If you are working in a shelter, I am sure you already found yourself asking this question: is this pet spayed or neutered? That’s indeed an important one, because you don’t want her to go through an invasive surgery for no reason. And from a clinical standpoint, it’s not always something easy to answer! In males, if you do not observe the testes in the scrotum, it does not necessarily mean they are not there: they could indeed be retained (aka ectopic testis).In females, you might not see anything that looks like a surgical scar, but maybe it really healed well. When I was working at the vet school in Paris, we were seeing every year approximately 10 dogs or cats that had been adopted out and supposed to be neutered… while, in fact, this was not the case! Good news however: if you have any doubt about the neutered status, there are things that can now be done to double-check !
– In tomcats: testes are the main source of secretion of the hormone testosterone. Non castrated male cats will show specific testosterone-dependant spikes on their penis (see picture below). If you observe these penile spikes, there is definitely at least a testis secreting testosterone somewhere that needs to be looked for. If the animal can be easily manipulated, this is a very easy way to confirm the animal’s neutered status. Following castration, these spikes usually disappear in a month.
– In tomcats/queens/male dogs/bitches: the gonads (testes in the males; ovaries in the female) are involved in the regulation of the hormonal secretions of the reproductive function (see graph below). Gonadal hormones influence the secretion of a pituitary hormone called LH by what we call a negative feedback: to make it short when gonads are present, LH blood levels are usually low (except during the animal’s seasons, but then if seasons are observed why would you check, right?). If the gonads were removed, this negative feedback is lost and LH concentrations will always be higher. Semi-quantitative LH tests are available on the veterinary market, and therefore a simple blood simple can let you know if gonads are present… or not! The test is easy to performed, in house, and results will be obtained in minutes.