Efficacy of levonorgestrel when administered as an irradiated, slow-release injectable matrix for feline contraception
Publication Type: |
Journal Article |
Year of Publication: |
2001 |
Authors: |
Sheri Looper, Gary Anderson, Yichun Sun, Atul Shukla, Bill Lasley |
Publication/Journal: |
Zoo Biology |
Publisher: |
Inc., John Wiley & Sons |
Keywords: |
cat, estrogen, pregnancy, progesterone |
ISBN: |
1098-2361 |
Abstract:
Abstract 10.1002/zoo.1039.abs Reliable and safe methods of reversible contraception are needed for use in zoo felids. The efficacy of levonorgestrel (LNG) as a contraceptive, when delivered as a cesium-irradiated, slow-release, injectable matrix, was tested in domestic cats as a model for exotic cats. An increase (P = 0.0017) in body weight was observed in treated but not control queens (P = 0.2146). All control queens (n = 6), which received injections of matrix only, but none of the LNG-treated queens (n = 6) became pregnant during the trial. Levonorgestrel was effective in preventing pregnancy for at least 36 weeks after two injections of drug-loaded formulations (40 mg/kg body weight), administered 68 days apart. Throughout the study, all control queens displayed luteal activity and fluctuating fecal estradiol concentrations, whereas the LNG-treated queens displayed lower estradiol concentrations and no luteal activity after treatment. We conclude that LNG, when delivered as a cesium-irradiated, slow-release, injectable matrix, is an effective contraceptive in domestic cats, reducing follicular activity, and thus, preventing mating and luteal activity. Zoo Biol 20:407–421, 2001. © 2001 Wiley-Liss, Inc.