Urine scald shows up as red, irritated, sometimes raw-looking skin in areas that stay wet with urine. In pets, you typically see hair loss, redness, and moist or crusty patches around the back end, belly, and inner thighs. In severe cases the skin breaks down into open sores. The condition affects dogs, cats, and rabbits as well as humans with incontinence, and while the visual details differ by species, the underlying damage follows a similar chemical pathway. The appearance can range from subtle pinkness to outright ulceration depending on how long the skin has been exposed and whether infection has set in.
How Urine Damages Skin
The core problem is ammonia. Urine contains urea, a waste product that is relatively harmless on its own. But bacteria that live on skin and in the environment produce an enzyme called urease, which converts urea into ammonia. That ammonia does two things at once: it raises the pH of the skin surface, pushing it from its normal slightly acidic state toward alkaline, and it directly irritates skin cells. Research on human skin found that ammonia itself causes the damage, not just the high pH. When researchers exposed skin to a high-pH solution that did not contain ammonia, the skin’s pH rose but the tissue stayed intact and did not turn red. When ammonia was present, the skin’s outer barrier broke down and visible redness appeared.
1PubMed Central. The multi-factorial modes of action of urease in the pathogenesis of incontinence associated dermatitisOnce ammonia compromises the skin’s outermost layer, moisture does the rest. Prolonged wetness softens and swells skin cells in a process called maceration. Macerated skin is fragile and tears easily, which is why urine scald often progresses from simple redness to cracked, weeping, or peeling patches. Feces makes the situation worse because stool contains additional bacteria and digestive enzymes that compound the irritation. In humans, this combination of urine, stool, and damaged skin is formally called incontinence-associated dermatitis, and it is characterized by pain, redness, maceration, erosion, and scaling, with secondary infection occurring frequently.
2PubMed Central. Incontinence-Associated Dermatitis in Older Adults: A Critical Review of Risk Factors, Prevention and ManagementWhat Urine Scald Looks Like in Dogs and Cats
A retrospective study of urine scalding in dogs and cats documented the range of lesions that develop. In mild cases the skin around the genitals, belly, groin, and upper legs shows white papules or raised plaques. As the damage progresses, discrete nodules appear. In more advanced cases the skin breaks down into open ulcers. Under the microscope, the hallmark changes include thickening of the skin’s outer layers, marked swelling of individual skin cells, and a diffuse flaky surface. When the damage is severe enough, erosion and ulceration set in, typically accompanied by bacterial infection and tissue death.
3PubMed. Clinical and histopathological features of urine scalding in dogs and catsThe location of the lesions is a key visual clue. Urine scald concentrates in perigenital areas, the skin directly around the vulva or prepuce, and can extend down the inner thighs, across the belly, and into the inguinal folds where urine pools. In dogs that lie down frequently, the belly and chest can also be affected because the animal is resting in its own urine. This distribution pattern distinguishes urine scald from allergic skin disease, which tends to affect the ears, paws, and face, and from flea dermatitis, which clusters along the lower back and tail base.
Hair loss is often the first thing an owner notices. The fur in the affected region may look thin, stained yellow or orange, matted, or damp. The exposed skin underneath ranges from pink and slightly swollen in early stages to angry red or even purplish when inflammation is pronounced. A foul smell is common because bacteria thrive in the warm, moist environment. Some dogs develop a thickened, leathery texture to the skin over time if the exposure is chronic, as the body tries to protect itself by building up extra layers.
Urine Scald in Rabbits
Rabbits are especially vulnerable to urine scald for a few reasons. They sit low to the ground, often in bedding that absorbs and holds urine. Their skin is thin and delicate compared to dogs. And many pet rabbits have underlying urinary problems that cause them to dribble urine continuously. A histological survey of rabbit kidneys found that roughly a third of unhealthy rabbits had kidney lesions, and a quarter of apparently healthy rabbits did too, which underscores how common renal disease is even in rabbits that seem fine.
4In Practice. Diagnosing and treating urinary tract disease in rabbitsIn a rabbit with urine scald, the fur around the hindquarters, tail, and perineum becomes soaked and matted. As the condition worsens, patches of fur fall out entirely, revealing reddened, moist skin. The skin may look raw or develop a whitish, crusty film. Severe cases can progress to open wounds. Many owners first notice a strong ammonia odor before they notice the skin changes, especially if the rabbit is long-haired and the damage is hidden under matted fur.
