The two major reasons for neutering a nonbreeding dog have been for better behavior and health. As one of the species to have a prostate, an intact male dog shows a higher risk for prostate problems the older he gets. In many cases, a dog will show signs of these problems on average by the age of 8: benign prostatic hyperplasia or BPH, bacterial prostatis, paraprostatic cysts and prostatic neoplasia -- also known as cancer.
BPH results from the natural aging process of a dog's working prostate. Neutered males lose most function of the prostate after surgery. If older dogs show signs of bloody urethral discharge, tenesmus, or bloody or painful ejaculate -- for breeders -- even infrequently, these could be signs of BPH. Further, because of the risk of glandular hypertrophy associated with this problem, prostatic cysts may develop. The most effective treatment is neutering the dog, although some medicinal choices do exist.
Bacterial prostatis results from an infection of the prostate gland. Though occurring at any age, this illness is mostly seen in older dogs with BPH. It is more severe than BPH despite having similar symptoms, which also are more severe. It can cause ascending infections throughout the dog's body; therefore, fever, pelvic discomfort, and partial anorexia are additional signs. If left untreated, prostatic abscesses may develop. The abscesses can be life-threatening due to the risk of septicemia, endotoxemia and localized peritonitis. These abscesses constitute an emergency and have a high mortality rate when ignored. Neutering is the advisable solution.
These cysts, unlike those found with BPH, are not "true" prostatic cysts. They are found around or attached to the outside of the prostate gland, while BPH-related cysts are found within it. In a radiograph, paraprostatic cysts can appear as large as a second bladder in the dog. Though they typically remain benign, the cysts should be removed before they grow large enough to interfere with the urinary tract or cause infection. Once infected, these cysts most often result in prostatic abscesses.
Almost all prostate problems are heralded by the dog having trouble defecating since the prostate is so close to the rectum. Neoplasia is no exception. Prostatic disease does not mean a dog will get cancer. Only 5 to 7 percent of dogs with prostate troubles get neoplasia; however, neoplasia is the most lethal due to the diagnosis coming too late to stop metastatis. Most dogs with neoplasia will have prostatic adenocarcinoma, which infects both intact and castrated dogs. Other dogs may get transitional cell carcinoma -- which recent studies claim may be caused by neutering -- leiomyosarcoma, and hemangiosarcoma. Dogs suffering from neoplasia will show signs of other prostate diseases, but also may have abdominal or lumbar pain, rear limb weakness, weight loss and more. Adenocarcinoma often has a survival rate of one to two months post-diagnosis.
- Atlantic Coast Veterinary Conference 2001: Diagnosis and Medical Management of Canine Prostatic Disease; Melissa S. Wallace, DVM, Dipl. ACVIM
- Professor's House: Prostate Cancer in Dogs
- National Center for Biotechnology Information: A Population Study of Neutering Status as a Risk Factor for Canine Prostate Cancer; Jeffrey N. Bryan, et al
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