Infectious Osteitis of the Mandible Treated with Antimicrobial Impregnated Equine Cancellous Bone Allograft

An 11 years old P.R.E. stallion presented with infectious osteitis of the right mandibular ramus after cheek teeth 406 and 407 had been removed several weeks earlier. The disease process led to severe osteolysis. Initial treatment consisted of surgical removal of the bony fragments and thorough debridement in conjunction with systemic antimicrobial treatment according to bacteriological testing results (Enrofloxacin). However, the initiated treatment remained unsuccessful and a repeated bacteriologic examination of the bony fragments revealed a severe infection with ESBL E. coli and MRSA. A plan was subsequently made to treat the infectious osteitis with a cancellous bone allograft. Prior to surgery a CT scan was used to evaluate the extent of the bony defect and for the calculation of the volume of cancellous bone graft needed to fill the defect.

The horse was anaesthetized and after intense debridement and removal of unhealthy appearing bone, 150 ml of equine cancellous bone graft impregnated with Vancomycin, Tobramycin and Meropenem was packed tightly into the defect.

The alveoli were closed with dental silicon.

In the immediate post-operative period the stallion was fed slurry food and remained on NSAID’s (Meloxicam). However, only 4 days after surgery it was noticed that the skin wound over the bony defect started to dehisce and pieces of the bone graft were pushed out. Additionally, the silicon plug failed to protect the bone graft from contamination with saliva and food from the oral cavity.

A follow up CT scan showed the complete loss of the bone graft and the affected mandible appeared unstable.  [...]