The DC-recorded dog electroretinogram in ketamine-medetomidine anaesthesia

A new selective alpha 2-adre-noreceptor agonist, medetomidine hydrochloride was combined with low dosage ketamine hydrochloride and vecuronium bromide for d.c. (direct current) recordings of fast electroretinographic (ERG) components in nine ophthalmoscopically healthy dark adapted dogs. The dogs were tracheally intubated and manually ventilated. They were given full field single flash stimuli of different intensities starting with near b-wave threshold blue light (tests 1-3), followed by white light (tests 4-6) and 30 Hz photopic flicker (test 7). The a- and b-wave amplitudes and flicker responses were measured from the base line. The latencies were measured from the stimulus moment to the highest point of the different waves.Statistical analysis of results gave individual differencies which had a good constancy. This showed that the dogs had an individual ERG profile according to the standardized method. The latencies varied very little as expected, but the amplitudes differed individually and showed a good constancy as seen by reproducibility tests made nine to ten days later on three of the dogs’ ipsilateral eyes. The combination of drugs used in this study was considered suitable for short term (10-12 minutes) stable d.c.–ERG recordings in dogs as the rod and cone responses had higher amplitudes when compared to an identical examination made with other anaesthetic combinations on the same dogs.Involuntary eye movements and other involuntary muscular activity caused by ketamine in dogs were negligible when using medetomidine premedication and was completely absent when using vecuronium.The anaesthetic method described can be recommended for ambulatory ERG recordings in dogs because of the above mentioned advantages.     

Effects of thiopentone on the equine electroencephalogram during anaesthesia with halothane in oxygen

Objective To characterise the effects of thiopentone on the equine electroencephalogram during halothane anaesthesia. Study design Prospective controlled study. Animals Eight healthy Welsh mountain pony geldings between 5 and 9 years old and weighing between 270 and 330 kg (mean 301 kg). Methods Anaesthesia was induced with thiopentone and maintained using halothane in oxygen. End tidal halothane was maintained above 0.75 and below 0.85%. EEG was recorded continuously and a binaural broad band click stimulus was provided throughout the experiment at 6.1224 Hz. An infusion of 500 mg thiopentone was given over 5 minutes. Samples were taken for blood gas analysis and plasma thiopentone assay (HPLC) 5 minutes prior to the start of the infusion and at 3, 5, 7, 10, 15, 20, 30, 45 and 60 minutes. The median and 95th percentile of the EEG were calculated using standard statistical techniques and the mid‐latency of the auditory evoked response was generated. The values of EEG variables at each time point were compared to the average value for the 15 minute period before the infusion was started. Arterial blood gas values and plasma thiopentone concentration were compared to the baseline sample taken prior to the start of the infusion. Comparisons were made using analysis of variance for repeated measures followed by Dunnett's test if a significant difference was detected. Results The peak serum plasma concentration was 14.5 ± 2.4 µg mL^?1 (mean ± SD) occurring 5 minutes after the start of the infusion. The 95% spectral edge frequency of the EEG decreased by a maximum of 27.4 ± 18.4% 7 minutes after the start of the thiopentone infusion. No changes were seen in median frequency of the EEG or the second differential of the middle latency auditory evoked response. Conclusions These results, coupled with the lack of antinociceptive action of thiopentone, support the hypothesis that median frequency of the EEG may be a useful indicator of nociception in anaesthetized animals. Clinical relevance If the EEG is to become a useful monitoring technique then it is important to understand the relative contribution of changing plasma concentrations of the agents used in anaesthesia.     

Analysis of a deletion in the nephronophthisis 4 gene in different dog breeds

Cone‐rod dystrophy is a progressive inherited retinal degenerative disorder that occurs in humans and dogs. The deletion in the nephronophthisis 4 (NPHP4) gene was established as a causative mutation in standard wire‐haired Dachshunds. We analyzed all varieties of Dachshunds from the Czech Republic and five other dog breeds and found that the deletion in the NPHP4 (in heterozygous state) is present not only in standard‐, but also in miniature wire‐haired Dachshunds, but not in other varieties of Dachshunds or in other breeds.     

