SYMPTOM
Straining to urinate
Visible effort, prolonged posturing, or producing only small amounts of urine during attempts to urinate.
Lower Urinary Tract Inflammation
Inflammation of the bladder (cystitis) or urethra can produce a frequent urge to urinate, discomfort, and straining during urination. Bacterial infections are a common cause of lower urinary tract inflammation in dogs, while in cats under about ten years old bacterial infection is uncommon and the most frequent diagnosis is feline idiopathic cystitis, a sterile inflammation of the bladder with no infection or stone found. Feline lower urinary tract disease (FLUTD) is the umbrella term for lower urinary tract signs in cats from any cause, including infection and idiopathic cystitis as well as stones, urethral plugs and tumours. In cats over about ten, bacterial infection becomes considerably more common, particularly alongside conditions such as kidney disease or diabetes. In a cat that is not blocked, an episode of idiopathic cystitis often settles by itself within one to two weeks, although it tends to recur. The irritated bladder wall creates a persistent urge to pass urine, prompting frequent attempts to urinate that may produce only small volumes, and the animal may strain visibly during each attempt.
Urinary Obstruction
Partial or complete blockage of the urinary tract by stones, crystals, mucus plugs, or other material can produce straining as the animal attempts to force urine past the obstruction. This is a particularly significant consideration in male cats, where the narrow urethra is susceptible to blockage. The straining may produce little or no urine output despite visible effort, and the animal may vocalise or show signs of increasing distress. Complete urinary obstruction prevents the body from eliminating waste products and can lead to a dangerous rise in blood potassium and kidney waste products over the following one to two days, which can slow the heart and prove fatal.
Urolithiasis
Stones (uroliths) can form within the urinary tract from mineral deposits, and their presence can irritate the bladder lining, partially obstruct urine flow, or cause pain during urination. The type, number, and location of stones influence the specific pattern of urinary signs. Bladder stones may produce chronic, intermittent straining, while stones lodged in the urethra may cause more acute and severe straining. Some stone types are influenced by diet, urine pH, and genetic predispositions, and they can recur even after removal.
Prostatic Disease
In male dogs, the prostate gland surrounds the urethra. Prostatic tumours, infection of the prostate (prostatitis) and large prostatic cysts can make urination difficult by narrowing or inflaming the urethra. Benign prostatic enlargement in dogs usually grows outwards, away from the urethra, so it more often causes straining to pass faeces, blood in the urine or a bloody discharge from the prepuce than difficulty passing urine. Because an enlarged prostate can press on the rectum, straining in prostatic disease may affect both urination and defecation.
Neoplastic
Tumours affecting the bladder, urethra, or surrounding structures can produce straining through direct obstruction of urine flow, irritation of the bladder wall, or invasion of the urethral tissues. Transitional cell carcinoma is the most common bladder tumour in dogs and frequently develops at the trigone region where the ureters enter the bladder, potentially affecting urine drainage from both the kidneys and the bladder. Urinary straining from neoplastic causes tends to develop progressively and may be accompanied by blood in the urine.
Why timing matters
Early observation
Early straining to urinate may present as slightly more effort during urination, more frequent trips to the usual elimination area, or a modest increase in the time spent posturing before urine flow begins. The animal may still produce a reasonable volume of urine but take longer or appear less comfortable during the process. In cats, early signs may include more frequent visits to the litter tray, spending longer in the tray, or producing smaller clumps than usual. These subtle changes can be easy to overlook, particularly in cats that use outdoor elimination areas or in multi-cat households where individual litter tray use is difficult to monitor. In a male cat, this early stage can progress to complete obstruction with little warning, so an early picture does not in itself mean that time is available.
Later presentation
As straining becomes more pronounced, the animal may make repeated, frequent, and visibly effortful attempts to urinate with diminishing results. Urine output may decrease to drops or cease entirely, and the animal may vocalise, lick at the genital area, or show signs of increasing discomfort between attempts. In cats, repeated visits to the litter tray, urinating outside the tray, or blood-tinged urine may become apparent. The animal's overall demeanour may shift from mild discomfort to visible distress as the ability to void urine becomes increasingly compromised.
The trajectory of urinary straining varies significantly with the underlying cause. Inflammatory conditions may produce episodic straining that worsens and improves over days, while obstructive causes can move from frequent straining to a complete inability to pass urine with little warning, particularly in male cats. Once the urethra is fully blocked, the changes in blood chemistry that can stop the heart develop over roughly one to two days. Stone-related straining may fluctuate as stones shift position within the urinary tract. Benign enlargement and prostatic tumours in male dogs usually develop gradually over weeks to months, whereas acute bacterial prostatitis comes on suddenly with fever, pain and lethargy, and a prostatic abscess can cause similar signs. Understanding the speed of onset and the pattern of progression can help distinguish between different categories of underlying causes.
