Dr. Valissitie Heeren, a veterinarian at Green Lake Animal Hospital in Seattle, answers a reader's question.

Question: I have a 3-year-old rat terrier. His teeth are good. The vet says he is healthy. I am using dental products to clean and diminish tartar and plaque almost daily. Still, he has bad breath. Is it from him licking himself? Should I try a water additive?

Answer: Halitosis, or bad breath, is one of the most common complaints of people regarding their pets. The most obvious cause of halitosis is dental disease, especially in an adult small-breed dog.

Bacterial populations thrive in the oral cavity, and the biggest issue is typically with plaque and tartar below the gum line. This means that your dog's teeth may look very clean, but the odor-causing problem is not visible. It is important to maintain your dog's teeth and gums with daily brushing.

However, if brushing and dental products are not effective, it is time to discuss your concerns with your veterinarian.

There may be a need to look past the obvious.

The odor may be the result of some other underlying problem. For example, some "bearded" dogs will have persistently wet fur that can cause bacterial skin infections around the mouth. Similarly, dogs can have problems with certain dietary indiscretions, including the ingestion of fecal matter.

Another potential cause of bad breath is gastrointestinal disease. Specific disorders such as inflammatory bowel disease, exocrine pancreatic insufficiency, reflux esophagitis and delayed gastric emptying can all lead to malodorous breath.

If the smell is coupled with any intestinal symptoms, your veterinarian may recommend a specific diet change or dietary supplement such as a probiotic.

More in-depth diagnostics may be needed, including blood work and endoscopy.
One final consideration would be an odd oral odor resulting from either kidney disease or diabetes. Dogs suffering from either of these problems typically drink a large volume of water. Your veterinarian will recommend blood work and urine tests if he/she suspects either problem.

The important thing is to always voice your concerns. A routine checkup may prompt your vet to do some additional testing, or may simply give reassurance that the smell is just a hypersensitive nose picking up on a very normal odor.

Dr. Valissitie Heeren

Heeren earned a bachelor's degree in medical biology from Beloit College in Wisconsin. She graduated from Iowa State University's College of Veterinary Medicine and interned in small-animal medicine and surgery at Denver Veterinary Specialists in Colorado. She has a passion for surgery and emergency medicine and volunteers her time spaying and neutering feral cats with the Feral Cat Project. She also provides veterinary care at the Doney Clinic, a veterinary clinic for the homeless. She has one pet, a black lab mix named Indy.

Read our past Q&As:

Veterinary Q&A: Incontinence in dogs
Veterinary Q&A: Hanging tongue syndrome
Veterinary Q&A: Bad breath in dogs
Veterinary Q&A: How much is too much exercise for my dog? Part 2
Veterinary Q&A: How much exercise does my dog need? Part I
Veterinary Q&A: A killer called bloat
Veterinary Q&A: Initial care for new puppies
Veterinary Q&A: Knee problems in dogs
Veterinary Q&A: Flea-control treatment
Veterinary Q&A: Bearded dragon lizards
Veterinary Q&A: Vaccinations for indoor cats
Veterinary Q&A: Lumps and bumps
Veterinary Q&A: More on aging dogs and arthritis
Veterinary Q&A: Aging dogs and arthritis
Veterinary Q&A: Puppy and geriatric exams
Veterinary QA: What dogs can safely chew
Veterinary QA: Why does it cost so much to clean a dog's teeth?
Veterinary QA follow-up: More on cleaning a dog's teeth
Veterinary QA: When to spay or neuter

Do you have a question about pet health? Ask now! We'll pose some of your questions to a local vet in an upcoming post.