Actinomycosis in Ruminants (Lumpy jaw)

Annu Yadav, Ankit Kumar, Tarun Kumar

Department of Veterinary Medicine Lala Lajpat Rai University of Veterinary and Animal Sciences Hisar – 125004 (Haryana)

Introduction

Ÿ Caused by Actinomyces bovis, a gram-positive, non-encapsulated, branching, filamentous bacterium that is normal inhabitant of the ruminant mouth. Ÿ The disease occurs mainly in cattle but on rare occasion affect sheep or goats Ÿ It enters the tissues and bone through oral abrasions, openings and punctures associated with dental or gingival disease, hard plant awns (e.g., foxtails), thorns, stickers, or dry, coarse, stemmy feeds. Ÿ Lesions may begin as cavities (caries) in the dentin or dental pulp . Ÿ Lesions are sporadic and occur mainly in the mandible and less commonly in the maxilla. Ÿ The preponderance of mandibular lesions, with the development of periosteal new bone and fibrosis, gives the disease its common name

“lumpy jaw". Ÿ Lesions occasionally occur in soft tissues of the head, esophagus, forestomach and trachea.

Clinical Signs

Ÿ Typically, a hard, immovable, painless, bony mass on the mandible, mainly common on the horizontal ramus. Ÿ Initially it is nondraining (has no fistulous tracts) but it may develop fistulous tracts and involve tooth roots as the condition progresses. Ÿ When teeth become involved, evidence of pain during chewing may be seen, and weight loss may result. Ÿ A careful examination of the mouth required to detect loose teeth, plant

guns, or severe gingivitis and to rule out a pathologic fracture. Ÿ If a fistula is present, it is useful to flush the tract with organic iodine and perform contrast radiographs to determine if it communicates with the mouth.

Clinical Pathology

Ÿ Hematologic and clinical chemistry findings may be normal or may reflect a chronic infection. Ÿ Radiographs of the lesion are helpful in determining if there is dental involvement or a pathologic fracture.

The radiographic lesion consists of multiple central radiolucent areas of osteomyelitis surrounded by periosteal new bone and fibrous tissue. Ÿ If a fistulous tract is present, a contrast study done while flushing into the tract may help determine the extent of the fistula. Before flushing, material from the core of the lesion should be aspirated or biopsied. Ÿ Gram stain and culture of pus should be performed. The organism is grampositive, filamentous, and branching. “Sulfur granules” club like rosettes or club colonies found after crushing between two glass slides

Differential diagnosis 1. Tooth root abscess 2. Fracture 3. Tumors

A mandibular swelling that continues to enlarge despite therapy should be radiographed for evidence of a fracture or sequestrum.

Treatment

Medical treatment of actinomycosis involves the use of sodium iodide, isoniazid, and penicillin or another antimicrobial drug to which the organism is sensitive. Ÿ Sodium iodide is given IV at a dose of 70 mg/kg as a 10% to 20% solution.

It can be given every 7 to 10 days or more often until signs of iodinism occur (i.e., lacrimation, cough, inappetence, diarrhea, and dandruff). If repeated intravenous treatments are difficult, oral organic iodides can be given at the rate of 60 mg/kg/day for 3 weeks. As with actinobacillosis, the beneficial therapeutic effects of iodides appear to lie in their ability to reduce granulomatous inflammation rather than in direct antimicrobial effects.

Iodides do not appear to cause abortion and can be safely given to pregnant cows, ' although care should be used because there are anecdotal reports to the contrary, and products are labeled with a contraindication for pregnant cattle. Ÿ Isoniazid (10 mg/kg/day given PO for 1 month) is effective at arresting actinomycosis of the mandible in cattle.” It is inexpensive and readily consumed in a small amount of grain. Ÿ Penicillin (10,000 U/kg IM twice daily) or another antimicrobial drug such as florfenicol or ampicillin can be added to the treatment regimen

Prevention and Control

Actinomyces bovis is a normal mouth inhabitant of ruminants; therefore the only possible means of prevention is to avoid feeding coarse, stemmy feeds, feeds with hard, penetrating plant awns, or feeds with other sharp materials.