EFFECTS OF ANESTHETIC PROTOCOL ON NORMAL CANINE BRAIN UPTAKE OF 18F‐FDG ASSESSED BY PET/CT

The purpose of this study was to assess the effects of four anesthetic protocols on normal canine brain uptake of 2‐deoxy‐2‐[¹⁸F]fluoro‐d ‐glucose (FDG) using positron emission tomography/computed tomography (PET/CT). Five clinically normal beagle dogs were anesthetized with (1) propofol/isoflurane, (2) medetomidine/pentobarbital, (3) xylazine/ketamine, and (4) medetomidine/tiletamine–zolazepam in a randomized cross‐over design. The standard uptake value (SUV) of FDG was obtained in the frontal, parietal, temporal and occipital lobes, cerebellum, brainstem and whole brain, and compared within and between anesthetic protocols using the Friedman test with significance set at P<0.05. Significant differences in SUVs were observed in various part of the brain associated with each anesthetic protocol. The SUV for the frontal and occipital lobes was significantly higher than in the brainstem in all dogs. Dogs receiving medetomidine/tiletamine–zolazepam also had significantly higher whole brain SUVs than the propofol/isoflurane group. We concluded that each anesthetic protocol exerted a different regional brain glucose uptake pattern. As a result, when comparing brain glucose uptake using PET/CT, one should consider the effects of anesthetic protocols on different regions of the glucose uptake in the dog's brain.     

Effects of Hormonal Supplementation on Nuclear Maturation and Cortical Granules Distribution of Canine Oocytes During Various Reproductive Stages

The aim of this study was to evaluate the effects of hCG, progesterone and oestradiol supplementation on nuclear and cytoplasmic maturation of canine oocytes cultured for 24, 48, 72 and 96 h. Oocytes obtained from 18 healthy bitches were divided into three groups according to their reproductive status (follicular, luteal and anoestrus stages) and cultured in TCM 199 + 25 UI/ml of hCG + 1 μg/ml of progesterone + 1 μg/ml of 17‐β oestradiol or without hormonal supplementation (control) for different periods. Then, they were stained with FITC‐LCA‐Hoescht for chromatin configuration and cortical granules distribution and evaluated under an epifluorescence microscope. Culture time and the influence of different stages of the oestrous cycle were also evaluated. The present study demonstrated that there was no significant difference among the reproductive stages. With regards to culture medium, only oocytes from the supplemented medium were able to complete meiosis; however, significant difference was only noticed in the percentage of MI stage oocytes (p < 0.05) in the follicular and luteal group at 72 h of culture. Most oocytes in germinal vesicle, germinal vesicle breakdown and metaphase I stage had cortical granules distributed throughout the cytoplasm (immature pattern), irrespective of the culture period (p < 0.05). Cortical granules distributed immediately beneath the plasma membrane (mature) was only observed in metaphase II stage oocytes, but not all of them presented matured cytoplasm. Our results reveal that cortical granules distribution in canine oocytes matured in vitro did not progressed in correspondence with nuclear stage changes and are in accordance with those from other species.     

Response of Thawed Epidi dymal Red Deer Spermatozoa to Increasing Concentrations of Hydrogen Peroxide,and Importance of Individual Male Variability

Oxidative stress represents a challenge during sperm manipulation. We have tested the effect of increasing hydrogen peroxide (H₂O₂) levels on red deer spermatozoa after cryopreservation, and the role of male‐to‐male variation in that response. In a first experiment, eight thawed samples were submitted to 0, 25, 50, 100 and 200 μm H₂O₂ for 2 h at 37°C. Intracellular reactive oxygen species (H₂DCFDA‐CM) increased with H₂O₂ concentration, but we only detected a decrease in sperm function (motility by CASA and chromatin damage by sperm chromatin structure assay) with 200 μm . Lipoperoxidation assessed by the thiobarbituric acid reactive substance (TBARS) method increased slightly with 50 μm H₂O₂ and above. In a second experiment, samples from seven males were submitted to 0 and 200 μm H₂O₂ for 2 h, triplicating the experiment within each male. Males differed at thawing and regarding their response to incubation and H₂O₂ presence. We found that the kinematic parameters reflected male‐to‐male variability, whereas the response of the different males was similar for lipid peroxidation and viability. A multiparametric analysis showed that males grouped differently if samples were assessed after thawing, after incubation without H₂O₂ or after incubation with H₂O₂. Red deer spermatozoa are relatively resilient to H₂O₂ after thawing, but it seems to be a great male‐to‐male variability regarding the response to oxidative stress. The acknowledgement of this individual variability might improve the development of optimized sperm work protocols.     

