Weight loss increases ground reactive force in overweight dogs with osteoarthritis

A comprehensive weight-loss program that returns overweight dogs to optimal body weight and body condition can improve osteoarthritic dogs' ability to move more normally. In a study conducted at Texas A&M University, moderately overweight to obese dogs lost weight through a combination of a weight-management diet and increased exercise. Based on force-plate gait analysis, the dogs exerted significantly more force on each limb and moved more quickly. The abstract below, published in the proceedings of the 2000 Purina Nutrition Forum, provides additional details.

Weight loss has been determined to benefit dogs with hip dysplasia based on subjective assessments and elimination of analgesic medication. The present study was done to determine whether force-plate measurements could objectively document gait improvement from weight loss in overweight dogs suffering clinical pain from hip dysplasia.

Sixteen privately owned, moderately overweight to obese dogs—clinically lame from hip dysplasia—were studied. Osteoarthritis in coxofemoral joints was confirmed by radiographically evident bony changes and resentment of manipulation to the coxofemoral joints. No other orthopedic or neurologic abnormalities were identified upon orthopedic or neurologic examination.

The weight loss program consisted of:

• Purina Veterinary Diets® OM Overweight Management® brand Canine Formula (formerly known as Purina® CNM™ Canine OM-Formula®) in prescribed amounts,

• 20 to 60 minutes of daily leash walking, and

• rechecks of weight loss every two weeks.

Dogs were trotted across an AMTI OR6-5 force plate connected to an IBM personal computer via a Vishay 2200 amplifier at the beginning and end of weight loss until three to five trials were obtained of each ipsilateral pair of limbs cleanly striking the plate at a measured velocity of 1.7 to 2.2 m/sec and < ±0.2 m/sec2 of acceleration. Trials were averaged for each limb and data separated into best and worst front and rear limbs, based on the magnitude of average peak ground reactive force for each limb at the beginning of weight loss. Paired t-tests were used to compare parameters measured at the beginning and end of weight loss.

The relative weight of dogs entering the study ranged from 113% to 129% of optimal body weight, and body condition score ranged from six to eight (out of nine, where one is emaciated and nine is grossly obese). Dogs lost from 3.9 to 12 kg of body weight. All dogs achieved individual goals for weight loss, and body condition scores returned to four to five (out of nine). For results on the average peak ground reactive force, see Table 1.

Table 1. Results of Force-Plate Analysis

The data indicate weight loss to optimal body condition allows dogs with hip dysplasia to exert more force at less body weight in less time during the stride, and a force plate can objectively quantify this benefit.