Efficacy of sarolaner (Simparic™) against induced infestations of Amblyomma cajennense on dogs.

BACKGROUND: Amblyomma cajennense is the main vector of Rickettsia rickettsii which causes Brazilian spotted fever. This adult tick preferably infests horses and capybaras, but has low host specificity during its immature stages, thus posing a threat to humans and dogs. In this study, the efficacy of sarolaner (Simparic™/Simparica®, Zoetis) when administered once orally to dogs at 2 mg/kg was evaluated against induced infestations of A. cajennense nymphs for up to 35 days after treatment. METHODS: Based on pretreatment tick counts, 20 dogs were randomly allocated to treatment with sarolaner (Simparic™) dosed at 2 mg/kg of body weight or a placebo on Day 0 of the study. Artificial infestations were performed using laboratory raised A. cajennense nymphs on study days -2, 5, 12, 19, 26 and 33. Efficacy was determined at 48 h post-treatment or post-infestation at each time point relative to the counts for dogs that received placebo. RESULTS: There were no adverse reactions to treatment. A single dose of sarolaner (Simparic™) provided 100% efficacy on study days 2, 7 and 14; and ≥ 99.6% on days 21, 28 and 35. Geometric mean live tick counts for sarolaner were significantly lower than those for placebo on all days (P < 0.0001). CONCLUSIONS: Under the conditions of the present study, sarolaner (Simparic™) administered once orally at 2 mg/kg provided 100% efficacy against existing infestations and ≥ 99.6% efficacy within 48 h against weekly challenges of A. cajennense for at least 35 days after treatment.

Hydrocortisone inhibits IFN-γ production in equine, ovine, and bovine PBMCs.

Hydrocortisone is widely accepted as an anti-inflammatory agent and there are many products available containing hydrocortisone as an active ingredient. Surprisingly, there is little data available specifically on the immunological effects of hydrocortisone in large animals. Glucocorticoids are well-characterized for their ability to repress inflammation via a wide variety of mechanisms including suppression of cytokine production. In this study the effects of hydrocortisone on IFN-γ production by equine, bovine, and ovine PBMCs were assessed using flow cytometric or ELISpot analysis. Hydrocortisone suppressed mitogen-driven IFN-γ production by PBMCs from all three species of animals, confirming that this agent mediates anti-inflammatory effects in large animals. Although the results from this study were expected based on the precedence set in murine and human systems, it is important to understand the effects of administration of a compound or product in the species of interest as species-specific indications are not always available.