Q: The veterinarian says my cat has tooth resorption, so I made an appointment for her to have dental X-rays and probably tooth extraction. What can you tell me about this condition?

A: Tooth resorption, previously called feline odontoclastic resorptive lesions or neck lesions because they’re often seen on the neck of the tooth where the visible crown meets the root, occurs in 25% to 75% of adult cats, making it their most common dental disease.

Tooth resorption occurs when odontoclasts, cells that normally dissolve and absorb the roots of baby teeth as the adult teeth erupt, instead attack adult teeth. The assault usually begins within the root but may start on the neck or crown of the tooth.

No one knows for sure why the odontoclasts attack adult teeth, but certain risk factors are recognized:

» Adult cats are affected, usually by 4 to 6 years of age. Females are at higher risk than males.

» Domestic cats experience tooth resorption more often than feral cats. Purebred cats are at greatest risk, especially the Abyssinian, Oriental shorthair, Persian, Russian blue, Scottish fold and Siamese breeds.

» Infection by the feline immunodeficiency virus increases risk.

» Cats that eat only table food, a low-calcium diet or raw liver are at elevated risk.

Prevalence is higher in cats that drink municipal water rather than well water. Risk is also greater in cats that gulp their food instead of chew it.

When only the root is being resorbed, the cat’s mouth appears normal. However, tooth resorption inevitably progresses, and once the neck or crown is affected, the lesion is exposed to oral bacteria that cause painful inflammation of the surrounding gums.

Clinical signs then include drooling, mouth rubbing, head shaking, teeth chattering, an area of reddened gum covering the lesion, bad breath, trouble eating, decreased appetite, sneezing and lethargy.

Dental radiographs, or X-rays, show the extent of tooth resorption and guide treatment, which often involves extraction.

Because the disease progresses and affects multiple teeth, dental radiographs are repeated annually as long as some teeth remain. Fortunately, the prognosis is excellent once the affected teeth are extracted.

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Q: Dash, the greyhound I adopted a few months ago, retracts his lips and shows his teeth when I arrive home from work. It looks like he may be smiling, and his tail and rear end wag vigorously. Still, his teeth are big, so he looks intimidating.

He acts like he’s happy, but I’m not entirely sure whether he’s smiling or snarling. When he does this in front of my friends, he frightens them. What’s happening?

A: It sounds like Dash is giving you a submissive grin, a greeting that communicates that he is delighted to see you and wants you to know that he doesn’t pose a threat. My childhood collie did the same thing and even squealed as he grinned.

This behavior is inherited and can also be learned. Dash will repeat it more often if you and others reward him with praise and attention. Interestingly, dogs display the submissive grin not only to humans but also to other dogs.

A submissive grin can scare people if they mistake the baring of teeth for an angry snarl. But, snarling is accompanied by a stiff posture, not the wiggly body and wagging tail Dash displays.

So, explain Dash’s greeting behavior to your friends before they arrive. With a little understanding, they’ll feel flattered, not frightened.

Lee Pickett DVM

Lee Pickett DVM

Lee Pickett DVM practices companion animal medicine in North Carolina. Click here to ask her questions for her weekly column. The opinions expressed are her own.