Experimental and Clinical Studies on Plasma Leptin in Obese Dogs.

Abstract

ABSTRACT. Leptin is a protein synthesized and secreted primarily by adipocytes, and the circulating leptin concentration is elevated in obese humans and rodents. Recently, we have established a sandwich enzyme-linked immunosorbent assay for canine leptin. In the present study, plasma leptin concentrations were measured in experimentally developed obese beagles and in clinically obese dogs. When 5 male beagles were given a high-energy diet for 3 months, all of them became obese and the plasma leptin concentration significantly increased from 2.4 ± 1.2 to 4.9 ± 0.9 ng/ml, positively correlating with body fat content estimated by the deuterium oxide dilution method (r=0.87). The leptin concentrations of plasma samples collected from 59 dogs in veterinary practices were compared with their body condition scores (BCS). The plasma leptin concentrations of obese dogs were 9.7 ± 0.7 and 12.3 ± 1.5 ng/ml at BCS=4 and BCS=5, respectively, which were significantly higher than those of optimal (BCS=3) dogs (2.7 ± 0.3 ng/ml). There was no significant effect of sex and breed. A weak positive correlation (r=0.37) was found between the plasma leptin concentration and age, probably due to the lesser content of visceral fat in puppies younger than 1 year old. These results indicate that plasma leptin is a good index of adiposity in dogs regardless of breed, age and sex, and may be useful for quantitative assessment of obesity in small animal practice.

Plasma leptin concentration in dogs: Effects of body condition score, age, gender and breeds

“…In small animal practices, however, the patients and their conditions are considerably heterogeneous. In preliminary studies using 19 overweight and/or obese dogs visiting veterinary practices, we also found elevated plasma leptin concentrations compared with non-obese optimal weight dogs (Ishioka et al, 2002b). Consistent with our preliminary results, the present large-scale retrospective study using 166 clinical cases clearly showed higher plasma leptin concentrations in subjects with higher BCSs; that is, the mean concentration was 3.0 ng/mL in BCS 3, and increased to 8.6 and 12.8 in BCS 4 and 5, respectively.…”

“…We have shown that plasma leptin concentrations correlate positively with body fat content in experimentally induced obese beagles (Sagawa et al, 2002, Ishioka et al, 2002b, suggesting that plasma leptin is a good index of adiposity in the dog, as has been well-establised in humans and rodents. In our previous studies using beagles, the subjects were chosen for homogeneity of age, gender, breed, and housing conditions such as room temperature, lighting conditions, and feeding time.…”

“…Using this ELISA method, we demonstrated a highly positive correlation between plasma leptin concentration and body fat content estimated by a deuterium oxide dilution method in experimentally induced obese beagles (Sagawa et al, 2002, Ishioka et al, 2002b. We also found, in preliminary studies, higher plasma leptin concentrations in dogs with higher BCSs visiting veterinary practices (Ishioka et al, 2002b), but the sample size was too small to analyse the effects of various factors other than BCSs statistically. In the present study, we collected plasma samples from 166 dogs visiting 8 veterinary practices and performed a retrospective study focusing on the relationship of the plasma leptin concentration to BCS, age, gender and breed.…”

“…Previously, we cloned canine leptin gene (Iwase et al, 2000b), produced recombinant protein, and established a sandwich ELISA specific to canine leptin (Iwase et al, 2000a). Using this ELISA method, we demonstrated a highly positive correlation between plasma leptin concentration and body fat content estimated by a deuterium oxide dilution method in experimentally induced obese beagles (Sagawa et al, 2002, Ishioka et al, 2002b. We also found, in preliminary studies, higher plasma leptin concentrations in dogs with higher BCSs visiting veterinary practices (Ishioka et al, 2002b), but the sample size was too small to analyse the effects of various factors other than BCSs statistically.…”

Serum Adipokine Concentrations in Dogs with Naturally Occurring Pituitary‐Dependent Hyperadrenocorticism

“…In dogs with PDH, several factors might contribute to higher leptin concentrations than those in healthy overweight dogs. First, circulating leptin level is correlated with the body fat mass in dogs,21 so it is possible that an increased fat mass in the abdomen might lead to excessive hyperleptinemia. Second, in humans, it has been suggested that an increase in visceral fat has a relatively stronger effect on serum leptin in patients with Cushing's syndrome than it does in subjects with normal cortisolemia 22, 23, 24, 25.…”