Amblyomma americanum was confirmed as a competent vector in the transmission of Cytauxzoon felis to domestic cats. Infection with C. felis was produced and replicated in four domestic felines by the bite of A. americanum adults that were acquisition fed as nymphs on a domestic cat that survived cytauxzoonosis. Numerous attempts to transmit C. felis with Dermacentor variabilis at the same time were not successful. All cats upon which infected A. americanum were transmission fed exhibited disease typical of cytauxzoonosis, and the eitiologic agent's presence was confirmed. Clinical signs including fever, inappetence, depression, and lethargy were observed beginning 13 d postinfestation. Pale mucus membranes, splenomegaly, icterus, and dyspnea were also observed during the course of the disease. Rectal temperatures of the C. felis-infected principal cats fluctuated from high to subnormal before returning to the normal range. Clinical signs of cytauxzoonsis improved by 24 d postinfestation in all but one cat, with survivors remaining parasitemic and subclinically infected with C. felis. Unengorged A. americanum and D. variabilis were collected from wild habitats to determine the minimum infection rate of C. felis in ticks from an enzootic area. Infection of C. felis was found only in wild-collected A. americanum. The minimum infection rate of C. felis in A. americanum was 0.5% (one of 178) in males, 0.8% (three of 393) in nymphs, and 1.5% (three of 197) in females. We found no wild-collected D. variabilis infected with C. felis. Our results confirm that A. americanum is a primary vector of C. felis.

Pulmonary inflammation and the development of spontaneous lung tumors are important age-related lesions in mice. Therefore, gross and histological examination of the respiratory system is a critical component of geropathology research studies for translating surrogate endpoints to clinical aging studies. Collection, trimming, and processing of lung tissue from aged mice require a high-quality sequential process since aged mice are irreplaceable resource-intensive animal models. This protocol provides a basic technique that provides excellent sections for histological evaluation of the respiratory system of old mice suitable for most research applications. The points of emphasis are infusing the lungs at necropsy with formalin through the airways to prevent atelectasis artifacts that can preclude accurate histological evaluation, and embedding of anatomically oriented in toto lung lobes to allow for complete and thorough evaluation of all lung regions.