Dear Dr. John,

Our older dog is nearly 11. He is a neutered large wirehaired dog that has been healthy except for successful ACL surgeries on both knees.

Our younger dog is a Golden Retriever who is always pestering him to play. In the last year he has taken to a chronic licking of his lips or in the air for long periods. Our vet has not found anything. What could be the possible causes and is anything being overlooked? He has also had recent bouts of diarrhea and vomiting yellow bile a few times. Our vet gave him metronidazole for the stomach issues. Does that sound right, and could the licking be related to his stomach upsets? K.F.

Dear K.F.,

Older dogs can and do sometimes lick aimlessly in the air or at their lips and there are various reasons for this behavior. Some of the causes include boredom, stress, cognitive dysfunction or doggie Alzheimer’s, or a foreign body stuck in their mouth. I cannot help but wonder if he has anxiety from the younger dog always bothering him, as you stated. Since you have seen this going on for some time, there is also the possibility of dental discomfort or pain, but if your veterinarian has examined him then that can likely be ruled out. When was the last dental cleaning done and were radiographs taken? Even a subtle issue can cause discomfort.

It is also possible that the licking is related to the gastrointestinal upset signs that you are seeing. He could have chronic nausea, or he could be licking something that may be upsetting to his stomach. He may also have something like an irritated bowel or pancreatitis given the vomiting and diarrhea that you have also seen. Strangely enough, the behavior can also now be a compulsive, quirky, and habitual behavior that developed. I like the idea of trying the dog on metronidazole as it is an excellent medication for various gastrointestinal issues.  If this does not resolve the issue, then a more extensive workup of his digestive system would be in order. I hope that you find answers to this situation. Good luck.

Dr. John de Jong is President of the World Veterinary Association. He owns and operates the Boston Mobile Veterinary Clinic and can be reached at 781-899-9994.