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Compendium August 2002 Infective Endocarditis 623 Table 2. Intravenous and Subcutaneous Antibiotic Dosages Recommended for Treating Bacterial Endocarditis 11,14 Antibiotic Dose (mg/kg) Frequency Ampicillin 20–40 tid Amoxicillin–clavulanate 20 bid Cephalosporins First generation 22 tid Second generation Cefuroxime a 15 tid Cefaclor b 10–15 tid Cefoxitin c 20–30 tid Third generation Cefotaxime 50 bid Ceftiofur 2.2–4.4 bid Clindamycin 10 tid Azithromycin d 5–10 bid Enrofloxacin 10 Once daily 5 bid Ticarcillin, ticarcillin– 50–100 tid clavulanate Gentamicin 6 Once daily Amikacin 10 Once daily a Ceftin ® , GlaxoSmithKline. b Ceclor ® , Eli Lilly Co. c Mefoxin ® , Merck and Co. d Zithromax ® , Pfizer Inc. in relative resistance to systolic and diastolic blood flow facilitates increased forward stroke volume and decreased aortic regurgitation. Systemic blood pressure should be monitored as adjuvant afterload reduction is initiated and up-titrated. Amlodipine and felodipine are effective afterload reducers when instituted at 0.1 mg/kg PO q12h and up-titrated every 4 to 7 days to a maximum of 0.3 to 0.4 mg/kg PO q12h. Indirect blood pressure monitoring is important, although it is subject to inaccuracies. Dogs that subsequently develop signs of hypotension have consistently had lower indirect blood pressures compared with pretreatment and during early dose titration. We discontinue up-titration if the systolic blood pressure is less than approximately 110 mm Hg. If clinical signs of hypotension (e.g., lethargy, trembling, weakness, anorexia) occur, withdraw amlodipine, ACE inhibitor, spironolactone, and diuretic therapy for 24 hours, and then reinstitute all drugs with amlodipine at the previous lower dose. Severe hypotension requires IV fluid administration. Anticoagulant Therapy Anticoagulant therapy has not been shown to prevent embolization and may increase the risk of hemor- www.VetLearn.com rhage. 52 The role of aspirin in preventing embolization is under evaluation. 53 However, it may reduce vegetation bacterial density, bacterial dissemination, and embolic events. 53 PROGNOSIS The prognosis for long-term survival of dogs with IE is poor. 1–4,6,8–14 Early diagnosis followed immediately by aggressive antibiotic therapy is critical for long-term survival, especially when the aortic valve is infected. Unfortunately, early diagnosis is difficult, and valvular damage is often advanced by the time of diagnosis. Aortic valve endocarditis is associated with a grave prognosis because animals with it develop left-sided CHF (often within 1 to 3 months, and almost always within 6 months of diagnosis). PREVENTION Chemoprophylaxis is controversial because the risk:benefit ratio and economic rationale can be questioned and clinical studies supporting efficacy are limited. 9–11 Chemoprophylaxis, even if effective, does not apply to the majority of cases. However, the mortality associated with IE warrants chemoprophylaxis in patients at increased risk. 54,55 It is recommended to use prophylactic antibiotics when performing dental scaling, dental extractions, or surgery in dogs with congenital heart diseases. 9–11 Such procedure-focused chemoprophylaxis should not be initiated several days before the procedure because of the potential to select for antibiotic-resistant organisms. 8 Maintenance of oral hygiene is a more important preventive than procedure-focused chemoprophylaxis. 8 The male dog’s urinary tract is suspected to be a common source of chronic bacteremia; therefore, castration can be viewed as a prophylactic measure because it reduces the risk of bacterial prostatitis. For oral/dental procedures in patients that are at increased risk, it is prudent to administer ticarcillin or a first-generation cephalosporin intravenously 1 hour before and 6 hours after the procedure. Because incision and drainage of infected skin are associated with coagulase-positive staphylococci, a first-generation cephalosporin, ticarcillin, or ticarcillin–clavulanate is a good choice for prophylaxis. 54,56 REFERENCES 1. Shouse CL, Meier H: Acute vegetative endocarditis in the dog and cat. JAVMA 129:278–289, 1956. 2. Sisson D, Thomas WP: Endocarditis of the aortic valve in the dog. JAVMA 184:570–577, 1984. 3. Lombard CW, Buergelt CD: Vegetative bacterial endocarditis in dogs: Echocardiographic diagnosis and clinical signs. J Small Anim Pract 24:325–329, 1993. 4. Anderson CA, Dubielzig RR: Vegetative endocarditis in dogs.
