If you noticed that your dog has sunken eyes, you're right to be concerned; sunken eyes can be a symptom of something serious. Consult your vet as soon as possible.
Many of my patients need to be on it all of the time although I do have some that can have several weeks off of medication and do well. There are no known side effects of long term use of Tylosin. However, it does have a bit of a yucky taste. I have found that little dogs real...