The goal of this report is to present an interesting case of generalized demodicosis, associated with a generalized pyoderma due to a resistant strain of Staphyloccocus aureus, and haematogenous osteomyelitis. Acute bacterial osteomyelitis caused by haematogenous spread is uncommon, with most cases occurring in puppies. Spread to the epiphysis is rare since the growth plate acts as a barrier. Superficial pyoderma is commonly associated to generalized Demodicosis, and Staphyloccocus aureus is frequently isolated, nowadays we have to face infections due to cephalosporins resistant strains.

The puppy was a 3 months old mastiff of 17 kg of body weight.

History: He had been diagnosed pyoderma and treated with cephalexin orally during 7 days, then he had fever and mild lameness of the left rear limb, at that moment the dog received a single dose of dexamethasone, then an X-ray was taken and osteomyelitis of the left femur was diagnosed and treated with ceftriaxone IM for ten days, he was also given dipyrone, vitamin B and proteolytic enzymes.

The puppy was presented to our office severely ill. The main complaint of the owners was the lameness and swelling of the left rear limb and partial anorexia. The body temperature was 39,9, the leg was painful and 90% of the body was covered with pustules and crusts, and many folds were observed on the face. Blood samples were taken, skin scrapings, fecal flotation were done, a sample of one pustule was obtained by means of a 0,5x16mm needle and 1 ml syringe so that culture and antibiogram were performed. A bone biopsy was practised under generalized anesthesia.

The puppy had anemia and neutrophilia. Eggs of Ancylostoma caninum were identified. Many Demodex canis mites were seen under microscope. A resistant strain of Staphyloccocus aureus was isolated only sensible to Rifampicin and Vancomycin, resistant to cephalosporins (1^st, 2^nd and third generation). The histopathologic findings were of osteodystrophy, osteomyelitis, chondrodystrophy, though no bacteria could be isolated from the bone sample. We diagnosed: Demodicosis, Haematogenous osteomyelitis, Ancylostomiasis. The dog was treated with analgesics,( tramadol 1mg/kg tid), rifampicin orally 300mg every 24 hours, during 2 month and moxidectin 400mcg/kg every 24 hours, during 6 months (till two months after negative skin scrapings). The dog is now one year of age and no lameness or Demodectic relapses have occurred.