Here are 4 insights as to why your dog's diaper keeps falling off:
The diaper may be too loose. Check the fit of the diaper and make sure it is not too big for your dog. The diaper may not be fastened properly. Make sure the diaper is securely fastened at the waist and around the legs. You may be using the wrong kind of diaper. Some diapers are designed better than others. Try a different brand or style of diaper. If your dog is overweight, has a skin condition, or is constantly scratching at its diaper, this could be the cause. Talk to your veterinarian to rule out any other possible causes.
If these steps do not help you figure out why your dog's diaper keeps falling off, talk to your veterinarian for more ideas.