Pregnancy prevention raises much concern to many pet owners. Female cats usually show undesirable behaviour during oestrus. Nowadays, researchers try to explore the reliable and effective ways to prevent oestrus signs in queens. The results of their studies prove that hormone therapy is probably one of the most reliable methods for this purpose. The aim of our study was to compare the effect of three steroidal preparations on oestrus suppression in queens. Twenty clinically healthy adult female cats and three healthy adult male cats with natural libido were used in the present study. The female cats were randomly divided into 4 groups (n = 5). The male cats were caged separately and maintained near females for sexual stimulation. The photoperiod was regulated artificially to induce oestrus in cats (14 h light and 10 h dark). The experimental cats were kept in a roofed room for about 3 months for adaptation and confirmation of oestrus detection. After this period, group I (control group) did not receive any treatment, group II received 12.5 mg methyltestosterone/week orally for 90 days, group III received one tablet of contraceptive LD/day (0.15 mg levonorgestrel + 0.03 mg ethinyloestradiol) orally for 90 days and group IV received 3 mg medroxyprogesterone acetate intramuscularly. The cats were monitored clinically every day (4 h in the morning and 4 h in the afternoon). The number of queens observed in oestrus and the number of oestrous cycles were recorded during the study. The results of the present study showed that in group I (control) oestrus was detected twice in 2 out of 3 cats. In group II oestrus was detected 3 times in 3 cats, which was not statistically different to that of the group I (P>0.05). In group III oestrus was detected 13 times (more than the other groups). All 5 cats of this group showed oestrus, which was statistically increased compared to group I (P<0.05). In group IV no oestrus was detected, which was statistically decreased compared to group I (P<0.05). According to our results, methyltestosterone prevented the oestrus for only 1 month so that it can be used for oestrus suppression for a short time; contraceptive LD unexpectedly increased the frequency of oestrus in queens, therefore this drug can not be advised for prevention of the oestrus in queens; medroxyprogesterone acetate completely prevented the oestrus during the treatment. This drug is reliable, and only one injection is sufficient to prevent the occurrence of the oestrous cycle.

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