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Actinomycosis in Dogs

By Otto M. Radostits, CM, DVM, MSc, DACVIM (Deceased), Professor Emeritus, Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan ; David A. Ashford, DVM, MPH, DSc, Assistant Area Director, International Services, APHIS, USDA ; Craig E. Greene, DVM, MS, Professor, Department of Small Animal Medicine, College of Veterinary Medicine, University of Georgia ; Eugene D. Janzen, DVM, MVS, Professor, Production Animal Health, Faculty of Veterinary Medicine, University of Calgary ; Bert E. Stromberg, PhD, Professor, Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota ; Max J. Appel, DMV, PhD, Professor Emeritus ; Stephen C. Barr, BVSc, MVS, PhD, DACVIM, Professor of Medicine, Department of Clinical Sciences, College of Veterinary Medicine, Cornell University ; J. P. Dubey, MVSc, PhD, Microbiologist, Animal Parasitic Diseases Laboratory, Beltsville Agricultural Research Center, USDA ; Paul Ettestad, DVM, MS, State Public Health Veterinarian, Epidemiology and Response Division, New Mexico Department of Health ; Kenneth R. Harkin, DVM, DACVIM, Associate Professor, College of Veterinary Medicine, Kansas State University ; Delores E. Hill, PhD, Parasitologist, U.S. Department of Agriculture ; Johnny D. Hoskins, DVM, PhD, Small Animal Consultant ; Jodie Low Choy, BVSc, BVMS, IVAS Cert, Menzies School of Health Research; University Avenue Veterinary Hospital, Northern Territory, Australia ; Barton W. Rohrbach, VMD, MPH, DACVPM, Associate Professor, Department of Comparative Medicine, Veterinary Teaching Hospital, University of Tennessee ; J. Glenn Songer, PhD, Professor, Department of Veterinary Science and Microbiology, University of Arizona ; Joseph Taboada, DVM, DACVIM, Professor and Associate Dean, Office of Student and Academic Affairs, School of Veterinary Medicine, Louisiana State University ; Charles O. Thoen, DVM, PhD, Professor, Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University ; John F. Timoney, MVB, PhD, Dsc, MRCVS, Keeneland Chair of Infectious Diseases, Gluck Equine Research Center, Department of Veterinary Science, University of Kentucky ; Ian Tizard, BVMS, PhD, DACVM, University Distinguished Professor of Immunology; Director, Richard M. Schubot Exotic Bird Health Center, Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University

Also see professional content regarding actinomycosis.

Actinomyces bacteria normally live in the mouth and in the nasal passages near the throat. Several species are associated with diseases in dogs.

Actinomyces bovis has been identified infrequently in infections in dogs and other mammals. Disease occurs when this bacterium is introduced to underlying soft tissue through penetrating wounds of the mouth (such as those that occur from carrying sharp objects in the mouth or running through underbrush). Involvement of the nearby bone frequently results in facial distortion, loose teeth (making chewing difficult), and difficulty breathing due to swelling of the nasal cavity. Treatment is rarely successful in longterm cases in which bone is extensively involved, due to poor penetration of antibacterial drugs into the infected area. In less advanced cases, your veterinarian may prescribe an antibiotic.

Actinomyces hordeovulneris causes abscesses on the liver and spleen and generalized infections, such as inflammation of the cavity surrounding the lungs, inflammation of the lining of the stomach, and bacterial arthritis in dogs. One factor that appears to be related to infection with this organism is the presence of foxtail grass (Hordeum species) particles that have migrated into the body tissues, allowing penetration of the bacteria. Treatment includes surgical removal of the contaminated tissue and drainage, followed by longterm treatment with an antibiotic.

Actinomyces viscosus causes chronic pneumonia, inflammation of the cavity surrounding the lungs, and abscesses under the skin in dogs. Lesions generally develop after a traumatic injury such as a bite wound. Treatment of inflammation of the chest cavity with an antibiotic may be successful if begun early in the disease course. Treatment is more likely to be successful with a localized infection under the skin, which your veterinarian will also treat with an antibiotic.