Dear Dr. John,

Shortly before we moved, our middle-aged dog developed a bilateral ear infection. She was given something called Baytril which has an antibiotic in it called enrofloxacin. It started to show some promise, and her ears were clearing when we moved. However, within a day or two she developed signs of a urinary tract infection which was confirmed by the new vet. Could the stress of the move cause the problem? Either way, the second vet put her on something called Clavamox. Is it safe to have her on two antibiotics at the same time?

— M.M.

Dear M.M.,

Your question about taking more than one antibiotic at a time is a good one as is the general question of the possibility of drug interactions when a patient, dog, human, or other species takes multiple medications.

The stress of the move might have triggered your dog’s urinary issue. Did you inform the second veterinarian that she was already taking another medication? In some cases, there can be serious negative side effects due to various drug interactions. This is why it is always important to make sure that all doctors treating a patient are aware of what else that patient might be taking. In the case of your dog, I suspect that she is taking Baytril Otic for her ears, a strong and good treatment for bacterial and yeast infections of the ear canals. As a topical medication, she is not ingesting it as she is the Clavamox for her UTI. As such, there is little, if any, chance for the two medications to be in any part of her system simultaneously.

Even if she was taking both enrofloxacin and clavamox orally, it would be safe to do so. The best way to avoid trying multiple antibiotics to fight any bacterial infection is to do a culture and sensitivity of what seems to be infected to find out which antibiotic will be most effective. In the case of simultaneous infections, a veterinarian will always try to pick one antibiotic that will cover all problems rather than more. My guess is that your dog’s two problems will resolve soon.

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.