Influence of Cholinergic Blockade on the Development of Epinephrine-Induced Ventricular Arrhythmias in Halothane- and Isoflurane-Anesthetized Dogs

The arrhythmogenic effects of anesthetic drugs are assessed using the arrhythmogenic dose of epinephrine (ADE) model. The purpose of this study was to determine the influence of cholinergic blockade (CB) produced by glycopyrrolate (G) on ADE in 1.5 minimum alveolar concentration (MAC) halothane (H)- and isoflurane (I)-anesthetized dogs. Eight dogs (weighing between 12.5 and 21.5 kg) were randomly assigned to four treatment groups (H, HG, I, and IG) and each treatment was replicated three times. Anesthesia was induced and maintained with H (1.31%, end-tidal [ET]) or I (1.95%, ET) in oxygen. Ventilation was controlled (carbon dioxide [PCO₂] 35 to 40 mmHg, ET). G was administered 10 minutes before ADE determination at a dose of 22 μg/kg (11 μg/kg, intravenous [IV] and 11 μg/kg, intramuscular [IM]). The ADE was determined by IV infusion of epinephrine at sequentially increasing rates of 1.0, 2.5, and 5.0 μg/kg/min; and defined as the total dose of epinephrine producing at least four ectopic ventricular contractions (EVCs) within 15 seconds during a 3-minute infusion and up to 1 minute after the end of the infusion. Total dose was calculated as the product of infusion rate and time to arrhythmia. Data were analyzed using a randomized complete block analysis of variance. When significant (P < .05) F values were found a least significant difference test was used to compare group means. Values are reported as means ± standard error. The ADE (μg/kg) for H, HG, I, and IG were 1.53 ± 0.08, 3.37 ± 0.46, 1.61 ± 0.21, and > 15.00, respectively. Heart rates (HRs) (beats/min) and systolic pressures (mmHg) at the time of arrhythmia formation for H, HG, I, and IG were (60.3 ±4.0 and 142.0 ± 7.6), (213.0 ± 13.1 and 239.2 ± 7.1), (62.9 ± 4.5 and 151.9 ± 6.3), and (226.3 ± 6.1 and 323.5 ± 3.4), respectively. The H and I ADE were not different. The HG ADE was significantly less than the IG ADE. The H and I ADE were significantly less than the HG and IG ADE. We conclude the following from the results of this study of epinephrine infusion in halothane- and isoflurane-anesthetized dogs: (1) two distinct mechanisms are responsible for the development of arrhythmias, (2) CB produced by G significantly increases ADE but is associated with higher rate pressure products (RPP) and myocardial work, and (3) ADE methodology could be improved by determining ADE with and without CB.     

PET/CT today and tomorrow in veterinary cancer diagnosis and monitoring: fundamentals,early results and future perspectives

Functional imaging using positron emission tomography (PET) plays an important role in the diagnosis, staging, image‐guided treatment planning and monitoring of malignant diseases. PET imaging complements conventional anatomical imaging such as computed tomography (CT) and magnetic resonance imaging (MRI). The strength of CT scanning lies in its high spatial resolution, allowing for anatomical characterization of disease. PET imaging, however, moves beyond anatomy and characterizes tissue based on functions such as metabolic rate. Combined PET/CT scanners were introduced commercially in 2001 and a number of technological advancements have since occurred. Radiolabelled tracers such as ¹⁸F‐fluorodeoxyglucose (FDG) and ¹⁸F‐fluorothymidine (FLT) allow visualization of various metabolic processes within cancer cells. Many studies in human oncology evaluating the utility of PET/CT have demonstrated clinical benefits. Few veterinary studies have been performed, but initial studies show promise for improved detection of malignancy, more thorough staging of canine cancer and determination of early response and disease recrudescence.     

The effect of short day treatments on containerized Douglas-fir morphology,physiology and phenology

The effect of short day treatments (blackout) on Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) container seedlings at the time of lift and following cold storage was investigated. Variables measured included height, root collar diameter (RCD), root growth capacity (RGC), photosynthetic efficiency after –18 °C freezing (PEF), and days to terminal bud break (DBB). From one to four blackout dormancy induction treatments were started on three dates (July 12, July 26, and August 10) with 10 or 20 d between multiple blackouts. Increasing the number of blackout treatments resulted in lower RCD, lower DBB in the late winter/early spring, and higher PEF in the early fall. Later blackout start dates decreased PEF in the early fall, and increased overall height and late fall RGC as compared to earlier blackout start dates. Nurseries growing Douglas-fir seedlings from coastal Pacific Northwest provenances should be aware that blackout regimes can decrease RGC in the late fall, and cause quicker dormancy release in the early spring. Coastal Douglas-fir can be lifted and planted in the early fall, when RGC and DBB are relatively high. If planting between February and April is necessary, seedlings given blackout should be cold stored in January to maintain an adequate level of dormancy, RGC and PEF.     

