In the wild, inherent male behaviour was necessary for survival of the fittest. In modern society, male dogs often destroy property whilst seeking out females. They will be a risk to themselves and other people as they negotiate roads. Male dominance aggression will increase the danger to all involved in these situations.
Vasectomised and entire male dogs will nearly all develop prostatic disease in old age. Diseases vary from benign prostatic hyperplasia to cancer, which is usually malignant and often already spread upon diagnoses.
Signs of any prostatic disease are similar despite the cause:
- blood in the urine,
- straining to urinate,
- straining to defecate and
- generally unwell.
Diagnosis is based on ultrasound, x-rays, blood tests, and prostatic sampling. Treatment often involves admittance to hospital, long courses of medication (due to prostatic resistance to drugs) and castration is usually recommended, since removing the source of testosterone will cause the prostate to shrink. Chemical castration is a possibility however it is less reliable than surgical.
And so it is for medical and societal reasons that castration is recommended over vasectomizing dogs and cats. Castration is a relatively easy procedure to perform, fast and inexpensive, and in the long run has many benefits over vasectomizing pet dogs.