Nonpharmacologic Modalities for Pain Management
Although pharmacological agents are often necessary to assist with managing discomfort,nonpharmacological modalities are critically important in the management of chronic pain and maintaining the body in an active state. Thus, it is advisable for veterinarians to be prepared with substantiated options.
Adipose tissue secretes a mixture of cytokines that circulate throughout the body, contributing to the pathology of many diseases, including OA, other inflammatory conditions, and the pain-associated hypersensitization process. Studies in human medicine have linked obesity with increased progression of OA in weight-bearing joints as well as non–weight-bearing joints, meaning these cytokines play an important role in the degradation process. Longitudinal cohort studies in the veterinary literature strongly support maintenance of a lean body condition score (caloric restriction over the lifetime of the dog) for decreasing the rate of OA progression and extending life span.122,123 With respect to pain, obesity is most often linked to OA pain, but, increasingly, it is becoming apparent that an obese state contributes to other pain conditions, such as neuropathic pain.124
As described above, caloric restriction assists in preventing obesity, and this has a positive effect on helping prevent painful disease, such as OA, and likely helps decrease pain associated with other conditions. Beyond calories, there has long been an interest in “nutritional supplements” for the management of pain, especially OA or degenerative joint disease. The most comprehensive review on the efficacy of nutraceuticals to alleviate the clinical signs of OA concluded that the strength of evidence was low for all nutraceuticals except for omega- 3 fatty acid in dogs.125
Exercise and Rehabilitation Therapy
The profound health benefits of movement and exercise are well established in human medicine, including the benefits of exercise in reducing and controlling pain.66,67,126 The strength of these data in humans suggests that the same is highly likely to be true for cats and dogs, although clinical study evidence is sparse. However, daily walking has been associated with a decrease in the severity of lameness in dogs with hip dysplasia.68 Whereas the terms physiotherapy and physical therapy refer to the treatment of humans, the most appropriate terminology in veterinary medicine is rehabilitation therapy. Rehabilitation therapy broadly encompasses the use of varied manual techniques (joint mobilization, passive range of motion, stretching, massage, and myofascial release, to name a few), treatment modalities (therapeutic ultrasound, photobiomodulation-laser therapy, extracorporeal shock wave therapy, neuromuscular electrical stimulation, and thermal modification of tissue), and therapeutic exercises including hydrotherapy.
Although there is a dearth of controlled prospective clinical trials in the veterinary literature, the advisory panel believes that rehabilitation therapy should be considered part of a comprehensive wellness plan for patients who are affected by acute or chronic pain.
“Therapeutic exercise” usually refers to specific exercise targeting particular goals, such as restoring range of motion in arthritic joints, building muscle following surgery or prolonged immobility, or retraining the proprioceptive system after neurological injury. Creative planning between an owner and a trained rehabilitation specialist can often yield at-home alternatives to buying specific animal fitness equipment.
Cold therapy has a long history as an analgesic modality for acute pain. Applying cold therapy to skin decreases temperature up to a depth of 2–4 cm, resulting in decreased activation of tissue nociceptors and slowed conduction velocity along peripheral axons.127 Cold therapy also decreases edema formation via vasoconstriction, decreased delivery of inflammatory mediators to injured tissues, and decreased neurogenic inflammation as a result of decreased neuronal activity in sensory nerves. The practical application of cold therapy to patients was recently reviewed, and its use in acute and chronic pain conditions was discussed.47
Several studies in veterinary medicine have demonstrated that cryotherapy or cold compression therapy applied with the first 72 hours following stifle stabilization surgery resulted in decreased pain, decreased lameness, and increased joint range of motion.128
Environmental modification is the adjustment of environmental surroundings to positively influence comfort. In the hospital environment, this can be as simple as separating cats from dogs, placing pets in appropriately sized cages or runs, providing cage pads in addition to bedding, and having hiding places for cats. Reducing noise can decrease stimulation and secretion of cortisol, which can reduce patient stress.129
At home, environmental modification can also be used to preserve access to preferred areas. Owners can provide injured, arthritic, or neurologic pets with secure footing (carpet runners) or with ramps or steps to areas that would otherwise be inaccessible. Animals in discomfort often feel vulnerable and prefer to rest in areas of the house that are quieter or more protected, such as a behind a couch or under a bed. Cat doors or baby gates can be used to provide “restricted access” areas in the home and allow pets to rest more comfortably. Placing these areas at a manageable distance from food or litter boxes may encourage mobility and exercise, particularly for cats.
There is not an abundance of evidence-guided studies supporting the use of acupuncture. However, a 1997 National Institutes of Health Consensus Statement indicated promising results for the use of acupuncture in humans postoperatively, for treating chemotherapy nausea and vomiting, and in cases of postoperative dental pain. In the veterinary literature, acupuncture has been reported to be helpful as an adjunct treatment for postoperative pain following ovariohysterectomy in cats130 and dogs and for managing intervertebral disc disease, but it was not found to be beneficial for the treatment of pain associated with OA in dogs.131 Further work is needed to fully define the role of acupuncture in pain control.