Peer-reviewed veterinary case report
Phage vaccine tested to control fertility in male cats
By Johnson, Aime K et al.·Published in Journal of feline medicine and surgery·2020·Department of Clinical Sciences, United States·View original on PubMed →
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Original publication title: Phage constructs targeting gonadotropin-releasing hormone for fertility control: evaluation in cats.
- Species:
- cat
Plain-English summary
A group of sexually mature male cats received a new vaccine designed to control fertility by targeting a hormone called gonadotropin-releasing hormone (GnRH). After receiving the vaccine, all cats developed antibodies against GnRH, which led to a significant drop in testosterone levels and a decrease in testicular size over several months. While the cats continued to produce sperm, the quality of the sperm was reduced. This vaccine shows promise for managing fertility in cats, especially in situations like shelters or zoos, but more research is needed to refine the treatment and determine the best age for vaccination.
People also search for: cat fertility control vaccine · male cat testosterone levels · how to reduce cat sperm quality · cat contraception options
Abstract
OBJECTIVES: Phage-gonadotropin-releasing hormone (GnRH) constructs with potential contraceptive properties were generated in our previous study via selection from a phage display library using neutralizing GnRH antibodies as selection targets. In mice, these constructs invoked the production of antibodies against GnRH and suppressed serum testosterone. The goal of this study was to evaluate this vaccine against GnRH for its potential to suppress reproductive characteristics in cats. METHODS: Sexually mature male cats were injected with a phage-GnRH vaccine using the following treatment groups: (1) single phage-GnRH vaccine with adjuvant; (2) phage-GnRH vaccine without adjuvant and half-dose booster 1 month later; or (3) phage-GnRH vaccine with adjuvant and two half-dose boosters with adjuvant 3 and 6 months later. Anti-GnRH antibodies and serum testosterone, testicular volume and sperm characteristics were evaluated monthly for 7-9 months. RESULTS: All cats developed anti-GnRH antibodies following immunization. Serum antibody titers increased significantly after booster immunizations. In group 3, serum testosterone was suppressed 8 months after primary immunization. Total testicular volume decreased in group 1 by 24-42% and in group 3 by 15-36% at 7 months after immunization, indicating potential gonadal atrophy. Vacuolation of epididymides was observed histologically. Although all cats produced sperm at the conclusion of the study, normal morphology was decreased as much as 38%. Phage alone produced no local or systemic reactions. Immunization of phage with AdjuVac produced unacceptable injection site reactions. CONCLUSIONS AND RELEVANCE: Our phage-based vaccine against GnRH demonstrated a potential for fertility impairment in cats. Future research is required to optimize vaccine regimens and identify animal age groups most responsive to the vaccine. If permanent contraception (highly desirable in feral and shelter cats) cannot be achieved, the vaccine has a potential use in zoo animals or pets where multiple administrations are more practical and/or reversible infertility is desirable.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/31566070/