Chronic wasting disease in Canada: Part 1

The purpose of part 1 is to provide an overview of published literature (1980-2002) on chronic wasting disease (CWD) to inform Canadian readers about the disease and to explain Canadian regulatory approaches to the surveillance and control of CWD. Much of the scientific information is drawn from American publications obtained from internet searches in PubMed and Medline databases. The following keywords were used: chronic wasting disease, prion, diagnosis, transmissible spongiform encephalopathies, CWD and deer, CWD and elk, and CWD and environment. The article also presents information from Canadian publications and unpublished observations, Canadian Food Inspection Agency (CFIA) documents, and both government and nongovernment internet Web sites. The article highlights some different features of CWD in Canada, as compared with the situation in the United States, and mentions public health implications of the disease. It also describes the basis for development of Canada's surveillance and control program. Part 2 will detail the activities and results of the surveillance and control program during 2000 to 2002 and discuss factors that will influence the feasibility of eradicating CWD. Chronic wasting disease appears to have been introduced into Canada through the importation of infected farmed elk from the United States in the late 1980s and early 1990s, at a time when little was known about the disease. Since then, eradication efforts in Canada have led to the control of the spread of CWD in the farmed elk industry. Still, management of this disease, especially in free-ranging cervids, is a challenge.     

Management factors affecting stereotypies and body condition score in nonracing horses in Prince Edward Island

In North America, there are few representative data about the effects of management practices on equine welfare. In a randomized survey of 312 nonracing horses in Prince Edward Island (response rate 68.4%), owners completed a pretested questionnaire and a veterinarian examined each horse. Regression analyses identified factors affecting 2 welfare markers: body condition score (BCS) and stereotypic behavior. Horses' BCSs were high (mean 5.7, on a 9-point scale) and were associated with sex (males had lower BCSs than females; P < 0.001) and examination date (P = 0.052). Prevalences of crib biting, wind sucking, and weaving were 3.8%, 3.8%, and 4.8%, respectively. Age (OR = 1.07, P = 0.08) and hours worked weekly (OR = 1.12, P = 0.03) were risk factors for weaving. Straw bedding (OR = 0.3, P = 0.03), daily hours at pasture (OR = 0.94, P = 0.02), and horse type (drafts and miniatures had a lower risk than light horses; P = 0.12) reduced the risk of horses showing oral stereotypies. Some of these results contradict those of other studies perhaps because of populations concerned.     

The effect of speed and gradient on hyperextension of the equine carpus

The equine carpus has a well-defined limit to joint extension at approximately 180 degrees . During locomotion however, the carpus hyperextends during stance phase. Hyperextension is resisted by the carpal bones and ligaments, and it has been proposed that large increased hyperextension might relate to potentially damaging stress levels in the carpus. The aim of this study was to investigate the relationship between peak hyperextension of the carpus (PCE) and speed during locomotion on the level and on an incline. Five Thoroughbred horses were exercised on a treadmill at speeds between 1.8 and 10 m/s at 0% and +7.5% gradients. PCE was obtained using optical motion capture and linear regression used to describe the relationship between PCE and speed on each gradient. PCE increased linearly with speed during locomotion. The rate of increase was greater on a +7.5% gradient. The fit of the regression equations was increased considerably by subtracting standing carpal angle from PCE during locomotion.     

Coprological analyses on apparently healthy Alpine ibex (Capra ibex ibex) from two Swiss colonies

To provide baseline parasitological data for health surveillance in free-ranging Alpine ibex (Capra ibex ibex), we assessed the endoparasite population and level of parasitism in apparently healthy ibex. Faecal samples from 148 ibex were collected between 2006 and 2008 in two different Swiss ibex colonies. They were analysed by coprology, including combined sedimentation/flotation method, sedimentation method, Baermann funnel technique and Ziehl-Neelsen staining. Gastrointestinal parasites and lungworms were identified in 100% and 81.8% of the examined animals, respectively. Highest prevalences were recorded for gastrointestinal strongylids other than Nematodirus/Marshallagia spp. (100%), Eimeria spp. (100%), Muellerius spp. (79.8%) and Nematodirus/Marshallagia spp. (79.0%). We report for the first time Cryptosporidium sp. in free-ranging Alpine ibex and Cystocaulus spp. in free-ranging ibex from Switzerland. On average, ibex were infected with 3.9 different parasites taxa (range: 1-8). Parasite prevalence and diversity varied significantly between sexes, study sites and seasons. Parasite egg output was low in 95.7% and moderate in 5.3% of the samples. Overall, the results indicate that Alpine ibex are widely infected with endoparasites and suggest that multiple infections are very common in apparently healthy populations. Furthermore, our data underline the potential influence of factors such as sex, study site and season on parasitological findings.     

