Information for cats and dogs on symptoms of enlarged prostate glands and prostatitis infections.

What is an Enlarged Prostate?

Male dogs and cats have a prostate gland just like human men. It is a small gland located just behind the bladder, surrounding the urethra (the tube that carries urine from the bladder to the penis and out of the body) and below the rectum.

The gland’s function is to produce fluid found in semen, which provides nourishment for sperm cells during breeding. The gland begins to develop before your pet reaches puberty. This is determined by the male sex hormone, testosterone, that occurs in intact males. By 2 years of age, the gland reaches its maximum size.

A male pet’s normal gland size varies depending on breed, size, age and neutering status. Enlargement in pets can result from many causes, including the enlargement of epithelial cells, development of pre-cancerous cells, or inflammation in cells.

Since the urethra passes through the prostate gland, enlargement puts pressure on the urethra and makes urination uncomfortable. Complete obstruction is rare, but affected pets will spend a long time urinating and may only produce a weak stream of urine. Severe enlargement can also compress the colon, creating problems with bowel movements.

Your veterinarian can make a definitive diagnosis.

What Causes Enlarged Prostate?

Enlargement of the gland is common in intact male dogs, but less common in cats and other pets.

The most common related disease in intact male dogs is benign prostatic hyperplasia (BPH). It is frequently seen in unneutered dogs after the age of 5. BPH can worsen and improve cyclically, especially if females in heat are nearby.

Bacterial prostatitis, abscesses, cysts and cancer are much less common, but these forms of canine prostate enlargement can also be found in neutered males.

Causes of enlarged prostate:

• Benign prostatic hyperplasia (BPH) or cystic hyperplasia
• Prostatisis - bacterial infection and inflammation (either acute or chronic)
• Cancer – rare in dogs; typically, either an adenocarcinoma that originates in glandular tissue or a transitional carcinoma that spreads from the urinary tract. To confirm cancer, a biopsy is done.
• Paraprostatic cysts - large fluid filled sacs that form outside the gland and connect to it by a thin stalk
• Squamous metaplasia – enlargement of the gland caused by excessive exposure to estrogen
• Abscess – a pocket of infected fluid develops within the gland
• Prostatic neoplasia – tumors of the gland
• Squamous metaplasia – benign changes in the lining of the gland
• Sarcoma – cancer of the connective or support tissue (bone, muscle, blood, fat, cartilage) or soft tissue
• Hormonal imbalances

When a male pet is neutered, most of the prostate gland is removed. As a result, enlargement problems seldom occur in neutered pets.

Canine enlarged prostate mostly affects older intact males. When an intact dog grows older, their testosterone and estrogen sex hormone levels change and can cause the gland to swell. The swelling causes extreme discomfort and pain, making urinating and defecating very difficult.

Diagnosing Enlarged Prostate

Because there are many causes, your veterinarian will assess your pet’s individual situation. Diagnosis will vary depending on your dog’s overall health and symptoms.

The veterinarian will do a thorough physical examination, including a review of the pet’s medical history and a rectal exam. The vet may order tests such as urinalysis, urine culture, blood tests, x-rays, ultrasound and biopsy to confirm a diagnosis.

Ultrasound is an effective tool used to determine whether or not the gland is enlarged and to identify if there are cysts or abscesses. Blood tests may include complete blood count (CBC) and chemical blood profile. Urinalysis can determine if an infection is present in the bladder or urinary tract. Lab tests will often detect the presence of blood in the urine, along with bacteria and pus if infection is present.

An examination of prostatic fluid for the presence of blood can help your vet gather more information. A fine needle aspiration can draw fluid or cell tissue for further study. Fine needle aspiration is generally simple and safe, but like any procedure it carries some risks. Your vet can help you understand the risks and benefits of the procedure for your pet.

Biopsy is the most invasive diagnostic procedure, but also the most effective for diagnosing the cause of enlargement.

The common symptoms and signs of an enlarged prostate include:

Treatment for Enlarged Prostate in Pets

Treatment will vary depending on the underlying cause. Your veterinarian will prescribe treatment options including medications or surgical procedures best suited to your dog’s individual needs.

Prevention

Preventive measures ideally begin with neutering pets at an early age, usually before puberty, to prevent the normal growth of the gland. If your pet is neutered later in life, the gland will shrink after the testosterone is removed.

BPH

Dogs with benign enlargement (BPH) caused by excess hormone levels may undergo surgical castration (neutering) to relieve symptoms. BPH responds very well to hormone therapy. Testosterone and estrogen form in the testicles, so neutering is usually effective. After neutering, the prostate typically returns to its normal size within a month after surgery. If not treated, BPH can lead to infertility and serious infections.

Bacterial infections

Bacterial infections are usually treated with aggressive antimicrobial prostate medication for dogs. A combination of antibiotics and sex hormone therapy is usually effective. If left untreated, these common infections can become life-threatening. Treatment lasts for several weeks to months, because it is difficult for the antibiotics to penetrate the prostate gland. Antibiotics used for canine bacterial infections include enrofloxacin, erythromycin, ciprofloxacin, chloramphenicol, doxycycline, and trimethoprim-sulfonamides. Since the bacterial infection is often caused by another disease, this treatment is part of a larger overall treatment plan.

Abscesses and cysts

Abscesses or cysts can be surgically drained.

Cancer

Prostate cancer is rare and usually occurs only in neutered male dogs. Both adenocarcinoma and transitional carcinoma have poor prognosis and are life-threatening. Surgery is not usually an option, and medicine may only help briefly. These types of canine cancers are confirmed via biopsy. Ultrasound-guided biopsy can be used instead of more invasive surgical procedures. In dogs with prostatic carcinoma, external beam radiotherapy may help relieve pain.

During and after treatment, your vet will want to assess if the treatments are working. Abdominal x-rays or ultrasonography may be used to check progress. For bacterial infections, your vet will also collect urine and fluid cultures to determine if the antimicrobial treatment is working.

More Information on Enlarged Prostate

Tips to manage a pet with an enlarged prostate

1. “Prostate Gland Enlargement in Dogs.” PetMD. Accessed October 10, 2019. https://www.petmd.com/dog/conditions/reproductive/c_dg_benign_prostatic_hyperplasia
2. Greer, Marty. “Prostate Disorders: How to Handle Them in Your Male Dogs Without Neutering.” American Kennel Club. Accessed October 10, 2019. https://www.akc.org/expert-advice/health/prostate-disorders-in-male-dogs/
3. Llera, Ryan. “Prostatic Disease in Dogs.” VCA Hospitals. Accessed October 10, 2019. https://www.akc.org/expert-advice/health/prostate-disorders-in-male-dogs/
4. Kutzler, Michelle. “Overview of Prostatic Diseases.” Merck Manual Veterinary Manual. Accessed October 10, 2019. https://www.merckvetmanual.com/reproductive-system/prostatic-diseases/overview-of-prostatic-diseases
5. “Prostate Enlargement in Dogs.” PetMD. Accessed October 11, 2019. https://www.petmd.com/dog/conditions/endocrine/c_dg_prostatomegaly?page=2