By John Lewis, VMD, FAVD, DAVDC

A veterinary anesthesiologist recently asked me a question regarding an important topic I've been intending to discuss in this column for quite some time. He asked my thoughts on whether veterinarians should offer to perform a dental cleaning when a patient is undergoing anesthesia for an unrelated procedure.

There is quite a bit to discuss here, and this topic will likely span multiple monthly Dental Pearls columns. There are at least three considerations that immediately come to mind:

1) What effect will adding a dental procedure have on the success of the primary procedure?

2) How will adding the dental procedure to a primary procedure affect the quality of the dental procedure and, therefore, its potential benefit?

3) What are the benefits/risks of considering a combined procedure versus separating them into two anesthetic procedures?

One fact is well established, and therefore, is likely in the forefront of your mind. Bacteremia occurs during dentistry procedures—it's a fact. Within five to 40 minutes of initiation of a dental cleaning, bacteria can be cultured from the blood, the same bacteria isolated from gingival cultures.^1-3 The prevalence of bacteremia varies among studies. One showed bacteremia occurred in 100 percent of 20 adult greyhounds regardless of the severity of their periodontal disease,¹ whereas another study in dogs showed a 30 percent occurrence of bacteremia during dental cleaning.³

Not out of the ordinary

The occurrence of bacteremia sounds very concerning until you learn it is consistently seen in 30 percent of people when asked to eat an apple.⁴ The simple act of using the teeth in a functional manner can result in translocation of subgingival bacteria into the bloodstream. In reality, humans and their pets often deal with bacteremia throughout their lives with no overtly untoward effects. The spleen and other components of the immune system do their job and clear out bacteremia.

Not every study has found an increased presence of bacteremia associated with dental procedures compared to other procedures. One study in dogs found there were no significant differences between the number of positive blood cultures in dogs receiving dental cleanings and dogs undergoing anesthesia for non-dental procedures.³

One possible sequela of bacteremia is bacterial endocarditis (a.k.a. infective endocarditis). This infection is amazingly rare in our veterinary dental patients, especially considering the severity of periodontal disease seen in dogs and cats, and the fact they often have concurrent heart disease. Bacterial endocarditis is most common in large-breed dogs,⁵ whereas periodontal disease is most common in small-breed dogs,⁶ which speaks to the possibility a risk factor other than periodontal disease may be playing a role in development of infectious endocarditis.

Though there are only a few veterinary studies that have explored prevalence of bacteremia during dental cleanings, we can glean comparisons on this topic from the human literature. In one study of 56 humans undergoing dental cleaning, 61 percent of patients who did not receive penicillin prophylaxis developed a bacteremia. There was a significant decrease in detectable bacteremia in patients receiving penicillin prophylaxis, although the authors clarified the recovery of Streptococci was not significantly different in the two groups.⁷ The study, which was performed in 1982, concluded parenteral penicillin prophylaxis for dental cleaning decreased detectable bacteremia rates significantly and could be recommended for patients with valvular heart disease who are known to be vulnerable to endocarditis.

However, there is much debate regarding the clinical significance of bacteremia and what role it plays, if any, in development of adverse events, such as infective endocarditis. Even though dental procedures are known to cause bacteremia, one retrospective study in dogs did not find dental procedures to be linked to developing infectious endocarditis. Yet, the same study did find that dogs with endocarditis were significantly more likely to have undergone a non-oral surgical procedure requiring general anesthesia in the preceding three months. Interestingly, preexisting cardiac disease (congenital or acquired) was not found to be a risk factor.⁸

Another retrospective study looked at 59,296 dogs with naturally occurring periodontal disease and a similar number of control dogs without periodontal disease. This one found significant associations between the severity of periodontal disease and the subsequent risk of cardiovascular-related conditions, such as endocarditis and cardiomyopathy.⁹ This study had very large numbers of patients and controls. However, some cardiologists have questioned the methods of diagnosis of endocarditis and the unexpectedly high survival rate of patients diagnosed with endocarditis in the study.¹⁰ Released in 2007, the American Heart Association's (AHA's) guidelines suggest a lack of association between dental procedures and infective endocarditis, and concluded that only an extremely small number of cases of infective endocarditis might be prevented through the use of antibiotic prophylaxis.¹¹

Does the coupling of a clean sterile surgery and a dental cleaning increase risk of infection at the sterile site? This is a study that still needs to be done in our veterinary patients, but in next month's column we will discuss literature that provides insight into risk factors of surgical site postoperative infection in clean surgical sites.

If you have any comments or questions, drop me an email at info@siloacademy.com.

John Lewis, VMD, FAVD, DAVDC, practices dentistry and oral surgery at Veterinary Dentistry Specialists and is the founder of Silo Academy Education Center, both located in Chadds Ford, Pa.

References

¹ Nieves MA, Hartwig P, Kinyon JM, Riedesel DH. Bacterial Isolates From Plaque and From Blood During and After Routine Dental Procedures in Dogs. Vet Surg 1997:26(1);26-32.

² Black AP, Crichlow AM, Saunders JR. Bacteremia during ultrasonic teeth cleaning and extraction in the dog. J Am Anim Hosp Assoc. 1980:16;611-616.

³ Harari, J, Besser TE, Gustafson SB and Meinkoth K. Bacterial Isolates from Blood Cultures of Dogs Undergoing Dentistry. Vet Surg. 1993:22;27-30.

⁴ Sreenivasan PK, Tischio-Bereski D, Fine DH. Reduction in bacteremia after brushing with a triclosan/copolymer dentifrice-A randomized clinical study. J Clin Periodontol. 2017;44(10):1020–1028.

⁵ Peddle G, Sleeper MM. Canine bacterial endocarditis: a review. J Am Anim Hosp Assoc. 2007;43(5):258–263.

⁶ Harvey CE. Periodontal disease in dogs. Etiopathogenesis, prevalence, and significance. Vet Clin North Am Small Anim Pract. 1998;28(5):1111–vi.

⁷ Baltch AL, Schaffer C, Hammer MC, Sutphen NT, Smith RP, Shayegani M. Bacteremia following dental cleaning in patietns with and without penicillin prophylaxis. Am Heart J. 1982:104(6);1335-1339.

⁸ Peddle GD, Drobatz KJ, Harvey CE, Adams A, Sleeper MM. Association of periodontal disease, oral procedures, and other clinical findings with bacterial endocarditis in dogs. J Am Vet Med Assoc. 2010 Sep 15;237(6):694]. J Am Vet Med Assoc. 2009;234(1):100–107.

⁹ Glickman LT, Glickman NW, Moore GE, Goldstein GS, Lewis HB. 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. 2009;234(4):486–494.

¹⁰ Peddle GD, Sleeper MM, Ryan MJ, Kittleson MD, Pion P. Questions validity of study on periodontal disease and cardiovascular events in dogs. J Am Vet Med Assoc. 2009;234(12):1525–1527.

¹¹ Wilson W, Taubert KA, Gewitz M, et al. Prevention of infective endocarditis: guidelines from the American Heart Association: a guideline from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee, Council on Cardiovascular Disease in the Young, and the Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and the Quality of Care and Outcomes Research Interdisciplinary Working Group [published correction appears in Circulation. 2007 Oct 9;116(15):e376-7]. Circulation. 2007;116(15):1736-1754.