Prostate cancer in humans is well-known, but what about prostate cancer in dogs? Although prostate cancer in dogs is not as common as in humans, in dogs it is more insidious. It is important that dogs have routine examinations so that problems can be detected early which often makes for a better prognosis. Prostate cancer can affect all dogs, but some breeds appear to be particularly predisposed. Learning more about the symptoms of prostate cancer in dogs is important. Signs of prostate cancer in dogs should prompt a veterinary examination so to rule out or confirm this condition. Following is information about prostate cancer in dogs by veterinarian Dr. Ivana Crnec.
A Lesson in Anatomy
To make things clear, we need to say a word or two about the dog's prostate anatomy and physiology. A dog's prostate gland is an integral part of the male reproductive system.
This organ wraps around the top of the urethra at the bladder outlet. The dog's prostate has a walnut-like appearance and its size is determined by the testosterone levels.
Categorized as an accessory sex organ, the prostate is responsible for producing the fluid that carries sperm and makes up semen. In addition, the prostate fluid nourishes the sperm cells.
As dogs age, the prostate gland naturally increases in size, usually reaching its maximum size between six and ten years of age. This gradual increase in size is commonly known as prostate enlargement.
Prostate Cancer in Dogs
Prostate cancer is a serious and potentially life-threatening condition among dogs older than 6 years. The condition is more common in intact male dogs, but it is not impossible in neutered males too.
As previously stated, over time, all prostates enlarge due to natural aging. The enlargement is triggered by the constant and prolonged gland exposure to the testosterone’s effects and usually does not affect the normal function of the reproductive system. This naturally occurring enlargement is called benign prostatic hypertrophy (BPH).
However, in some dogs the enlargement is due to tumors. Prostate tumors can be either benign or malignant. Malignant prostate tumors are referred to as prostate cancers.
There are two types of prostate cancers in dogs: adenocarcinoma which originates from the prostate’s glandular tissue. This type is more common and malignant. Transitional cell carcinoma which originates from the urethra lining in the prostate. It grows slowly and is less malignant.
Prostate cancers have high metastatic potentials. This means they are very likely to spread on to other tissues and organs. Prostate cancers usually tend to spread to lungs, bones and lymph nodes.
Certain dog breeds are more prone to developing cancers. These breeds include: golden retrievers, Bernese mountain dogs, Rottweilers and beagles.
Signs of Prostate Cancer in Dogs
There are several signs of prostate cancer in dogs, but dog owners may not readily recognize the early signs of prostate cancer which may be similar to other health conditions. Generally speaking, the clinical signs of prostate cancer include: general pain, overall debilitation and weakness, decreased appetite and weight loss.
As the dog's prostate enlargement progresses the prostate pushes itself against the urethra’s wall. Due to this pressure, the affected dog shows trouble urinating (stranguria) and blood in the urine (hematuria).
Because of the urination difficulties, affected dogs manifest frequent urination urges and an abnormal posture while urinating (humped back).
If the enlargement is significant in size, it will put pressure on the dog's rectum, thus, causing the dog to pass flat, ribbon-like feces. The pressure against other surrounding tissues may also lead to hind leg lameness.
What Happens At The Vet's Office
The clinical diagnosis is based on thorough physical examination and additional diagnostic procedures. Rectal palpation is an integral part of the physical examination. By palpating the dog's prostate gland through the rectum, the vet will inquire data about its size and shape.
Additional diagnostic procedures include bloodwork (to assess the dog’s general health status), urinalysis (to detect presence of cancer cells), abdominal ultrasound (to evaluate the prostate’s size and shape) and full body X-ray imaging (to determine the presence of metastasis).
Since the manifesting signs and symptoms are non-specific and easy to associate with other conditions, they do not significantly contribute to the diagnostic process.
When the diagnosis is confirmed, it is advisable to perform an ultrasound guided biopsy. The biopsy will determine the exact type of cancer and its malignancy degree. These data are necessary for tailoring the right treatment approach and giving an evidence-based prognosis.
Treatment of Prostate Cancer in Dogs
The most radical treatment option is surgery. However, it has been shown that surgical removal of the entire prostate gland results in urinary incontinence (involuntary urination). In addition, considering the common rate of metastasis, eliminating the original cancerous tissue does not resolve the problem. Therefore, although radical and aggressive, surgical treatment is rarely recommended.
Another aggressive treatment option is intensity-modulated, image-guided radiation. This type of treatment is more effective than regular radiation, but its disadvantage is that it has some side effects like incontinence and gastrointestinal and genitourinary toxicosis. While treated, the dog needs to be hospitalized and closely monitored for side effects development.
With that being said, it can be concluded that conservative approaches are more suitable. Using non-steroid anti-inflammatory drugs (NSAID’s), such as carprofen (Rimadyl) and piroxicam, can prolong the dog’s survival time to an average of 7 months.
For the moment, combining NSAID’s with radiation therapy and chemotherapy is the most effective treatment. This treatment combination prolongs the survival time to as much as 20 months.
The prognosis for patients with prostate cancers is guarded. Depending on the type of tumor, the treatment option and how well the dog responds to that option, the average survival rate varies between 6 weeks and 1 year.
Did you know? The best prevention option for prostate cancer in dogs is neutering. In dogs neutered before puberty, the prostate does not develop due to the lack of testosterone. In dogs that are neutered after puberty, the prostate gland shrinks. Either way, the risk of developing prostate cancer in neutered dogs is significantly low.
- BPH - Prostate enlargement problems, 26 February 2016, Akcmdu9