Hot Literature: Shedding weight helps shed the pain of osteoarthritis in dogs

Studies in obese people demonstrating a significant link between obesity and the development of certain forms of osteoarthritis (OA)-and an improvement in clinical signs with weight loss-have resulted in a popular area of research for the veterinary scientific community. Several previous studies have shown that weight loss can improve lameness in obese dogs with OA. A recent study took a clinically relevant approach, selecting obese, client-owned dogs with OA in one or more limbs and evaluating lameness both subjectively and objectively during a dietary weight-loss program.

The 14 dogs included in this study were of varying ages, sexes, and breeds, but all weighed at least 20% more than their ideal body weight and had clinical signs of lameness in one or more limbs with radiographic evidence of hip or elbow OA. Dogs with abnormal blood screening results or that had been treated with nonsteroidal anti-inflammatory medications within three weeks of the study were excluded.

The dogs were weighed and their pelvic circumferences were measured initially and at six follow-up visits throughout the 16-week weight-loss program. Lameness of the most affected limb was evaluated subjectively (numerical rating system and visual analogue scale) and objectively (force plate measurements). Each dog’s caloric intake was calculated to result in a 0.5% to 1% body weight reduction per week, and owners were asked not to change their dogs' exercise level during the study.

By the end of the study, the dogs had lost an average of 8.6% of their initial body weight (an average of 0.55% per week) and 6.92% of their initial pelvic circumference. There was no difference in these changes based on whether a forelimb or hindlimb was most affected. By two weeks into the weight-loss program, visual analogue scale scores were dramatically improved, and by the end of the study, 82% of the dogs showed improvement in their numerical rating system scores. For both subjective lameness assessment methods, there was no difference based on which limb was most affected.

However, force plate initial measurements and study results showed significant differences depending on whether the most affected limb was a forelimb or hindlimb. For dogs with forelimb lameness, there was considerable asymmetry at the start of the study, but by the seventh visit, the force plate measurements were in line with values for normal dogs. There was little asymmetry for dogs with hindlimb lameness, and force plate evaluations did not change significantly for these dogs by the end of the study. These findings may have been due to the fact that OA of the hips is often bilateral, and selecting the most affected limb is difficult. Also, a larger percentage of body weight is borne by the forelimbs, so weight reductions may be felt first by the forelimbs. These force plate results contradict previous, longer studies that show improvement with weight loss and physiotherapy.

Weight loss alone was shown to produce significant improvement in subjective assessments of lameness in dogs with OA regardless of the limbs affected. Furthermore, the results indicate that a weight loss of 6.1% and above can produce a significant improvement in the clinical signs of lameness due to OA and a significant improvement in kinetic gate analysis for dogs with elbow OA.

Marshall WG, Hazewinkel HAW, Mullen D, et al. The effect of weight loss on lameness in obese dogs with osteoarthritis. Vet Res Commun 2010;34(3):241-253.

Link to full text: http://www.springerlink.com/content/bp21027620h7n387/fulltext.html