Littoral spawning habitats of three southern Arctic charr (Salvelinus alpinus L.) populations

Abstract Arctic charr populations in southern latitudes are nonmigratory, with all life‐stages limited to freshwater lakes and in‐ or out‐flowing tributaries. Although many of these populations are reported to also spawn in lake littorals, little is known about the physical characteristics of putative spawning grounds. A total of 23 discrete spawning sites within three Irish lakes were located by fyke netting of spawning adults and snorkelling in littoral habitats. Spawning sites were found to be long, narrow strips running parallel to the shore at a maximum depth of 124 cm. Spawning sites were limited to areas of coarse mineral substrate with an adequate (c. 8 cm) depth of clean interstitial spaces. In individual lakes, combined areas of spawning sites made up 0.4–0.7% of available littoral. Egg densities varied considerably between sites (33–900·eggs m^?2) and were significantly correlated with gradient and width of spawning sites. No evidence of redd digging was found. The shallow, localised and restricted nature of spawning grounds makes such populations vulnerable to anthropogenically induced postoviposition changes in surface water level, eutrophication processes such as increased lake sedimentation and elevated nutrient status.     

The thermal antinociceptive effects of a high-concentration formulation of buprenorphine alone or followed by hydromorphone in conscious cats

ObjectiveTo evaluate the thermal antinociceptive effects of a high-concentration formulation of buprenorphine alone or followed by hydromorphone in conscious cats.Study designRandomized, blinded, placebo-controlled crossover study design.AnimalsA total of six purpose-bred, adult female ovariohysterectomized Domestic Short Hair cats.MethodsCats were allocated into three treatments each consisting of two injections, subcutaneous then intravenous (IV) administration, 2 hours apart: treatment SS, two injections of 0.9% saline; treatment BS, buprenorphine (0.24 mg kg^–1, 1.8 mg mL^–1) and saline; and treatment BH, buprenorphine (0.24 mg kg^–1) and hydromorphone (0.1 mg kg^–1). Skin temperature (ST) and thermal threshold (TT) were recorded before (baseline) and for 24 hours following first injection. TT data were analyzed using mixed linear models and a Benjamini–Hochberg sequential adjustment procedure (p < 0.05).ResultsThere were no significant differences among treatments for baseline ST and TT values, treatment SS over time and between treatments BS and BH. Compared with baseline, TT was significantly increased at all time points in treatments BH and BS except at 2 hours in treatment BS. TT was significantly higher than SS at 3–18 hours and 4–12 hours for treatments BS and BH, respectively. Maximal increases in TT were 47.5 °C at 2 hours, 53.9 °C at 3 hours and 52.4 °C at 6 hours in treatments SS, BS and BH, respectively.Conclusions and clinical relevanceAdministration of IV hydromorphone following high-concentration buprenorphine provided no additional antinociception and decreased the duration of effect when compared with high-concentration buprenorphine alone. Alternative analgesics should be considered if additional analgesia is required after administration of high-concentration buprenorphine.     

TRUNCATION ARTIFACT IN MAGNETIC RESONANCE IMAGES OF THE CANINE SPINAL CORD

The truncation artifact in magnetic resonance (MR) images is a line of abnormal signal intensity that occurs parallel to an interface between tissues of markedly different signal intensity. In order to demonstrate the truncation artifact in sagittal images of the canine spinal cord and the effect of changing spatial resolution, we conducted an experimental in vitro study. A section of fixed canine spinal cord was imaged using a 1.5T magnet. Spatial resolution was increased by increasing the acquisition matrix and reconstruction matrix, producing series of T2‐weighted (T2w) images with the following pixel sizes: A, 1.6 (vertical) × 2.2 mm² (horizontal); B, 1.2 × 1.7 mm²; C, 0.8 × 1.1 mm²; D, 0.4 × 0. 6 mm². Plots of mean pixel value across the cord showed variations in signal intensity compatible with truncation artifact, which appeared as a single, wide central hyperintense zone in low‐resolution images and as multiple narrower zones in high spatial resolution images. Even in images obtained using the highest spatial resolution available for the MR system, the edge of the spinal cord was not accurately defined and the central canal was not visible. The experiment was repeated using an unfixed spinal cord specimen with focal compression applied to mimic a pathologic lesion. Slight hyperintensity was observed within the spinal cord at the site of compression although the cord was normal histologically. Results of this study suggest that caution should be applied when interpreting hyperintensity affecting the spinal cord in T2w sagittal images of clinical patients because of the possibility that the abnormal signal could represent a truncation artifact.     

Keratomycosis in five dogs

Five cases of canine keratomycosis were diagnosed and treated at a private Veterinary Ophthalmology Practice in Melbourne, Australia. Clinical presentations varied between dogs. Predisposing factors were identified in 4 of 5 cases. Diagnostic modalities utilized were corneal cytology and fungal culture. Corneal cytology confirmed the presence of fungal organisms in all five cases. Aspergillus, Scedosporium, and Candida were cultured from three cases, respectively. Specific antifungal treatment included 1% voriconazole solution or 1% itraconazole ointment. Keratectomy and conjunctival grafting surgery was performed in two patients. Resolution of infection and preservation of vision were achieved in 4 of 5 patients.     

Angiographic Anatomy of External Iliac Arteries in the Sheep

External iliac artery atherosclerotic disease and aneurism occur in man. For treatment, imaging is required to facilitate minimally invasive introduction and advancement of stents within the intended vessels. Sheep are commonly used to test and improve stents. However, little information is published regarding the angiographic anatomy of the iliac arteries in the ovine species. The objective of this study was to describe the angiographic anatomy of the iliac arteries in the sheep. Computed tomography (CT) angiography and gross anatomical dissection were performed in, respectively, 10 and 43 adult ewes. Diameters and lengths of the arteries were measured. In comparison with man, salient anatomical differences were identified in the sheep: (1) the absence of common iliac arteries, (2) the common trunk at the origin of internal iliac arteries and (3) the location of the bifurcation of the external iliac arteries into femoral arteries in the pelvis (not in the limb). External iliac arteries in this series of sheep were 86 mm long in average and had a mean diameter of 7.5 mm. Lengths of arteries are only slightly different between man and sheep, while diameters are rather similar. Therefore, the sheep model appears to be sufficiently similar to man to test stent properties. This study provides useful reference images and measures of lengths and diameters of relevant arteries that could be applied to research with ovine models.     

Postnatal development of canine axial globe length measured by B-scan ultrasonography

OBJECTIVE: The objectives of this study were to document the development of axial globe length (AGL) in normal mesocephalic cross-bred dogs between 2 and 52 weeks of age, to determine a relationship between AGL and age, and derive an equation to predict AGL in normal mesocephalic cross-bred dogs. ANIMALS STUDIED AND PROCEDURE: The AGL of twenty normal mesocephalic cross-bred dogs was measured at 12 time points from 2 to 52 weeks of age using B-scan ultrasonography. RESULTS: The mean (+/- SEM) AGL increased from 12.65 mm (+/- 0.18) at 2 weeks of age to 19.52 mm (+/- 0.18) at 52 weeks of age. The correlation between AGL and age was evaluated by fitting possible variables to a regression pattern. A linear model of natural logarithmic-transformed value of AGL (mm) and age (week) was established. Side (left or right eye) and gender did not correlate with development of AGL. CONCLUSIONS: A reverse transformation of the formula can be used to predict AGL in mesocephalic cross-bred dogs: AGL = 10.847 * age in weeks 0.1653.