Effects of thiopentone,propofol and alfaxalone on laryngeal motion during oral laryngoscopy in healthy dogs

Objective

To compare the effects of thiopentone, propofol and alfaxalone on arytenoid cartilage motion and establish the dose rates to achieve a consistent oral laryngoscopy examination.

Effects of thiopentone and propofol on lower oesophageal sphincter and barrier pressure in the dog

The effects of thiopentone and propofol on oesophageal pressures were examined in 39 bitches. The dogs were premedicated with either atropine (n = 13), acepromazine maleate (n = 13) or a combination of atropine and acepromazine. Anaesthesia was induced with either thiopentone (15 dogs) or propofol (24 dogs), both given intravenously. Immediately following the induction of anaesthesia, gastric pressure and lower oesophageal sphincter pressure (LOSP) were measured and oesophageal barrier pressure determined. There were no significant differences attributable to the premedication regimens used but both LOSP and barrier pressure were significantly lower in the dogs anaesthetised with propofol compared to the animals given thiopentone (LOSP 12-2 ± 4-2 cm H₂O propofol group versus 26-8 ± 6-5 cm H₂O thiopentone group).     

Synovial fluid eosinophilia: a case report in a dog and review of the literature

The first known report of synovial fluid eosinophilia in a dog is described here. The occurrence of eosinophils in joint fluid is rare. Sporadic cases have been recorded in humans and most can be related to immunemediated reactions, both parasitic and non- parasitic. The dog in this case report had 20-52% eosinophils in multiple joints, as well as hemarthrosis and marked mononuclear cell reactivity. An intense peripheral eosinophilia was demonstrated one week later. The associated lameness resolved with non-steroidal anti-inflammatory therapy. Lack of remarkable history or other clinical symptoms led to a diagnosis of idiopathic, eosinophilic, polyarthritis, likely immune-mediated.     

The effects of physostigmine on the electroretinogram in the beagle dog

The purpose of the study was to correlate electroretinogram (ERG) parameters with increasing levels of plasma, erythrocyte and ocular tissue cholinesterase inhibition using the beagle dog as a model for human neurovisual toxicity. The anticholinesterase compound physostigmine was administered at various steady-state intravenous infusion rates based on pharmacokinetic estimates of plasma and red blood cell cholinesterase inhibition. The most sensitive parameter was the b-wave amplitude of the rod response, which was significantly depressed compared to pretreatment at all levels of acute cholinesterase depression. The overall maximal ERG response demonstrated a trend of declining a-and b-wave amplitudes, which corresponded with the increased levels of cholinesterase depression, but these differences were not significant. The depression of the electroretinogram rod and cone amplitudes appeared to parallel plasma cholinesterase inhibition more closely than erythrocyte cholinesterase activity. Ocular tissue cholinesterase activity was significantly depressed in the retina (70%), cornea (60%) and dorsal rectus extraocular muscle (46%). Electroretinography may be a useful physiological tool for evaluating the ocular toxicity of certain chemicals or pharmaceuticals associated with cholinesterase biomarker activity.Abbreviations AChE acetylcholinesterase - Amp amplitude - BuChE butyrylcholinesterase - C _p plasma level - C _ss steady-state plasma concentration - D _L loading dose - e ^–kt the rate of elimination over time (t) - ERG electroretinogram - k elimination rate constant - Lat latency - MBW metabolic body weight - O₁–O₅ consecutive oscillatory potential wavelets - PreTx pretreatment - R rate of infusion - R _Inf rate of infusion - V _d volume of distribution     

Effects of six carbohydrate sources on dog diet digestibility and post-prandial glucose and insulin response

The effects of six extruded diets with different starch sources (cassava flour, brewer's rice, corn, sorghum, peas or lentils) on dog total tract apparent digestibility and glycemic and insulinemic response were investigated. The experiment was carried out on thirty-six dogs with six dogs per diet in a completely randomized design. The diets containing brewer's rice and cassava flour presented the greatest digestibility of dry matter, organic matter and gross energy (p < 0.05), followed by corn and sorghum; pea and lentil diets had the lowest. Starch digestibility was greater than 98% in all diets and was greater for brewer's rice and cassava flour than for lentils and peas diets (p < 0.05). Dogs' immediate post-prandial glucose and insulin responses (AUC < or = 30 min) were greater for brewer's rice, corn, and cassava flour diets (p < 0.05), and later meal responses (AUC > or = 30 min) were greater for sorghum, lentil and pea diets (p < 0.05). Variations in diet digestibility and post-prandial response can be explained by differences in chemical composition of each starch source including fibre content and starch granule structure. The nutritional particularities of each starch ingredient can be explored through diet formulations designed to modulate glycemic response. However, more studies are required to support these.     

