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===Characteristics===
*Formerly known as ''Actinomyces pyogenes'' and ''Corynebacterium pyogenes''
*Small facultatively anaerobic rod
*Grows slowly on blood agar to produce small, white colonies surrounded by a zone of beta-haemolysis after 48 hours
*Produces hazy haemolysis after 24 hours; pin-point colonies after 48 hours
*Coryneform morphology, like Chinese characters; may be curved with slightly swollen ends
*Found in nasopharyngeal mucosa and genital tract of cattle, sheep, pigs
===Pathogenicity===
*Opportunistic infections following injury or viral/mycoplasma infection in ruminants and pigs
*Extracellular toxins including haemolysin, proteases, DNase and neurominidase
*Haemolytic toxin, pyolysin, member of the thiol-activated cytolysins (pore-forming toxins); possibly cytotoxic to phagocytic cells; dermonecrotising activity
===Clinical infections===
*Suppurative infections
*Abscesses especially in liver
*Lymphadenitis, [[Bones - inflammatory#Osteomyelitis|osteomyelitis]], peritonitis and neural abscessation
*Pyometra
*Endometritis
*Summer mastitis
*Ovine foot disease
*Arthritis
*Umbilical infections
*[[Bacterial infections#Acute exudative pneumonia|Acute exudative pneumonia]] and contributes to [[Bacterial infections#Enzootic pneumonia of calves|Enzootic pneumonia of calves]]
*May cause [[Muscles - inflammatory#Abscesses|myositis]]
===Treatment===
*Penicillin or broad spectrum antibiotics
*Unclassified ''Actinomyces'' species isolated from closed cases of [[Bursae and Tendons - inflammatory#Poll Evil and Fistulous Withers|Poll Evil and Fistulous Withers]]