An enlarged prostate is a common issue that affects many aging intact male dogs. There are a number of causes of an enlarged prostate in dogs and in this blog post, we will explore some of the most common causes of an enlarged prostate in dogs. These include benign prostatic hyperplasia (BPH), prostatic cysts, prostate cancer, and prostatic infections. We will also discuss treatment options and how to keep your dog healthy and comfortable.
What is the prostate and what are its functions?
Firstly, let's start with understanding what the prostate gland is and its function in dogs. The prostate gland is a walnut-sized organ located near the bladder and surrounds the urethra. Its main function is to produce semen, which helps transport sperm during breeding.
What is an enlarged prostate in dogs?
An enlarged prostate occurs when the prostate gland grows in size beyond its normal range, causing it to press against the bladder, urethra, and sometimes the colon if it is large enough. This can result in various symptoms such as difficulty urinating, straining during urination, blood in urine or semen, straining to defecate, and pain or discomfort in the abdominal area.
1. Benign Prostatic Hyperplasia (BPH)
Benign prostatic hyperplasia (BPH) is the most common cause of an enlarged prostate in dogs. BPH is a non-cancerous growth of the cells in the prostate gland. It occurs due to hormonal changes as the dog ages and is particularly influenced by testosterone.
The enlarged prostate can compress the urethra and cause difficulty urinating. BPH is most commonly seen in older intact male dogs but can occasionally affect dogs by 2 years of age.
BPH is usually diagnosed based on history and physical exam findings. Your veterinarian will palpate your dog's prostate, and BPH-diagnosed dogs often have a bilaterally symmetrical, non-painful enlargement of the prostate.
While most dogs with BPH have no clinical symptoms, some dogs may have blood in their urine (hematuria), straining to defecate (tenesmus), and/or straining to urinate (stranguria). Although very uncommon, urinary outflow obstruction may also occur.
Diagnosis of BPH in dogs involves physical examination, blood tests, and imaging studies such as abdominal radiographs and ultrasound.
In most asymptomatic dogs, there is no need for treatment for BPH, but they should be monitored for progression and the appearance of clinical symptoms. If your dog is displaying symptoms, castration or neutering is the best course of treatment. This method can result in a 50% decrease in prostate size within 2-3 weeks.
If castration is not an option and clinical symptoms are present, medical management is recommended. Finasteride is the most commonly used medication to treat BPH in dogs as it inhibits the uptake of testosterone into the prostate, which decreases the prostate size.
2. Prostatic Cysts
Prostatic cysts are another common cause of an enlarged prostate in dogs. The cysts can be very large in size and are often fluid-filled and most commonly affect middle-aged intact male dogs. They can become large enough to compress other abdominal organs, including the colon, urethra, and urinary bladder.
Prostatic cysts are growths that develop from obstruction of the ducts in the prostate gland, which causes a build-up of prostatic secretions. The cysts can be either single or multiple in number and can vary in size.
Paraprostatic cysts, however, are fluid-filled sacs that are found next to the prostate gland, but not actually inside it. They are connected to the prostate by a thin tissue, much like a stem or stalk. These cysts are separate from the main tissue of the prostate and do not have a direct connection to the urethra, which is the tube through which dogs pass urine.
Both types of prostatic cysts in dogs are diagnosed with a detailed physical examination and imaging studies such as abdominal radiographs, abdominal ultrasound, and contrast radiography.
Some dogs with prostatic cysts may be asymptomatic. Possible clinical symptoms include straining to urinate (stranguria), blood in the urine (hematuria), enlarged abdomen, and difficulty defecating (tenesmus).
The treatment of choice for prostatic cysts in dogs is surgical drainage and excision of the cyst(s) if possible. Additionally, ultrasound-guided drainage can be an effective way to treat prostatic cysts. Castration is also recommended at the time of therapy.
