Periostitis Ossificans in a Litter of Belgian Malinois Puppies

Periostitis ossificans (PO) is a subtype of chronic osteomyelitis characterized by subperiosteal bone formation as a reaction to mild infection or irritation. In the veterinary medicine literature, it has been described in large breed dogs, aged 3 to 5 months, and was postulated to be caused by mild inflammation related to tooth eruption. This report describes 3 Belgian Malinois puppies from the same litter diagnosed with PO at 3 months of age. The puppies presented with non-painful distal mandibular swellings. Diagnostic procedures included intraoral dental radiographs, a computed tomography scan of the head, and bone biopsies submitted for histopathological examination. PO is typically a self-limiting condition and likely caused by inflammation due to tooth eruption. Therefore, treatment focuses on pain management and monitoring until the permanent teeth emerge. Long-term follow up until two and a half years of age showed a significant decrease to total resolution of the swelling, with minor bone changes evident on advanced imaging. Histopathologic findings are not pertinent for the diagnosis of PO and imaging shows pathognomonic features of the condition. Mandibular PO, craniomandibular osteopathy, and calvarial hyperostotic syndrome are all self-limiting proliferative bone diseases of the skull in juvenile dogs with an implied genetic component. The authors' findings support grouping them as a single disorder called "Idiopathic Canine Juvenile Cranial Hyperostosis" with predilection sites that vary between breeds.