“Divinum Est Opus Sedare Dolorem” (Divine Is the Work to Subdue Pain)
—Galen

Jeremy Bentham is credited with saying, “The question is not: ‘Can they reason?’ or ‘Can they talk?’ but ‘Can they suffer?’” And, of course, we know the answer to that question is “Yes”! Because the majority of pet owners consider their pets to be members of the family and, perhaps, even a better companion than the other humans in the family, we will enjoy a special level of job security into perpetuity. Leon Bernard, a French physician from long ago, stated that “Medicine should be practiced as a form of friendship,” and friends don’t let friends hurt.

When we think about pain, in people and in animals, we look to the International Society for the Study of Pain (IASP) for their definition:

“An unpleasant and emotional experience associated with actual or potential tissue damage. The inability to communicate in no way negates the possibility that an individual is experiencing pain and is in need of appropriate pain-relieving treatment.”

Pain in both people and animals is a complex, multifaceted experience with a sensory-informational component, an emotional dimension (suffering aspect), and a cognitive-evaluative component (attention, previous experience, perceived threat to individual). That makes pain complex and scientifically intriguing, clinically challenging, and easy to overlook. But, it is worth making changes to improve treatment.

Why is pain important? We now know that we must stop chronic pain before it occurs. In a study on total knee replacement in people, a group of patients received a continuous femoral nerve block for two days vs. additional parenteral opioid therapy. The results were surprising. These patients had improved analgesia for the first two days postop, but the most impressive outcome was improved range of motion and earlier discharge from the rehabilitation center (Capdevila et al. 1999).

Clifford Woolf, MD, coined the language “adaptive” vs. “maladaptive” pain. Adaptive pain includes nociceptive pain (transient pain in response to a noxious stimulus) and inflammatory pain, which can lead to spontaneous pain and hypersensitivity to pain in response to tissue damage and inflammation. This, if left untreated or undertreated, can serve as the gateway to chronic maladaptive pain. Maladaptive pain includes neuropathic pain (spontaneous pain and hypersensitivity to pain in association with damage to or a lesion of the nervous system) and functional pain (hypersensitivity to pain resulting from abnormal central processing of normal input) (Woolf 2004).

Bottom line, we need to address, prevent, and reverse the phenomenon of wind-up. Wind-up involves sensitization of nociceptors, and peripheral and central pain pathways, in response to a barrage of afferent nociceptive impulses resulting in expanded receptive fields and an increased rate of discharge. This is maladaptive pain. And, as we consider pain in our patients, we must remember that Cats are not small dogs!

When making a pain plan, begin at the beginning. That means a thorough examination with a complete metabolic profile. Complete an appropriate diagnostic plan, e.g., don’t miss an OSA and then treat it as OA. Treat the treatable—and treat all the treatable. Make your plan and then work the plan. Chronic pain is best addressed with a multimodal pain plan, so it is no longer appropriate to throw an NSAID or two at the patient. Multimodal means multi-tasking. Also, the client is an absolutely essential partner.

Most chronic pain patients are less active and often overweight, so the most important physiotherapy for chronic pain patients is normalizing body condition/composition. Diagnose and treat hypothyroidism in dogs. Choose a nutrient profile proven to facilitate weight loss and up-regulation of “lean” genes (see nutrogenomic data). Break the pain cycle pharmacologically as quickly and effectively as possible. NSAIDs remain the cornerstone of pain management. They decrease inflammation and reduce pain. They act at various spots in the nervous system. Remember that there is no “best” NSAID, and failure/sensitivity to one NSAID does not necessarily mean no NSAIDs. Once pain is controlled, one can titrate NSAIDs to the lowest effective dose (only with a multimodal plan in place).

Because chronic pain is generally “maladaptive” or “maldynic” (pain as disease), maladaptive pain demands we target the dorsal horn of the spinal cord. “Targeted therapy” is a relatively new concept in human pain management and exceptionally new in veterinary medicine. The best tool for this part of the job is gabapentin. Gabapentin affects α₂-δ subunit of the calcium channel in the dorsal horn and is important for chronic, maladaptive pain management in humans. We need to dose it appropriately, 5–10 mg/kg BID–TID to start, and then provide regular dose escalations to effect. You will see activity within 24–48 hours and peak effects in 5–10 days. Sedation is the only relevant side effect, so simply reduce the dose, don’t stop using it. Do not stop abruptly, otherwise, you will see rebound pain, and the patient will have an excruciating experience. So, be sure to educate your clients about this! Long-term dosing is fine—no worries about kidneys or liver.

