GnRH Irnmunocontraception of Male Cats

Authors

Megan K. Ross, College of Veterinary Medicine, University of Florida
Julie K. Levy, University of Florida
Lowell A. Miller, National Wildlife Research Center, USDAFollow
Cynda Crawford, University of Florida
Jerry W. Ritchey, Oklahoma State University
Kathleen A. Fagerstone, National Wildlife Research Center, USDA

Document Type

Article

Date of this Version

January 2005

Abstract

The develop~llenot f nonsurgical co~ltraceptivesf or cats may facilitate population control of the species. The purpose of this study was to investigate the utility of GI&H for iinillu~locontraceptioo~fl male cats. Male cats (11=12) were divided into groups of tlxee and were inunuilized once with 0 (sham), 50, 200, or 400 i g synthetic GI&H coupled to keyhole limpet hernocyanin and combined with a nlycobacterial adjuvant to e~lhance inullunogenicity. GI&H ailtibody titer, serunl testostero~lec oncentration, and scrota1 size were detenniiled monthly. At 6 1110, semen was collected by electroejaculation and testes were examined histologically. GnRH antibodies were detected in all cats receiving GuRH vaccine by 1 nlo post-treatment and persisted tl~oughouth e study. No dose effect of GnRH was observed as titers were not significantly different between cats treated with 50, 200, or 400 i g GnRH (P = 0.5). Six of ni11e treated cats were classified as responders based on high GIIRH ailtibody titers (>32,000). By 3 mo post-treat~llent,r espo~lderc ats had undetectable testosteroile and testicular atrophy. Nonrespoilder cats had GnRH titers of 4,000 to 32,000 and testosterone conce~ltrationsin tei-nlediate between responder and sllailr treated cats. At 6 mo, total spenn counts were similar for shamtreated cats (3.1 i 1 S x lo6 sperm) and noixesponder cats (3.4 k 1.6 x lo6 sperm; P = 0.7). Only one of the six responder cats produced spei-111, none of which were motile. Co~llbinedte sticular weights of respoilder cats (1.3 k 0.1 g) were lower than sha~n-treatedc oiltrols (5.3 * 1.3 g; P = 0.02) and ilomesponder cats (2.9 k 0.3 g; P = 0.02). Histologic evaluatioil of the testes revealed that in responder cats, the interstitial cells that were present were pale and shruilltei~c onlpared to the pluillp, polyhedral eosinophilic cells in shan~treatedc ats. GnRH responder cats had marked tubular atrophy with vacuolated Sertoli cells and a paucity of germ cells. SingIe-dose GnRH treatment resulted in testosterone concelltrations and semen quality coilsistent with imrnunocastration in a majority of cats treated.