Conditions commonly associated
Feline Idiopathic Cystitis
Feline idiopathic cystitis inflames the bladder lining, and this irritation triggers spasms of the bladder wall and urethra, making the passage of urine uncomfortable and leading cats to strain and pass only small amounts at a time. In male cats, the same inflammation can form a urethral plug that blocks the urethra completely.
Urinary Tract Infection in Dogs
Bacterial urinary infection is a common cause of straining to urinate in dogs. Inflammation of the bladder wall and urethral mucosa from bacterial infection produces spasm and irritation that makes the passage of urine uncomfortable and effortful.
Urinary Stones (Urolithiasis)
Straining to urinate is a common sign of urinary stones, occurring when stones irritate the bladder wall or partially obstruct urine flow through the urethra.
Prostate Disease
Prostatic tumours, prostatitis and large prostatic cysts can narrow or inflame the urethra, leading to difficulty initiating or maintaining urine flow.
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Transitional Cell Carcinoma
The tumour irritates the bladder and can obstruct urine flow, causing straining and difficulty urinating.
Hydronephrosis
Straining can occur when the underlying blockage responsible for the kidney swelling also affects urine flow further down the tract.
Hyperparathyroidism in Dogs
Straining can develop when the excess calcium filtered into the urine goes on to form bladder or urethral stones.
Phimosis and Paraphimosis
A narrowed or swollen preputial opening can obstruct the normal urine stream, causing visible straining.
Prostatic Hyperplasia
In dogs the enlarged gland usually grows outwards, away from the urethra, so straining to urinate is an uncommon sign of benign enlargement; straining to pass faeces, blood in the urine or a bloody discharge from the prepuce are more typical.
Vaginal Hyperplasia
When the swollen tissue is large enough to partly block the urethral opening, passing urine becomes noticeably harder.
Urethral Obstruction
Urethral obstruction, most often in male cats and less often in male dogs with urethral stones, produces repeated straining with little or no urine. A complete blockage can cause fatal changes in blood potassium and kidney function within one to two days.
Constipation and Megacolon in Cats
Straining to pass faeces in the litter tray can look very similar to straining to urinate, and the two are easily confused at home. A blocked male cat can be mistaken for a constipated one.
When to explore further
Straining that produces little or no urine despite repeated, effortful attempts may suggest significant obstruction of the urinary tract. This pattern is particularly concerning in male cats, whose long, narrow urethra can be blocked by a plug of crystals and inflammatory material or by a small stone. A blocked cat may cry, lick at the penis, pass a few drops of bloody urine, hide, vomit or become quiet, and as potassium rises the heart can slow and the cat can collapse; death can occur in less than 48 hours. Male dogs, particularly those with a history of bladder stones, can also become blocked when a stone lodges in the urethra.
Visible blood in the urine accompanying straining may suggest inflammation, infection, stones, or tissue damage within the urinary tract. The colour and amount of blood, ranging from a slight pinkish tinge to frank red blood, can provide some information about the severity and location of the bleeding.
Straining that is accompanied by signs of systemic unwellness such as vomiting, lethargy, loss of appetite, or abdominal distension may suggest that the urinary problem is affecting the animal's overall health. These systemic signs can develop when the body is unable to adequately eliminate waste products through the urinary system.
Recurrent episodes of urinary straining, particularly in cats, may suggest an underlying predisposition to lower urinary tract disease that tends to flare under certain conditions. Stress, dietary factors, and environmental changes are commonly associated with recurrent episodes in cats.
Straining to urinate in a male dog, particularly if accompanied by changes in defecation, blood in the urine, or discharge from the prepuce, may suggest prostatic involvement. In an entire dog, prostatic disease is most often benign enlargement or infection. In a neutered dog, whose prostate would normally shrink, an enlarged prostate is more likely to be a tumour.
Straining in the litter tray can look much the same whether a cat is trying to pass urine or faeces, and a blocked male cat is sometimes taken to be constipated. Whether fresh urine clumps are appearing at all is one of the few distinctions an owner can make; repeated straining with no clumps is the pattern that points towards obstruction rather than constipation.
Straining to urinate carries very different weight depending on who is straining and whether urine is actually being passed. In a male cat, repeated trips to the litter tray that produce only drops or nothing at all are the classic pattern of urethral obstruction. A bladder that cannot empty allows potassium and waste products to build up in the blood over hours, and death can follow within one to two days, so this is not a pattern in which a period of observation at home is a safe middle course. Whether a small output means a full, blocked bladder or an empty, inflamed one cannot be told by watching the litter tray; it takes a veterinary examination to feel the bladder, and often blood tests as well. For an animal that is still passing reasonable amounts of urine, notes on the number of attempts, the size of urine clumps or puddles, any blood, and when the straining began give a useful picture for whoever examines the animal.
Last reviewed: 9 October 2026 · Dr Alastair Greenway MRCVS