Actinobacillosis

Actinobacillosis



Basic Information image



Definition




• Actinobacillus spp. is a gram-negative group of bacteria that causes a variety of clinical syndromes in horses.


• Actinobacillus equuli subsp. equuli


• Actinobacillus equuli subsp. haemolyticus



Epidemiology



Species, Age, Sex


All species of horses are susceptible. A. equuli is associated with sepsis of foals and is a common bacteria isolated from abortions caused by the eastern tent caterpillar (ETC).



Risk Factors




• ETC (Malacosoma americanum) ingestion and intoxication


• Failure of passive transfer of immunoglobulin in foals



Geography and Seasonality


ETC infestation of the environment may fluctuate from year to year and is associated with fruiting trees, hatching in the spring.



Associated Conditions and Disorders


Mare reproductive loss syndrome (MRLS)



Clinical Presentation



Disease Forms/Subtypes




• Opportunistic infections of many organs and body systems of adults


• Septicemia of foals



History, Chief Complaint




• Adults: History and chief complaint referable to the affected system: MRLS—abortion, pericarditis


• Neonates: Neonatal sepsis within the first 2 weeks of life



Physical Exam Findings




• Adults: Examination referable to the organ system affected consisting of abortion, metritis, mastitis, septicemia, arthritis, endocarditis, meningitis, pneumonia, and pleuritis


• Foals: Weakness, failure to suckle, hypothermia, and congested mucous membranes. If overwhelming liver infection is present, the foal may be icteric. Often fatal in foals.



Etiology and Pathophysiology




• A. equuli subsp. equuli: Causative agent of highly fatal septicemia in foals.


• A. equuli subsp. haemolyticus: Associated with opportunistic infections causing various diseases.


• Both subspecies are associated with abortion and pericarditis of mares with MRLS.


• Common commensal of the equine oral, pharyngeal, and intestine mucous membranes.


• Invasion of body cavities.


• With MRLS, it is hypothesized that ingestion of the ETC results in mucosal absorption of the exoskeleton and setae of the caterpillar. This allows concomitant bacterial infection of the pericardium and placenta.


• Neonatal sepsis likely occurs through ascending vaginal infections before and after foaling through the umbilical structures and respiratory and alimentary tracts.

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Jul 24, 2016 | Posted by in SMALL ANIMAL | Comments Off on Actinobacillosis

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