624 Small Animal/Exotics Compendium August 2002 JAAHA 20:149–152, 1984. 5. Freedman LR: The pathogenesis of infective endocarditis. J Antimicrob Chemother 20:1–6, 1987. 6. Calvert CA: Valvular bacterial endocarditis in the dog. JAVMA 180:1080–1084, 1982. 7. Weinstein L, Schlesinger JJ: Pathoanatomic, pathophysiologic and clinical correlations in endocarditis. N Engl J Med 291:1122–1126, 1974. 8. Karchmer AW: Infective endocarditis, in Braunwald E (ed): Heart Disease: A Textbook of Cardiovascular Medicine, ed 5. Philadelphia, WB Saunders Co, 1997, pp 1077–1099. 9. Miller MW, Sisson D: Infectious endocarditis, in Fox PR, Sisson D, Moise NS (eds): Textbook of Canine and Feline Cardiology, ed 2. Philadelphia, WB Saunders Co, 1999, pp 552, 567–580, 908. 10. Kittleson MD: Infective endocarditis, in Kittleson MD, Kienle RD (eds): Small Animal Cardiovascular Medicine. St. Louis, Mosby, Inc, 1998, pp 402–412. 11. DeFrancesco TC: CVT update: Infectious endocarditis, in Bonagura JD (ed): Kirk’s Current Veterinary Therapy VIII. Philadelphia, WB Saunders Co, 2000, pp 768–772, 1241–1264. 12. Calvert CA, Greene CE, Hardie EM: Cardiovascular infections in dogs: Epizootiology, clinical manifestations, and prognosis. JAVMA 187:612–616, 1985. 13. Calvert CA, Greene CE: Bacteremia in dogs: Diagnosis, treatment, and prognosis. Compend Contin Educ Pract Vet 8: 179–184, 1986. 14. Calvert CA: Cardiovascular infections, in Greene CE (ed): Infectious Diseases of the Dog and Cat, ed 2. Philadelphia, WB Saunders Co, 1998, pp 567–582, 790–919. 15. Thompson J, Meddens MJ, Thorig L, et al: The role of bacterial adherence in the pathogenesis of infective endocarditis. Infection 10:196–198, 1982. 16. Lepeschkin E: On the relation between the site of valvular involvement in endocarditis and the blood pressure resting on the valve. Am J Med Sci 224:318–322, 1952. 17. Rodbard S: Blood velocity and endocarditis. Circulation 27: 18–20, 1963. 18. Buchbinder NA, Roberts WC: Left-sided valvular infective endocarditis: A study of forty-five necropsy patients. Am J Med 53:20–35, 1972. 19. Muna WF, Ferrans VJ, Pierce JE, et al: Discrete subaortic stenosis in Newfoundland dogs: Association of infective endocarditis. Am J Cardiol 41:746–754, 1978. 20. Kienle RD, Thomas WP, Pion PD: The natural clinical history of canine congenital subaortic stenosis. J Vet Intern Med 8:423–431, 1994. 21. Wahl MJ: Myths of dental-induced endocarditis. Arch Intern Med 154:137–144, 1994. 22. Bender IB, Barkan MJ, Einstein A: Dental bacteremia and its relationship to bacterial endocarditis: Preventive measures. Compend Contin Educ Pract Vet 10:472, 475–477, 1994. 23. Black AP, Crichlow AM, Saunders JR: Bacteremia during ultrasonic teeth cleaning and extraction in the dog. JAAHA 16:611–616, 1980. 24. Ellison GW, King RR, Calderwood-Mays M: Medical and surgical management of multiple organ infarctions secondary to endocarditis in a dog. JAVMA 193:1289–1291, 1988. 25. Ramirez-Ronda CH: Effects of molecular weight of dextran on the adherence of Streptococcus sanguis to damaged heart valves. Infect Immun 29:1–7, 1980. www.VetLearn.com 26. Hamill RJ: Role of fibronectin in infective endocarditis. Rev Infect Dis 9(Suppl 4):360–371, 1987. 