Disappearance of signs of heat and induction of ovulation in oestrous queens with gonadorelin: a clinical study

Abstract

Objectives The objective of this study was to assess the efficacy of a single intramuscular administration of gonadorelin to induce ovulation in queens in oestrus. Methods Twenty-seven queens presented in oestrus for elective ovariectomy were divided into a treatment (n = 19) and a placebo (n = 8) group. Treated queens received a 50 µg dose of gonadorelin, while placebo-treated queens were injected intramuscularly (IM) with an equal amount of saline solution. All treatments were performed between the second and fourth days of heat. Results Two days later, signs of behavioural heat had disappeared in all gonadorelin-treated queens, while 5/8 placebo-treated queens were still in heat. Following ovariectomy, performed 4 days after drug administration, the ovaries of each queen were evaluated histologically and the number of corpora lutea were counted. Sixteen of 19 (84%) gonadorelin-treated queens had ovulated and developed five (range 2–9) corpora lutea, while 3/8 (37%) placebo-treated queens had ovulated and developed five (range 3–6) corpora lutea. Conclusions and relevance This is the first study to document the efficacy of a 50 µg/cat gonadorelin dose to induce ovulation in oestrous queens when administered IM on days 2–4 following the onset of oestrus.