Bartonella, a genus of Gram-negative bacteria, are associated with a wide spectrum of life-threatening diseases in both animals and humans around the world. To date, more than 45 Bartonella species have been described. In dogs, Bartonella henselae and Bartonella vinsonii subsp. berkhoffii are the most frequent species reported and have been associated with inflammatory and neoplastic diseases. Lesions can be localized to a single organ/tissue or disseminated. Prompt diagnosis is crucial, as appropriate treatment at an early stage can result in complete remission.

Nevertheless, Bartonella diagnosis remains challenging due to its fastidious and slow-growing nature, low and intermittent bacteremia, and lack of sensitivity of the techniques currently available. Serology and polymerase chain reaction (PCR), the two most used techniques, have the disadvantage of inaccessibility to cellular localization. The researchers hypothesize that RNAscope In Situ Hybridization, a new technique, will substantially improve the visualization of Bartonella, can be a powerful tool in pathology diagnostic, and ultimately lead to a better understanding of the disease in dogs. In addition, knowing the limitations and best conditions to process samples is integral for understanding the potential reasons for false-negative results and optimizing the probability of bacterial detection.