Effects on general health and behaviour of a chronic treatment with a 9.4 mg deslorelin implant in female cats

Objectives – Deslorelin is a long-acting GnRH agonist marked for use in male dogs, male cats and prepuberal bitches, that is also used off-label for reproduction control in queens. The study aimed to determine the potential efficacy, duration and chronic effects on the general health of long-term treatment with the 9.4 mg deslorelin implant in queens. In addition, behavioural changes during the flare-up and downregulation phases were assessed in implanted queens compared to surgically sterilised ones. Methods – The 17-month study was conducted on a research population of 10 queens of different ages and breeds. This population consisted of a treatment group (5 queens administered with a 9.4 mg deslorelin implant) and a control group (3 neutered queens and 2 intact queens). Effects on general health, efficacy, duration and side effects were assessed through clinical exams, laboratory data and telephone interviews. Behavioural changes were studied in a population of 19 queens. Six questionnaires for flare-up, 5 for downregulation phases and 8 for surgical sterilisation were answered by the queen’s owners. Results – The efficacy of the implant was confirmed (5/5). This work is based on the collection of partial data from 17 months of a 4-year study. So far, the duration of efficacy is between 11 and 17 months. Deslorelin did not affect the general health of the females. No injection site side effects were observed. Weight gain was observed (4/5) (+19.05-52.63%). Mammary fibroadenomatosis was observed (1/5) regressing spontaneously 2 months after implantation. Oestrus behaviour increased during the flare-up phase and decreased during the downregulation phase and surgical sterilisation. Affection and attention-seeking increased while roaming behaviour and physical activity decreased during the treatment. Conclusions – The efficacy and safety of the 9.4 mg deslorelin implant for anoestrus induction were confirmed. No severe side effects were observed. The flare-up phase was characterised by the manifestation of oestrus behaviour, and no solution has yet been found for the fertile oestrus inducted during this phase. Instead, positive behavioural changes were reported after treatment, with queens being more docile and affectionate without oestrus behaviour manifestations. Further studies are needed to standardise and compare behavioural changes between chemical and surgical sterilisation. Few results were collected and therefore no analytical statistics were performed.