Retrospective Evaluation of the Utility of Blood Cultures in Dogs (2009-2018): 45 Cases

Background: There is no consensus on obtaining blood cultures routinely in companion animals with suspected sepsis, and there is a paucity of evidence concerning their utility. The objectives of this retrospective study were to determine the yield of positive blood cultures from hospitalized dogs, the prevalence of resistant bacteria, and the frequency and nature of changes to antimicrobial therapy once the culture result became available.

Key Findings: Forty-five dogs had a blood culture submitted over a 10-year period, of which 9(20%) yielded positive growth and 36 (80%) yielded no bacterial growth. The most frequent reasons for submission of blood culture were pyrexia of unknown origin (n = 14), suspected soft tissue infection (7), and suspected discospondylitis (7). The most frequent final diagnoses were soft tissue infection (n = 11), discospondylitis (7), and unknown (6). No significant difference was found between the culture-positive versus culture-negative groups with regard to the most frequent reasons for blood culture (P = 0.55), final diagnoses (P = 0.80), survival until the blood culture result (P = 0.37), or whether the infection was hospital- or community-acquired (P = 0.99). There were significantly more immunosuppressed dogs in the culture-positive group (P = 0.02). Resistance to one or more antimicrobials was documented in all dogs with susceptibility reported. In the culture-positive dogs, 63% had antimicrobial de-escalation and none had escalation, whereas 19% of the culture-negative dogs had de-escalation and 7% had escalation.

Conclusion: Blood cultures were submitted infrequently, but the proportion of resistance was higher than expected and supports the use of blood cultures in cases of suspected infection resulting in bacteremia.