3. Prostate Cancer
Prostate cancer is another cause of an enlarged prostate in dogs. It is caused by the uncontrolled growth of prostatic cells. Most prostatic cancers are malignant, but benign tumors can also occur, though they are rare.
Prostate tumors in dogs are usually very aggressive and have high rates of spreading and mortality. Most primary prostate tumors in dogs are carcinomas, specifically adenocarcinomas.
There is not a full understanding of what causes prostate cancer in dogs. It is possible that genetics play a role in the development of dogs. Although uncommon, prostate cancer can develop in neutered male dogs.
Histopathology (biopsy) is required for a definitive diagnosis and there are genetic tests available that may help to indicate a dog's risk of developing prostate cancer. The veterinary equivalent of the PSA test performed in human males is not widely used in dogs as it is not as accurate.
Clinical signs of prostate cancer in dogs include blood in the urine (hematuria), weight loss, lethargy, anorexia, hind-end weakness, and difficulty urinating or defecating.
As prostate cancer in dogs is very aggressive and has a high rate of metastasis at the time of diagnosis, treatment options are limited. Surgical removal of the prostate is not widely used because of this. Radiation therapy is another option but its use is limited because of the tumor location and potential for damage to surrounding tissues. Various chemotherapy protocols and NSAIDs use have been used to treat prostate cancer in dogs.
4. Prostatitis
Prostatitis is an inflammation of the prostate gland and it's the second most common prostatic disease in dogs who haven't been neutered. Prostatitis is usually caused by bacteria (mostly E. coli) migrating up from the urethra to the prostate. Prostatitis can occur secondarily to benign prostatic hyperplasia (BPH) as the changes associated with BPH can make the prostate more susceptible to prostatitis.
As prostatitis causes an enlarged prostate in dogs, your veterinarian will need to palpate the prostate for any changes. Prostatic infections in dogs are typically painful, so your dog may show signs of discomfort when the prostate is palpated. A urinalysis will often reveal bacteria and/or white blood cells, which can help to confirm a diagnosis of prostatitis. Further testing, such as urine culture, may also be recommended.
Clinical symptoms can vary based on the type of inflammation in the prostate. In cases of acute prostatitis, dogs may exhibit symptoms similar to a severe urinary tract infection. These can include blood in the urine (hematuria), painful urination (dysuria), discharge from the urethra, and loss of bladder control (urinary incontinence).
Additionally, dogs might experience constipation, straining during defecation (tenesmus), a stiff walk, or a reluctance to move. Pain in the prostate may also occur, leading to discomfort in the lower back, pelvis, or abdomen. Systemic symptoms, such as loss of appetite (anorexia), lethargy, fever, and vomiting, can also be present in these cases.
In contrast, chronic prostatitis often presents without symptoms (asymptomatic) in dogs. However, intermittent signs indicative of a urinary tract infection may be observed. Other signs like straining during defecation (tenesmus), constipation, and infertility can also occur in chronic cases.
The mainstay treatment for prostatitis in dogs is antibiotics. Culture results and the ability of the antibiotic to pass through the prostate are used to select an appropriate antibiotic. A special type of antibiotic called enrofloxacin is typically used for 4-6 weeks to treat acute prostatitis and may require longer treatment durations for chronic pancreatitis.
If the dog is intended for breeding purposes, your veterinarian may also recommend finasteride to help reduce the size of the prostate without affecting testosterone levels.
Castration and neutering is a recommended course of action to help control infection in cases of chronic bacterial prostatitis and also to help reduce prostate size in dogs that are not going to be used for breeding.
An enlarged prostate in dogs is a common problem that can occur in any breed of dog but is most commonly seen in older male dogs. There are a number of different causes of an enlarged prostate, including benign prostatic hyperplasia (BPH), prostatic cysts, prostate cancer, and prostatic infections. Prostatic diseases usually occur in intact dogs but can also affect neutered dogs. If you think your dog may have an enlarged prostate, please contact your veterinarian for further testing and treatment options.