Animal Reproduction and Embryology [LL250]; Veterinary Pharmacology and Anaesthesiology [LL882]; Animal Health and Hygiene (General) [LL800]; Animal Welfare [LL810]; Prion, Viral, Bacterial and Fungal Pathogens of Animals [LL821]; mares; ovulation; efficacy; adverse effects; HCG; animal welfare; pandemics; coronavirus disease 2019; viral diseases; horses; Severe acute respiratory syndrome coronavirus 2; Equus; Equidae; Perissodactyla; mammals; vertebrates; Chordata; animals; eukaryotes; Severe acute respiratory syndrome-related coronavirus; Betacoronavirus; Coronavirinae; Coronaviridae; Nidovirales; positive-sense ssRNA Viruses; ssRNA Viruses; RNA Viruses; viruses; deslorelin; deslorelin acetate; mare; adverse reactions; human chorionic gonadotropin; human gonadotropic hormone; urogonadotropin; animal rights; SARS-CoV-2; viral infections