27. Rubinstein E, Lang R: Fungal endocarditis. Eur Heart J 16 (Suppl B):84–89, 1995. 28. Scheld WM, Mandell GL: Enigmatic enterococcal endocarditis. Ann Intern Med 100:904–905, 1984. 29. Eriksen K, Fossum K, Gamlem H, et al: Endocarditis in two dogs caused by Erysipelothrix rhusiopathiae. J Small Anim Pract 28:117–122, 1987. 30. Takahashi T, Tamura Y, Yoshimura H, et al: Erysipelothrix tonsillarum isolated from dogs with endocarditis in Belgium. Res Vet Sci 54:264–265, 1993. 31. Breitschwerdt EB, Kordick DL, Malarkey DE, et al: Endocarditis in a dog due to infection with a novel Bartonella subspecies. J Clin Microbiol 33:154–160, 1995. 32. Raoult D, Fournier PE, Drancourt M, et al: Diagnosis of 22 new cases of Bartonella endocarditis. Ann Intern Med 125: 646–652, 1996. 33. Breitschwerdt EB, Atkins CE, Brown TT, et al: Bartonella vinsonii subsp. berkhoffi and related members of the Alpha Subdivision of the Proteobacteria in dogs with cardiac arrhythmias, endocarditis, or myocarditis. J Clin Microbiol 37:3618–3626, 1999. 34. Breitschwerdt EB, Kordick DL: Bartonellosis. JAVMA 206: 1928–1931, 1995. 35. Bennett D, Bilbertson EM, Grennan D: Bacterial endocarditis with polyarthritis in two dogs associated with circulating autoantibodies. J Small Anim Pract 19:185–196, 1993. 36. Bennett D, Taylor DJ: Bacterial endocarditis and inflammatory joint disease in the dog. J Small Anim Pract 29:347–353, 1988. 37. Neugarten J, Gallo GR, Baldwin DS: Glomerulonephritis in bacterial endocarditis. Am J Kidney Dis 3:371–379, 1984. 38. Perez GO, Rothfield N, Williams RC: Immune-complex nephritis in bacterial endocarditis. Arch Intern Med 136: 334–336, 1976. 39. Caywood DD, Wilson JW, O’Leary TP: Septic polyarthritis associated with bacterial endocarditis in two dogs. JAVMA 171:549–552, 1977. 40. Gutman RA, Striker GE, Gilliland BC, et al: The immune complex glomerulonephritis of bacterial endocarditis. Medicine 51:1–25, 1972. 41. Root CR, Bahr RJ: The heart and great vessels, in Thrall DE (ed): Textbook of Veterinary Diagnostic Radiology, ed 3. Philadelphia, WB Saunders Co, 1994, pp 304–318. 42. Dow SW, Curtis CR, Jones RL, et al: Bacterial culture of blood from critically ill dogs and cats: 100 cases (1985–1987). JAVMA 195:113–117, 1989. 43. Washington JA: The microbiologic diagnosis of infective endocarditis. J Antimicrob Chemother 20:29–39, 1987. 44. Washington JA: The role of the microbiology laboratory in the diagnosis and antimicrobial treatment of endocarditis. Mayo Clin Proc 57:22–32, 1982. 45. Hoen B, Selton-Suty C, Lacassin F, et al: Infective endocarditis in patients with negative blood cultures. Clin Infect Dis 20:501–506, 1995. 46. Cremieux AC, Maziere B, Vallois JM, et al: Evaluation of antibiotic diffusion into cardiac vegetations by quantitative autoradiography. J Infect Dis 159:938–944, 1989. 47. Working Party of the British Society for Antimicrobial Chemotherapy. Antibiotic treatment of streptococcal, enterococcal, and staphylococcal endocarditis. Heart 1998 79:207–210, 1998.
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