Serum insulin-like growth factor-1 concentrations in healthy cats before and after weight gain and weight loss

Abstract

Background: Measurement of serum concentrations of insulin-like growth factor (IGF)-1 is used to diagnose acromegaly in cats. Hypothesis: Changes of body weight do not affect serum concentrations of IGF-1 in cats. Animals: Ten healthy purpose-bred cats. Methods: Prospective study. In lean cats, food availability was stepwise increased during the first week and given ad libitum for a total of 40 weeks to increase their body weight. From week 41 to week 60, food access was limited to reach a weight loss of 1% to 2% each week. Measurement of IGF-1 was performed at week 0, 16, 40, and 60. Insulin-like growth factor-1 was measured by radioimmunoassay. Body weight and IGF-1 were compared among the 4 time points. Results: Body weight increased by 44% from week 0 (4.5 ± 0.4 kg) to week 40 (6.5 ± 1.2 kg) (P