Feline toxicological emergencies: when to suspect and what to do

PRACTICAL RELEVANCE: Confirmed or suspected intoxications with a wide variety of agents represent a small but important group of feline emergency cases. Generally it is thought that toxicities are less common in cats compared with dogs, with a higher proportion relating to dermal as opposed to oral exposure. CLINICAL CHALLENGES: Once toxicity is suspected or diagnosed, it must be recognised that treatment regimes may need modification compared with those established for dogs. Different drugs or different dosages may be warranted and the choice of available drugs may be reduced. EVIDENCE BASE: This review draws on published studies, case reports and clinical experience to summarise key features of the general management of the intoxicated feline patient before describing some of the more serious and common intoxications in more detail. AUDIENCE: The focus throughout the review is on the peculiarities of feline metabolism and how they may impact on presentation and treatment. The aim is to assist companion animal and feline practitioners, who are in the frontline when it comes to managing these emergency cases.     

Ten-year regeneration responses to varying levels of overstory retention in two productive southern British Columbia ecosystems

We investigated survival and growth responses of planted and advance natural regeneration species of varying shade tolerance to partial retention harvesting in moist warm Interior Cedar-Hemlock (ICHmw2) and dry cool Montane Spruce (MSdk) ecosystems of southeastern British Columbia, Canada. Treatments included three levels of overstory basal area retention (none, light (∼25%), or heavy (∼50%)) installed by two harvest methods (handfelled or a pushover falling technique being tested for its ability to control the spread of root disease). After 10 years, growth of both planted and natural regeneration species of varying shade tolerance tended to increase with decreasing overstory retention and associated increases in light availability. In contrast, significant survival responses to retention level were lacking except in the case of shade-intolerant western larch. Harvest method had a variable effect on regeneration survival and growth. Where significant responses did occur, they were generally attributed to harvesting effects on the characteristics of planting microsites rather than root disease spread. Natural regeneration densities at the ICHmw2 site were high at all retention levels, whereas stocking was less consistent at the MSdk site. We concluded that moderately shade-tolerant to shade-tolerant interior spruce and western redcedar can, under conditions similar to those of our study sites, be successfully established under overstories of up to approximately 25 m²/ha basal area, but that growth performance is likely to be significantly lower than in clearcuts. Despite early survival issues, conclusions regarding Douglas-fir were similar. Poorer survival and vigour of shade-intolerant western larch suggested this species is not suitable for regeneration in partial retention systems where timber production is the primary objective. Where non-timber objectives predominate, survival and acceptable growth of even a small proportion of larch could add to the diversity of the regenerating stand.     

Wetlands, carbon, and climate change

Wetland ecosystems provide an optimum natural environment for the sequestration and long-term storage of carbon dioxide (CO₂) from the atmosphere, yet are natural sources of greenhouse gases emissions, especially methane. We illustrate that most wetlands, when carbon sequestration is compared to methane emissions, do not have 25 times more CO₂ sequestration than methane emissions; therefore, to many landscape managers and non specialists, most wetlands would be considered by some to be sources of climate warming or net radiative forcing. We show by dynamic modeling of carbon flux results from seven detailed studies by us of temperate and tropical wetlands and from 14 other wetland studies by others that methane emissions become unimportant within 300 years compared to carbon sequestration in wetlands. Within that time frame or less, most wetlands become both net carbon and radiative sinks. Furthermore, we estimate that the world’s wetlands, despite being only about 5–8 % of the terrestrial landscape, may currently be net carbon sinks of about 830 Tg/year of carbon with an average of 118 g-C m^?2 year^?1 of net carbon retention. Most of that carbon retention occurs in tropical/subtropical wetlands. We demonstrate that almost all wetlands are net radiative sinks when balancing carbon sequestration and methane emissions and conclude that wetlands can be created and restored to provide C sequestration and other ecosystem services without great concern of creating net radiative sources on the climate due to methane emissions.     

Elemental Speciation and Distribution in Sediments of a Eutrophied Subtropical Freshwater Reservoir Using Postextraction Normalisation

The speciation and distribution of trace and major elements (Al, As, Cd, Cr, Cu, Fe, Mn, Ni, P, Pb and Zn) in the sediments of Emigrant Creek Dam (ECD), New South Wales Australia were investigated using sequential extraction, postextraction normalisation and spatial mapping to indicate source and dispersion patterns. Subsurface coring provided an estimate of elemental enrichment and showed that As 1.9?>?P 1.7?>?N 1.5????Cd 1.5?>?Mn 1.3 were enriched. Moreover, a high proportion of the enriched elements (mean 57, 34, 47 and 87?% for As, P, Cd and Mn, respectively) were assessed as being bioavailable. Comparisons with ISQGs found that sediments from sites in proximity to Emigrant Creek inflows had the highest accumulations of metals and the greatest potential for causing biological harm. Spatially, contaminants accumulate in ECD sediments adjacent to anthropogenic sources including a cattle dip site, dredged sediment and macrophyte dump areas, and agricultural/residential runoff. Moreover, the integrated technique and postextraction normalisation allow assessment of texturally diverse and difficult sediments.     

