Canine cancer: Prostate cancer

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Description

We generally hear human beings developing prostate cancer. But dogs can also develop the same disease. In fact prostate cancer is much more insidious in dogs compared to human beings. It accounts for 0.67% of all reported malignancies in dogs. Prostate cancer has a very high metastatic potential and can spread to organs like the lungs, bones and lymph nodes.

But before we delve into this cancer deeply, it is important for us to understand how the prostate gland functions in dogs. It looks like a walnut and is located behind the urinary bladder and directly below the rectum. Also called an accessory sex organ, it’s size is usually determined by the male hormone testosterone and various other disease conditions. Semen constitutes 25-30% of the fluid secreted by the prostate gland. It also provides nourishment to the sperm cells and helps in breeding.

Prostate cancer is more common in intact males. The effects of the hormone testosterone on the gland over time triggers the disease. Very often it leads to benign prostatic hypertrophy (BPH) in older male dogs. Dogs more than 8 years of age are prone to develop prostate cancer.

Symptoms

The clinical signs may include general pain, debilitation and weight loss. Due to the enlargement of the prostate gland, it may push itself up against the wall of the urethra. This exerts pressure on the penis leading to stranguria (difficulty with urination). and hematuria (blood in the urine).

Other abnormalities include lameness in the hind leg, humped back, weird posture while urinating, urge to urinate more frequently but not producing sufficient urine and taking shorter steps while walking.

Diagnostic work-ups

It is not very easy to detect the disease because these symptoms are also present in dogs with other kinds of kidney and urinary bladder infections. The malignancy goes undiagnosed till it has reached an advanced stage. It can be detected through tests like urinanalysis, contrast X-rays, ultrasound scans, abdominal and rectal palpations and biopsy.

Ultrasound determines whether the prostate is actually swollen or it has polyps, cysts or tumors that are causing problems. However, it does not tell us whether the tumor is cancerous. So, in order to find out whether this is a malignant tumor or not, doctors go for biopsy of the rectal wall. If it is found to be a case of malignancy, the examination also tells the doctor what kind of a cancer this is.

Treatment

Normally, prostate cancer is non-amenable to surgery because of its location. So, the other options available include chemotherapy and radiation therapy. But if the cancer is hormone responsive, it can be treated with castration. But unfortunately prostate cancers are not hormone responsive. So they do not respond to anti-androgen medicines (hormone receptor compounds that inhibit the growth of male sex hormones).

Prognosis

Prognosis for prostate cancer is guarded. The average survival rate is 6 weeks- 1 year.