Documenting patterns of host specificity in parasites relies on the adequate definition of parasite species. In many cases, parasites have simplified morphology, making species delimitation based on traditional morphological characters difficult. Molecular data can help in assessing whether widespread parasites harbour cryptic species and, alternatively, in guiding further taxonomic revision in cases in which there is morphological variation. The duck louse genus Anaticola (Phthiraptera: Philopteridae), based on current taxonomy, contains both host-specific and widespread species. Mitochondrial and nuclear DNA sequences of samples from this genus were used to document patterns of host specificity. The comparison of these patterns with morphological variations in Anaticola revealed a general correspondence between the groups identified by DNA sequences and morphology, respectively. These results suggest that a more thorough taxonomic review of this genus is needed. In general, the groups identified on the basis of molecular data were associated with particular groups of waterfowl (e.g. dabbling ducks, sea ducks, geese) or specific biogeographic regions (e.g. North America, South America, Australia, Eurasia).

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OBJECTIVE: To determine the intracoelemic (ICe) dose of alfaxalone required to induce loss of righting reflex (LRR) in garter snakes (Thamnophis sirtalis) and to evaluate the tactile stimulus response in unanesthetized and alfaxalone-anesthetized snakes. ANIMALS: 8 healthy mature garter snakes. PROCEDURES: During the first of 3 phases, snakes received each of 3 doses (10, 20, and 30 mg/kg) of alfaxalone, ICe, with a 2-week washout period between treatments. Times to LRR and return of righting reflex were determined after each dose. During phase 2, unanesthetized snakes underwent tactile stimulation testing with Semmes-Weinstein monofilaments once daily for 3 consecutive days to determine the baseline tactile pressure required to elicit purposeful movement. During phase 3, snakes were anesthetized with alfaxalone (30 mg/kg, ICe), and the tactile pressure required to induce purposeful movement was assessed at predetermined times after LRR. RESULTS: Intracoelomic administration of alfaxalone at doses of 10, 20, and 30 mg/kg induced LRR in 0, 5, and 8 snakes, respectively. For snakes with LRR, median time to LRR following the 30-mg/kg dose (3.8 minutes) was significantly shorter than that following the 20-mg/kg dose (8.3 minutes); median time to return of righting reflex did not differ between the 2 doses. Mean ± SD tactile pressure that resulted in purposeful movement in unanesthetized snakes was 16.9 ± 14.3 g. When snakes were anesthetized, the mean tactile pressure that resulted in purposeful movement was significantly increased from baseline at 10, 20, and 30 minutes after LRR. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested ICe administration of alfaxalone might be effective for anesthetizing garter snakes.

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