The development of a novel percutaneous lung biopsy procedure for use on feedlot steers

The purpose of this study was to develop a percutaneous lung biopsy technique to be used on steers in a commercial feedlot setting. Thirty-four crossbred steer and heifer calves from a commercial feedlot in southern Alberta were used in this study. The calves originated from the auction market and all were chronically affected with bovine respiratory disease (BRD). A technique was developed to obtain a lung sample from the right cranioventral lung lobe, intercostal space (ICS) 2, using a manual or an automatic biopsy instrument with a 14- or 12-gauge (ga) biopsy needle. Overall, lung parenchyma was successfully harvested in 55.9% of experimental animals and in 55.0% of lung biopsy trials. Compared with postmortem diagnosis, the biopsy resulted in the same pathologic diagnosis for 75% of biopsy samples when evaluated using standardized criteria by the same veterinary pathologist. The success rate was 61.5% and 42.9% in a hospital or field setting, respectively. With an automatic instrument, lung was recovered from 57.9% and 37.5% of samples obtained using a 12- or 14-ga biopsy needle, respectively. One experimental animal or 2.9% of the total had fatal complications from the procedure. In a commercial feedlot setting, the procedure took 20 min for each animal. Percutaneous lung biopsy of the right cranioventral lung lobe may be a viable technique when used on feedlot steers affected with chronic pneumonia. These findings suggest that using an automatic instrument with either a 14- or 12-ga biopsy needle may yield lung samples that are suitable for histopathological evaluation. However, this technique needs to be further evaluated in a field setting.     

Leishmania spp. in Didelphis albiventris and Micoureus paraguayanus (Didelphimorphia: Didelphidae) of Brazil

Leishmaniasis is kept in nature by the participation of several animal species. This study evaluated the presence of Leishmania spp. in skin samples of free-ranging marsupials Micoureus paraguayanus (n=95) and Didelphis albiventris (n=191), captured in Morro do Diabo State Park and in sections of its surrounding forest, in the region of Pontal do Paranapanema, S?o Paulo State, Brazil. The samples were tested for the presence of kDNA of Leishmania spp. by polymerase chain reaction (PCR) and by real time PCR (qPCR). All samples from D. albiventris tested by PCR were negative for the presence of kDNA of Leishmania spp. However, when tested by qPCR, the positivity was 1.6%. A positivity of 7.4% by PCR and 11.6% by qPCR was observed for M. paraguayanus. Sixty-four per cent (9/14) of positive animals were limited to the same forest fragment. Presence of Leishmania (Leishmania) amazonensis and Leishmania (Viannia) braziliensis was detected in M. paraguayanus samples. While D. albiventris is the most studied marsupial species due to its urban habits, other marsupial species such as M. paraguayanus can be potential reservoirs of Leishmania spp. and should also be studied.     

Evidence that the 36 kb plasmid of Brachyspira hyodysenteriae contributes to virulence

Swine dysentery (SD) results from infection of the porcine large intestine with the anaerobic intestinal spirochaete Brachyspira hyodysenteriae. Recently the genome of virulent Australian B. hyodysenteriae strain WA1 was sequenced, and a 36 kilobase (kb) circular plasmid was identified. The plasmid contained 31 genes including six rfb genes that were predicted to be involved with rhamnose biosynthesis, and others associated with glycosylation. In the current study a set of PCRs was developed to amplify portions of nine of the plasmid genes. When used with DNA extracted from virulent strain B204, PCR products were generated, but no products were generated with DNA from avirulent strain A1. Analysis of the DNA using pulsed field gel electrophoresis (PFGE) identified a plasmid band in strains WA1 and B204, but not in strain A1. These results demonstrate that strain A1 does not contain the plasmid, and suggests that lack of the plasmid may explain why this strain is avirulent. To determine how commonly strains lacking plasmids occur, DNA was extracted from 264 Australian field isolates of B. hyodysenteriae and subjected to PCRs for three of the plasmid genes. Only one isolate (WA400) that lacked the plasmid was identified, and this absence was confirmed by PFGE analysis of DNA from the isolate and further PCR testing. To assess its virulence, 24 pigs were experimentally challenged with cultures of WA400, and 12 control pigs were challenged with virulent strain WA1 under the same conditions. Significantly fewer (P=0.03) of the pigs challenged with WA400 became colonised and developed SD (13/24; 54%) compared to the pigs infected with WA1 (11/12; 92%). Gross lesions in the pigs colonised with WA400 tended to be less extensive than those in pigs colonised with WA1, although there were no obvious differences at the microscopic level. The results support the likelihood that plasmid-encoded genes of B. hyodysenteriae are involved in colonisation and/or disease expression.     

Interlaboratory evaluation of a real-time multiplex polymerase chain reaction method for identification of salmon and trout species in commercial products

This interlaboratory study evaluated a real-time multiplex polymerase chain reaction (PCR) method for identification of salmon and trout species in a range of commercial products in North America. Eighty salmon and trout products were tested with this method by three independent laboratories. Samples were collected in the United States and Canada, and only the collecting institution was aware of the species declaration. Following analysis with real-time PCR, all three laboratories were able to identify species in 79 of the 80 products, with 100% agreement on species assignment. A low level of fraud was detected, with only four products (5%) found to be substituted or mixtures of two species. The results for two of the fraudulent products were confirmed with alternate methods, but the other two products were heavily processed and could not be verified with methods other than real-time PCR. Overall, the results of this study show the usefulness and versatility of this real-time PCR method for the identification of commercial salmon and trout species.