Long term effect of the GnRH antagonist acyline on corporal and radiographic development of domestic cats

M. PRIOTTO; M. RODRIGUEZ; M. GRISOLIA; C. MARCHETTI; P. FURLAN; C. GOBELLO; M. FAYA

Berlin

Congreso; 22nd EVSSAR Congress; 2019

European Veterinary Society For Small Animal Reproduction

Introduction and aim: GnRH analogs use for contraception has been described, but there is little objectively obtained data to describe their influence on development. In a previous study, it was described the effect of a GnRH antagonist, acyline (NIH, Bethesda, MD, USA) vs. control cats (1). Data was described until puberty and no radiographic description was made. This study pretends enlarge the data of the same protocol until the cats finished growth and describe radiographic parameters.Materials and Methods: Thirteen male and twelve female cats were included in this study. Treated group received acyline 33 μg/100 g sc within the first 24 hours of birth, and was repeated weekly until 3 months of age; control group remained untreated. Follow up was performed until they finish growth, which was defined when three consecutive body measurements were constant. Body weight(kg), withers height (cm), and body length (cm) measured from the most cranial aspect of the scapula to the most caudal aspect of the ischium, were recorded weekly. Lateral and front radiographs of the antebrachium were taken monthly, beginning at 4 weeks of age. Radial length was measured on the radiograph from the most proximal aspect of the radial head to the most distal aspect of thebone. Proximal and distal radial physis were considered closed when a radiolucent line was no longer visible. Measurement of the bone cortex and bone marrow was also performed. Age at end of growth in both groups was compared by a Student t test. Corporal measurements as radial length was calculated by repeated measures ANOVA. Pearson correlation was performed between body measurements and radial length.Results: Age (weeks) at end of growth for acyline vs. control male cats was 31.5 ± 1.7 vs. 33.6 ± 1.1 (p > 0.05) and 36.0 ± 2.1 vs. 37.0 ± 1.0 (p > 0.05) in acyline vs. control female cats. The final estimated body weight, withers height and body length in acyline vs. control male cats were 3.49 vs. 3.04, 29.79 vs. 31.22 and 36.75 vs. 35.50 respectively (p > 0.05). The same parameters in female cats were 2.54 vs. 2.59, 28.84 vs. 28.05 and 34.78 vs. 32.28 (p > 0.05).The average rate of growth (weeks) for body weight, withers height and body length in male cats were 18.41 vs. 16.92, 8.38 vs. 7.80 and 8.59 vs. 8.52 (p > 0.05). The same parameters in female cats were 16.42 vs. 16.93, 7.71 vs. 7.11 and 8.23 vs. 7.98 (p > 0.05). The least squares mean estimated for radial length (cm), in acyline vs. control male cats was 8.48 vs. 8.23 respectively (p < 0.05). In female cats the radial length was higher between 8 and 28 weeks (p < 0.05). The thickness of radial bones cortex was lower in acyline vs. control females from week 32 onward (p < 0.05). No difference was detected in thickness of the radial bone marrow (p > 0.05) in all groups. All groups closed their proximal and distal physis within the normal ranges described for the species. Correlation coefficient between male radial length and body length, wither height and weight, were 0.93, 0.92 and 0.91 (p < 0.01) respectively. For females were 0.96, 0.93 and 0.93 (p < 0.01).Conclusions: While no differences were detected in body measurements, acyline treated animals presented longer radial length than control animals, different to what was previously reported in gonadectomized cats (2). Although there is a high correlation between radial length and body measurements, it is not enough to detect the difference in the last ones because it is perhaps too small. The ages of physis closure agree with the normal values reported (3). Clinicalrelevance of the lower thickness of cortical bone in treated female cats requires further investigation.