Cytauxzoonosis is an emerging tick-borne disease of domestic and wild felids produced by infection of Cytauxzoon felis, an apicomplexan protozoan similar to Theileria spp. Transmitted by Amblyomma americanum, lone star tick, and Dermacentor variabilis, American dog tick, infection of C. felis in cats is severe, characterized by depression, lethargy, fever, hemolytic crisis, icterus, and possibly death. Cytauxzoonosis occurs mainly in the southern, south-central, and mid-Atlantic United States in North America, in close association with the distribution and activity of tick vectors. Infection of C. felis, although severe, is no longer considered uniformly fatal, and unless moribund, every attempt to treat cytauxzoonosis cats should be made. Herein we review cytauxzoonosis, including its etiology, affected species, its life cycle and pathogenesis, clinical signs, diagnosis, and epidemiology, emphasizing clinical pathology findings in cats infected with this important emerging tick-borne disease in North and South America.

Telomeres are emerging as correlates of fitness‐related traits and may be important mediators of ecologically relevant variation in life history strategies. Growing evidence suggests that telomere dynamics can be more predictive of performance than length itself, but very little work considers how telomere regulatory mechanisms respond to environmental challenges or influence performance in nature. Here, we combine observational and experimental data sets from free‐living tree swallows (Tachycineta bicolor) to assess how performance is predicted by the telomere regulatory gene POT1, which encodes a shelterin protein that sterically blocks telomerase from repairing the telomere. First, we show that lower POT1 gene expression in the blood was associated with higher female quality, that is, earlier breeding and heavier body mass. We next challenged mothers with an immune stressor (lipopolysaccharide injection) that led to “sickness” in mothers and 24 h of food restriction in their offspring. While POT1 did not respond to maternal injection, females with lower constitutive POT1 gene expression were better able to maintain feeding rates following treatment. Maternal injection also generated a 1‐day stressor for chicks, which responded with lower POT1 gene expression and elongated telomeres. Other putatively stress‐responsive mechanisms (i.e., glucocorticoids, antioxidants) showed marginal responses in stress‐exposed chicks. Model comparisons indicated that POT1 mRNA abundance was a largely better predictor of performance than telomere dynamics, indicating that telomere regulators may be powerful modulators of variation in life history strategies.

Long telomeres have become nearly synonymous with a variety of fitness-related traits and may be mediators of ecologically relevant variation in life history strategies. Growing evidence suggests that telomere dynamics are more predictive of performance than length itself, but very little work considers how telomere regulatory mechanisms respond to environmental challenges or influence performance in nature. Here, we combine observational and experimental datasets from free-living tree swallows (Tachycineta bicolor) to assess how performance is predicted by the telomere regulatory gene POT1, which encodes a shelterin protein that sterically blocks telomerase from repairing the telomere. First, we show that lower POT1 gene expression was associated with higher female quality, i.e. earlier breeding, and heavier body mass. We next challenged mothers with an immune stressor (lipopolysaccharide injection) that led to ‘sickness’ in mothers and 24h of food restriction in their offspring. While POT1 did not respond to maternal injection, females with lower constitutive gene expression were better able to maintain feeding rates following treatment. Maternal injection also generated a one-day stressor for chicks, who responded with decreased POT1 gene expression and elongated telomeres. Other putatively stress-responsive mechanisms (i.e. glucocorticoids, antioxidants) were not significantly different between control and stress-exposed chicks. Model comparisons indicated that POT1 mRNA abundance was a largely better predictor of performance than telomere dynamics, indicating that telomere regulators may be powerful modulators of variation in life history strategies.

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Supplemental feeding is a common anthropogenic influence on wildlife which, dependent on natural food availability, can have positive or negative effects on physiological condition. For example, animals may respond negatively to supplemental feeding if the artificial food source increases disease exposure or there may be negative consequences from removal of a supplemental food source. We manipulated supplemental food availability in a wild population of eastern bluebirds Sialia sialis to examine the influence on body mass, physiological metrics and nesting success. Adult and nestling bluebirds were randomly assigned to one of three feeding groups. The first treatment group received mealworm Tenebrio molitor larvae inside nest boxes throughout the breeding attempt, the second treatment group received mealworms from nest completion until nestlings hatched, and the third treatment group received no supplementation. We collected blood samples from adults and nestlings to quantify bacterial killing ability, corticosterone levels and heterophil to lymphocyte ratios. As measures of nesting success, we quantified hatching success and fledging success. Supplement group tended to impact nestling mass near fledging; however, neither the physiological metrics nor the nesting success metrics differed significantly among experimental groups. Our results suggest eastern bluebird supplementation is largely neutral with the exception of its removal at the time of hatching, at least when natural food sources are abundant. Bird feeding by hobbyists may attract birds to locations with available nesting sites without demonstrably negative or positive effects, unless practiced inconsistently during breeding.