Prostate disease is often thought of as a human medical issue; however, prostate problems are surprisingly common in dogs too, particularly in entire (unneutered) males as they get older. The prostate gland can be affected by a range of conditions, from relatively manageable age-related enlargement through to serious infection and aggressive cancer. 

Some prostate diseases develop gradually and cause subtle signs at first, while others can make dogs unwell very quickly. One of the challenges is that the symptoms are often vague and can easily be mistaken for constipation, arthritis, urinary disease or simple signs of ageing. Knowing what to watch for can therefore make a big difference. 

In this article, we will discuss some of the main prostate diseases seen in dogs, such as benign prostatic hyperplasia (BPH), prostatitis and prostatic neoplasia. We will also discuss how these conditions are diagnosed, treated and, in some cases, prevented. Read on to find out more. 

What is the prostate gland? 

The prostate is a small gland located just behind the bladder and surrounding the urethra, which is the tube carrying urine out of the body. Its role is to produce fluid that forms part of semen. The gland is heavily influenced by male hormones, particularly testosterone, which is why prostate disease is seen predominantly in entire male dogs. In younger dogs the prostate is usually small and causes no issues. As dogs age, changes within the gland become increasingly common. 

Benign prostatic hyperplasia (BPH) 

Benign prostatic hyperplasia is by far the most common prostate disorder in dogs. The condition refers to a non-cancerous enlargement of the prostate gland caused by hormonal stimulation over time. Studies suggest that the majority of entire male dogs develop some degree of BPH as they age, even if they never show obvious clinical signs. Microscopic changes can begin relatively early in life, sometimes by two to three years of age, although symptoms are more commonly noticed in middle-aged to older dogs. 

Why does BPH happen? 

This enlargement develops gradually due to the ongoing effects of testosterone on the prostate over time. As the gland becomes larger, it can also become more delicate and prone to developing small cysts. Importantly, benign prostatic hyperplasia (BPH) is not cancerous and does not usually turn into cancer. However, an enlarged prostate can increase the risk of other issues, including infection and cyst formation.  

Signs of BPH in dogs 

Some dogs with BPH appear completely normal, and the condition is only discovered during a routine examination. Others develop symptoms linked to the enlarged gland pressing on nearby structures. 

Common signs include: 

  • Straining to pass faeces 
  • Passing ribbon-shaped stools 
  • Blood dripping from the penis unrelated to urination 
  • Increased licking of the prepuce 
  • Difficulty urinating 
  • Reduced fertility 
  • Stiffness or discomfort around the back end 

Owners are often surprised to learn that prostate enlargement can also affect a dog’s ability to pass faeces. This is because the prostate sits just beneath the rectum, so when it becomes enlarged it can press on the bowel. This pressure may make it uncomfortable or more difficult for a dog to pass stools normally. 

Diagnosing BPH 

Your vet will usually begin with a physical examination, including a rectal examination where possible. In many dogs with BPH, the prostate feels symmetrically enlarged but smooth and non-painful. 

Further investigations commonly include: 

  • Ultrasound scanning 
  • X-rays 
  • Urine analysis 
  • Blood tests 
  • Sampling of prostatic fluid in selected cases 

Ultrasound is very useful because it allows assessment of the prostate’s size and structure. Dogs with uncomplicated BPH often have a uniformly enlarged gland, although cysts may also be present. 

Treatment for BPH 

The most effective treatment for BPH is castration. Once testosterone levels fall, the prostate usually shrinks significantly over a period of weeks. In many cases, clinical signs improve after neutering. The gland may reduce by as much as 50% within a few weeks and continue shrinking. 

For breeding dogs where castration is not desirable, medical management may sometimes be considered. Drugs such as osaterone acetate can temporarily reduce prostate size and improve clinical signs, although recurrence is common once treatment stops. It is worth remembering that dogs with untreated BPH are still at a greater risk of developing secondary prostatitis or prostatic cysts later on. 

Prostatitis in dogs 

Prostatitis refers to inflammation and infection within the prostate gland. This condition can range from mild chronic disease to severe life-threatening illness. Bacterial infection is the most common cause. These bacteria usually travel up from the urinary tract into the prostate, but they can also reach it through the bloodstream.  

Entire male dogs with benign prostatic hyperplasia (BPH), are more at risk. This is because the enlarged prostate changes its structure, making it easier for bacteria to settle and cause infection.  

Acute prostatitis 

Dogs with acute prostatitis are often obviously unwell. The infection develops rapidly and can cause systemic illness. 

Signs may include: 

  • Fever 
  • Lethargy 
  • Pain 
  • Reduced appetite 
  • Vomiting 
  • Difficulty urinating 
  • Blood in the urine 
  • Straining to defecate 
  • Abdominal discomfort 
  • A stiff or hunched gait 

Some dogs become septic, meaning the infection spreads through the bloodstream. These cases require urgent veterinary treatment. On rectal examination, the prostate is often enlarged and painful. 

Chronic prostatitis 

Chronic prostatitis can be much harder to recognise. Some dogs show only vague or intermittent symptoms, while others appear outwardly normal between flare-ups. 

Possible signs include: 

  • Recurrent urinary tract infections 
  • Intermittent blood in the urine or ejaculate 
  • Reduced fertility 
  • Occasional discomfort 
  • Lethargy 
  • Mild urinary signs 

Because bacteria can persist deep within prostatic tissue, chronic infection may be present for long periods. 

Diagnosing prostatitis 

Diagnosis usually involves a combination of tests. Urine testing is often an important part of the investigation, although infections within the prostate do not always show up clearly in urine samples, as bacteria may not be shed into the urine all the time.  

