Comparison among Feline’s Body Mass Index, Leptin Hormone Serum Level and Body Condition Score to Diagnose Obesity in Domestic Cats

Abstract

Background: Today, obesity is a condition commonly seen in small animal internal medicine. This condition is defined as excess of body fat resulting from increased energy absorption or reduced energy expenditure, and it is classified as a nutritional and metabolic disorder.  Obesity results from excessive formation of adipose tissue, and can pose severe consequences to the animal's health. It can also become an aggravating factor for several diseases, frequently exerting direct effects on morbidity and mortality.  This study aimed to evaluate feline body mass index (FBMI), and associate this parameter with body condition score (BCS) and leptin hormone serum levels.

Materials, Methods & Results: This study was conducted in a private Veterinary Clinic exclusively dedicated to feline care in the neighborhood of Botafogo, city of Rio de Janeiro, Brazil. Ninety-six feline patients (Felis catus) were randomly selected independent of their gender (male or female - intact or not), breed, or age from cats that were submitted for surgical interventions. The population was then divided into two groups according to FBMI: group 1, with non-obese animals (FBMI < 30%), totaling 53 animals; and group 2, with obese animals (FBMI ≥ 30%), totaling 43 animals. Physical examination was conducted on all animals. During this procedure, the weight of the animals was recorded; obesity was determined subjectively using the BCS, and objectively using plasma leptin concentration as assessed by radioimmunoassay (RIA). Leptin concentration in the plasma of the 96 animals included in this study was 13.81 ± 13.06 ng/mL HE. The average for group 1 was 3.85 ± 3.08 ng/mL HE, while the average for group 2 was 26.08 ± 9.61 ng/mL HE. The average leptin concentration in animals with body condition scores 1 and 2 (lean) was 2.53 ± 1.22 ng/mL HE; the average leptin concentration in animals with a BCS of 3 (ideal) was 4.23 ± 3.67 ng/mL HE; the average leptin concentration in animals with body condition scores 4 and 5 (above the ideal weight) was 21.29 ± 12.47 ng/mL HE. Animals with scores 1, 2, and 3 were present only in group 1, with averages of 2.53 ± 1.22 ng/mL HE for animals with scores 1 and 2, and 4.23 ± 3.73 ng/mL HE for animals with a score of 3. Animals with scores 4 and 5 in group 1 had an average leptin concentration of 5.24 ± 4.41 ng/mL HE, and animals with scores 4 and 5 in group 2 had an average leptin concentration of 26.08 ± 9.61 ng/mL HE. In cats, plasma leptin has been determined in experimental studies under controlled conditions, but not in clinical studies. It is possible that this is the first study in which this parameter has been assessed under heterogeneous conditions; therefore, caution should be taken if this technique is used in the clinical routine for determination of obesity in domestic cats.

Discussion: Plasma leptin concentration may be a quantitative parameter for evaluation of obesity in dogs, humans, and rodents. Assessment of plasma leptin concentration could be included in obesity monitoring programs for cats and, additionally, constitute a helpful parameter in scientific studies on obesity in this species. In addition to providing descriptive data on obesity in cats in Rio de Janeiro, the results reported in this study may help veterinarians to predict which cats are prone to becoming obese. Prevention of feline obesity can be as or more important than curing it.