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Beagles are less susceptible to Rhipicephalus sanguineus sensu lato tick due to the production of the allomones benzaldehyde and 2-hexanone. Our previous published work showed that these compounds can reduce tick burden on susceptible dogs. Here we tested the hypothesis that an increase in repellent dose and release rate could increase repellent efficacy and persistence. Slow-release formulations of these compounds, with higher doses and release rates, were tested on artificially-infested dogs. Ten dogs were randomly assigned to two groups with five dogs each. The treated group received collars with slow-release formulations of the compounds attached, while the control group received collars with clean formulations attached. Five environmental infestations were performed, with the number of ticks (at all stages) on the dogs being counted once a day for 40 days. No significant increase in repellent efficacy was observed with the higher doses and release rates, whereas a greater persistence in repellent activity was observed. Treatment with the formulations resulted in a two-to-three-fold reduction in the number of immature stage ticks for up to three weeks. However, the number of adults was similar in both groups. Loss of repellent activity after the third week of testing coincided with a marked change in the relative release rates for the two compounds. It is hypothesized that relative amounts, rather than absolute amounts, of repellent release from slow-release formulations are important for repellent activity. We also hypothesize that the avoidance of less-preferred hosts by ticks relies on olfactory-mediated perception of specific blends of volatile cues from less preferred hosts.

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Although the epizootiological profile of canine distemper in Goiânia is unknown, there is clinical evidence for a high incidence of canine distemper virus (CDV) infection among dogs. Therefore, this study determined the epizootiological characteristics of canine distemper in naturally infected dogs. Data of 46 dogs that tested positive for the CDV based on immunochromatography or reverse transcription-polymerase chain reaction were collected. Data on the sex, breed, age, and vaccination status were obtained from these dogs, and extraneural and neural sign analyses were performed. Although, the infected dogs belonged to both sexes, different breeds, and different age groups, a greater proportion of cases were seen in adults (1-6 years), undefined breeds, and unvaccinated dogs. Among the CDV-positive dogs, 10.87% had been vaccinated. In addition, 4.35% showed neural signs, 8.69% showed extraneural signs, and 86.96% showed both. High lethality was observed, with viral antigen and/or DNA detected in 82.61% dead dogs. Only 8.70% of the total CDV-infected dogs remained alive at the time of their assessment.

No abstract