Additional investigations may include: 

  • Blood tests 
  • Ultrasound examination 
  • Urine culture 
  • Prostatic fluid analysis 
  • Fine needle aspiration in selected cases 

Ultrasound findings can vary depending on whether the disease is acute or chronic. Abscesses, cysts and areas of irregular tissue may sometimes be visible. 

Treatment for prostatitis 

Treatment depends on the severity of the disease. Dogs with acute prostatitis often require hospitalisation for: 

  • Intravenous fluids 
  • Pain relief 
  • Antibiotics 
  • Supportive care 

Choosing the correct antibiotic is important because not all drugs reach the prostate effectively. Antibiotic selection is ideally based on culture results wherever possible. 

Chronic prostatitis frequently requires a longer antibiotic course, sometimes lasting several weeks. 

Castration is strongly recommended in most cases because reducing hormonal stimulation helps shrink the prostate and improve treatment success. Entire dogs treated medically without neutering are much more likely to relapse. Some dogs develop prostatic abscesses, which may require drainage or surgery. 

Prostatic neoplasia (prostate cancer) 

Fortunately, prostate cancer is uncommon in dogs. The bad news is that when it does occur, it tends to behave very aggressively. 

The most frequently diagnosed forms are adenocarcinoma and transitional carcinoma involving the prostate. Unlike BPH and prostatitis, prostatic neoplasia can occur in both neutered and entire male dogs.  

Signs of prostate cancer in dogs 

Clinical signs can initially resemble other prostate conditions. Affected dogs may show: 

  • Difficulty urinating 
  • Straining to defecate 
  • Weight loss 
  • Lethargy 
  • Blood in the urine 
  • Hindlimb weakness 
  • Pain 
  • Stiffness 

As the disease progresses, the cancer can start to spread into surrounding tissues and to other parts of the body. Common sites affected include the lymph nodes, lungs, and bones.  

Bone involvement can cause significant pain and lameness, particularly affecting the spine or pelvis. 

Diagnosing prostatic neoplasia 

Diagnosis typically involves imaging and tissue sampling. Investigations may include: 

  • Ultrasound 
  • Radiography 
  • CT scanning 
  • Cytology 
  • Biopsy 

On imaging, the prostate may appear enlarged, irregular, or uneven in shape, and there can sometimes be signs that the surrounding tissues are also affected (which is called metastatic disease). 

Chest imaging is often recommended as well, as this type of cancer can spread to the lungs relatively early in the course of the disease.  

Treatment options for prostatic neoplasia 

Unfortunately, treatment that completely cures prostatic cancer is uncommon. Surgery to remove the prostate is complicated and can carry significant risks, including long-term urinary incontinence. In many dogs, the disease has already spread or become locally advanced by the time it is diagnosed, which means surgery is not always a suitable option. Treatment usually focuses on improving quality of life and slowing disease progression. 

Options may include: 

  • Non-steroidal anti-inflammatory drugs (NSAIDs) 
  • Chemotherapy 
  • Radiation therapy 
  • Palliative care 
  • Urinary stenting in selected cases, although less commonly used 

Some dogs may show temporary improvement with certain medications that can help reduce inflammation and may slow tumour progression for a period of time. The overall prognosis is unfortunately guarded to poor in most cases. 

How common is prostate disease in dogs? 

BPH is extremely common in entire older male dogs and is considered a normal ageing change to some extent. Prostatitis is less common but still regularly encountered in first opinion practice, particularly in dogs with underlying BPH. Prostatic cancer remains relatively rare overall. 

One important point is that several prostate issues can occur at the same time. For example, a dog with BPH may also develop prostatitis or cyst formation. This overlap can sometimes complicate diagnosis and treatment. 

Can prostate disease be prevented? 

Neutering is the most effective way to prevent benign prostatic hyperplasia (BPH) and can also reduce the risk of prostatitis linked to an enlarged prostate. Once testosterone levels reduce after castration, the prostate usually shrinks significantly over time. 

That said, neutering decisions should always be made on an individual basis. Factors such as breed, age, behaviour, lifestyle, and overall health all need to be considered when deciding what is best for each dog. 

It’s also important for owners to seek veterinary advice if they notice signs such as difficulty urinating, straining to pass faeces, blood from the penis, or signs of discomfort in older male dogs, as early assessment often makes management more straightforward.  

When should owners contact a vet? 

Owners should contact their vet if they notice any of the following: 

  • Straining to urinate or defecate 
  • Blood from the penis 
  • Recurrent urinary infections 
  • Back-end pain or stiffness 
  • Changes in stool shape 
  • Lethargy or fever 
  • Reduced appetite 
  • Difficulty walking 

While prostate disease is not always the cause, these signs need investigation. Many prostate conditions are far easier to manage when identified early before complications develop. 

Final thoughts 

Prostate disease is something many owners are unfamiliar with until it affects their own dog, yet these conditions are relatively common, particularly in older entire males. Benign prostatic hyperplasia is by far the most commonly diagnosed prostate condition and often responds very well to castration. Prostatitis can vary from a low-grade chronic infection to a much more serious illness, while prostatic cancer unfortunately tends to carry a poorer outlook. 

The positive news is that many dogs with prostate disease can still maintain a good quality of life, especially when problems are identified early and managed appropriately. Signs such as straining to pass faeces, blood dripping from the penis, or recurring urinary issues should not simply be put down to “getting older”. 

As with many health conditions, noticing subtle changes early and seeking veterinary advice promptly can make a significant difference. If you have any concerns, always speak to your vet straight away.