Hemolysis as a factor in clinical chemistry and hematology of the dog

Serum biochemical, hemostatic, and hematologic analytes were determined by four laboratories on dog serum or plasmas containing increasing amounts of hemolysate. From the results of testing, interferographs were prepared to aid in decision making and to enhance visualization of the effects of hemolysis on the determination of the analytes. Heniktsus consistently interfered with the analysis of creatinine phosphokinase, lactic dehydrogenase, aspartate aminotransferase, lipase, and albumin, all of which appeared to increase with increasing hemolysis. The results for the remainder of the biochemical, hemostatic, and hematologic analytes varied greatly among analyzers or methods, rarely in a predictable manner, indicating that each laboratory should evaluate the effects of hemolysis on each analyzer and for each method used, in order to make informed decisions on the use of hemolyzed but irreplaceable samples.     

Effect of hypothermia on recovery from general anaesthesia in the dog

OBJECTIVE: To discern the effects of anaesthesia protocols and decreasing core body temperature on time to recovery from general anaesthesia. MATERIALS AND METHODS: Healthy adult dogs undergoing desexing surgery were enrolled. More excitable dogs were premedicated with intramuscular acepromazine and morphine; calmer dogs were not premedicated. Anaesthesia was induced using halothane, isoflurane or sevoflurane delivered by mask, or by intravenous propofol, and maintained in standard fashion using one of the three inhalant agents. Thermostat controlled heat mats were used during surgical preparation and surgery. Oesophageal temperature was recorded throughout surgery. The time from cessation of anaesthetic administration until the dog successfully raised itself to sternal recumbency was considered the time of recovery. RESULTS: Sixty-nine dogs completed the study, 42 males anaesthetised for 60.4 +/- 20.5 min, and 27 females anaesthetised for 85.4 +/- 33.2 min. Oesophageal temperature at the end of surgery was 36.8 +/- 0.80 degrees C. Oesophageal temperature had a significant effect on recovery time, with lower temperatures contributing to slower recoveries. Premedication significantly lengthened recovery times. The choice of induction or maintenance anaesthetic agent had no effect on recovery time. DISCUSSION: Hypothermia is a common complication of general anaesthesia and surgery. Amongst other deleterious effects, it is associated with slower recovery from anaesthesia, likely due to a number of different mechanisms.     

Canine behavioral problems and their effect on relinquishment of the Jindo dog

The purpose of this study was to evaluate behavior problems of the Jindo dog, the native dog of Korea, based on an owner''s survey and their effect on pet relinquishment. To live a better life with their own pet and prevent relinquishment, it is important to understand the innate behavior characteristics of dog breed and the potential causes of relinquishment. Information concerning various factors and demonstration of the five most common behavior problems was collected via 189 completed questionnaires. No factors significantly affected the demonstration of behavior problem. A total 151 of 189 dogs had behavior problems (79.9%) and 38 dogs did not have behavior problems (20.1%). Among 151 dogs, 139 dogs showed single behavior problem (92.1%). They were ''excessive excitability'' (46.8%), ''excessive vocalization'' (30.2%), ''inappropriate elimination'' (17.3%), ''destructive behavior'' (4.3%), and ''aggressive behavior'' (1.4%), respectively. In addition, 12 dogs showed two concurrent behavior problems (7.9%) According to the results, the relinquishment of Jindo dogs was not significantly associated with canine behavior problems, which is the single greatest risk factor of relinquishment in general. The possible reasons for potential behavior problems include improper raising, lack of socialization, and insufficient dog training classes, therefore canine behavior would be improved by owner education.     

