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Health & Wellness

Urinary obstructions in dogs and cats

Knowing your pets’ bathroom habits can help them get treated faster for any possible issues.

When a dog or cat has a blockage preventing them from going to the bathroom, a urinary obstruction can occur — kidney stones, crystals, chronic inflammation, scar tissue or cancer can stop your dog or cat from easily urinating. 

And although urinary blockages aren’t incredibly common, they can be very painful or even fatal if they occur, Dr. Elizabeth Devitt, DVM, veterinary consultant for Fetch, says. Here’s how to spot the symptoms and get your dog or cat the help they need. 

What causes urinary obstructions in dogs and cats?

Both cats and dogs can get urinary obstructions, but male cats are particularly prone to blocking because of their narrow urethras. A buildup of mucus and urinary crystals can form into a plug in the pet’s urethra, preventing them from urinating.

“It’s always good to be aware of how often and how much your pet typically urinates,” Dr. Devitt says. “Any change in regular ‘toilet’ habits can be an important clue to your pet’s health.”

Signs and symptoms of urinary obstructions 

When pets have urinary obstructions, they may want frequent walks to try to go to the bathroom or make multiple trips to the litter box. Due to the obstruction, your pet won’t actually be able to urinate, leaving them in pain. 

Straining to urinate without producing anything is an important symptom pet parents should pay attention to — and one that should result in a visit to the vet as soon as possible. 

“The symptoms in dogs and cats are often similar,” Dr. Devitt says. “Cats often make frequent trips to the litter box or cry when they try to urinate but never leave any clumps of urine. Sometimes they try to urinate in inappropriate places, like the bathtub. Sometimes, when pets strain to urinate, it looks like they are constipated. But they can poop just fine; the problem is they can’t pee.”

When a pet’s bladder is full, they may become so uncomfortable that they lay down in awkward poses, don’t get up or don’t want to play. An obstructed pet may also stop eating and/or vomit. These more general signs of sickness occur because the kidneys help filter toxins from the blood and get them out of the body through the urine. When a urinary obstruction is present, these toxins build up and imbalances of important electrolytes like potassium can occur. 

Too much potassium in the blood can result in fatal heart arrhythmias. The kidneys are also under strain as urine backs up and may begin to fail. Urinary obstructions can cause death within days if untreated, so it’s important to check with your vet right away if there’s any change in your pet’s regular bathroom habits.  

Bladder stones in dogs and cats

Some pets have an inherited tendency to form bladder stones (also called uroliths), which can cause urinary obstructions. But most dogs and cats with stones get them when there’s an abnormal accumulation of stone-forming minerals in the bladder. Bladder stones can occasionally travel to the urethra and get stuck there, causing urinary obstruction.

Bladder stones are similar to kidney stones but found in the bladder. Once formed, they usually cause discomfort and may be associated with infections or blood in a pet’s urine. Large or many stones can lead to partial or complete urinary obstruction.

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Struvite crystals in dogs and cats

The most common types of stones in dogs and cats are made of struvite (sometimes called magnesium phosphate or triple phosphate) or calcium oxalate. In dogs, struvite stones are usually associated with a bacterial urinary tract infection. 

“Struvite crystals are a mineral made of magnesium ammonium phosphate,” Dr. Devitt says. “The crystals are tiny, but they can irritate the lining of the bladder. Unlike dogs, struvite crystals in cats are not typically associated with a bacterial infection. But a significant amount of any crystals in the bladder can cause urinary tract inflammation, pain and obstruction (especially in male cats).”

The stones may also form as a result of nutritional imbalances, metabolic diseases or high levels of calcium in the blood.

Treating urinary obstructions 

Urinary obstructions are always an emergency. If your pet shows signs of urinary obstruction, prompt medical care is important, as the condition can be fatal. When a pet’s condition is stable, the first thing your veterinarian will want to do is find out what is causing the obstruction. It could be a bladder stone, stones in the urethra, crystals in the urine, inflammation, infection or a combination of things. 

A urinalysis, X-rays and/or an ultrasound help determine where the urinary tract is blocked. Your veterinarian may also run blood tests to make sure the kidneys are working normally, and potassium levels are in a normal range.

Your veterinarian will also take steps to relieve the actual obstruction. In almost all cases, the dog or cat will need sedation so a urinary catheter can be placed to allow urine to flow out of the bladder again. If a urinary catheter isn’t an option, your vet may perform emergency surgery to remove the blockage. 

When bladder stones are causing the blockage, your veterinarian needs to know the type of stone since some can be dissolved with prescription diets and treatment of urinary tract infections, while others need to be surgically removed. In particularly difficult situations, male cats and dogs may require surgery to create a permanently wider opening in their urethra. 

After the obstruction is removed, your pet will likely need several days of hospitalization for supportive care while they recover. Intravenous (IV) fluids and correction of electrolyte imbalances, as well as pain medications and medications to prevent urethral spasms, will likely be given. It’s important that the pet is able to urinate on their own before they get to go home. 

Risk of recurrence

Male cats who have experienced a urinary obstruction are at an increased risk of recurrence. To prevent urinary obstructions, pet parents should encourage their cats and dogs to drink plenty of water. 

Your vet may also recommend a prescription diet to help prevent future formation of the crystalline matrix that causes urethral plugs.

“Canned diets have more moisture than dry foods, so your vet may recommend you switch,” Dr. Devitt says. “For cats, water fountains are easy and interesting ways for them to get more water. You can boost fluid intake for your dog by adding low-sodium broth to their food.”

Again, urinary obstructions can be fatal and should always be considered a veterinary emergency. Call your veterinarian right away if you suspect your pet has an obstruction — this is one of those emergencies that can’t wait until morning, so call your local emergency clinic if your regular vet’s office is closed. Prompt care can help ensure a better chance of a positive result for your pet.

The Dig, Fetch's expert-backed editorial, answers all of the questions you forget to ask your vet or are too embarrassed to ask at the dog park. We help make sure you and your best friend have more good days, but we’re there on bad days, too.

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