In this issue – November 2011

H1N1 influenza in pigs in Australia · Postnatal neurogenetic disorders · Deltamethrin collar for paralysis ticks in dogs · Myocardial laceration from sewing needle · Physiotherapy for tetanus in a foal · Morbillivirus in a bottle‐nosed dolphin · Sarcoptic manage in a swamp wallaby · Psychological health of veterinarians in Australia · History of the Australian College of Veterinary Scientists     

Spatiotemporal Distribution of Two Euschistus spp. Stink Bugs (Hemiptera: Pentatomidae) in Southeastern Farmscapes

Stink bugs (Hemiptera: Pentatomidae) are ubiquitous, cryptic, phytophagous pests that are found in many crops. In agroecosystems, individuals disperse from adjacent noncrop hosts and tend to aggregate or cluster within fields. In this study, we characterized the distribution of Euschistus servus (Say) and Euschistus tristigmus (Say) (Hemiptera: Pentatomidae) over 2 yr at three southeastern United States farmscapes. Stink bugs were captured in pheromone-baited traps, and Spatial Analysis by Distance Indices (SADIE) used to identify the location of significant aggregations by habitat type and season. Euschistus servus adults were more likely to be captured in pecan orchards, cotton, other crops, or unmanaged habitats than in woodland habitats. Significant aggregations of E. servus were detected in a variety of habitats including pecan, corn, cotton, peanut, and tobacco, as well as fallow and hay fields, pastures, and hedgerows. Fewer adult E. tristigmus were captured than E. servus adults, and E. tristigmus adults were typically trapped and aggregated in woodland habitats. The resulting data provide an important understanding regarding the seasonal movement and relative abundance levels of stink bug populations, which are critical to the development of integrated pest management strategies.     

Adaptation to a Fat-Supplemented Diet by Cutting Horses

In a crossover experiment, eight mature Quarter Horses were exercised by simulated cutting-horse training and fed either a control concentrate (C) or a 10% fat-supplemented concentrate (F) with Bermuda grass hay in a 60:40 ratio. The experiment consisted of two 28-day experimental periods with a 28-day standardization period between treatments. Digestion trials and standardized exercise tests (SET) were conducted every 7 days during experimental periods. Dietary fat had no detrimental effect on digestion of diet constituents, and all digestion coefficients were within expected ranges. Likewise, there was no significant difference in heart rates between treatments or SET days. Plasma lactic acid concentrations did not differ (P > .05) between treatments, however, there was a decline (P < .05) with advancing SET day. When horses were fed fat, there was an increase (P < .05) in muscle glycogen storage from days 0 to 28, but there was no increase (P > .05) in muscle glycogen over time when horses were fed C. On days 7, 14, and 28, muscle glycogen utilization increased (P < .05) from day 0 when horses were fed fat but not C. Pre-exercise data were normalized such that day 0 values equaled zero, due to higher (P < .05) glycogen concentrations for C than F on day 0. Subsequently, muscle glycogen concentrations on day 28 before exercise were higher (P < .05) when horses were fed F than C. The results of this study indicate that Quarter Horses in simulated cutting-horse training can adapt to digestion of a fat-supplemented diet by day 14. However, it may take up to 28 days of adaptation to a fat-supplemented diet to observe increases in glycogen storage and use.     

Clinical Feline Toxoplasmosis

Clinical toxoplasmosis was diagnosed in 15 cats by correlating serologic evidence of infection and clinical signs to either response to therapy or histopathologic demonstration of the organism. Ophthalmic manifestations, primarily involving the anterior segment, were common. Other common physical examination abnormalities included muscle hyperesthesia, fever, and weight loss. Response to therapy was variable, but administration of clindamycin hydrochloride resulted in resolution of all clinical signs not involving the eyes in surviving animals. This drug, alone or in combination with corticosteroids, led to total resolution of clinical signs in four of four cats with active retinochoroiditis and in six of nine cats with anterior uveitis. Four of the 15 cats had concurrent infection with feline immunodeficiency virus (FIV). Feline leukemia virus antigen or antibodies to feline infectious peritonitis virus were not detected.     

Integrated models that unite local and regional data reveal larger-scale environmental relationships and improve predictions of species distributions

Context

The scale of environmental relationships is often inferred through the use of species distribution models. Yet such models are frequently developed at two distinct scales. Coarse-scale models typically use information-poor (e.g., presence-only) data to predict relative distributions across geographic ranges, whereas fine-scale models often use richer information (e.g., presence–absence data) to predict distributions at local to landscape scales.

Objectives

We unite presence–absence and presence-only data to predict occurrence of species, what we refer to as integrated distribution models. We determine if integrated models improve predictions of species distributions and identification of characteristic spatial scales of environmental relationships relative to presence–absence modeling and ensemble modeling that averages predictions from separate presence-only and presence–absence models.

Methods

We apply recent advances in integrated distribution models to predict Sherman’s fox squirrel (Sciurus niger shermani) distribution in north-central Florida. Presence-only data were collected through a citizen-science program across its geographic range, while presence–absence data were collected using camera trapping surveys across 40 landscapes.

Results

Integrated models estimated environmental relationships with greater precision and identified larger characteristic scales for environmental relationships than using presence–absence data alone. In addition, integrated models tended to have greater predictive performance, which was more robust to the amount of presence–absence and presence-only data used in modeling, than presence–absence and ensemble models.

Conclusions

Integrated distribution models hold much potential for improving our understanding of environmental relationships, the scales at which environmental relationships operate, and providing more accurate predictions of species distributions. Many avenues exist for further advancement of these modeling approaches.