Rabbits that are obese, arthritic, or have dental problems may struggle to groom their back ends, which accelerates the problem. Normally, rabbits consume their cecotropes (soft droppings) directly from the anus, and this regular grooming keeps the area relatively clean. When a rabbit cannot reach, the combination of urine, feces, and cecotropes creates a perfect storm for skin breakdown.
Fly Strike as a Dangerous Complication
One of the most serious risks of urine scald in rabbits is fly strike, a condition where flies lay eggs on the damp, irritated skin and the resulting maggots burrow into the tissue. This is not a theoretical concern: it is a well-documented clinical emergency. The warm, moist, ammonia-scented skin of a rabbit with urine scald is highly attractive to flies, and eggs can hatch into feeding larvae within hours in warm weather.
5In Practice. Veterinary care of rabbits with myiasisFly strike can be fatal within a day or two. The maggots release toxins as they feed, which can send a rabbit into shock. An owner who spots urine scald on a rabbit should check twice daily for any sign of eggs (tiny white clusters that look like grains of rice) or larvae, particularly between April and October in temperate climates. Prevention is straightforward in principle: keep the skin clean and dry, treat the underlying urinary issue, and use fly screens around outdoor hutches. In practice, it requires consistent daily attention.
Common Underlying Causes
Urine scald is always a symptom of something else. The skin damage does not happen because the animal (or person) has unusually corrosive urine. It happens because urine is in prolonged contact with skin, which means something is causing that contact. The causes differ by species, but they share a common theme: either too much urine is being produced, urine is leaking involuntarily, or the individual cannot move away from the wetness.
In dogs, the study of urine scalding cases found that all the animals had either urinary incontinence from conditions like ectopic ureters, bladder stones, urinary tract infections, or sphincter weakness, or a conformational issue with their genitals that trapped urine against the skin.
3PubMed. Clinical and histopathological features of urine scalding in dogs and catsIn rabbits, the causes include kidney disease, bladder sludge (a buildup of calcium sediment in the bladder that is common in rabbits), urinary infections, spinal problems that impair bladder control, and obesity that prevents self-grooming. Arthritis in older rabbits is another frequent contributor: the rabbit may be producing normal urine but simply cannot lift itself away or clean up.
In humans, incontinence-associated dermatitis affects people who wear pads or briefs due to urinary or fecal incontinence. Older adults in care facilities are at particularly high risk because of limited mobility, cognitive decline that prevents them from communicating discomfort, and the logistical challenges of maintaining perfectly dry skin around the clock.
2PubMed Central. Incontinence-Associated Dermatitis in Older Adults: A Critical Review of Risk Factors, Prevention and ManagementHow to Tell Urine Scald Apart From Other Skin Problems
The location of the damage is the single most helpful diagnostic clue. Urine scald respects the contact zone: it appears where urine actually touches skin. In a dog, that means the vulva or prepuce, the inner thighs, the lower belly, and sometimes the hocks. In a rabbit, it is the perineum, base of the tail, and inner legs. If irritated skin shows up on the ears, back, flanks, or paws, urine is almost certainly not the cause.
Fungal infections like ringworm can look superficially similar, with hair loss and flaky, reddened skin, but ringworm tends to form circular patches that can appear anywhere on the body. Bacterial skin infections (sometimes called “hot spots” in dogs) are usually isolated, clearly demarcated moist patches, whereas urine scald tends to involve a broader, more diffuse area. Allergic dermatitis may cause redness and itching in the groin region, but it typically also affects the ears, feet, and face, and it responds to anti-itch medication in a way that urine scald does not.
In humans, incontinence-associated dermatitis is sometimes confused with pressure injuries because both occur in bedridden patients and can appear in the sacral or buttock region. The distinction matters for treatment: a pressure injury is caused by sustained pressure cutting off blood flow, while incontinence-associated dermatitis is caused by chemical irritation from urine and stool. The two can also occur simultaneously, which complicates assessment.
