The dictionary definition of halitosis is wonderfully understated: “breath that smells unpleasant when it comes out of the mouth.” This really gives no impression of the gross foulness of a dog with stinky breath.
I have known a dog whose breath was so bad that his human was driven from the room whenever the dog entered. Even worse is the affectionate dog with offensive breath who tries to lick you!
The reason for halitosis is usually an infection in the mouth, but bear in mind that infection usually happens as a result of tissue damage. There are many different causes of halitosis, such as kidney failure and uncontrolled diabetes, causing the body to emit unpleasant-smelling toxins.
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Most people are all too aware when their dog has halitosis. You may notice it especially if the dog has been left in a room and the smell hits you when you go in.
Dogs often have halitosis because of infection due to another problem; they may drool heavily or have bloodstained saliva. Some dogs have oral pain and find it difficult to pick up or chew food, while others may drink more than usual — because they are trying to get rid of a horrible taste in their mouth.
Healthy gums and teeth do not smell, and commonly halitosis is caused by infection in the mouth due to other problems. This list is extensive, but it boils down to things that damage the mucus membrane in the mouth or disease elsewhere in the body that releases toxins (such as kidney disease or diabetes).
While not exhaustive, this list gives an idea of the common problems affecting the mouth:
- Dental calculus. Soft, sticky foods build up on the teeth and become mineralized by phosphate and calcium in saliva. These hard deposits are called tartar; it pushes on the gums, causing inflammation. Food gets trapped between the teeth, which also causes inflammation and a bad smell.
- Stomatitis and gingivitis. This is inflammation of the gums and can occur because of a high bacteria count in the mouth. Red, sore gums are more vulnerable to colonization by bacteria, which cause halitosis.
- Oral foreign bodies. These are things that wedge in the mouth and cause damage to the tissue, which becomes infected. Most common of these are pieces of stick or fragments of chewed-up bone.
- Oral cancer. Cancers of the oral cavity and tongue, such as squamous cell carcinoma or malignant melanoma, often become infected and cause a bad smell.
- Lip-fold dermatitis. Although not strictly inside the mouth, certain breeds, such as Cocker Spaniels, have deep folds of skin around the lower lip. In the warm, moist environment of the mouth, these folds often become infected and can smell very unpleasant.
- Renal disease and diabetes. When kidneys struggle to function, a toxin called urea builds up in the blood, which can cause oral ulceration and bad breath. Likewise, dogs with uncontrolled diabetes become loaded with ketones, and this sickly, sweet odor is given off on the breath.
Diagnosing bad breath is not difficult — after all, you only have to sniff, but the trick is to identify the reason underlying the halitosis.
The first step is a really good look inside the dog’s mouth, checking for tartar buildup, oral ulceration, gingivitis, cancers and objects in the mouth such as sticks or bones. In cases of abnormal tissue in the mouth, a biopsy can give a definitive diagnosis.
If disease elsewhere in the body is suspected, then blood tests can identify problems such as kidney failure or diabetes.
Treatment for bad breath involves seeking out the infection and correcting the underlying problem.
If an alien object is present in the mouth, this needs to be removed; likewise, teeth with dental calculus require cleaning. Options for treating oral cancer are limited but include surgical removal where possible, and radiotherapy in some cases.
The blooper at the end of this video on how to brush your dog’s teeth truly makes it a worthwhile watch:
One of the most common reasons for halitosis is dirty teeth and dental calculus. This is entirely preventable with regular teeth cleaning.
If regular cleaning is not possible, then dental chews or dry diets with a teeth cleaning action go some way to slowing down the deposition of tartar.
- “Periodontal disease and diet in domestic pets.” Gorrel, 1998. J Nutr., 128: 2712S–2714S.
- Veterinary Dentistry. Steven Holmstrom, DVM. Publisher: Saunders.
This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed May 17, 2016.