My cat Moby recently started peeing on a bathroom rug, much to the dismay of the humans who use that bathroom. I took the alleged perpetrator to the clinic and ran tests on him. Later that same week, we found urine in front of a litter box, and one of our dogs had urinated in the living room. It was a urine hell, and I had to figure out what was going on before my husband tossed us all out the door.

There are many causes for a pet urinating on the floor. Most common is a bladder infection, especially in dogs. Female dogs are also more likely to have issues if they have an immature or tucked vulva; this is where the vulva is more covered by skin folds, leading to entrapment of urine (or fecal material) that can ascend into the urethra and the bladder. Dogs with bladder infections feel the urge to pee frequently, often just small amounts at a time. Bladder stones and sometimes a urinary bladder tumor are other underlying causes of infections.

A urinalysis is your veterinarian’s first test. It tells a lot about the bladder and kidneys. If there’s an infection, bacteria, protein, white blood cells, and red blood cells are present. Crystals can be due to infection, diet, or genetics and can clump together to form bladder stones. The specific gravity (spec grav), or concentration, is important too. If the spec grav is low, the urine will look pale, which indicates the pet is drinking a lot. This can change throughout the day, so your vet may ask you to collect the first-morning urine sample, which is when the urine should be most concentrated.

If there isn’t a urinary bladder infection and the spec grav is low, then we start on our list of causes for PU/PD. Polyuria (PU) is the production of abnormally large amounts of dilute urine, and polydipsia (PD) is excessive water consumption. At least 23 diseases or conditions can cause PU/PD in pets, so it can take time to figure out the specific cause.

Sometimes, a little detective work is all that’s needed to figure out why a pet might be drinking more. A change in diet or new treats that are high in sodium can be the culprit. Did your dog steal pizza off the counter? He will likely be drinking more water for a day or so. When a pet drinks more, the bladder fills up more quickly, and they may not be able to wait for their regular walk. Removing the salty food should stop the excessive drinking quickly.

More often, there’s an underlying disease causing the pet to drink more water. Cushing’s disease, or hyperadrenocorticism, is fairly common, particularly in middle-aged and older small-breed dogs. This disease is caused by an overproduction of steroids in the body due to either a tumor on the pituitary, which tells the body to produce more steroids, or by a tumor on the adrenal gland, which makes the steroids. Steroids, including those taken orally, given by injection, or used topically, also have the side effect of PU/PD. A urinalysis on a dog with Cushing’s (or treatment with steroids) will show a low spec grav and protein. Bloodwork will show high liver enzymes, and diagnosis is through additional blood testing. Interestingly, the opposite condition, Addison’s disease (hypoadrenocorticism) can also cause PU/PD.

Another endocrine disease that causes PU/PD is diabetes. Pets with diabetes aren’t producing enough insulin or their cells aren’t properly responding to insulin, so glucose (sugar) doesn’t get into the cells. Because the cells aren’t getting enough glucose, the liver makes more glucose, which ends up in the bloodstream. The kidneys can’t reabsorb all of it, so glucose ends up in the urine. This sugar pulls water with it into the bladder, leading to a lot of urine being produced. The loss of water then causes an increase in thirst, leading to PU/PD. Diabetic animals may have a high spec grav, but the urine will test positive for glucose. Diabetics will also be losing weight and are hungry all the time.

Some severe infections will cause PU/PD. Pyelonephritis, a kidney infection, or a pyometra, an infection in the uterus in an intact female, leads to the release of bacterial endotoxins, which can alter hormones responsible for water regulation. In addition to drinking and urinating a lot, these pets typically feel very sick.

In older cats and some dogs, their kidneys will stop working well, and they’ll be diagnosed with chronic kidney failure. There are four stages to kidney failure, with most people noticing a change in their pet by stage two. Most people first notice their cat drinking more or having larger urine clumps in the litter. A urinalysis will show a low spec grav, as the kidneys are no longer working to retain water in the body. While kidney failure can’t be reversed, it can be slowed down with special diets and other supportive care, so doing regular bloodwork and urinalyses as your pet ages is very important.

Psychogenic polydipsia is a neurologic disorder that causes dogs to compulsively drink water. Some liver diseases lead to high ammonia levels, which affects the brain. Psychogenic PD can be seen in puppies experiencing stress; behavioral treatment can be helpful. Hungry or malnourished puppies may also drink a lot if there isn’t food available.

Diabetes insipidus is a rare disease where either too little antidiuretic hormone (ADH) is produced or the kidneys aren’t responding to the hormone. ADH tells the kidneys to reabsorb water. In animals without this hormone, all the water that passes through the kidneys goes to the bladder, leading to PU. Diagnosis is often by giving the pet nose drops containing an ADH analog to see if they stop being PU/PD.

The tests I ran on Moby were all normal. It turned out that Moby peeing on the bath mat was his way of telling us he didn’t like the new litter. He stopped once we switched back to the previous brand. When urine started showing up in front of a litter box, I suspected another cat was involved. It turned out that Eddie did have a bladder infection; antibiotics stopped that urine issue. As for the dog urine, not being let out late enough in the evening and being startled by a loud noise in the morning—owner errors—were primary factors.

Don’t assume all urine messes in the house are bad behavior. Dogs and cats don’t pee in the house because they’re angry; there’s an underlying reason, and your vet is in the best position to help figure out the cause and how to treat it.

Lori Scarlett, DVM is the owner and veterinarian at Four Lakes Veterinary Clinic. For more information, visit fourlakesvet.com.