Another drug that targets the dorsal horn is amantadine, an NMDA receptor antagonist that can be used to complement the NSAID and gabapentin. The dosing in the literature is 2–5 mg/kg/day (Lascelles et al.). It is well-tolerated long-term, and compounding is the only way to make it affordable. I actually don’t often use this medication any longer with the other pain management tools I put into place.

Next, consider PSGAGs (Adequan®). I use this off-label! It is useful in dogs and cats. PSGAGs are the building blocks of cartilage but will not replace cartilage that is gone. It heals micro-fractures, increases the viscosity of synovial fluid, and thus provides an indirect anti-inflammatory effect. As for dosing, use 2 mg/# SQ two times weekly for four weeks, weekly for four weeks, and then every 10–15 days. Inject SQ, not IM (teach clients how to do this at home). Start using as early as possible, as long-term use is OK. It is in the synovial joints within 72 hours.

Non-pharma options abound. When using nutraceuticals, we need to follow the evidence! One option is to use a therapeutic (joint support) nutrient profile. Another tool is the omega-3 FAs. We need to use the triglyceride formulation, not the esterized form (the esterized form is not bioavailable). Another nutraceutical contains UC-II (undenatured collagen type II). In a rat model of OA, UC-II slowed the deterioration of articular cartilage. It induces “oral tolerance,” which is immune modulation via lymphoid tissue (Peyer’s patches) in the gut. This stimulates the recognition of type II collagen, which prompts the production of anti-inflammatory cytokines. There were significant outcomes in humans, dogs, and horses.

Another non-pharma option uses a milk protein isolated from hyper-immunized cows, which inhibits cytokines which in turn inhibit neutrophils from migrating to sites of inflammation. This blocks the upregulation of inflammation, thus decreasing destructive chronic inflammation. It uses a different mechanism than NSAIDs and steroids, so it can be used with NSAIDs or corticosteroids. It takes time to achieve peak effects—initial effects within five to seven days, peak effects at 10–14 days—so overlap the use of milk protein with other modalities. Once you establish pain relief, you can then begin titrating down the dose of the NSAID or the corticosteroid. There are few side effects reported (primarily GI).

Finally, the green-lipped mussel (Perna canaliculus) contains essential fatty acids (EPA, etc.), as well as a palette of bioactive lipids. It can be complemented by HA molecules of specific molecular weight. It must be manufactured in a way that does not denature or interfere with efficacy.

With all nutraceuticals, it is the formulation, not simply the ingredients, that must be evaluated in the target species.

Non-pharma pain management options include physiotherapy and physical medicine modalities:

• Heat
• Cold
• Therapeutic laser
• NMES
• TENS
• Therapeutic U/S
• Tissue mobilization
• Medical massage
• Tui Na
• Acupuncture
• Chiropractic/osteopathic manipulation
• Myofascial trigger point therapy
• Hydrotherapy
• E-stim whirlpool
• Swimming
• UWT

A unique physical medicine option is targeted pulsed electromagnetic field (tPEMF) therapy. The biophysics of tPEMF includes increased Ca2+ signaling and decreased production of NO, and this combination decreases overall inflammation. This modality decreases both acute and chronic inflammation, is safe, effective, and non-invasive, and actively engages owners. Pet owners want to participate in their pets’ care, and they appreciate being able to do something positive for their pets each and every day.

Don’t forget about using assistive devices like wheelchairs (walking, two-wheel, four-wheel), slings, supportive vests, and rolling carts/wagons. Help clients modify the home environment and home activities. Have them raise food and water dishes to elbow height. Cover slippery floors and modify access to stairs. Have them use a ramp for vehicle entry/exit and modify play with other pets.

Don’t forget client homework. Be as specific as possible, write everything down, and have clients keep an “activities of daily living” diary. Direct your attention towards pain to identify trends and thus guide therapy.

Is the pet experiencing pain, fear, anxiety, stress? With unacceptable behaviors, always think about pain. Remember that anxiety exacerbates pain, and pain exacerbates anxiety. Look at the whole patient, ask lots of questions, and listen to clients for clues. Ask for pictures of the home environment and videos of activities of daily living. Older dogs and cats may be fearful because they are painful! While animals cannot and do not anticipate or fear their own death, they certainly can and do anticipate and fear pain. Any pet that is reluctant to be handled must have the benefit of our concern that they may be painful. Keep an open mind about this…

Also, it is time for us all to be Fear Free™. Thank you!