A model to investigate hepatic extraction of oxygen during anaesthesia in the dog

Measurement of hepatic oxygen extraction was performed on six healthy Greyhound dogs over a two hour period. The Greyhounds were anaesthetised and a right subcostal surgical incision performed. Ultrasonic flow transducers were used to measure flow rate in the hepatic artery and the portal vein. The blood oxygen tensions in arterial blood and in the portal and hepatic veins were also measured. Hepatic oxygen extraction remained stable throughout the study, despite a steady decline in arterial blood pressure. The methodology described in this study provides a direct measure of oxygen uptake by the liver in the dog and could readily be used to investigate hepatic uptake of drugs.     

Effects of acepromazine and dexmedetomidine,followed by propofol induction and maintenance with isoflurane anaesthesia,on the microcirculation of Beagle dogs evaluated by sidestream dark field imaging: an experimental trial

ObjectiveTo investigate the effects of intramuscularly administered acepromazine or dexmedetomidine on buccal mucosa microcirculation in Beagle dogs.Study designExperimental, blinded, crossover study.AnimalsA group of seven Beagle dogs aged 7.5 ± 1.4 years (mean ± standard deviation).MethodsMicrocirculation was assessed on buccal mucosa using sidestream dark field videomicroscopy. After baseline measurements, 5 μg kg^–1 dexmedetomidine or 30 μg kg^–1 acepromazine were administered intramuscularly. After 10, 20 and 30 minutes, measurements were repeated. At 40 minutes after premedication, anaesthesia was induced with propofol intravenously and maintained with isoflurane. Measurements were repeated 50, 60 and 65 minutes after the injection of the investigated drugs. Analysed microcirculatory variables were: Perfused de Backer density, Perfused de Backer density of vessels < 20 μm, Proportion of perfused vessels and Proportion of perfused vessels < 20 μm. Heart rate (HR), systolic, diastolic (DAP) and mean (MAP) arterial pressures were recorded at the same time points. Macro- and microcirculatory variables were analysed using a linear mixed model with baseline as a covariate, treatment, trial period and repetition as fixed effects and time and dog as random effect. Results are presented as effect size and confidence interval; p values < 0.05 were considered significant.ResultsAfter acepromazine, Perfused de Backer density was greater during sedation and anaesthesia [3.71 (1.93–5.48 mm mm^–2, p < 0.0001) and 2.3 (0.86–3.75 mm mm^–2, p < 0.003)], respectively, than after dexmedetomidine. HR was significantly lower, whereas MAP and DAP were significantly higher with dexmedetomidine during sedation and anaesthesia (p < 0.0001 for all) compared with acepromazine.Conclusions and clinical relevanceThe sedative drugs tested exerted a significant effect on buccal mucosal microcirculation with a higher Perfused de Backer density after the administration of acepromazine compared with dexmedetomidine. This should be considered when microcirculation is evaluated using these drugs.     

The effect of Hetastarch (670/0.75) in vivo on platelet closure time in the dog

Objective – To evaluate the effect of 6% hydroxyethyl starch (HES) solution in vivo, with an average molecular weight of 670 kDa and degree of substitution of 0.75, on canine platelet function.
Design – Prospective, controlled-experimental study.
Setting – University of California, Davis, Veterinary Medical Teaching Hospital.
Animals – Seven healthy employee-owned dogs.
Interventions – Seven dogs were included in the treatment group. Four of these dogs also served as the control group. Platelet closure time (CT) was measured using a platelet function analyzer and collagen/ADP cartridges. Dogs were given 20 mL/kg of either sodium chloride 0.9% (control group, n =4) or HES (treatment group, n =7) IV over 1 hour. CT was measured before the infusion, and at 1, 3, 5, and 24 hours after the start of the infusion.
Measurements and Main Results – There was a significant change over time from 0 to 24 hours ( P <0.001), a significant difference between groups across time ( P <0.001), and a significant group-by-time interaction ( P =0.007). At 3 hours, mean CT for the treatment group was 122.3±18.1 seconds, which was significantly different ( P <0.001) from the control group (71.0±3.5 s). At 5 hours, mean CT for the treatment group was 142.7±33.9 seconds, which was significantly different ( P =0.001) from the control group (75.0±8.6 s). Mean CT at 24 hours was within the reference interval for both the control and treatment group (66.0±2.9 and 81.8±11.9 s, respectively); however, CT in 3 individual dogs in the treatment group at this time point remained prolonged.
Conclusions – A clinically relevant dose of HES 670/0.75 prolongs CT in dogs for up to 24 hours. This may be due to platelet dysfunction in addition to the effects of hemodilution, and therefore, may increase the risk of bleeding.     

