CONDITION
Prostate Disease
Prostate disease in dogs refers to a collection of conditions affecting the prostate gland, a walnut-sized structure that sits just behind the bladder in male dogs. The prostate can become enlarged, inflamed, infected, or — more rarely — affected by tumours. Benign prostatic hyperplasia, a non-cancerous age-related enlargement, is extremely common in intact males and affects the majority of dogs over six years of age; cysts, abscesses, and bacterial infections can also develop. Neutered dogs are protected from benign enlargement but may still develop other prostatic conditions. Owners often notice straining during urination or defecation, ribbon-shaped stools, or blood dripping from the penis, though many dogs with early prostate changes show no outward signs at all. These patterns can overlap across different underlying causes, and the clinical picture tends to depend on the size of the gland, whether infection or pain is present, and how the prostate is pressing on nearby structures. This page explores what signs may prompt investigation, the spectrum of conditions that can affect the prostate, how each is identified through imaging and sampling, and the range of approaches — medical and surgical — used to manage them. The goal is to help you understand what prostate disease can look like, what may be happening beneath the surface, and how the condition is typically investigated and addressed.
Why this matters now
Prostate changes can begin as early as two to three years of age in intact male dogs, though clinical signs are uncommon at this stage. By five to six years of age, benign prostatic hyperplasia develops in the majority of intact males, and by nine years this affects nearly all. Neutered dogs do not develop benign enlargement, but epidemiological studies have found they carry a higher risk of prostatic carcinoma than intact dogs, though carcinoma remains an uncommon diagnosis overall.
In many dogs, the gland enlarges slowly over years without causing noticeable problems. In others, the enlargement may eventually compress the rectum or urethra, leading to straining or changes in urination. Cystic changes within the gland can develop over time, and in some cases infection or abscess formation may follow. The trajectory varies widely between individuals, and some dogs reach old age without any outward signs of prostate disease.
Signals & patterns
Early signals
Ribbon-shaped or flattened faeces
When the prostate enlarges, it can press against the rectum from below, flattening the stool as it passes. This is often one of the first changes an owner notices, though the dog may otherwise seem comfortable.
Intermittent straining to defecate
The dog may adopt a defecation posture repeatedly or hold it longer than usual, particularly if the enlarged gland is compressing the lower bowel. This can come and go, and is not always accompanied by constipation.
Drops of blood from the prepuce
Small amounts of blood may drip from the sheath between urinations, often noticed on bedding or flooring. This can occur when the prostate is congested or contains cysts, and the blood originates from the gland rather than the urinary tract itself.
Stiff or shortened rear-leg stride
Some dogs develop a slightly cautious or stilted gait in the hind limbs, thought to reflect discomfort from pressure within the pelvis. The change may be subtle and intermittent, and can be mistaken for orthopaedic stiffness.
Later signals
Persistent straining with little output
As the gland enlarges further or if complications develop, straining to urinate or defecate may become more frequent and less productive. The dog may adopt the posture repeatedly with minimal result, and this can signal more significant compression or obstruction.
Blood-tinged urine
Haematuria may become more apparent if the prostate is substantially enlarged, infected, or contains areas of inflammation or neoplasia. The blood may appear as streaks or diffuse discolouration, and is often intermittent.
Lethargy or reluctance to move
Dogs with more advanced prostate disease, particularly if infection or abscessation is present, may become quieter, less willing to walk, or show general malaise. Fever and systemic signs can accompany these changes.
Click to read about the biological mechanisms
How this is usually investigated
Investigation typically begins with a detailed history covering urination, defecation, gait, and any systemic signs such as fever or lethargy. Physical examination includes rectal palpation to assess the size, symmetry, and texture of the prostate. From there, imaging and laboratory tests help to distinguish between benign enlargement, infection, cyst formation, and neoplasia.
Physical examination
Abdominal ultrasound
Urinalysis with sediment
Bacterial culture and sensitivity
Cytology
Options & trade-offs
Management depends on what is found and on the degree to which the condition affects the animal's comfort and daily function. Approaches range from monitoring alone through medical management to surgery, and in many cases a combination is used. What works well for one household and one dog may be less suitable for another, and priorities shift as the animal ages or as the condition evolves.
Neutering (castration)
Surgical removal of the testes eliminates testosterone drive and leads to gradual shrinkage of benign prostatic hyperplasia over several weeks to months. Neutering is widely used when benign hyperplasia is causing clinical signs and the dog is not intended for breeding. It does not reverse established infection or neoplasia, though it may make medical management of concurrent prostatitis easier.
Trade-offs: The effect on prostate size is gradual rather than immediate, so signs may persist for some weeks post-operatively. Neutering does not address prostatic carcinoma, and epidemiological studies have found a higher incidence of prostatic cancer in castrated dogs, though the absolute risk remains low and the reasons for this association are not fully understood.
