Objective: To investigate the influence of dietary supplementation with l-carnitine on metabolic rate, fatty acid oxidation, weight loss, and lean body mass (LBM) in overweight cats undergoing rapid weight reduction. Animals: 32 healthy adult neutered colony-housed cats. Procedures: Cats fattened through unrestricted ingestion of an energy-dense diet for 6 months were randomly assigned to 4 groups and fed a weight reduction diet supplemented with 0 (control), 50, 100, or 150 μg of carnitine/g of diet (unrestricted for 1 month, then restricted). Measurements included resting energy expenditure, respiratory quotient, daily energy expenditure, LBM, and fatty acid oxidation. Following weight loss, cats were allowed unrestricted feeding of the energy-dense diet to investigate weight gain after test diet cessation. Results: Median weekly weight loss in all groups was ≥ 1.3%, with no difference among groups in overall or cumulative percentage weight loss. During restricted feeding, the resting energy expenditure-to-LBM ratio was significantly higher in cats that received l-carnitine than in those that received the control diet. Respiratory quotient was significantly lower in each cat that received l-carnitine on day 42, compared with the value before the diet began, and in all cats that received l-carnitine, compared with the control group throughout restricted feeding. A significant increase in palmitate flux rate in cats fed the diet with 150 μg of carnitine/g relative to the flux rate in the control group on day 42 corresponded to significantly increased stoichiometric fat oxidation in the l-carnitine diet group (> 62% vs 14% for the control group). Weight gain (as high as 28%) was evident within 35 days after unrestricted feeding was reintroduced. Conclusions and Clinical Relevance: Dietary l-carnitine supplementation appeared to have a metabolic effect in overweight cats undergoing rapid weight loss that facilitated fatty acid oxidation.

During the last ten years, numerous species have been treated with deslorelin implants to induce contraception. The aims of the study were 1) to assess contraceptive efficacy of 4.7 mg subcutaneous deslorelin implants in rats, 2) to determine the latency of contraceptive effect, and 3) to determine potential side effects. Three experimental females were implanted and their estrous cycle was studied by vaginal smear. Two weeks after implantation, a male whose fertility was previously assessed with a control female, was introduced into their cage. No female conceived during the 4 mo following implantation. Additionally, 38 pet rats were recruited from clients in practice to test for potential side effects, including 6 males and 32 females with a mean age of 14 mo. Local reaction and transient weight gain during the first 2 wk, as well as behavioral changes were recorded. According to this pilot study, deslorelin implant could be used as a contraceptive method in female rats. The latency period is about 2 wk. Nevertheless, it might be possible to refine the treatment further using hormonal measurements. The duration of contraceptive effect is to be determined in an upcoming study.