Polymerase Chain Reaction on In-cage Filter Paper at Different Time Points to Detect Helicobacter spp.

Helicobacter spp. infections in mice can have broad-ranging effects on gastrointestinal, reproductive, and immune systems. This can introduce significant confounding variables for research and may reduce scientific rigor. Screening mouse colonies for Helicobacter species can be accomplished via noninvasive PCR testing on filter paper placed in animal-free dirty bedding sentinel cages. In our facility, one tablespoon of dirty bedding from each cage on a rack is added to a designated sentinel cage every 3 wk at cage change, and PCR testing is performed on in-cage filter paper quarterly. We hypothesized that cages that received Helicobacter spp.-positive bedding at later time points would have a lower detection rate of Helicobacter spp. with PCR testing compared with cages that received positive bedding at earlier time points due to the filter paper becoming saturated. To determine if screening would be able to detect one positive row of cages on a rack, 9 tablespoons of Helicobacter-positive bedding and 71 tablespoons of negative bedding were added at the 3-, 6-, or 9-wk time points to 14 empty sentinel cages per time point. Negative bedding was added every 3 wk to cages not scheduled to receive positive bedding. Negative controls received 80 tablespoons of negative bedding and positive controls received 80 tablespoons of positive bedding at each time point. Filter paper was tested via PCR for Helicobacter spp. at 12 wk. All positive controls tested positive, and all negative controls tested negative. Two 3-wk cages, two 6-wk cages, and three 9-wk cages were positive, indicating no difference between time points. This resulted in a 16.7% Helicobacter spp. detection rate. These results indicate that PCR on in-cage filter paper may not be reliable in detecting low levels of Helicobacter spp. nucleic acid in dirty bedding.

Aural hematoma in lambs associated with Otobius megnini (Ixodida: Argasidae) infestation.

In this report we described a case of aural hematomas in three lambs associated with Otobius megnini (Ixodida: Argasidae) infestation. From April to May 2021, five 3-month-old Hampshire cross lambs presented with unilateral aural hematomas. Upon otoscopic examination, engorged soft ticks (O. megnini) were observed in the external ear canals of three of the five lambs. The remaining two lambs had lesions consistent with infestation and were in a shared environment and deemed likely to have been infected. The treatment of all animals was based on the drainage of the serosanguinous fluid through an incision in the internal space of the ear pinna. Upon physical inspection of the entire flock (n = 310), O. megnini infestation was observed in one additional animal that did not have a hematoma. Following animal and environmental ectoparasiticide treatment with permethrin, no recurrences or additional cases of aural hematomas were observed in the flock in the following two-year period. To the authors' knowledge, this is the first description of aural hematomas in lambs associated with O. megnini infestation with successful recovery after surgery and off-label acaricide treatment.