A Rapid Method of Calculating the Downwind Distributions from Aerial Atomisers1

There are many diverse views about the effects of wind on aircraft sprays. Some operators wish to spray only when the air is still, others will not spray unless the wind speed is at least 3 m/s. The basis of this difference is the fear of, as against the use of, the downwind movement of droplets. This note uses a simple model of droplet behaviour in a wind to try to predict the deposit distributions downwind of a spraying aircraft. The results demonstrate that the level of turbulence caused by the wind blowing over the earth's vegetation reduces the downwind distance most small drops travel before being captured. Trees create more turbulence than cereal crops, which create more turbulence than bare earth or short grass. The deposit density at a given distance downwind reduces with decrease in aircraft flying height, wind speed and smoothness of the canopy. It remains roughly constant with increasing droplet size until a critical diameter is reached when it falls rapidly with increase in droplet size. This critical size depends upon windspeed and turbulence intensity. A downwind buffer zone between the spray area and a sensitive crop is desirable and its minimum size can be determined using the techniques discussed in the paper.     

Influence of anions on dispersion and physical properties of the A horizon of a Red-brown earth

Three groups of anions were distinguished in order of effectiveness with respect to the dispersion and flocculation of soil samples treated with Fe(III) polycations: phosphate and fulvate citrate, oxalate, silicate and tartrate and salicylate, catechol, aspartate, lactate and acetate. This was also the order of the amount of anion adsorbed by the soil. The addition of phosphate and fulvate to soil samples with a net charge of zero lowered the zero point of charge producing particles with a net negative charge. This increased the amount of dispersible clay present from 0 to 9% by weight of soil. The sorption of phosphate and fulvate by soil samples with a net positive charge reduced the zero point of charge and caused flocculation of dispersed clay. Electrophoretic and electron microscopic studies confirmed the dispersion-flocculation phenomena.Treatments which produced dispersed clay led to increased bulk densities, plastic limits and moduli of rupture but lower porosities, water holding capacities and hydraulic conductivities. The sorption of anions on soil samples with a net charge of zero reduced friability.     

Effects of Compound Plant Nutrients on Rumen Fermentation Parameters,Rumen Microbiota and Fatty Acid Composition of Longissimus dorsi Muscle in Finishing Small Tail Han Sheep北大核心CSCD

This study was conducted to investigate the effects of compound p1ant nutrients (CPN) on rumen fermentation parameters, rumen microbiota and fatty acid composition of longissimus dorsi musc1e in finishing sma11 tai1 Han sheep. Sixteen 4-month-o1d finishing sma11 tai1 Han sheep with an initia1 body weight (BW) of (24.18±0.31) kg were random1y divided into two groups, name1y, with 8 rep1icates per group and 1 sheep per rep1icate. The sheep in the contro1 group were fed a basa1 diet, whereas the sheep of the contro1 group (CPN group) was fed the basa1 diet supp1ementation with 3‰ CPN. The experiment 1asted for 97 days after 7 days adaption. The resu1ts showed as fo11ows: compared with the contro1 group, 1) adding CPN decreased the concentration of ammonia nitrogen (NH3-N) (P<0.05); 2) CPN supp1ementation affected beta diversity of rumen microbiota; 3) the re1ative abundance of Acidobacteriota, Erysipe1otrichaceae_UCG-002, Lactobacillus, and Megasphaera were enhanced by adding CPN (P<0.05), whereas, the re1ative abundance of Bacteroidetes and Prevotella was 1ower (P<0.05); 4) the supp1ementation of CPN had no significant effect on fatty acid composition of longissimus dorsi musc1e of fattening sma11-tai1ed Han sheep (P>0.05); 5) the contents of tota1 MUFA, C18:1n9c, C14:1, C16:1, C18:2n6c, C18:3n3 and n-3PUFA in the longissimus dorsi musc1e were corre1ated with the re1ative abundance of Megasphaera, Erysipe1otrichaceae_UCG-002, Succiniclasticum and Ruminococcus (P<0.05). In conc1usion, CPN can regu1ate the rumen microbiota structure and reduce the rumen NH3-N concentration of fattening sma11-tai1ed Han sheep. In production practice, CPN can be used as a rumen eco1ogica1 regu1ator. © 2023 Authors. All rights reserved.     

