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7 Reasons Your Dog Has Bad Breath

By Elizabeth Xu


Spend a few minutes with any dog and you’ll likely catch a whiff of his breath because dogs aren’t shy. They also aren’t known for fresh-smelling mouths. But bad breath isn’t just an unpleasant thing for you—it can mean something serious for your pup.


Sometimes a simple tooth brushing might suffice, but other times, bad breath is the sign of a more serious problem that requires veterinary care. Learn the common causes of bad breath in dogs so that you can protect your four-legged friend. 

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Dental or Gum Disease

Bad breath (known medically as halitosis) in dogs can occur when your dog has a dental condition—from gum disease or infection to tooth decay.


“A lot of times you can lift up the dog’s lip, look at their gums, [and see that] they’re very red and inflamed,” says Dr. Jeffrey Stupine, VMD, Head Veterinarian, Wellness of the Pennsylvania SPCA. “You can see the tartar build up on the teeth.” He notes that some issues can’t be seen though, including cavities below the gum line.


Although your vet looks for obvious signs of dental disease during your dog’s annual checkup, it’s a good idea to make an appointment in between visits if you suspect a dental issue.



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Kidney Disease

Metabolic diseases like kidney disease or failure can cause bad breath. In fact, a decrease in kidney function can make a dog’s breath smell like ammonia, Stupine says.


“The waste products that are normally eliminated by the kidneys build up in the bloodstream and then show up in the breath of affected individuals,” says Dr. Steve Barghusen, DVM, of Pet Crossing Animal Hospital and Dental Clinic in Minnesota.

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A Toxic Substance

All dogs are different, but there’s a common assumption that some dogs will eat anything, including things that are bad for them. Sometimes it’s true.


“There’s a whole number of toxic substances out there, and if they smell bad, that might cause a dog to have bad breath at the same time,” Stupine said. If you suspect your dog has ingested a potential toxin (antifreeze or a rodenticide, for example), call your vet immediately, as emergency care may be required.



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Diabetes, specifically diabetic ketoacidosis, can also make a dog’s breath smell unusual, giving it a sweet, almost fruity smell. Uncontrolled diabetes can also “suppress the immune system, allowing bacteria in the mouth to grow unchecked,” according to Barghusen.



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Foreign Substances

Unfortunately, dogs eat plenty of non-food items that aren’t good for their bodies or their breath.  Dr. Jennifer Quammen, DVM, of Grants Lick Veterinary Hospital in Kentucky says that she has seen bones, fishing hooks and sticks all cause foul breath in dogs. Those objects can all get stuck in a dog’s mouth or teeth, she says.


Barghusen agrees that dogs do sometimes eat some pretty undesirable things: “Eating disgusting stuff like feces and long-dead animals can also cause significantly bad breath.”



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Oral Tumors

Your dog’s teeth and gums aren’t the only areas for concern when it comes to possible causes of bad breath. Oral tumors are another potential cause due to the fact that their growth is often too fast for blood vessels to keep up, thus causing dead areas, Bargusen says. Bacteria then takes over the dead areas, and that bacteria is often what causes a foul odor, he says.


Barghusen notes that oral tumors can vary in shape and size so if you notice any masses or discolorations in your dog’s mouth, they should be checked out by a veterinarian. 



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While garbage or another non-approved substances can make your pup’s breath smell undesirable, even dog-approved foods and treats don’t always freshen breath.


Dry food and wet food both have pros and cons when it comes to how they affect breath; some types of dry food can be better for teeth and helping keep the mouth clean overall, but wet food has more water which is also good for a dog’s mouth, Stupine says.


If you’re concerned that it’s simply your dog’s food that is causing bad breath, you can work with your veterinarian to find the best option for your dog. 



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