Cat spray comes from the same place as regular urine: the bladder and urinary tract. Despite the distinctive smell, spray is not a separate substance produced by a special gland. It is urine, but delivered in a unique posture and enriched with specific proteins and sulfur-based compounds that make it far more pungent than what you find in the litter box. The difference lies in how it’s deposited, what’s concentrated in it, and why.
Spray Is Urine, Delivered Differently
When a cat urinates normally, it squats and empties its bladder onto a horizontal surface. Spraying looks completely different. The cat stands upright, backs up to a vertical surface like a wall, door frame, or piece of furniture, and holds its tail straight up. You may notice the tail quivering and the cat “treading” or paddling its back feet. A small amount of urine is then projected backward onto the surface, typically at nose height for other cats.
Both male and female cats can spray, and the behavior isn’t limited to cats that haven’t been fixed. Roughly 10% of neutered males and 5% of spayed females still spray. The posture is instinctive across all cat breeds, and it serves a fundamentally different purpose than emptying the bladder. Normal urination is elimination. Spraying is communication.
What Makes Spray Smell So Much Worse
The intense, lingering odor of cat spray comes down to a single amino acid called felinine. All cat urine contains felinine, but intact male cats produce dramatically more of it. An unneutered male excretes about 122 micromoles of felinine per kilogram of body weight per day, roughly three times the amount produced by neutered males or adult females (around 36 to 41 micromoles).
Felinine itself isn’t particularly smelly when fresh. The real stench develops after the urine is exposed to air. Bacteria break felinine down into a group of volatile sulfur compounds, the same class of chemicals responsible for the smell of rotten eggs and skunk spray. These sulfur-based breakdown products are what give cat spray its notorious, eye-watering odor that can persist for weeks or months if not properly cleaned.
In intact males, felinine levels surge during puberty. Concentrations in urine peak between 11 and 13 months of age, dip briefly, then climb to their highest point around 17 months. This timeline closely tracks testosterone levels, which is why the spray of a young, unneutered male smells so much stronger than that of a kitten or a fixed cat.
Anal Sac Secretions Add Another Layer
Cats also have a pair of anal sac glands located on either side of the anus. These small pouches are lined with two types of glands (apocrine and sebaceous) and produce a pungent liquid of their own. While anal sac secretions are not the primary component of spray, cats can release small amounts of this fluid during marking behavior. The combination of concentrated urine and anal sac compounds creates the complex scent profile that other cats can read like a bulletin board, identifying the sprayer’s sex, reproductive status, and individual identity.
Why Cats Spray
Spraying falls into two broad categories: sexual and reactional. Sexual spraying is tied to reproduction. Intact males spray to advertise their presence and status to females and rival males. Intact females sometimes spray when they’re in heat. Reactional spraying has nothing to do with mating. It happens when a cat feels its resources or territory are threatened. A new cat in the household, a stray visible through the window, a change in routine, or even rearranging furniture can trigger it.
Stress and anxiety are among the most common drivers. Multi-cat households see more spraying because competition for food, litter boxes, resting spots, and attention creates ongoing social tension. Medical conditions affecting the urinary tract can also cause spraying-like behavior, so a sudden change in a cat’s elimination habits is worth investigating with a vet before assuming it’s purely behavioral.
How Neutering Affects Spraying
Neutering is typically the first recommendation for an intact cat that sprays, and it works in many cases because it dramatically reduces testosterone, which in turn lowers felinine production and decreases the hormonal motivation behind sexual marking. The spray of a neutered cat is measurably less pungent than that of an intact male.
That said, neutering is not a guarantee. About 10% of neutered males and 5% of spayed females continue to spray, particularly when the behavior is driven by stress or territorial anxiety rather than hormones. For these cats, the solution involves addressing the environmental triggers: reducing competition, adding vertical space, providing more litter boxes, and minimizing sources of stress.
Finding and Removing Spray
Cat spray can be hard to locate, especially on dark surfaces or in corners. A UV black light with a wavelength between 365 and 395 nanometers will cause dried urine to fluoresce, making hidden spots visible. Lights below that range aren’t strong enough to reveal the deposits, and lights above it are too close to natural light to be useful.
Once you find the spray, standard household cleaners won’t fully eliminate the smell. Cat urine contains uric acid crystals that bind tightly to surfaces and resist water, soap, and vinegar. They can seem gone when wet, then reactivate and smell again when dry. The only effective approach is an enzyme-based cleaner. These products use enzymes to break uric acid down into carbon dioxide and ammonia, both of which are gases that evaporate completely. Without enzymatic treatment, the residual scent can actually encourage a cat to spray the same spot again.