Equine Veterinary Journal Early View June 2016


Heather Ferguson


Bacteraemia before, during and after tooth extraction in horses in the absence of antimicrobial administration


Kern, I., Bartmann, C.P., Verspohl, J., Rohde, J. and Bienert-Zeit, A.



In this prospective study, the prevalence of bacteraemia in horses following tooth extraction and bacterial species involved was documented in 20 horses presented with dental disease to a single facility in Germany. Half underwent cheek tooth extraction and the other half underwent canine or incisor extraction. Oral extraction under sedation and local anaesthesia was performed in a standard manner.


Blood samples for culture were obtained immediately after catheter placement and at 1, 5 and 20 minutes after the first gingival incision and then every 30 minutes thereafter until the tooth was extracted. At each sampling point the surgical activity was recorded. Blood and swabs from extracted teeth were cultured under aerobic, anaerobic and microphilic conditions. Horses’ temperatures were recorded every 3 hours until 48 hours post-operatively.


After surgery, the temperature of 3 horses rose to 38.0-38.5°C while 4 horses developed pyrexia (>38.5°C). The mean time for the first temperature elevation to occur was around 8 hours post-operatively. Bacteraemia (indicated by positive blood culture) was detected in 18 out of 20 (90%) of horses at one or more time points.


In the majority of these (12 horses), mixed growth of aerobic and anaerobic bacteria were present. Bacteraemia was detected in some horses at almost all time points, generally within the first 50 minutes of surgery. The highest number of positive cultures was obtained 1 minute after the start of surgery, and elevation of the gingiva was the part of the procedure most commonly associated with bacteraemia suggesting that bacteria can enter the bloodstream via damaged capillaries in gingival tissue without any manipulation of the tooth.


From blood, Streptococcus and Actinomyces were the most common aerobic isolates and Fusobacterium was the most common anaerobic isolate. In all but one horse, both aerobic and anaerobic isolates were obtained from extracted teeth and A large range of bacterial species were found. No particular bacteria were associated with specific dental diseases. Furthermore, the bacterial flora did not seem to correspond with the gingival health of the patients. These results highlight that there is potential for complications associated with bacteraemia e.g. infectious endocarditis and pneumonia in tooth extraction cases.



Bottom line:


Bacteraemia occurs in almost all horses during tooth extraction, most commonly at the time of gingival incision and some horses develop fever. A wide variety of bacterial isolates are involved.




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