Skin discoloration in boxers

[ddane60]

Has anyone had skin problems with their dog? My boxer is 2 years old.  We've taken our dog to the vet several times.  They did blood work for hypothyroid and it came back clear. They also did skin scrapings several times. I was convinced it was mange but, that came back clear.  Our dog is not lethargic, he doesn't itch or appear uncomfortable.  The doctor prescribed Tramodol and Melatonin. Tramadol for pain which he doesn't have and Melatonin for hair loss. The label on the Melatonin label says it is a sleep aid.  Lost and don't know what else to do. We've been dealing with this condition for two months. Thanks in advance!  

[ddane60]

His skin discoloration looks like a white cows black spots, and his fur is thining in those areas.  We've been giving him the melatonin and now he has loose, bloody stools (frank blood). So we have stopped the melatonin. I checked the stool for worms and didn't see any. Would i be able to see worms in the stool?

[Aleda M Cheng, D.V.M., C.V.A]

Could you describe the discoloration to me in detail so that I may be able to help you better?  

Just because the skin scraping has come back negative doesn't mean that your dog does not have demodex mites.  Demodex mites cause a discoloration to hair and skin that makes the affected area appear moth eaten.  Demodex mites do not cause itching usually.

Melatonin is perfectly safe, but only give it at night.