Defining important canine zoonotic pathogens within the Prairie Provinces of Canada

The goal of this study was to establish a short list of zoonotic pathogens involving the domestic dog that can be prioritized for a companion animal surveillance program specific to the Prairie Provinces of Canada. A list of pathogens documented in dogs was created through a comprehensive review of infectious disease textbooks for the following taxonomical categories: bacteria, ectoparasites, fungi, helminths, protozoa, rickettsia, and viruses. This created an initial list of 594 pathogens that was then pared down through an extensive review of the literature using the following criteria: i) the pathogen is zoonotic/sapronotic/anthroponotic; ii) the dog is involved in transmission to humans, maintenance, or detection of the pathogen; and iii) there is a level of risk for occurrence of the pathogen in Canada. This process yielded a final list of 84 pathogens and 3 supplementary lists of canine zoonotic/sapronotic/anthroponotic pathogens that may become relevant to future surveillance programs.     

Testing whether adrenal steroids mediate phenotypic and physiologic effects of elevated salinity on larval tiger salamanders

Salinity (sodium chloride, NaCl) from anthropogenic sources is a persistent contaminant that negatively affects freshwater taxa. Amphibians can be susceptible to salinity, but some species are innately or adaptively tolerant. Physiological mechanisms mediating tolerance to salinity are still unclear, but changes in osmoregulatory hormones such as corticosterone (CORT) and aldosterone (ALDO) are prime candidates. We exposed larval barred tiger salamanders (Ambystoma mavortium) to environmentally relevant NaCl treatments (<32–4000 mg·L⁻¹) for 24 days to test effects on growth, survival, and waterborne CORT responses. Of those sampled, we also quantified waterborne ALDO from a subset. Using a glucocorticoid antagonist (RU486), we also experimentally suppressed CORT signaling of some larvae to determine if CORT mediates effects of salinity. There were no strong differences in survival among salinity treatments, but salinity reduced dry mass, snout–vent length, and body condition while increasing water content of larvae. High survival and sublethal effects demonstrated that salamanders were physiologically challenged but could tolerate the experimental concentrations. CORT signaling did not attenuate sublethal effects of salinity. Baseline and stress-induced (after an acute stressor, shaking) CORT were not influenced by salinity. ALDO was correlated with baseline CORT, suggesting it could be difficult to decouple the roles of CORT and ALDO. Future studies comparing ALDO and CORT responses of adaptively tolerant and previously unexposed populations could be beneficial to understand the roles of these hormones in tolerance to salinity. Nevertheless, our study enhances our understanding of the roles of corticosteroid hormones in mediating effects of a prominent anthropogenic stressor.     

Photosynthetic induction responses to variable light under field conditions in three species grown in the gap and understory of a Fagus crenata forest

Photosynthetic induction responses to abrupt increases in photon flux density (PFD) to 800 and 1500 &mgr;mol m(-2) s(-1) from either darkness or 100 &mgr;mol m(-2) s(-1) were examined in situ in leaves of Fagus crenata Blume, Daphniphyllum humile Maxim., and Acer rufinerve Siebold & Zucc. growing in a gap and the understory of an F. crenata forest. Among the species studied, F. crenata exhibited the highest assimilation rate (A(100)), stomatal conductance (g(s100)) at the background PFD of 100 &mgr;mol m(-2) s(-1), and A(100)/A(max) (A(max) = maximum assimilation rate), in both the gap and the understory. Time required for full induction depended on both background PFD and maximum PFD. The induction period was 2-4-fold shorter at a background PFD of 100 &mgr;mol m(-2) s(-1) than in darkness. For the three understory species, time required to full induction was 2-3-fold longer when irradiance was increased from darkness to 800 &mgr;mol m(-2) s(-1) than when irradiance was increased from darkness to 1500 &mgr;mol m(-2) s(-1). Acer rufinerve showed higher initial stomatal conductance (g(s0)) and a shorter induction period in the understory than in the gap. Fagus crenata exhibited a similar g(s0) and induction period in both habitats. Daphniphyllum humile demonstrated lower g(s0) and a longer induction period in the understory than in the gap. These findings indicate that initial stomatal conductance is closely correlated with the photosynthetic induction response. We conclude that the photosynthetic induction response is affected by the light conditions experienced by plants before the sudden increase in irradiance and by the extent of the increase in irradiance.     

Kinetics of energy source utilization in Boophilus microplus (Canestrini, 1887) (Acari: Ixodidae) embryonic development

The present work evaluates the kinetics of utilization of the main potential energy sources throughout the embryonic developmental stages of Boophilus microplus. The embryonic development of this arthropod is completed in 21 days. Cellularization of the blastoderm occurs on the 6th day and is rapidly followed by germ band extension and segmentation, whose first signs are visible on the 7th day. Cellularization is typically a maternal-driven process, carried out by molecular determinants deposited in the oocyte during oogenesis. On the other hand, segmentation is of zygotic nature, being the consequence of the synthesis of various components by the growing embryo. The enhancement in total B. microplus RNA was observed after cellularization, corroborating the replacement of maternal-driven processes by embryonic zygotic expression. An abrupt increase in oxygen consumption was observed from cellularization until the 8th day of development. The reduction in dry weight at the same period and the susceptibility of oxygen consumption to KCN suggest that the respiration process is activated during early embryonic development. A marked decrease in total lipid content occurred between the 5th and 7th days of development, suggesting this is the main energy source for cellularization. A major reduction in carbohydrate content occurred later, between the 7th and 9th days, and it could be assigned to the morphological segmentation of the embryo. Although the total amount of proteins remains unchanged from oviposition to hatching, a 15% reduction in vitellin (VT) content was observed before cellularization, up to the 4th day after egglaying. This observation was correlated to the synthesis of new proteins needed to support early embryo development. Additional 20% of VT was consumed thereafter, mainly at the end of embryogenesis, and in this case VT is probably used as energy source to the older embryo. Altogether, these data indicate different energy sources for maternal and zygotic driven processes.     

