The treatment of acute and chronic pain is usually predominantly drug based; however, other adjunctive therapies can be incorporated or in some cases used alone. Adjunctive therapies include but are not limited to acupuncture, medical massage, hydrotherapy, cold therapy, ultrasound, therapeutic laser therapy, physical rehabilitation, diets and dietary supplements. All treatments used in veterinary medicine must be held to the same standards, and claims for safety and efficacy must be proven by the scientific method. Several of these modalities are included in the WSAVA Global Pain Council Guidelines for recognition, assessment and treatment of pain (www.wsava.org/guidelines/global-pain-council-guidelines).

Acupuncture

The legitimacy of acupuncture has been questioned in the western world, but in 1997 the office of alternative medicine based at the National Institutes of Health (USA) stated that "acupuncture provides pain relief and improves function for people with arthritis and serves as an effective complement to standard care." In a review of the animal-specific acupuncture literature, Habacher¹ stated that more well-controlled studies were required in this field but that there were enough promising results to support pursuing acupuncture as a viable treatment in veterinary patients. There are many veterinarians throughout the world now qualified in this discipline.

Acupuncture involves placing needles at specific points on the body that are rich in neurovascular or muscular structures. Different types of acupuncture include dry needles, electro-acupuncture, aqua-acupuncture, moxibustion, low-intensity laser therapy and acupressure. The cause of the resultant analgesia is complex but involves the release of endorphins, enkephalins, norepinephrine, oxytocin and serotonin.

Most dogs and many cats tolerate needle placement surprisingly well, and acupuncture should be considered a viable choice for analgesic therapy, especially for chronic conditions. Each patient is unique and is usually treated differently even if the underlying cause of the pain (for example, osteoarthritis of the elbow) is the same. Xie and Ortiz-Umpierre² have written a good review on what conditions acupuncture can and cannot be used for. In a small study of dogs with elbow osteoarthritis,³ electro-acupuncture was not shown to significantly improve their performance (compared to sham treatment) as measured by force plate testing; however, eight out of nine owners correctly guessed when their dog had received acupuncture treatment.

Acupuncture can also be used to counteract some of the side effects of drug treatment and has shown efficacy in reducing nausea and vomiting in dogs given morphine.⁴

Risks of acupuncture are very low and include unintentional puncture of vital structures (e.g., the lung) and infection (only sterile, single-use needles should be used). Implantation of gold beads cannot be recommended.

Physical Rehabilitation

Physical rehabilitation is the objective assessment, diagnosis and treatment of musculoskeletal and neurological impairments. The physical rehabilitation assessment carefully evaluates posture, gait, function, strength, and passive range of motion to create a problem list and develop a targeted treatment plan. Physical rehabilitation is now commonly incorporated into many veterinary practices for post-surgical patients and those with chronic pain syndromes, most commonly degenerative joint disease. This is a rapidly expanding area of veterinary medicine and will continue to grow with the establishment of specialty colleges (e.g., www.vsmr.org). Outcome measures have been described for this veterinary discipline so that the efficacy of different therapies can be scientifically studied.⁵ In veterinary medicine, the greatest efficacy is seen with exercise and cooling modalities.

Exercise improves blood and lymph flow and by increasing muscle mass and strength increases support to skeletal and spinal structures. Simple exercise such as static weightbearing can generally be utilized in the acute phase of injury, followed by a gradual increase in difficulty as healing progresses.

Cooling techniques are inexpensive, readily available, and are evidence based. They can substantially reduce the degree of damage in acute injury. Mechanisms for these effects include decreased bleeding and swelling as a result of local vasoconstriction. Drygas and colleagues reported that compared to a control group, cold compression therapy resulted in lower pain scores, lower lameness scores, less swelling and an increased range of motion in dogs following tibial plateau levelling osteotomy.⁶

Nutritional Approaches

Weight loss can significantly reduce the pain related to degenerative joint diseases and other orthopedic conditions in dogs and cats. In overweight dogs with hind limb lameness secondary to hip osteoarthritis, weight reduction alone resulted in a substantial improvement in clinical lameness.⁷ This is one of the reasons a nutritional evaluation is a critical component of the examination of every pet, particularly those in which pain is identified. An optimal body condition score of 4–5/9 should be the goal.