A neurologic syndrome in Golden Retrievers presenting as a sensory ataxic neuropathy

BACKGROUND: A sensory ataxic neuropathy has been observed in Swedish Golden Retrievers recently. ANIMALS: Twenty-one affected Golden Retrievers. METHODS: Clinical and neurologic status, electrophysiologic, and pathologic status as well as pedigree analyses were evaluated. RESULTS: Clinical signs had an insidious onset between 2 and 8 months of age and a slowly progressive course. Affected dogs were ataxic and dysmetric. They had abnormal postural reactions and decreased spinal reflexes but no apparent muscle atrophy. Clinical pathology, radiography, and electrophysiology of motor systems were all within reference values. Sensory nerve conduction results of affected dogs were significantly different from those of a group of control dogs. Necropsy revealed a chronic progressive central and peripheral sensorimotor axonopathy; the proprioceptive pathways were most severely affected. CONCLUSIONS AND CLINICAL IMPORTANCE: This disease in these Golden Retrievers is distinct from other canine breed-related neurodegenerative diseases or hereditary neurodegenerative diseases described in humans. Pedigree analyses indicated a hereditary background, but the mode of inheritance could not be established.     

Urethral conformation and position in relation to urinary incontinence in the bitch.

The conformation of the urethra, the position of the bladder neck and the distance between the external urethral orifice and the cranial pubic brim were compared in 30 continent and 30 incontinent bitches with incompetence of the urethral sphincter mechanism, using the measurements made from vagino-urethrograms. The bladder neck was significantly (P less than 0.001) further caudal in incontinent dogs than in continent dogs. Its position was not affected by neutering and could not be explained by the degree of urethral curvature. The distance from the external urethral orifice to the cranial pubic brim was correlated (P less than 0.001) with bodyweight but was not significantly different in the continent and incontinent bitches. In neutered animals, the distance between the cranial pubic brim and the external urethral orifice was significantly (P less than 0.05) shorter than in entire animals.     

Genetic Differentiation of Puccinia triticina Populations in Central Asia and the Caucasus

ABSTRACT Isolates of Puccinia triticina collected from common wheat in the Central Asia countries of Kazakhstan, Uzbekistan, Tajikistan, and Kyrgyzstan and the Caucasus countries of Azerbaijan, Georgia, and Armenia were tested for virulence to 20 isolines of Thatcher wheat with different leaf rust resistance genes and molecular genotype at 23 simple sequence repeat (SSR) loci. After clone correction within each country, 99 isolates were analyzed for measures of population diversity, variation at single SSR loci, and for genetic differentiation of virulence phenotypes and SSR genotypes. Isolates from Central Asia and the Caucasus were also compared with 16 P. triticina isolates collected from common wheat in North America that were representative of the virulence and molecular variation in this region and two isolates collected from durum wheat in France and the United States. Populations from the Caucasus, Uzbekistan, Tajikistan, and Kyrgyzstan were not significantly (P > 0.05) differentiated for SSR variation with F(st) and R(st) statistics. Populations from the Caucasus, Uzbekistan, Tajikistan, and Kyrgyzstan were significantly (P < 0.05) differentiated from the populations in South and North Kazakhstan for SSR variation. All populations from Central Asia and the Caucasus were significantly differentiated from the North American isolates and isolates from durum wheat for SSR variation and virulence phenotypes. There was a correlation between virulence phenotype and SSR genotype among individual isolates and at the population level. Mountain barriers may account for the differentiation of P. triticina geographic populations in Central Asia and the Caucasus.     

Attempted transmission of Ehrlichia risticii by field-captured Dermacentor variabilis (Acari: Ixodidae)

The capability of field-collected American dog ticks, Dermacentor variabilis, to infect horses with Ehrlichia risticii, causative agent of Potomac horse fever (PHF), was examined by allowing adult ticks collected from horse farms with a history of PHF to feed on susceptible horses. More than 500 male and female ticks attached and fed on 3 test horses; however, no clinical or serologic evidence of PHF was observed in treated or control horses. All horses were challenge exposed with E risticii-infective blood by inoculation at 60 to 65 days after ticks fed, and all developed clinical PHF with subsequent seroconversion. The data, therefore, indicated that adult D variabilis, a common parasite of horses on Maryland premises where PHF is enzootic, may not serve as a vector of E risticii.