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 < .001) and decreased by 25% from week 40 to week 60 (4.9 ± 0.7 kg) (P < .001). Serum IGF-1 concentrations did not differ during the study period (week 0, 16, 40, 60: 500 ± 188, 479 ± 247, 470 ± 184, 435 ± 154 ng/mL, respectively; P = .38). Correlations with body weight were not observed.Conclusions and Clinical Importance: Insulin-like growth factor-1 might not be influenced by changes of body weight in healthy cats, possibly suggesting that the latter is unimportant when interpreting IGF-1 results in this species.

Method Validation and Establishment of Reference Intervals for an Insulin-like Growth Factor-1 Chemiluminescent Immunoassay in Cats

“…Another factor potentially affecting IGF-1 concentration and impacting the RI might be the body weight of included cats. Although weight gain or weight loss was not associated with significant changes in IGF-1 concentration in a small study including ten healthy research cats [ 37 ], Strage et al detected a significant association between body weight and IGF-1 in 55 healthy cats [ 23 ]. In that previous study, an increase of 1 kg in body weight was associated with an estimated increase in IGF-1 concentration of 38% [ 23 ].…”

MRI-based quantification of adipose tissue distribution in healthy adult cats during body weight gain

“…The prospective, experimental study was approved by the Cantonal Veterinary Office, ethics committee, license number ZH118/16, was conducted in accordance with Animal Welfare Act of Switzerland as part of a larger concurrent study (19), and is reported in accordance with ARRIVE guidelines. Cats were acquired as kittens, years before, as research animals from a breeding station for research animals (Liberty Research Inc., Waverly New York 14892, United States).…”

“…During the first week of dietary intervention, the daily ration was stepwise increased. In particular, during the first 2 days each cat was fed the resting energy requirement (19) increased by 50%. The daily resting energy requirement was doubled on day 3 and 4.…”

“…On day 5 and 6 the daily ration was increased to 2.5-fold of the resting energy requirements. From day 7, dry food (Hill's™ Science Diet™ Adult Optimal Care, Hill's Pet Nutrition) was provided ad libitum for a period of 40 weeks (19). Follow-up 1 was performed 20 weeks after the beginning of the study as documentation of BW gain and before a second period of equal length of BW gain stabilization.…”

“…The authors would like to acknowledge the Commission for Technology and Innovation (CTI) for their financial support of the main concurrent study (19), under Grant/Award Number: 18288.1 PFLS-LS. The team of the Research Group Diabetology of the Vetsuisse Faculty Zurich responsible for the management of the cats (L. Salesov, T. Lutz, and C. Reusch) also deserves recognition for their contributions to this work.…”