Medical androgen suppression
Drugs such as deslorelin (a GnRH agonist implant) or osaterone (an androgen receptor antagonist) reduce testosterone signalling without surgery. Deslorelin causes reversible chemical castration; osaterone blocks androgen receptors in the prostate itself. Both can shrink benign hyperplasia and are sometimes chosen when surgery is declined or breeding potential is to be preserved short-term.
Trade-offs: Effects are reversible once the implant expires or medication is stopped, so ongoing treatment is required. Osaterone is less widely available and both options are generally more costly over time than a single surgical procedure. Neither addresses infection or neoplasia directly.
Antimicrobial therapy
Bacterial prostatitis is treated with antimicrobials chosen on the basis of culture and sensitivity results. The prostate's blood–tissue barrier means that lipophilic, alkaline drugs such as enrofloxacin, trimethoprim-sulphonamide, or doxycycline are often selected. Treatment courses are prolonged, typically four to six weeks or longer, to penetrate the gland and clear chronic infection.
Trade-offs: Chronic or recurrent prostatitis may not fully resolve with antimicrobials alone, particularly if the underlying prostatic architecture remains abnormal. Prolonged courses increase cost and the risk of antimicrobial resistance, and some dogs experience gastrointestinal upset or other adverse effects.
Surgical drainage or debulking
Large prostatic cysts or abscesses that do not resolve with drainage via ultrasound-guided aspiration may require surgical marsupialisation (creating a permanent opening into the abdomen or urethra) or partial prostatectomy. Total prostatectomy is technically challenging and associated with high rates of urinary incontinence, so it is rarely performed.
Trade-offs: Prostatic surgery carries risks of haemorrhage, incontinence, and infection, and post-operative recovery can be prolonged. It is generally reserved for cases where medical management and less invasive drainage have failed or where large, symptomatic cysts dominate the clinical picture.
Supportive and palliative care
When neoplasia is confirmed or suspected and curative treatment is not pursued, management focuses on maintaining comfort. This may include analgesia, laxatives or stool softeners to ease defecation, anti-inflammatory drugs, and monitoring for urinary obstruction or secondary infection. Neutering may still be offered to reduce concurrent benign hyperplasia and simplify day-to-day management.
Trade-offs: Supportive care does not alter the course of prostatic carcinoma, which tends to progress and metastasise. The timeframe and quality of life vary widely between individuals, and ongoing adjustments are often needed as the disease advances.
Common misconceptions
"Neutering has no effect on, or only protects against, prostate disease."
Neutering is highly protective against benign prostatic hyperplasia, but multiple epidemiological studies have found that castrated dogs have a higher risk of prostatic carcinoma than intact dogs—roughly three to four times higher in some studies. Canine prostatic carcinoma is not androgen-dependent, and the reason for this increased risk with castration is not fully understood; castration appears to promote progression of existing prostatic tumours rather than initiate them. Prostate cancer nonetheless remains an uncommon diagnosis overall in dogs, and the benefits of neutering against far more common conditions such as benign prostatic hyperplasia generally outweigh this risk.
"Blood in the urine always means prostate disease in an older male dog."
Haematuria in older intact males can arise from the prostate, but it may also originate from the bladder, kidneys, urethra, or lower urinary tract—causes include urinary tract infection, bladder stones, transitional cell carcinoma, and idiopathic renal haematuria. Investigation typically includes urinalysis, imaging, and sometimes cystoscopy to localise the source. Prostatic disease is one possibility among several and cannot be assumed without further assessment.
Related conditions
Urinary Tract Infection in Dogs
Prostate enlargement can narrow the urethra where it passes through the gland, and prostatic infection can introduce bacteria into the urinary tract. Blood in the urine or straining to urinate may reflect either prostate disease or urinary infection, and in some cases both are present.
Cushings Disease in Dogs
Cushing's disease can predispose dogs to urinary tract infections and may influence prostate size and susceptibility to infection. Both conditions are more common in older dogs and can present with overlapping signs such as increased drinking, urination changes, and altered body condition.
Canine Cognitive Dysfunction
Older male dogs may experience both age-related prostate changes and cognitive decline. Straining behaviour or altered gait from prostate disease can sometimes be misinterpreted as confusion or disorientation, and both conditions often co-exist in the ageing dog.
Osteoarthritis in Dogs
A stiff-legged gait or reluctance to sit may be observed with both prostate enlargement and osteoarthritis. Discomfort in the pelvis from an enlarged prostate can alter movement in ways that resemble joint pain, and distinguishing between the two often requires careful examination.
Obesity in Dogs
Obesity increases mechanical load on the pelvic region and may worsen straining during defecation when prostate enlargement is present. Weight management can be relevant to both conditions, as excess body condition affects mobility, metabolic health, and the ease with which faecal material is passed.
Understanding how different prostatic conditions are distinguished and what each management path involves can help frame conversations at routine appointments or when signs first appear. The broader context of longevity and healthspan touches on many age-related changes beyond the prostate itself, and patterns of disease in one system often prompt review of others. Notes on urinary signs, defecation habits, and general comfort over time provide useful detail when the picture is less clear-cut.
Last reviewed: 24 April 2026 · Dr Alastair Greenway MRCVS