The WSAVA global nutrition guidelines contain extensive information on dog and cat diets including supplements: www.wsava.org/guidelines/global-nutrition-guidelines and www.wsava.org/nutrition-toolkit.

Veterinarians should remember that animal nutritional supplements and botanicals typically are not subject to pre-marketing evaluation for purity, safety, or efficacy and may contain active pharmacologic agents or unknown substances. The mechanism of action of many of the proposed compounds is not known. Surveys show that nutraceuticals are commonly recommended by practitioners with some considering nutraceuticals to be the first choice of treatment in dogs and cats with degenerative joint disease.⁸

Dietary supplements with potential benefits for pain management include the omega-3 fatty acids; eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have antiinflammatory effects which may reduce inflammation and pain from osteoarthritis. The optimal dose has not been determined, but studies of dietary omega-3 fatty acids at a dose of 0.41 g/100 kcal EPA and 0.34 g/100 kcal DHA (approximately 170 mg/kg EPA and 140 mg/kg DHA from the canine studies) have shown benefit. Veterinary diets marketed for dogs with osteoarthritis are all enriched in omega-3 fatty acids, but the amounts vary.

Glucosamine and chondroitin may have benefits in animals with degenerative joint disease through their antiinflammatory effects. There is no evidence for chondroprotective effects. Studies of glucosamine and chondroitin have been contradictory in terms of beneficial effects on pain, and a low to modest effect is all that can be expected. Glucosamine is an amino sugar, and although no adverse effects on glucose regulation have been seen in studies of healthy dogs or cats, studies of glucosamine supplementation in diabetic animals have not been reported. Currently no optimal dose has been determined.

Green-lipped mussels (Perna canaliculus) contain omega-3 fatty acids (EPA, DHA), chondroitin, glutamine, zinc, copper, manganese, and vitamins C and E. Although the exact mechanism of action is unknown, green-lipped mussels appear to have antiinflammatory effects. The optimal dose has not been determined, and some studies have shown positive effects and some have not, and it is not clear if this is related to dose or study design. A commercial therapeutic diet high in EPA and DHA content and supplemented with green-lipped mussel extract and glucosamine/chondroitin sulfate improved objective measures of mobility in cats with degenerative joint disease.⁹

Adjunctive analgesic modalities may be beneficial in some patients, but currently there is a lack of large, well-designed studies.

References

1.  Habacher G, Pittler MH, Ernst E. Effectiveness of acupuncture in veterinary medicine: systematic review. J Vet Intern Med. 2006;20(3):480–488.

2.  Xie H, Ortiz-Umpierre C. What acupuncture can and cannot treat. J Am Anim Hosp Assoc. 2006;42(4):244–248.

3.  Kapatkin AS, Tomasic M, Beech J, Meadows C, Boston RC, Mayhew PD, et al. Effects of electrostimulated acupuncture on ground reaction forces and pain scores in dogs with chronic elbow joint arthritis. J Am Vet Med Assoc. 2006;228(9):1350–1354.

4.  Koh RB, Isaza N, Xie H, Cooke K, Robertson SA. Effects of maropitant, acepromazine, and electroacupuncture on vomiting associated with administration of morphine in dogs. J Am Vet Med Assoc. 2014;244(7):820–829.

5.  Hesbach AL. Techniques for objective outcome assessment. Clin Tech Small Anim Pract. 2007;22(4):146–154.

6.  Drygas KA, McClure SR, Goring RL, Pozzi A, Robertson SA, Wang C. Effect of cold compression therapy on postoperative pain, swelling, range of motion, and lameness after tibial plateau leveling osteotomy in dogs. J Am Vet Med Assoc. 2011;238(10):1284–1291.

7.  Impellizeri JA, Tetrick MA, Muir P. Effect of weight reduction on clinical signs of lameness in dogs with hip osteoarthritis. J Am Vet Med Assoc. 2000;216(7):1089–1091.

8.  Anderson MA, Slater MR, Hammad TA. Results of a survey of small-animal practitioners on the perceived clinical efficacy and safety of an oral nutraceutical. Prev Vet Med. 1999;38(1):65–73.

9.  Lascelles BD, DePuy V, Thomson A, Hansen B, Marcellin-Little DJ, Biourge V, et al. Evaluation of a therapeutic diet for feline degenerative joint disease. J Vet Intern Med. 2010;24(3):487–495.