Intratesticular injection of a zinc-based solution for contraception of domestic cats: a randomized clinical trial of efficacy and safety.

It has been reported that a commercial zinc gluconate preparation disrupts spermatogenesis and apparently causes permanent sterilization in male dogs, but there is little information regarding similar approaches in the male cat. The objective of this study was to evaluate zinc gluconate as a permanent contraceptive for domestic male cats. Sixteen sexually mature mixed breed cats were allocated at random, by replicate, into two groups and given a single injection into each testis of either isotonic saline or zinc gluconate, respectively. Clinical and reproductive parameters were assessed immediately before injection and after 60 and 120 days. On day 120 the testis size of treated cats was decreased (P<0.05). Azoospermia occurred in 8/11 (73%) cats, and penile spines were decreased in 6/11 (55%) and absent in 4/11 (36%) cats, and there were substantial reductions in male behavior. However, plasma testosterone concentrations (single samples collected at each assessment) were not significantly different between treated and control cats at any time point. Although additional studies are warranted, intratesticular injection of zinc gluconate might have potential as a permanent contraceptive for cats.

In vitro evaluation of canine spermatozoa cryopreserved in different extenders

The efficacy of three extenders, tris-egg yolk-5 percent ethylene glycol (T1), lactose-egg yolk-5 percent ethylene glycol (T2) and lactose-egg yolk-5 percent dimethyl formamide (T3) on preserving the viability of post-thawing canine spermatozoa was evaluated. Three ejaculates per dog were obtained of five animals. The semen was packaged in 0.5ml straws and cooled to 4°C for 120min. The straws were frozen 4cm above the nitrogen level for 15min and thawed in water-bath at 37°C for 60sec and at 75°C for 7sec. Progressive motility and vigour were evaluated immediately after thawing (time 0) and at 30, 60, 90 and 120min. Structural and functional integrity of plasma membrane of the spermatozoa were evaluated, respectively, by fluorescent staining probes and hypoosmotic swelling test. Lactose-egg yolk based extenders showed better cryoprotectant capability and dimethyl formamide was an alternative cryoprotectant agent for dog sperm cells.

Avaliou-se a eficácia de três diluidores, tris-gema com 5 por cento de etileno glycol (T1), lactose-gema com 5 por cento de etileno glicol (T2) e lactose-gema com 5 por cento de dimetil-formamida (T3) na criopreservação do sêmen de cães. Foram obtidos três ejaculados por cão de um total de cinco animais. O sêmen foi envasado em palhetas de 0,5ml e resfriado até 4°C por 120min. As palhetas foram congeladas 4cm acima do nitrogênio líquido por 15min e descongeladas em banho-maria a 37°C por 60seg e 75°C por 7seg. A motilidade progressiva e o vigor foram avaliados imediatamente após a descongelação (tempo 0) e aos 30, 60, 90 e 120min. A integridade estrutural e funcional da membrana plasmática do espermatozóide foi avaliada, respectivamente, por meio da coloração de fluorescência e pelo teste hiposmótico. Os diluidores à base de lactose gema foram mais eficazes em preservar a viabilidade espermática pós-descongelação e a dimetil-formamida é um crioprotetor eficaz para espermatozóides de cães.