Canine prostate cancer is an uncommon but aggressive, and often fatal, disease. Prostate cancer can affect both neutered and intact male dogs but usually occurs in older canines. The function of the prostate gland is to supply the fluid that transports the sperm and it lies below the rectum and just behind the bladder. The most common type of canine prostate cancer is carcinoma. This highly aggressive and invasive cancer can rapidly spread to the lymph nodes, bones and lungs. The condition usually goes undetected until the later, more advanced stages are evident. Canine prostate cancer seems to develop without any known cause and can affect any breed of dog.
By DR. KARSTEN FOSTVEDT
Prostate cancer is the development of a malignant tumor of the prostate. Although castration protects against most other prostatic diseases, it does not always prevent prostate cancer. Castration does not increase the risk of prostate cancer. The most common type of prostate cancer is called transitional cell carcinoma, which typically spreads from the bladder or urethra. Occasionally, other types of cancer can spread to the prostate (metastasis) from cancers in other organs of the body. The only way to distinguish the different types of cancer is to biopsy the dog’s prostate and send the biopsy samples to a veterinary pathologist.
Clinical signs occur as the tumor enlarges and presses on the urethra, the tube conveying urine from the bladder to the penis. Bloody urine, bloody or yellow discharges from the penis, straining to urinate and straining to defecate may all occur. If the tumor grows into the urethra, it can obstruct urine flow. Prostate cancer can spread to the backbone, leading to pain or difficulty at the rear legs while walking. An enlarged and irregular prostate can be detected by rectal palpitation, just like in humans.
Diagnostic tests are always performed. These include blood tests, urinalyses and abdominal X-rays. Chest X-rays may be indicated to search for metastases. Examination of tissue specimens is necessary to confirm the diagnosis. Cells are attained by needle aspiration of the prostate using ultrasound to guide the needle into the prostatic tumor. These cells are sent to a pathologist to confirm the diagnosis.
Treatment of prostate cancer in dogs is still problematic. Surgical removal of the prostate can be attempted, but is often accompanied by urinary incontinence. A laser can be used to remove the prostatic tumor tissue, but that is performed at specialty centers and is very expensive. Prostatic cancer does not usually respond well to chemotherapy. Intraoperative radiation therapy may provide some benefit, but again needs to be done at veterinary specialists or universities.
Prognosis for prostate cancer in dogs is poor. In 40 percent of dogs, spread of the cancer has occurred before the cancer has been detected in the prostate. When metastasis is present, average survival time is three months. If metastasis is not present, some dogs may live for up to nine months with treatment.
Dr. Karsten Fostvedt is a veterinarian at St. Francis Pet Clinic in Ketchum.
Prostatic Adenocarcinoma in Dogs
From Pet MD
The prostate gland is an important part of the male reproductive system. It contains many valuable and essential enzymes, including calcium and citric acid,and also plays an important role in the protection and motility of sperm. The liquid secreted by the prostate gland aids in the liquefaction of semen after ejaculation, and in the protection of sperm in the vagina.
Adenocarcinoma is a malignant tumor originating in the glandular tissue, in this case the tissue of the prostate gland, with the capability for growing and metastasizing rapidly to other parts and organs of body, including the lungs, bones, and lymph nodes. Prostatic adenocarcinoma is seen in both intact and neutered dogs, representing about one percent of all malignant tumors found in dogs. This disease can develop in any breed, but it most commonly affects large breeds, and like most carcinomas, it affects older dogs between the ages of 9-10 years.
Symptoms and Types
In adenocarcinoma of the prostate, the symptoms may vary depending upon the presence, extent, and location of metastasis to other parts of the body. Following are the symptoms commonly seen in adenocarcinoma of prostate:
Ribbon-shaped stool
Poor appetite
Weight loss
Difficulty in passing urine
Complete urine blockage
Pain, especially when the area of prostate is touched
Causes
Idiopathic – the exact cause is still unknown
Hormonal imbalance is suggested as one possible cause
Diagnosis
You will need to give a thorough history of your dog’s health, including a background history of symptoms. Your veterinarian will perform a complete physical examination on your dog, including blood tests and a biochemistry profile. Urine tests are an important part of the diagnostic process. The urine will be examined for the presence of white blood cells, infection, and malignant cells. Abdominal radiographs and ultrasonography will also be performed to view the symmetry, size, and outline of the prostate gland. Prostate tissue will also be taken by prostatic biopsy to confirm the diagnosis.
Treatment for canine prostate cancer is limited and, in most cases, chemotherapy and radiation therapy are the best option. Surgery on the prostate is complex and can be very dangerous as well as cause complications for your dog such as urinary incontinence. In some cases, anti-androgen drugs are used to fight the cancer, however, most dogs do not respond to these drugs so they have little effect. Having your dog neutered can largely decrease the risk of developing prostate problems such as infections and inflammation; however, it will not prevent dogs from developing prostate cancer. The frequency of canine prostate cancer is similar with both castrated and non-castrated male dogs. Because the disease is not usually detected until it has fully developed, the median life expectancy of dogs with prostate cancer is approximately thirty days. Proper treatment, including chemotherapy drugs with anti-inflammatory agents, may help to extend the life of your dog.
