Cow, Holstein • 2 years of age • Female • Presented for persistent swelling on the lower jaw for months. • The swelling was ulcerated and got better with antibiotic therapy. • After 10 days, there was relaps of the ulceration and lack of improvement of the soft tissue swelling. At the clinical examination the cow was in good general body condition. There was a severe swelling ventral to the right mandibula. Radiographs were taken. Radiographic examination Right 45° dorsal-left ventral oblique view of the right mandibula Radiographic changes
- There is an ill defined, extensive area of very heterogenous radioopacity of the right mandibula. The opacity of the bone Dssue is decreased, with multiple lucent areas (arrows) surrounded by more opaque (sclerotic) rims of bone tissue. Additional severe thinning and focal interruption of the cortex is visible (small arrow). There is extensive amorphous new bone proliferation on the ventral mandibular border (empty arrow heads).
- The third premolar is displaced, with a diastema between P3 and M1. The roots of the tooth are embedded in the abnormal bone tissue.
- There is severe soft tissue swelling ventral to the ramus of the mandibula, with a very irregular delineation and heterogenous radioopacity.
- The radiologic diagnosis is aggressive bone lesion in the right mandibula with accompanying severe soft tissue swelling and possible soft tissue lesion.
- Secondary tooth instability.
- Differential diagnosis include osteomyelitis and neoplastic process.
- Considering the signalament and the radiographic findings, actinomycosis was suspected.
- The diagnosis was confirmed and euthanasia was suggested.
Radiographic changes Close up of the right 45° dorsal-left ventral oblique view of the right mandibula Comments
- Mandibular pyogranulomatous osteomyelitis ('lumpy jaw') is a specific condition which is common in cattle and is caused by Actinomyces bovis, a Gram positive branching filamentous microorganism.
- Actinomyces bovis is part of the normal flora of the oral cavity of the animal species in which it causes diseases.
- The lesion can occurr as a result of invasion of bacteria at the gum line when the teeth are infected and mandibular osteomyelitis can occurr secondary to periodontitis.
- Another way of infection is through the buccal mucosa, progressing to bone infection.
- Rarefying osteitis, osteoporosis interspersed with granulomatous tissue and pockets of pus containing yellow, sand-like granules are the main pathological changes found in bovine actinomycosis.
