Clinical Efficacy of hCG for Ovulation Induction in Maine Coon Queens: A Case Series from a Breeding Cattery in Uruguay

The present study evaluated the efficacy of human chorionic gonadotropin (hCG)-induced ovulation in Maine Coon queens under subtropical conditions, with catteries managed outdoors or indoors under controlled photoperiods. Seven queens in proestrus or estrus were selected based on vaginal cytology and received a single intramuscular injection of 100 IU hCG to induce ovulation. Serum progesterone levels were measured 24 hours post-treatment, and fertile toms were introduced for mating. All queens ovulated, became pregnant, and delivered within a 4-day window, with a mean gestation length of 67.9 ± 2.1 days. The mean litter size was 6.2 ± 3.2 kittens, significantly larger than historical records for the cattery (p ≤ 0.05), while neonatal mortality at birth was low (4.5%). These outcomes indicate that the applied protocol reliably induces ovulation, enhances fertility, and improves perinatal survival. The study also highlights breed-specific reproductive traits of Maine Coons, including late sexual maturity, large litter size, and susceptibility to spontaneous ovulation. Exogenous hCG administration was well tolerated, with no adverse effects observed. Overall, the findings support the use of hCG-induced ovulation as a practical and effective strategy for reproductive management in Maine Coon breeding programs, particularly under controlled environmental conditions, enabling optimization of litter timing, size, and neonatal survival.