The virB-encoded type IV secretion system is critical for establishment of infection and persistence of Brucella ovis infection in mice

Brucella spp. are gram-negative intracellular bacterial pathogens that cause chronic infections. Brucella virulence factors include a type IV secretion system (T4SS) and its lipopolysaccharide (LPS), which are essential for persistence. However, the role of the virB-encoded T4SS has not been investigated in naturally rough Brucella species such as Brucella ovis. In this study, male 6-week old BALBc mice were infected with B. ovis, Brucella abortus, and their respective ΔvirB2 mutant strains. During early infection, B. ovis and B. abortus wild type strains were similarly recovered from spleen. Interestingly, in contrast to ΔvirB2 B. abortus that was recovered at similar levels when compared to the wild type strain, the ΔvirB2 B. ovis was markedly attenuated as early as 24h post infection (hpi). The ΔvirB2 B. ovis was unable to survive and multiply in murine peritoneal macrophages and extracellularly within the peritoneal cavity at 12 and 24 hpi with lower splenic colonization than the parental strain at 6, 12 and 24 hpi. In contrast, wild type B. abortus and ΔvirB2 B. abortus had a similar kinetics of infection in this model. As expected, the T4SS was essential for intracellular replication of smooth and rough strains in RAW macrophages at 48 hpi. These results suggest that T4SS is important for survival of B. ovis in murine model, and that a T4SS deficient B. ovis strain is cleared at earlier stages of infection when compared to a similar B. abortus mutant.     

Potassium iodide capsule treatment of feline sporotrichosis

Sporotrichosis is a mycosis caused by Sporothrix schenckii. The most affected animal is the cat; it has played an important role in the zoonotic transmission of this disease, especially in Rio de Janeiro, Brazil, since 1998. In order to evaluate the treatment of feline sporotrichosis with potassium iodide, an observational cohort was conducted in 48 cats with sporotrichosis at Instituto de Pesquisa Clínica Evandro Chagas, Fiocruz. All cats received potassium iodide capsules, 2.5 mg/kg to 20 mg/kg q24h. The cure rate was 47.9%, treatment failure was 37.5%, treatment abandonment was 10.4% and death was 4.2%. Clinical adverse effects were observed in 52.1% of the cases. Thirteen cats had a mild increase in hepatic transaminase levels during the treatment, six of them presented clinical signs suggestive of hepatotoxicity. Compared to previous studies with itraconazole and iodide in saturated solution, potassium iodide capsules are an alternative for feline sporotrichosis treatment.     

Association of holidays, full moon, Friday the 13th, day of week, time of day, day of week, and time of year on case distribution in an urban referral small animal emergency clinic

Objective – To interrogate the association of variables: day of week, time of day, day of the year (major holidays, Friday the 13th, and the full moon), and month of year with the caseload of an urban academic emergency service.
Design – Retrospective study.
Setting – Urban small animal teaching hospital emergency clinic.
Animals – Cats and dogs that were presented to the emergency clinic.
Interventions – None.
Measurements and Main Results – The hospital computer database was searched for all visits to the Emergency Service of the Mathew J. Ryan Veterinary Hospital of the University of Pennsylvania from January 1, 1987 through December 31, 2002. Variables included in the electronic data were date of admission, time of day of admission, species (dog or cat), hospital service the case was transferred to for ongoing care and whether the case was discharged directly from the emergency service. The association of caseload with day of week, time of day, day of the year (major holidays, Friday the 13th, and the full moon), and month of year was described and statistically evaluated. Saturdays and Sundays were the busiest days of the week and significantly increased caseload was noted for the majority of holidays (except Easter Day and Thanksgiving Day) with Memorial Day being the busiest. Midweek evenings as well as Saturday and Sunday afternoons were the busiest periods of the day. There was no association with caseload and Halloween, the full moon, or Friday the 13th.
Conclusions – The busiest times were midweek evenings, Saturday and Sunday afternoons, and most major holidays.     

The impact of resistance on the use of second-generation anticoagulants against rats on farms in Southern England

Resistance amongst rats to second-generation anticoagulants, notably difenacoum, has been recognised since the 1970s. Although initially considered to be of practical significance, doubts were subsequently expressed that the degree of resistance was sufficient to explain ineffective rodenticide treatments. Research published elsewhere demonstrated the overriding importance of poor poisoned bait consumption, caused by the influence of certain ecological factors on rat behaviour, in reducing the effectiveness of second-generation anticoagulant treatments on farms in southern England. In this paper we consider, however, the subtle effects of resistance to anticoagulants on treatment outcome. The prevalence of resistance was increased amongst survivors of treatments and bait consumption by resistant survivors was higher than amongst susceptible survivors. The overall prevalence and degree of resistance to second-generation anticoagulants does not, however, currently represent a practical problem. Nevertheless, selection favouring increased resistance remains a long-term threat to the effectiveness of both difenacoum and bromadiolone.