Acute Pancreatitis in Dogs: Advances in Understanding,Diagnostics, and Treatment

Acute pancreatitis in dogs is a potentially reversible condition, but in severe forms it can cause systemic and local complications. These complications are driven by the cytokine, complement, and kinin systems, with the roles of these systems along with other substances such as nitric oxide being increasingly studied. The intestinal tract and altered pancreatic microcirculation also contribute greatly to the perpetuation of disease. Diagnosis remains difficult, because the true diagnostic utility of the current tests available is problematic to establish. Further understanding of the pathophysiology of this disease has opened up new areas of research into optimal treatments. In particular, the role of enteral nutrition has been the focus of much attention, and current recommendations are to feed earlier in the disease than previously thought.     

Circulating cytokine concentrations in dogs with different degrees of myxomatous mitral valve disease

Cytokines have been associated with the progression of congestive heart failure (CHF) in humans and may be implicated in the pathophysiology of myxomatous mitral valve disease (MMVD) in dogs. The aim of this study was to determine the serum concentrations of cytokines in dogs with MMVD. The study included 16 Cairn terriers with no or minimal mitral regurgitation (MR), 41 Cavalier King Charles Spaniels (CKCS) with different degrees of MR and 11 dogs of different breeds with CHF due to MMVD. Granulocyte-macrophage colony-stimulating factor, interferon-γ, interleukin (IL)-2, IL-6, IL-7, IL-8, IL-10, IL-15, IL-18, keratinocyte-derived chemokine, interferon-γ-induced protein and monocyte chemoattractant protein-1 (MCP-1) were measured using a canine-specific multiplex immunoassay. CHF dogs had significantly higher MCP-1 concentrations than dogs with no or minimal MR. Among the CKCS, IL-2 and IL-7 decreased with increasing left atrial size and IL-7 also decreased with increasing MR. IL-8 decreased with increasing left ventricular end-systolic internal dimensions. MCP-1 was increased in CHF dogs compared to healthy control dogs and IL-2, IL-7 and IL-8 decreased with increasing indices of disease severity. The results suggest a role for these cytokines in canine MMVD and CHF.     

Electrophysiological Evaluation of Pacific Oyster (Crassostrea gigas) Sensitivity to Saxitoxin and Tetrodotoxin

Pacific oysters (Crassostrea gigas) may bio-accumulate high levels of paralytic shellfish toxins (PST) during harmful algal blooms of the genus Alexandrium. These blooms regularly occur in coastal waters, affecting oyster health and marketability. The aim of our study was to analyse the PST-sensitivity of nerves of Pacific oysters in relation with toxin bio-accumulation. The results show that C. gigas nerves have micromolar range of saxitoxin (STX) sensitivity, thus providing intermediate STX sensitivity compared to other bivalve species. However, theses nerves were much less sensitive to tetrodotoxin. The STX-sensitivity of compound nerve action potential (CNAP) recorded from oysters experimentally fed with Alexandrium minutum (toxic-alga-exposed oysters), or Tisochrysis lutea, a non-toxic microalga (control oysters), revealed that oysters could be separated into STX-resistant and STX-sensitive categories, regardless of the diet. Moreover, the percentage of toxin-sensitive nerves was lower, and the STX concentration necessary to inhibit 50% of CNAP higher, in recently toxic-alga-exposed oysters than in control bivalves. However, no obvious correlation was observed between nerve sensitivity to STX and the STX content in oyster digestive glands. None of the nerves isolated from wild and farmed oysters was detected to be sensitive to tetrodotoxin. In conclusion, this study highlights the good potential of cerebrovisceral nerves of Pacific oysters for electrophysiological and pharmacological studies. In addition, this study shows, for the first time, that C. gigas nerves have micromolar range of STX sensitivity. The STX sensitivity decreases, at least temporary, upon recent oyster exposure to dinoflagellates producing PST under natural, but not experimental environment.     

Evidence of the exploitation of marine resource by the terrestrial insect Scapteriscus didactylus through stable isotope analyzes of its cuticle

Background  

About 4 × 10⁵ eggs in more than 5000 marine turtle nests are deposited every year on a 3.6 km long beach in French Guiana (South America). The dry biomass of eggs is estimated to be 5 × 10³ kg, yet only 25% of this organic matter will return to the ocean in the form of hatchlings. Such amounts of organic matter are supposed to drive the functioning of the beach ecosystem. Previous studies have shown that egg predators and detritivorous organisms dominate the trophic relationships and the dynamics of the system. The role of a terrestrial insect Scapteriscus didactylus (Latreille), which damages up to 40% of the eggs of the marine turtle (Dermochelys coriacea), was unexpected. However it was impossible from direct observations to prove that the mole cricket consumed a significant amount of these eggs. Therefore, the precise place of the mole cricket in the nitrogen and carbon cycles of the beach ecosystem could not be determined. In order to answer this question, we looked for a marine signature of carbon and nitrogen source metabolized by the mole cricket.