Endocarditis

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Immunohistochemical demonstration of bartonellae in the mitral valve with peroxidase-conjugated polyclonal rabbit anti–Bartonella sp. antibodies. The organisms stain dark orange against the hematoxylin counterstain[1]
A dog with infective endocarditis, showing vegetative lesions on the aortic valve cusps. One lesion has caused one cusp to split (arrow). This dog had severe aortic regurgitation and congestive heart failure[2]

Endocarditis (endocardiosis) refers to any inflammatory or infectious heart disease associated with the inner layer of the canine heart muscle.

Myocarditis and pericarditis are sometimes an accompanying complication.

Causes include:

- Streptococcus canis
- Staphylococcus aureus, Staphylococcus schleiferi[5], Staphylococcus lugdunensis[6]
- Escherichia coli[7]
- Enterococcus spp
- Pasteurella spp
- Bartonella vinsonii subsp berkhoffii[8], Bartonella koehlerae[9][10], Bartonella rochalimae[11] - often involve aortic valve
- Serratia marcescens (nosocomial)[12]
- Acinetobacter baumannii
- Blastomyces dermatitidis[13] - also associated with pericarditis and myocarditis
- Candida albicans[14]
  • Miscellaneous
- Congenital heart defects with secondary aseptic endocarditis due to degenerative and sclerotic changes - e.g. mitral valve endocardiosis, ventricular septal defect[15]
- Periodontitis[16]
- Extraskeletal osteosarcoma[17]

Bacterial endocarditis is a disease of primarily middle-aged to older, large-breed dogs that is associated with high morbidity and mortality[18]. The aortic valve is particularly predisposed to vegetative disease in larger breeds[19].

Regardless of the underlying cause, endocarditis results in impairment to myocardial contractility and functionality, leading to cardiac irregularities, murmurs and, in severe cases, congestive heart failure.

Lameness caused by immune-mediated polyarthritis, septic arthritis, or hypertrophic osteoarthropathy[20] are common complications with Streptococcus canis. Vascular encephalopathy is sometimes noted[21].

Factors negatively associated with survival included thrombocytopenia, high serum creatinine concentration, renal complications, Bartonella spp infections and thromboembolism[22].

Dogs with endocarditis secondary to Bartonella spp infection were often afebrile, more likely to develop congestive heart failure, rarely had mitral valve involvement, and had shorter survival times.

Symptoms are characterized by poor cardiac function, relating to exercise intolerance, an auscultatable heart murmur, ascites if pulmonary venous hypertension exists and dyspnea.

Diagnosis usually requires echocardiography, radiographs and ECG testing. Blood cultures require PCR identification to identify noncontaminant bacteria[23].

Treatment requires addressing the underlying etiology and pathology. Long-term treatment with broad-spectrum antibiotics may contribute to the timely treatment of the disease.

References

  1. Kelly P et al (2006) Bartonella quintana endocarditis in dogs. Emerg Infect Dis 12(12):1869-1872
  2. UC Davis
  3. Peddle GD et al (2009) Association of periodontal disease, oral procedures, and other clinical findings with bacterial endocarditis in dogs. J Am Vet Med Assoc 234(1):100-107
  4. Tou SP et al (2005) Mitral valve endocarditis after dental prophylaxis in a dog. J Vet Intern Med 19(2):268-270
  5. Kumar D et al (2007) Case of Staphylococcus schleiferi subspecies coagulans endocarditis and metastatic infection in an immune compromised host. Transpl Infect Dis 9(4):336-338
  6. Nakamura RK et al (2012) Isolation of methicillin-resistant Staphylococcus lugdunensis in a dog with endocarditis. J Vet Cardiol Oct 22
  7. Macdonald K et al (2010) Infective endocarditis in dogs: diagnosis and therapy. Vet Clin North Am Small Anim Pract 40(4):665-684
  8. Fenimore A et al (2011) Bartonella spp. DNA in cardiac tissues from dogs in Colorado and Wyoming. J Vet Intern Med 25(3):613-616
  9. Breitschwerdt EB et al (2010) PCR amplification of Bartonella koehlerae from human blood and enrichment blood cultures. Parasit Vectors 3:76
  10. Ohad DG et al (2010) Molecular detection of Bartonella henselae and Bartonella koehlerae from aortic valves of Boxer dogs with infective endocarditis. Vet Microbiol 141(1-2):182-185
  11. Henn JB et al (2009) Infective endocarditis in a dog and the phylogenetic relationship of the associated "Bartonella rochalimae" strain with isolates from dogs, gray foxes, and a human. J Clin Microbiol 47(3):787-790
  12. Perez C et al (2011) Fatal aortic endocarditis associated with community-acquired Serratia marcescens infection in a dog. J Am Anim Hosp Assoc 47(2):133-137
  13. Schmiedt C et al (2006) Cardiovascular involvement in 8 dogs with blastomyces dermatitidis infection. J Vet Intern Med 20(6):1351-1354
  14. Mohri T et al (2009) Purulent pericarditis in a dog administered immune-suppressing drugs. J Vet Med Sci 71(5):669-672
  15. Quintavalla C et al (2007) Aortic endocarditis associated with a perforated septal membranous aneurysm in a boxer dog. J Small Anim Pract 48(6):330-334
  16. Glickman LT et al (2009) Evaluation of the risk of endocarditis and other cardiovascular events on the basis of the severity of periodontal disease in dogs. J Am Vet Med Assoc 234(4):486-494
  17. Timian J et al (2011) Extraskeletal osteosarcoma of the heart presenting as infective endocarditis. J Am Anim Hosp Assoc 47(2):129-132
  18. Peddle G & Sleeper MM (2007) Canine bacterial endocarditis: a review. J Am Anim Hosp Assoc 43(5):258-263
  19. Arai S et al (2007) Heterotopic implantation of a porcine bioprosthetic heart valve in a dog with aortic valve endocarditis. J Am Vet Med Assoc 231(5):727-730
  20. Dunn ME et al (2007) Hypertrophic osteopathy associated with infective endocarditis in an adult boxer dog. J Small Anim Pract 48(2):99-103
  21. Cook LB et al (2005) Vascular encephalopathy associated with bacterial endocarditis in four dogs. J Am Anim Hosp Assoc 41(4):252-258
  22. Sykes JE et al (2006) Clinicopathologic findings and outcome in dogs with infective endocarditis: 71 cases (1992-2005). J Am Vet Med Assoc 228(11):1735-1747
  23. Meurs KM et al (2011) Comparison of polymerase chain reaction with bacterial 16s primers to blood culture to identify bacteremia in dogs with suspected bacterial endocarditis. J Vet Intern Med 25(4):959-962