Isolation and Molecular Detection of Salmonella spp. from the Feces of Apparently Healthy Dogs

Salmonella spp. is considered to be the most common bacterial zoonoses but although its significance and prevalence in food animals have been well-studied, its role in companion animals is less elucidated. To determine whether apparently healthy dogs can carry and shed salmonellae, a total of 62 fecal swabs were collected and tested for the presence of Salmonella spp. using conventional isolation procedures and polymerase chain reaction (PCR). Each sample was initially enriched in brain heart infusion (BHI) broth at 42 degrees C. For conventional isolation, these were subsequently plated on xylose lysine deoxycholate (XLD) agar and incubated at 37 degrees C for 24 h. Alkaline colonies with jet black center were picked, purified and biochemically tested. For PCR, DNA from each sample was extracted and the target sequence was subsequently amplified using the Salmonella DAS Kit (TM) (BIOTECH, UPLB). Salmonella spp. were detected in both conventional microbiological procedures (1 out of 62 or 1.6%) and PCR (26 out of 62 or 42%) of the samples tested. These results indicate that apparently healthy dogs can be carriers and shedders of potentially zoonotic salmonellae, and that PCR can be an effective means of detecting the said pathogen in canine fecal samples. Further work on isolation, serotyping, and molecular characterization of isolates are recommended to confirm the viability and nature of salmonellae carried by dogs and establish the role of this species in the epidemiology of the disease.