Bacterial Endocarditis

Bacterial endocarditis, also called infectious endocarditis, [IE]) is a disease of primarily middle-aged to older, large-breed dogs that is associated with high morbidity and mortality. It presents many challenges with respect to diagnosis and effective treatment.

The endocardium is the thin membrane that lines the heart cavity. Infection of endocardium typically involves one of the heart valves, although endocarditis of the cavity's wall may also develop. Infection is caused by bacteria carried in the blood. The infection gradually destroys the valve and keeps it from working properly.

Bacteria released from the infected valves enter the circulation and can infect other organs. Therefore, infective endocarditis can produce a wide variety of signs: fever that comes and goes, lameness, blood and pus in the urine, difficulty breathing, lethargy and depression.

Streptococci are the most common cause of IE and are more likely to infect the mitral valve and be associated with polyarthritis (generalized inflammation of the joints). Dogs with IE caused by Bartonella spp infection rarely have fever, are more likely to develop congestive heart failure and have shorter survival times. Vascular encephalopathy is a commonly encountered clinical complication of infectious endocarditis in humans, but it has been infrequently reported in dogs.

Diagnosis Various blood tests may be needed for diagnosis. X-rays may show enlargement of the heart chamber.

Treatment Treatment is directed at controlling signs of congestive heart failure. Since th outlook is poor in most dogs,

Living in a society of animal lovers, the dangers are often not always apparent. Injury from bites and scratches is an occupational hazard for those people who work with animals. Despite the high risk of secondary wound infection as a result of an animal bite, many patients do not receive treatment with an antimicrobial medication. A case of a previously fit and well 66-year-old female dog handler who, after an apparently minor dog bite to the hand, developed fulminant acute Staphylococcus aureus endocarditis and life-threatening aortic regurgitation has been reported. People who work in close contact with pets and animals need proper wound hygiene and consideration of prophylactic broad-spectrum antibiotics to prevent potentially fatal outcomes as a result of what initially seem to be minor injuries.

References:
1. Evaluation of the relationship between causative organisms and clinical characteristics of infective endocarditis in dogs: 71 cases (1992-2005).Sykes JE, Kittleson MD, Pesavento PA, Byrne BA, MacDonald KA, Chomel BB. Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, USA.
2. Endocarditis due to Staphylococcus aureus after minor dog bite.Bradshaw SE. Cambridge University School of Medicine, Cambridge, England, United Kingdom.