Effects of plasma expansion on the pituitary-adrenocortical response to halothane anaesthesia in sheep

The study aimed to investigate the stimulus to adrenocortical activity that is induced by halothane anaesthesia. Groups of 7 sheep were anaesthetised with thiopentone and halothane (TH) or acepromazine, thiopentone and halothane (ATH). During 120 min of anaesthesia hypotension was prevented (mean arterial blood pressure kept at pre-anaesthetic level) by infusion of a modified gelatine plasma replacer given to effect (0.34–1.1 litres with TH and 1.1–3.1 litres with ATH). Pulse rate, arterial blood pressure and gases were measured and sequential samples withdrawn for analysis of plasma cortisol, adrenocorticotrophic hormone (ACTH), arginine vasopressin (AVP), glucose and lactate. Heart rate increased in the ATH but not the TH group. All sheep were well oxygenated but developed hypercapnia and respiratory acidosis. In both groups, cortisol increased more than 2-fold 20 min after the end of anaesthesia but there were no significant changes in ACTH. AVP was measured in the TH group only and increased 3-fold at the end of anaesthesia. Glucose and lactate remained stable except for lactate in the TH group which decreased during anaesthesia. These data indicate that hypotension is a major component of the stimulus inducing adrenocortical activity during halothane anaesthesia. However, maintenance of normotension did not entirely depress the response; halothane itself or decreased perfusion may also contribute.     

Effects of serial ultrasound-guided renal biopsies on kidneys of healthy adolescent dogs

Ten healthy mixed-breed dogs were used to evaluate the functional and structural effects of serial ultrasound-guided renal biopsies obtained with an automated biopsy needle. In each dog, one lateral renal cortex was biopsied at 2, 4, and 6 months of age; the other kidney was the control. Five dogs had two tissue cores and five dogs had four tissue cores taken on each biopsy occasion, and one core was examined microscopically. One week before each biopsy and a month after the final biopsy, the glomerular filtration rate (GFR) was determined by renal scintigraphy. Dogs were then euthanized for evaluation of gross and microscopic lesions attributable to the biopsies. There was no difference between GFR values for biopsied kidneys and those of control kidneys ( P >0.05). Microscopic lesions were not identified in biopsies taken at 2 and 4 months, but focal lesions were found in three of 10 specimens taken at 6 months of age. At necropsy, six of 10 biopsied kidneys had small visible capsular scars, and linear tracts <2 mm wide were observed on cut surfaces in six of 10 biopsied kidneys cut transversely into slices 5 mm thick. Discrete light microscopic lesions were observed in 25 of 452 (5.5%) of randomly selected 6-mm-diameter sections of renal cortex from biopsied kidneys. We conclude that serial renal cortical biopsies can be obtained by our method from healthy adolescent dogs with minimal risk of inducing changes that might be confused with those of a progressive renal disease.     

不同生殖周期阶段对犬卵巢卵母细胞体外发育的影响

试验以屠宰场犬卵巢为材料,研究了不同生殖周期阶段(卵泡期、黄体期和乏情期)对犬卵母细胞体外发育的影响。结果表明,从卵泡期卵巢采集A类COCs的数量为22.67±11.02个,显著高于黄体期10.67±5.51个和乏情期7.25±4.92个(P＜0.05);体外培养48 h时,卵泡期、黄体期和乏情期卵母细胞达到MⅠ-MⅡ期比率分别为19.2%±15.3%、26.8%±21.1%、9.8%±10.4%,卵泡期与黄体期之间差异不显著(P＞0.05),但两者均显著高于乏情期(P＜0.05);体外培养72 h时,卵泡期、黄体期和乏情期卵母细胞达到MⅠ-MⅡ期比率分别为25.2%±13.5%、6.6%±6.7%、9.2%±5.5%,卵泡期显著高于黄体期和乏情期(P＜0.05)。同时,随体外培养时间延长,不同生殖周期阶段犬卵母细胞达到MⅠ-MⅡ期比率存在不同变化。说明不同生殖周期阶段对犬卵巢卵母细胞体外发育有一定影响,且与培养时间有关。