The use of proligestone, megestrol acetate and GnRH on queens with the aim of hormonal contraception


Abstract: The aim of this study was to investigate the efficacy of the use of two different progestagens either singly or in a combination with GnRH on queen contraception. The study was performed on a total of 73 female cats of various breeds at various stages of cycles. Queens at interoestrous (n=35) and oestrous periods (n=38) of sexual activity were treated under two main groups. Twenty cats of the first main group at interoestrous period (Group-1/A) were administered 30 mg/kg (sc) proligestone (PRG) and the remaining 15 cats (Group-1/B) were administered 25 mg (sc) megestrol acetate (MA). The cats at oestrous period were first given 50 \mug gonadotropin releasing hormone (GnRH) (im). 48-96 hours following the application 23 of these cats (Group-2/A) were administered 30 mg/kg (sc) PRG, while the other 15 cats (Group-2/B) were administered 25 mg (sc) MA. The disappearance of oestrous symptoms was established to be 2.85±0.74 days in Group-1/A, 2.93±1.35 days in Group1/B, 3.08±0.84 days in Group-2/A and 2.86±0.64 days in Group-2/B. Following hormonal injection the periods of remaining calm were established to be 8.00±2.20 months in Group-1/A, 3.33±1.01 months in Group-1/B, 7.57±2.35 months in Group-2/A and 4.90±2.65 months in Group-2/B. No difference has been established among mean values from the point of view of the disappearance of oestrous symptoms among groups (Group-1/A:Group-1/B= p<0.83, Group-2/A:Group-2/B= p<0.37). Following the injection of hormone the longest period of remaining calm was on average of 8.0 and 7.57 months in Group-1/A (PRG) and Group-2/A (GnRH+PRG) respectively and this period was found to be statistically significant with respect to periods of remaining calm in the other groups (Group-1/A:Group-1/B= p<0.0001; Group-2/A:Group-2/B= p<0.0038). It has been established that the GnRH application terminated the oestrous symptoms in 84.2% of the female cats within the first 3 days only, though in 15.8% of cats these symptoms continued decrease. In female cats on whom, PRG was applied, formation of pyometra and breast tumours was not observed while following the application of MA, pyometra formation was seen in 2 cats (6.6%). It has been determined that postponement of the oestrous and induction of ovulation with the use of PRG or GnRH+PRG provide long term and complication-free periods of remaining calm.

Keywords: Proligestone, Megestrol acetate, GnRH, Queen, Contraception

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