The Role of Bedding and Environment
For rabbits and other small animals, the type of bedding matters more than many owners realize. A study comparing different bedding materials for rabbits found that cotton bedding produced the best results for ammonia levels and overall litter cleanliness, likely because it absorbs and releases water efficiently and has a soft structure. Coarse bark mulch, by contrast, did not bind liquids well and led to increased contamination.
6PubMed. Influence of different types of bedding material on the prevalence of pododermatitis in rabbitsThe practical takeaway is that bedding that wicks moisture away from the animal’s skin and keeps ammonia levels low can meaningfully reduce the risk of urine scald. Fleece liners with an absorbent underlayer, changed frequently, work well for indoor rabbits. Newspaper alone is a poor choice because it stays wet on the surface. Straw is middling: it absorbs some moisture but compacts quickly and can harbor bacteria once soiled. Whatever material you choose, cleaning frequency is arguably more important than the material itself. Even the best bedding becomes a liability if it is not replaced before ammonia builds up.
For dogs with incontinence, waterproof bed pads with absorbent tops serve the same function. The goal is to keep the skin surface as dry as possible. Some owners apply a thin layer of petroleum jelly or a barrier cream to the skin in the contact zone, which creates a physical shield between urine and skin. This does not fix the underlying problem, but it buys time while you work with a veterinarian on the cause.
Treatment and What to Expect During Recovery
Treating urine scald effectively requires addressing both the skin damage and the reason the skin is getting wet. For the skin itself, the first step is gentle cleaning with lukewarm water and a mild, soap-free cleanser. Harsh soaps or antiseptics can strip the skin further. After cleaning, the area should be dried thoroughly, patted rather than rubbed, and a barrier product applied. Veterinarians commonly recommend zinc-oxide-based creams for animals, similar to the diaper creams used for human infants.
If the skin is already infected, which is common in moderate to severe cases, antibiotics may be needed. The bacterial infection is secondary, meaning it moved in after the skin barrier was compromised. In the histopathological study of dogs and cats with urine scald, bacterial infection and tissue death were present in the more advanced cases, confirming that untreated urine scald reliably progresses to infection.
3PubMed. Clinical and histopathological features of urine scalding in dogs and catsSkin recovery once the source of wetness is controlled tends to follow a predictable path. The redness fades first, usually within a few days. Macerated, peeling skin firms up over one to two weeks. Hair regrowth is the slowest phase and can take several weeks to months, and in cases where scarring has occurred, some patches may remain permanently thin or hairless. The skin may also be more vulnerable to re-injury for a period after it heals, because the newly regenerated outer barrier is thinner and less resilient than normal skin.
The harder part is usually resolving the underlying cause. Sphincter incompetence in spayed female dogs, for instance, is manageable with medication but rarely curable. Ectopic ureters can be surgically corrected, with good outcomes in many cases. Bladder sludge in rabbits may require a combination of dietary changes, increased water intake, and sometimes sedated bladder flushing. Arthritis can be managed with pain relief and weight loss but tends to be a lifelong issue. In all of these scenarios, some degree of ongoing skin care and environmental management is part of the long-term plan.
When Urine Scald Signals Something More Serious
Because urine scald is a downstream effect of another condition, its appearance should always prompt investigation into what is going wrong upstream. In rabbits, new-onset urine scald in a previously clean animal sometimes reveals kidney disease, a urinary infection, or even a spinal issue. In dogs, sudden incontinence in a young animal can point to a congenital abnormality, while new incontinence in a middle-aged spayed female is more likely hormonal sphincter weakness. In older cats, increased urination leading to urine scald might be the first visible sign of kidney disease or diabetes.
In humans, persistent incontinence-associated dermatitis that does not improve with standard barrier care sometimes indicates that the incontinence management plan itself needs reassessment, whether that means a different absorbent product, more frequent changing schedules, catheterization, or a review of medications that might be contributing to urinary frequency. The dermatitis is painful and significantly affects quality of life, and treating it as a skin-only problem while ignoring the incontinence misses the point.
A veterinarian or physician examining urine scald will typically want a urinalysis and possibly imaging of the urinary tract. For animals, a urine culture can identify bacterial infections, and X-rays or ultrasound can reveal stones, sludge, or anatomical abnormalities. These diagnostics are not optional extras: they are necessary to move past symptom management and address the real problem.