSAIDs, though its adverse event profile (GI signs) is similar and monitoring is still required.

Anti-Nerve Growth Factor (anti-NGF) Monoclonal Antibodies (mAbs): These agents (bedinvetmab for dogs, frunevetmab for cats) provide a targeted approach for OA pain by binding NGF within joints.

• Clinical Use: Ideal for patients with comorbidities that preclude NSAID use or those with inadequate analgesic response.
• Monitoring: While generally well-tolerated, monitor for adverse events – including UTI and skin infections, dermatitis (dogs) and gastrointestinal and dermatological conditions (cats). A comprehensive neurologic exam is recommended prior to initiation, as improved mobility from pain relief can unmask pre-existing neurologic conditions (e.g., Geriatric Onset Laryngeal Paralysis Polyneuropathy).
• Future Options: Long-acting mAbs (izenivetmab/Denivia for dogs, relfovetmab/Portela for cats) providing three months of action are expected to become available in 2026.

2. Adjunctive Analgesics: The Multimodal Support Team

These agents are not for monotherapy but are crucial for targeting neuropathic pain, central sensitization, and enhancing primary analgesic effects.

• Amantadine: An NMDA receptor antagonist used to combat central sensitization in chronic, refractory pain (e.g., OA). Dose: 2-5 mg/kg PO q12-24h.
• Gabapentin/Pregabalin: Bind to calcium channels to reduce neurotransmitter release, making them effective for neuropathic pain (e.g., IVDD, cancer pain, post-amputation). Not effective for acute pain.
  • Dosing (Gabapentin): Dogs: 10-20 mg/kg PO q8h; Cats: 5 mg/kg PO q12h.
  • Caution: Renally excreted; dose reduction is critical in geriatrics with renal impairment to avoid severe sedation/ataxia.
• Tramadol:
  • Cats: Can be a useful adjunctive analgesic (2-4 mg/kg PO q8-12h).
  • Dogs: Efficacy is low due to poor metabolism to the active opioid metabolite. Any benefit is likely from monoaminergic effects.
• Amitriptyline: A tricyclic antidepressant that may provide ancillary benefits for neuropathic pain by modulating descending inhibitory pathways.
  • Warning: Risk of serotonin syndrome when combined with other serotonergic drugs (e.g., tramadol). Avoid concomitant use. Sedation is a common side effect.
• Cannabidiol (CBD): Emerging evidence supports its use for OA pain, with studies showing improved mobility. It has a favourable safety profile in geriatrics, though mild sedation and elevated ALP can occur. The market is unregulated; always request a certificate of analysis from an independent lab to verify purity and potency.

3. Non-Pharmaceutical Modalities: Essential Components of Care

Integrating physical and environmental strategies is key to reducing drug burden and addressing all aspects of chronic pain.

• Photobiomodulation Therapy (PBMT): Uses red/near-infrared light to reduce inflammation and pain. It is safe to use alongside all analgesics. Studies show it can be superior to NSAIDs alone for OA. Effective dosing is critical: 10-20 J/cm² per joint for OA; higher irradiance (≥270 mW/cm²) for neuropathic pain.
• Rehabilitation Therapy and Acupuncture: These specialized modalities are invaluable for improving mobility, reducing pain, and treating conditions like myofascial pain syndrome (MPS), which commonly complicates chronic OA. Referral to a certified practitioner should be considered for refractory cases.
• Environmental Modification: Simple changes can have a profound impact.
  • Mobility: Use ramps for steps/vehicles, harnesses for support, and non-slip rugs or yoga mats on slippery floors.
  • Feline-Specific: Ensure litter boxes have a low entry side and use litter with a comfortable texture. OA is a primary cause of inappropriate elimination.
  • Weight Management: Involve the caregiver in assessing body condition score (BCS) to gain their commitment to a weight loss program. A prescription diet and regular weigh-ins are essential.

4. Interventional and Regenerative Options

For joints refractory to standard care, consider these options.

• Radiosynoviorthesis (Synovetin OA): Injection of radioactive tin-117m into the joint to induce apoptosis of inflammatory cells. Effects can last up to one year. Requires special licensing.
• Platelet-Rich Plasma (PRP): Injection of autologous concentrated platelets to release growth factors and promote tissue regeneration. Effects generally last 6-12 months. Can be used in both dogs and cats.

5. Botanicals and Nutraceuticals: Evidence and Caveats

Caregivers often seek these options. While some have evidence of benefit, they are not without risk.

• Botanicals with Evidence:
  • Boswellia: Inhibits 5-LOX, providing anti-inflammatory effects.
  • Turmeric: Anti-inflammatory, but bioavailability is poor; use enhanced formulations.
  • Devil’s Claw: COX-2 inhibition. Contraindicated in patients with gastric ulcers.
  • White Willow Bark: Contains salicin (aspirin precursor). Side effect profile may mimic NSAIDs. Avoid with anticoagulants and other NSAIDs.
• Nutraceuticals with Evidence:
  • Undenatured Type II Collagen: Reduces inflammation. May be less effective if given with glucosamine/chondroitin.
  • Green-Lipped Mussel: Source of glucosamine, chondroitin, and omega-3s.
  • Omega-3 Fatty Acids (EPA/DHA): Proven to improve joint health. Dogs require ~1:1 ratio; cats require more DHA (~1.5:1). Dogs cannot convert flaxseed to omega-3s.

Clinical Pearls and Pitfalls

• Pearls:
  • “Start low and go slow” with pharmaceuticals due to decreased hepatic/renal clearance.
  • Assume most geriatric patients have OA until proven otherwise.
  • Multimodal treatment reduces the risk of single-drug burden.
  • Social isolation from pain can accelerate decline; address mobility to keep pets engaged with the family.
• Pitfalls:
  • Beware drug interactions in a polypharmacy plan.
  • Do not ignore caregiver emotional fatigue; assess their ability to implement the plan.
  • Avoid overzealous, unproven treatments.

Key Insights from: Petty MC. Chronic Pain: Effective Relief Strategies for Geriatric Pets. The Veterinary Clinics of North America. Small Animal Practice. 2025 Nov 5:S0195-5616.