Date of this Version
Fischer, A., V.A.W. Benka, J.R. Briggs, M.A. Driancourt, J. Maki, D.S.O. Mora, K.N. Morris, K.A. Myers, L. Rhodes, L.M. Vansandt, G.R. Weedon, J. Wolf, and J.K. Levy. 2018. Effectiveness of Gonacon as an immunocontraceptive in colony-housed cats. Journal of Feline Medicine and Surgery 20(8):786-792. doi: 10.1177/1098612X18758549
Objectives Non-surgical contraceptive management of free-roaming cat populations is a global goal for public health and humane reasons. The objectives of this study were to measure the duration of contraception following a single intramuscular injection of a gonadotropin-releasing hormone-based vaccine (GonaCon) and to confirm its safe use in female cats living in colony conditions.
Methods GonaCon (0.5 ml/cat) was administered intramuscularly to 20 intact female cats (queens), and saline was administered to 10 queens serving as sham-treated controls. Beginning in late February, 4 months after injection, all cats were housed with fertile male cats in a simulated colony environment. Time to pregnancy, fetal counts and vaccine-elicited injection-site reactions were evaluated.
Results All control cats (n = 10/10) and 60% (n = 12/20) of vaccinated cats became pregnant within 4 months of the introduction of males. Two additional vaccinates became pregnant (70%; n = 14/20) within 1 year of treatment. Average fetal counts were significantly lower in vaccinated cats than in control cats. Vaccinates had a significantly longer (P = 0.0120) median time to conception (212 days) compared with controls (127.5 days). Injection-site reactions ranging from swelling to transient granulomatous masses were observed in 45% (n = 9/20) of vaccinated cats.
Conclusions and relevance A single dose of GonaCon provided contraception lasting for a minimum of 1 year in 30% (n = 6/20) of treated cats. The level of contraception induced by this GonaCon dose and vaccine lot was not sufficiently effective to be recommended for use in free-roaming cats.