Dogs acquire infections with the Anaplasmataceae family pathogens, E. canis, E. chaffeensis, E. ewingii, A. platys and A. phagocytophilum mostly during summer months when ticks are actively feeding on animals. These pathogens are also identified as causing diseases in people. Despite the long history of tick-borne diseases in dogs, much remains to be defined pertaining to the clinical and pathological outcomes of infections with these pathogens. In the current study, we performed experimental infections in dogs with E. canis, E. chaffeensis, A. platys and A. phagocytophilum. Animals were monitored for 42 days to evaluate infection-specific clinical, hematological and pathological differences. All four pathogens caused systemic persistent infections detectible throughout the 6 weeks of infection assessment. Fever was frequently detected in animals infected with E. canis, E. chaffeensis, and A. platys, but not in dogs infected with A. phagocytophilum. Hematological differences were evident in all four infected groups, although significant overlap existed between the groups. A marked reduction in packed cell volume that correlated with reduced erythrocytes and hemoglobin was observed only in E. canis infected animals. A decline in platelet numbers was common with E. canis, A. platys and A. phagocytophilum infections. Histopathological lesions in lung, liver and spleen were observed in all four groups of infected dogs; infection with E. canis had the highest pathological scores, followed by E. chaffeensis, then A. platys and A. phagocytophilum. All four pathogens induced IgG responses starting on day 7 post infection, which was predominantly comprised of IgG2 subclass antibodies. This is the first detailed investigation comparing the infection progression and host responses in dogs after inoculation with four pathogens belonging to the Anaplasmataceae family. The study revealed a significant overlap in clinical, hematological and pathological changes resulting from the infections.

Caution should be used when interpreting a positive test result of a dipstick or SSA test for canine or feline albuminuria.

CT was more sensitive than radiography for detection of pulmonary nodules. This was particularly evident in large-breed to giant-breed dogs. Thoracic CT is recommended in large-breed to giant-breed dogs with osteosarcoma if the detection of pulmonary nodules will change treatment.

No abstract

Ehrlichia chaffeensis, a tick-borne rickettsial organism, causes the disease human monocytic ehrlichiosis. The pathogen also causes disease in several other vertebrates, including dogs and deer. In this study, we assessed two clonally purified E. chaffeensis mutants with insertions within the genes Ech_0379 and Ech_0660 as vaccine candidates in deer and dogs. Infection with the Ech_0379 mutant and challenge with wild-type E. chaffeensis 1 month following inoculation with the mutant resulted in the reduced presence of the organism in blood compared to the presence of wild-type infection in both deer and dogs. The Ech_0660 mutant infection resulted in its rapid clearance from the bloodstream. The wild-type infection challenge following Ech_0660 mutant inoculation also caused the pathogen's clearance from blood and tissue samples as assessed at the end of the study. The Ech_0379 mutant-infected and -challenged animals also remained positive for the organism in tissue samples in deer but not in dogs. This is the first study that documents that insertion mutations in E. chaffeensis that cause attenuated growth confer protection against wild-type infection challenge. This study is important in developing vaccines to protect animals and people against Ehrlichia species infections.