In spay-neuter clinics, orchiectomy (castration) is the surgical procedure carried out on male dogs with the primary purpose of addressing population control. Removal of the testis prevents sperm production and therefore the establishment of pregnancy through copulation.
Castration also has other effects which vets should be aware of, particularly when advising owners:
Aggression. Aggression and territorial behaviours are reduced between animals, resulting in a lowering of the incidence fight injuries and potential for disease transmission.
Straying behaviours. The tendency to wander and seek out females in oestrus is reduced after neutering.
Health. One of the most important effects of controlling dog numbers is reducing the incidence of rabies, a deadly viral disease that is transmitted to dogs and humans through bites or the deposition of infected saliva on mucous membranes or damaged skin from an infected animal. The incidence of other zoonotic diseases is also reduced.
Testicular neoplasia is the second most common neoplasm in dogs; incidence varies from between 1.3 and 16.2% of the population1 2. Surgical removal therefore prevents tumour development. In addition, androgenic-driven conditions, such as benign prostatic hyperplasia, chronic prostatitis, and perineal hernia and adenomas, are also reduced.
There is confusing evidence regarding the association of castration with obesity with studies reporting both an increases in obesity in castrasted dogs compared to entire ones, and no differences3 4. Another study appears to demonstrate an increase in prevalence of obesity in dogs neutered after 6 months of age compared to before 6 months5. Other health considerations exist, such as a reported two-fold increase in developing a cranial cruciate rupture in neutered dogs compared to intact ones6-8.
Age. There are no significant health considerations with early neutering reported in males as compared to females, and no evidence to support early versus late neutering.
Type of surgical procedure
There are two main methods of approach to castrating dogs: pre-scrotal and scrotal. At our ITCs, we routinely teach the pre-scrotal method and this will be concentrated on in the following article. Castration can be carried out by a closed or open approach:
Closed. The parietal vaginal tunic is not entered and the entire spermatic cord is ligated. This is the method commonly taught at our ITCs. It avoids potential exposure into the abdominal cavity through the vaginal tunic.
Open. The parietal vaginal tunic is opened, and the ductus deferens and vascular cord are individually ligated before closing the vaginal tunic again. This method should not be used if orchitis is suspected.
Cryptorchid presentations
Cryptorchidism results from a failure of the gonads to descend into the scrotum from the abdominal cavity. If both testis cannot be palpated by eight weeks of ages, the dog is considered to by cryptorchid. Incomplete descent can occur in one or both testes and can result in complete retainment in the abdominal cavity or partial movement through the inguinal ring into the upper inguinal region.
Castration is always recommended for cryptorchid animals as the condition is thought to be a sex-linked, autosomal recessive trait and therefore can be passed on to offspring. In addition, retained testes have an increased incidence of testicular neoplasia and should be removed if possible.
A separate article will explain how to approach the surgical castration of cryptorchid dogs.