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Background: Ticks are common on horses, but recent publications characterizing equine tick infestations in North America are lacking. Methods: To further understand attachment site preferences of common ticks of horses, and to document the seasonality of equine tick infestation in northeastern Oklahoma, horses from eight farms were evaluated twice a month over a 1-year period. Each horse was systematically inspected beginning at the head and moving caudally to the tail. Attachment sites of ticks were recorded and all ticks collected were identified to species and stage. Results: Horses (26 males and 62 females) enrolled in the study ranged in age from 1 to 23 years (mean = 12, 95% CI 11–13). A total of 2731 ticks were collected; 84.1% (74/88) of the horses were infested (median = 3 ticks) at one or more examinations. Five tick species were identified, including Amblyomma americanum (78.2%; 2136/2731), Ixodes scapularis (18.2%; 497/2731), Dermacentor albipictus brown variant (2.6%; 71/2731), Dermacentor variabilis (0.7%; 20/2731), and Amblyomma maculatum (0.3%; 7/231). Most ticks were adults (83.6%; 2282/2731), but immature A. americanum (436/2136; 20.4%), D. albipictus (12/71; 16.9%), and A. maculatum (n = 1) were occasionally recovered. Amblyomma americanum were most often attached to the inguinal area, and I. scapularis and D. albipictus were most commonly found on the chest and axillary region (P < 0.0001). Ticks were found on horses in every month of the year. The largest number of ticks (638/2731; 23.4%) were collected in May (P < 0.0001). Amblyomma americanum, primarily immature, was the only tick recovered in September, I. scapularis and D. albipictus predominated October through February, and both A. americanum and I. scapularis were common in March. In the warmer months, April through August, A. americanum was the most common tick, followed by D. variabilis and A. maculatum. Conclusions: This research confirms that ticks common on horses in North America have attachment site preferences and that ticks infest horses in Oklahoma throughout the year, including during the winter. Additional research is warranted to fully understand the risk these infestations pose to equine health. [ABSTRACT FROM AUTHOR]

Dermacentor albipictus, a common one-host tick of large animals in North America, is most often reported from moose (Alces alces) and is rarely implicated as a parasite of cats and dogs. From 2018 to 2020, 4 dogs and 4 cats from United States and 3 dogs from Canada were infested with D. albipictus. The specimens were collected and submitted to university diagnostic specialists by veterinary clinics in Indiana, Kentucky, Minnesota, Colorado, Wyoming, Utah, Alberta, and British Columbia between the months of October to February (United States) and April to June (Canada). Six adults and five nymphal D. albipictus were collected in the United States while three adults were collected from pets in Canada, and most often a single D. albipictus was present. Identification of specimens collected in the United States were confirmed by amplification and sequencing of 16S rRNA and ITS-2 gene fragments. Rickettsia spp. were not detected in any D. albipictus collected in the United States by 17 kDa-based PCR. As tick populations continue to increase and expand in North America, correct identification of ticks collected from pets is critical to accurately track the progression and spread of ticks and tick-borne diseases., (Copyright © 2020 Elsevier B.V. All rights reserved.)