Pets don’t always smell particularly fragrant. Curious dogs and cats certainly can get into some stinky situations.

But at times a bad odor is a sign of something more serious. If you can rule out external factors — like rolling around in something foul-smelling — and a bad scent persists, it might be time to seek professional help.

“Your dog and cat probably have their ‘normal’ smell,” said Dr. Heather Berst, a veterinarian and medical lead with animal health company Zoetis. “If you notice a change in how your pet smells, do not try and mask it with a shampoo or spray. It may mean your pet is having a medical issue. Reach out to your veterinarian to make sure it is not part of a medical problem.”

Berst and other experts told HuffPost about some common medical conditions that manifest in odor changes and what scents to look out for.

“Skin infections frequently change how a dog or cat smells,” Berst said. “The smell may be associated with itching, redness, hair loss or change in coat texture.”

Malassezia dermatitis is a yeast infection of the skin that is fairly common in dogs and can occur in cats as well.

“Yeast usually smells musty or like stinky feet,” said Dr. Sarah Wooten, a veterinary expert with Pumpkin Pet Insurance.

Chronic skin yeast infections come with a number of other symptoms. Pay attention to abnormal smells, irritated skin or behavior that suggests skin discomfort. Pets with underlying allergies may also be more prone to developing skin infections.

“Staph infections on the skin may have no odor or might smell sweet,” Wooten said.

She noted that bacterial skin infections are usually associated with redness, hair loss, bumps that resemble pimples, skin flaking and oozing from skin folds.

“Skin that reeks of corn chips has an infection of Pseudomonas bacteria,” Wooten added. “This skin is just red and itchy as well. This is more severe than ‘Frito feet,’ which is a commonly searched term and considered normal in dogs.”

Bacteria can also cause skin abscesses ― pockets of pus on the body that can be quite painful and might produce a distinct odor.

“Abscesses smell terrible, putrid,” Wooten said. “You’ll never forget the smell! Abscesses are usually associated with local swelling of the skin, redness, pain, inflammation, and may be oozing pus.”

Yeast or bacterial infections can also occur in a pet’s ears. Ears that fold over often trap moisture, creating environments where yeast or bacteria can thrive.

“Ear infections frequently have a bad odor,” Berst noted. “Depending on what is causing the infection in the ear, you can have different smells, including a yeasty smell or a very foul smell.”

The smell will likely be stronger when you lift the animal’s ears, and there might be some discharge and redness. As with skin yeast infections, yeasty ears will smell musty or like stinky feet. They might produce a dark brown discharge.

“Ears infected with bacteria may smell sweet or fetid, or if they have a Pseudomonas infection will smell like tortilla chips and have white discharge,” Wooten said.

She added that ear mites, which are fairly common in cats, can cause an odor as well.

“Ear mites cause black debris in the ears, plus redness and severe itching,” Wooten said. “They smell like either yeast or bacteria ear infections.”

“Bad breath is very commonly to blame for a gross-smelling dog,” said Dr. Dana Wilhite, a consulting veterinarian with pet treat company Full Moon Pet. “Dental disease is usually the most likely cause, as malodorous odor-producing bacteria in the mouth produce a smell similar to a sewer. Excessive drooling due to rotten, painful teeth can cause the skin around the mouth to become infected as well, adding to the foul smell.”

A gum infection, bleeding mouth tumors or a nasal infection might also cause an odor, so have a veterinarian check it out. Even if there’s no underlying medical problem, a professional consultation can help with the issue.

“Living with a dog with a ‘rotten mouth’ is no fun for anyone involved, and you will be amazed at the difference a dental cleaning by your veterinarian can make,” Wilhite said.

She noted that bad breath is a very common odor complaint in cats.

“Although cats tend to keep themselves well groomed, they can’t brush their teeth on their own. And if they live long enough and haven’t been receiving routine dental care, they will end up with dental issues,” Wilhite said.

Beyond dental infection, changes in the smell of a pet’s breath could be a sign of complications with diabetes, which requires medical attention.

“A dog or cat with uncontrolled diabetes can have very sweet- and fruity-smelling breath,” Wooten said. “These dogs and cats usually also have weight loss, and drink a lot and pee a lot.”

Wilhite noted that stomatitis, gastrointestinal disease and respiratory infection may also cause a foul odor from the mouth.

“Dogs and cats have two anal glands at the 3 and 7 o’clock position of their anus,” Wooten said. “Usually there is no smell coming from these glands. However, dogs and cats may express their anal glands when they are scared, which can result in a strong, fishy, musty smell that hangs on even after you clean yourself and your pet.”

Though it can be normal for a pet to express their anal glands occasionally, take note if the strong odor appears frequently. This could be a sign of something wrong.

“When these glands become infected and an abscess develops, the smell can be magnified,” Wilhite said. “If your dog is scooting, acting uncomfortable, has swelling, blood or fluid leaking from this area, they will appreciate a visit to the veterinarian.”

Vets and groomers can express your pet’s anal glands when they get too full.

“Excessive gas is an odor that can be hard not to notice,” Wilhite said. “This can be diet-related and may be associated with the type and amount of dietary fiber in the food. Certain ingredients may work better for some dogs and cats than others with regards to gas production.”

Flatulence might be an indication that it’s time to change your pet’s diet. But if it continues even after making a switch, consider asking a vet for guidance.

“Nondietary causes of gas are typically the result of how much air a dog swallows but can sometimes be a sign of gastrointestinal disease,” Wilhite said. “Your veterinarian will be able to advise you as to how to remedy your dog’s excessive gas.”

Dogs and cats can also develop urinary tract infections that might manifest in odor changes.

“A strong urine smell could be a sign of urinary tract infection, especially if associated with other signs of a UTI, like increased urge [to urinate] or bloody urine,” Wooten said.

Look out for other issues in the urinary system, such as kidney failure, which can cause a urinelike odor.

“Cats that have severe kidney disease will have an ammonia smell to their breath and will act very sick ― not eating, lethargy,” Wooten noted.

New pet owners are on high alert for parvovirus, which can also have smell-related symptoms.

“Parvovirus is a highly infectious, often fatal viral disease that results in severe vomiting and diarrhea that is usually associated with a lower GI [gastrointestinal] bleed,” Wooten said. “The smell of parvo is terrible and can knock you off your feet. The dog and the stool smell like rotting meat and may have a metallic edge to it because of iron in the bloody stool.”

“Poor grooming can result in abnormal odor,” Wilhite said.

She added that if cats are unable to groom themselves properly, it might be the result of an underlying condition like obesity, arthritis, diabetes, hyperthyroidism or cancer.

“Cats that don’t feel well for any reason, including arthritis, will groom less and have a musty, greasy coat that is sometimes matted,” Wooten said. “They can accumulate fecal material around their back end ― ‘dingleberries’ ― that smell and look like feces.”