Efficacy of moxidectin 6-month injectable and milbemycin oxime/lufenuron tablets against naturally acquired trichuris vulpis infections in dogs

Efficacy of moxidectin injection (ProHeart 6 Sustained Release Injectable for Dogs, Fort Dodge Animal Health) against naturally acquired infections of Trichuris vulpis was compared with that of milbemycin oxime/lufenuron tablets (Sentinel Flavor Tabs, Novartis Animal Health). Eighteen dogs infected with T. vulpis were ranked by egg counts and randomly allocated to treatment with moxidectin (170 micro g/kg), milbemycin (500 micro g/kg)/lufenuron (10 mg/kg), or to an untreated control group (six dogs per treatment). Dogs were euthanized for worm counting 7 days after treatment. Efficacy of milbemycin/lufenuron against T. vulpis was 99.6 %, compared with 67.5 % for moxidectin. The commercial formulation of milbemycin oxime/lufenuron provided excellent control of whipworm infection, whereas moxidectin demonstrated variable efficacy against this parasite.     

Using operating area size and adjacency constraints to mitigate the effects of harvesting activities on boreal caribou habitat

Context

Sustained timber harvesting conflicts with the long-term viability of boreal caribou (Rangifer tarandus caribou) populations. The spatial arrangement of harvest blocks in the landscape could mitigate the impact of logging on caribou populations. For the forest industry, however, these measures represent constraints that reduce the annual allowable cut (AAC).

Objective

Estimate the long-term impacts of spatial constraints to harvesting, applied alone or in combination, on AAC and boreal caribou populations.

Methods

We divided a 30,000 km² region into 20 harvest block sizes varying from 50 to 1000 km², and modeled the implementation of spatially explicit harvest schedule plans in combination with wildfire and caribou population dynamics. We then evaluated the probability of persistence of boreal caribou populations.

Results

The probability of maintaining an AAC target declined with increasing target AAC, increasing size of operating area, and increasing adjacency constraints. In contrast, the probability of maintaining caribou populations declined with increasing AAC, decreasing size of operating areas, and decreasing adjacency constraints. An increase in operating area size from 50 to 300 km² produced a considerable gain in AAC for all adjacency constraints.

Conclusions

Because adjacency constraints led only to a small increase in the probability of maintaining caribou populations, we recommend adopting less constraining landscape management actions, such as a 70-year period between two consecutive harvests in the same ~300-km² operating area.

     

Using 3D animations to teach intracellular signal transduction mechanisms: taking the arrows out of cells

Traditional methods of teaching intracellular biological processes and pathways use figures or flowcharts with the names of molecules linked with arrows. Many veterinary students, presented with such material, simply memorize the names or chemical structures of the molecules and are then likely to forget the material once the examination is completed. To address this problem, the authors designed, created, and field-tested new teaching media that incorporate realistic three-dimensional (3D) animations depicting the dynamic changes that occur in intracellular molecules during cellular activation. Testing found that veterinary students taught using traditional teaching media (e.g., lectures, handouts, textbooks) are proficient in memorizing the names and order of intracellular molecules but unable to appreciate the interactions between these elements or their spatial relationships within cells. In contrast, more than 90% of veterinary students taught using 3D animations not only recall the facts about the intracellular elements but also develop accurate mental images of the interactions among these molecules and their spatial relationships. These findings strongly suggest that the comprehension of complex biological processes by veterinary students can be enhanced by the use of dynamic 3D depictions of these processes in the classroom.     

Western blot detection of PrP Sc in archived paraffin-embedded brainstem from scrapie-affected sheep

Scrapie is a naturally occurring fatal neurodegenerative disease of adult sheep and goats, one of a group of mammalian diseases known as transmissible spongiform encephalopathies (TSE) or prion diseases. Immunoassays that identify disease-associated prion protein (PrP Sc) are integral to the diagnosis of scrapie and other prion diseases. Results obtained by either immunohistochemistry (IHC) or Western blot (WB) assay are generally adequate for the definitive diagnosis. Approved or accepted methods for WB diagnosis of TSEs requires the use of fresh or frozen nonfixed tissue samples, whereas formalin-fixed, paraffin-embedded tissue is required for the localization of PrP Sc by IHC. Because disparate processing methods are used for these accepted diagnostic techniques, separate tissue samples are collected from the same animal. Occasions arise in which there is either insufficient quantity of tissue available to complete analysis by both techniques or initial tissue processing is incompatible with one of the assays. Also, results between the assays may differ because of the vagaries of sampling, especially in case material that contains moderate-to-low levels of PrP Sc. The present article describes a method to conduct a WB assay from the same paraffin-embedded brainstem sample used for the IHC diagnosis of experimentally induced sheep scrapie.     

Bordetella bronchiseptica-reactive antibodies in Canadian polar bears

Bordetella bronchiseptica is a promiscuous bacterium that infects a variety of species but has not been reported in free-ranging polar bears (Ursus maritimus). Sera from 385 polar bears from the western Hudson Bay region, 1986 to 2017, were tested for reactivity to B. bronchiseptica with enzyme-linked immunosorbent assays using anti-canine IgG and Streptococcus protein G as secondary reagents. Sera from bears had variable reactivity to B. bronchiseptica antigens, and there was no difference among bears that had a history of coming near the town of Churchill, Manitoba, and bears that did not. Although the sources of exposure were not determined, equivalent results in both groups suggest that potential exposure to humans (aside from handling during sampling) and their animals (dogs) was not an important co-factor in sero-positivity to B. bronchiseptica.     

An investigation of links between metabolic rate and feed efficiency in European sea bass Dicentrarchus labrax

Feed efficiency (FE) is the amount of body weight gain for a given feed intake. Improving FE through selective breeding is key for sustainable finfish aquaculture but its evaluation at individual level is technically challenging. We therefore investigated whether individual routine metabolic rate (RMR) was a predictor of individual FE in the European sea bass Dicentrarchus labrax, a major species in European mariculture. The European sea bass has three genetically distinct populations across its geographical range, namely Atlantic (AT), West Mediterranean (WM), and East Mediterranean (EM). We compared FE and RMR of fish from these three populations at 18 or 24 °C. We held 200 fish (62 AT, 66 WM, and 72 EM) in individual aquaria and fed them from ad libitum down to fasting. FI was assessed for an ad libitum feeding rate and for a fixed restricted ration (1% of metabolic body weight·day⁻¹, with metabolic body weight = body weight^0.8). After being refed 12 wk in a common tank, individual RMR was measured over 36 h by intermittent flow respirometry. There was a significant effect of temperature whereby fish at 18 °C had greater mean FE (P < 0.05) and lower RMR (P < 0.001). There was also a significant effect of population, where AT fish had lower FE (P < 0.05) and greater RMR (P < 0.001) than WM and EM, at both temperatures. Despite these differences in temperature and population means, individual FE and RMR were not significantly correlated (P > 0.05). Therefore, although the results provide evidence of an association between metabolic rate and FE, RMR was not a predictor of individual FE, for reasons that require further investigation.