Prevalence, risk factors of infection and molecular characterization of trichomonads in puppies from French breeding kennels

The trichomonad species Tritrichomonas fetus and Pentatrichomonas hominis were recently identified in the feces of dogs with diarrhea. However the prevalence and pathogenicity of these parasites in the canine population still remained poorly resolved. Therefore the aim of the present study was (1) to determine the prevalence of trichomonads infecting puppies living in French breeding kennels, (2) to confirm the predominance of P. hominis in dogs, (3) to investigate the genetic diversity of P. hominis isolates identified in the French canine population and (4) to evaluate the risk factors for infection by P. hominis and the influence of the parasite on feces consistency. A total of 215 both diarrheic and non-diarrheic puppies from 25 French breeding kennels were included in this epidemiological survey. Fecal samples from each puppy were examined for 6 gastrointestinal pathogens: parvovirus type 2 (CPV2), coronavirus, Toxocara canis, Cystoisospora ohioensis-complex, Cystoisospora canis, and Giardia intestinalis. A part of each collected stool was also tested for the presence of motile trichomonads by microscopy after culturing. The prevalence of trichomonad infection was 15.8% (34/215) among puppies and 20% (5/25) among breeding kennels. DNA from 26 of the 34 positive samples was successfully amplified using a trichomonad-specific primer pair. Analysis of the sequences of PCR products indicated that P. hominis was the only trichomonad infecting the canine population. All the puppies infected with P. hominis belonged to large breed dogs. Moreover, puppies from large breeding kennels, excreting a high level of G. intestinalis and/or excreting a high level of C. canis oocysts showed a higher probability of being positive for P. hominis infection. Univariate analysis also revealed an increased risk for P. hominis infection in puppies with abnormal feces. However, in a multivariate analysis, CPV2 was the only gastrointestinal pathogen associated with abnormal feces. Since enteropathogens were commonly found in dogs infected by P. hominis, the pathogenic potential of this trichomonad species remained uncertain and has to be further evaluated by experimental infection studies.