U.S. Department of Agriculture: Animal and Plant Health Inspection Service


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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


This document is a U.S. government work and is not subject to copyright in the United States.


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.

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