I have a three year old Yorkie; he has a flee alergy that we are treating, however, he has now developed a terrible cough. I plan to take him to the Vet next week when I have a day off, but I want to know what could be the reason behind this.

Thank,

There could be many reasons for this. Heartworms, kennel cough, heart problems are some of the possibilitites. It could be a simple viral infection. There are other less common things as well, such as fungal infections and lung worms. This dog will have to be examined and may need tests to determine this. Be sure and get him on good flea medicine from your veterinarian so he does not suffer from the allergy. If the dog is on prescription meds for the allergy, just make sure they are not the cause of his problems.