Presumed primary thiamine deficiency in a young African lion (Panthera leo).

A 1-yr-old intact male African lion (Panthera leo) fed only beef muscle meat was evaluated for episodes of hypermetric ataxia, generalized weakness and tonic-clonic front limb movements. A hemogram, biochemical profile, blood lead, electrocardiogram, survey radiographs, and brain computed tomography were normal. Cerebral spinal fluid analyses suggested mild inflammation. Acetylcholine receptor antibody and serologic tests for all infectious agents tested were negative. Clinical signs resolved completely 9 days after instituting oral thiamine (3 mg/kg/day) and a completely nutritional diet. This lion's pretreatment thiamine blood value (11 nmol/L) was markedly lower than that of a healthy lion (191 nmol/L) and a proposed reference range for adult African lions (160-350 nmol/L). The lion remained clinically normal 2 yr later when his blood thiamine value was 340 nmol/L. African lions can develop clinical primary thiamine deficiency and may respond favorably when thiamine treatment and adequate diet are instituted prior to irreversible neuronal necrosis.     

The pathology of atrial fibrillation in dogs

Atrial fibrillation (AF) occurs in dogs in a number of settings, the most common of which is congestive heart failure. This paper reviews what is known about the pathology of AF in dogs, as well as its clinical relevance. We begin by discussing several experimental AF paradigms in dogs, the associated pathology, and its relevance to AF mechanisms. We then discuss clinical AF in dogs and its relationship to experimental pathology. Finally, we conclude by assessing the potential therapeutic relevance of understanding AF-related pathology in dogs, as well as its potential to have practical applications in the future.     

Effects of Serum Deprivation and Cycloheximide on Cell Cycle of Low and High Passage Porcine Fetal Fibroblasts

Arrest of cells in G0/G1 cell cycle phase is desired for nuclear transfer procedures. Serum starvation and cell cycle inhibitors are different ways to induce synchronization of the cell cycle. This study investigated the effects of serum starvation and cycloheximide (CHX) on the cell cycle of low (5th) and high (15th) passages fetal porcine fibroblasts. Cell cycle phases were determined using fluorescent activated cell sorting. Fifth passage fibroblast cultures had higher (p < 0.05) proportion of cells in G0/G1 only after 72 h of serum starvation (77.60 ± 0.65) when compared with non‐starved cells (71.44 ± 1.88). Serum starvation for all periods tested induced an increase (p < 0.05) on proportion of cells in G0/G1 on the 15th passage. No significant differences were observed on the 5th passage cultures exposed to CHX, although, on the 15th passage an increase on proportion of cells was observed after all periods of exposure (p < 0.05). These data indicates that high passage cells in vitro are more susceptible to serum starvation and CHX G0/G1 synchronization.     

Pharmacokinetics of Tramadol and its Metabolites M1, M2 and M5 in Horses Following Intravenous, Immediate Release (Fasted/Fed) and Sustained Release Single Dose Administration

Tramadol (T) is a centrally acting analgesic structurally related to codeine and morphine. This drug displays a weak affinity for the μ and δ-opioid receptors, and weaker affinity for the κ-subtype; it also interferes with the neuronal release and reuptake of serotonin and noradrenaline in the descending inhibitory pathways. The metabolism of this drug has been investigated in different animals (rats, mice, Syrian hamsters, guinea pigs, rabbits, and dogs) and humans; similar metabolites are produced but in different amounts. The major metabolic pathways involved in phase I metabolite production (M1–M5) are O-demethylation, N-demethylation, and N,N-demethylation. The aim of the current study is to evaluate the pharmacokinetic profile of T in the horse, and its M1, M2, and M5 metabolites after single-dose administration (5 mg/kg body weight [BW]) by intravenous, sustained-release tablets and immediate-release capsules. We also will investigate the potential effects of fasting and feeding on bioavailability of immediate-release capsules. The study design was divided into four randomized phases. Twenty-four gelding Italian trotter race horses were divided into four groups (6 animals each) and administered T intravenously, with T immediate-release capsules in a fasting status, T immediate-release capsules in a feeding status, and T sustained-release in fasting status. Blood samples were collected at different times and analyzed by high-pressure liquid chromatography (HPLC) with fluorimetric detection. The limit of quantification was 5 ng/ml for T, M1, and M2, and 10 ng/ml for M5. A one-compartment model best fit the plasma concentrations of T and M2 after all treatments. Unfortunately, for M1 and M5, it was not always possible to fit plasma curves because of very low and variable concentrations. M2 was the main metabolite produced in the four different treatments and its concentration was higher than the concentration of T after sustained-release administration. Conversely, M1, the main metabolite in humans, and M5 seemed to be only marginally produced in the horse. When T was administered in both fasted and fed states, variations in some pharmacokinetic parameters were not considered clinically significant. We concluded that T could be administered in either a fasted or a fed condition.     

THE CORRELATION OF CANINE PATELLAR LUXATION AND THE ANTEVERSION ANGLE AS MEASURED USING MAGNETIC RESONANCE IMAGES

Measurements from magnetic resonance (MR) images can be used to examine the anteversion angle (AT-angle) and its influence on the lateromedial or mediolateral luxating forces on the patella. The AT-angle of the femoral neck was measured with the aid of MR imaging in 45 pelvic limbs without patellar instability, in 33 limbs with patellar luxation and in 6 limbs with rupture of the cranial cruciate ligament. The limbs with medial patellar luxation were divided into three groups based on clinical examination. The mean (range) AT-angle was 7.6 degrees (0 degrees to 24 degrees) in the "normal" group, 8.6 degrees (-10 degrees to 29 degrees) in the group "grade II," and -0.4 degrees in the group "grade III" (-28 degrees to 12 degrees). A mean (range) AT-angle of 4.8 (-4 degrees to 11 degrees) was measured in the pelvic limbs with rupture of the cranial cruciate ligament. Compared to literature that described AT-angles based on radiographs of normal limbs, reduced AT-angles were found in this study due to different lines of measurement of the femoral neck. This study documents that the AT-angle of the femoral neck does not influence patellar instability. This study also demonstrates that MR images can be used to make exact measurements of the canine AT-angle that represent the true anatomy of the femoral neck.