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Q: For the last three years I have been partnered with a drug-detector dog. The first year of our work together, he had surgery for bilateral laryngeal paralysis (a disease of the upper airway, making it difficult for the dog to breathe normally).

Then 10 days ago he had his lower right canine removed. Since then he has shown no interest in his work. He is also breathing heavily through his mouth. A colleague told me that detector dogs require their canine teeth to help them detect or search. Is this true? Also, is there a chance his laryngeal paralysis will come back? -- W.B., via e-mail

A: A dog's ability to detect odors is at least 10,000 times better than ours. That's why, for a dog, smell is the most important of all the senses. With your dog, who not only relies upon smell as a dog but also has a job that depends on his nose, your concern is understandable.

Dr. Gregg DuPont of the American Veterinary Dental College (www.avdc.org) and Dr. Kate Knutson of the American Animal Hospital Association (www.healthypet.com) were able to offer some advice, which we paraphrased:

The decreased sense of smell is not a direct result of the missing canine tooth. If fact, an infected tooth before removal can actually interfere with detection ability, because of strong odors created by the infecting bacteria in the mouth and from an overall sense of discomfort from chronic infection.

Your dog's loss of interest in detecting smells and his mouth-breathing may have started after the tooth was removed, but these symptoms are likely not related to the missing tooth.

The roots of canine teeth are long and curved, extending toward the back of the mouth. Because the roots extend deep into the jawbone, surgical extractions of these teeth are invasive. Both root curvature and length necessitate a significant portion of the jawbone to be removed in order to successfully extract the tooth. In addition, tissue is cut to get to the bone and arteries, and veins and small nerves are destroyed in the process. For several weeks there is considerable swelling in the tissue flap covering the extraction site.

The extensive nature of surgery and the postoperative swelling are likely contributors to your dog's decreased sense of smell. Stitches collecting food, bacteria and white blood cells can also affect the sense of smell. A drug reaction to antibiotics or pain medication taken after surgery can cause symptoms as well, which may be related to what you have seen.

Pain also contributes to behavior changes. Swelling of the bony socket that holds the tooth could be causing pain. Some dogs even tear out their stitches, leaving open bone exposed, and that can be extremely painful, as you might imagine. Your dog's panting behavior is likely a response to pain.

There can also be other, more serious reasons behind your dog's behavioral change, including a metabolic problem (such as renal failure) or aspiration pneumonia. Please take your dog back to your veterinarian for follow-up diagnosis and treatment as well as medication to address his pain.

You also inquired if laryngeal paralysis can reoccur following surgery. It would be unusual to see signs at the two-year post-surgery mark. However, nothing is impossible. If this is a concern, your dog needs to be lightly sedated so the surgical site can be evaluated. Again, talk to your veterinarian.

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