Retrobulbar Block in Combination with General Anesthesia for Equine Ophthalmic Surgery

The use of retrobulbar block in conjunction with general anesthesia was evaluated in the horse. A prospective study of 12 cases fulfilling criteria for application of retrobulbar block was compared to a retrospective survey of 25 cases (control group) in which retrobulbar block was not performed. Retrobulbar block was done using a modified Peterson technique and 2% lidocaine HCI without epinephrine. In the control group, four horses exhibited signs compatible with initiation of the oculocardiac reflex; three horses developed bradyarrhythmias and hypotension during global traction related to enucleation, and cardiac arrest occurred in one horse during cataract extraction. In the retrobulbar block group, one horse developed bradyarrhythmia subsequent to retrobulbar block.     

Comparisons of Sevoflurane, Isoflurane, and Halothane Anesthesia in Spontaneously Breathing Cats

The clinical effects of sevoflurane, isoflurane, and halothane anesthesia with or without nitrous oxide, were compared in healthy, premedicated cats breathing spontaneously during 90 minutes of anesthesia. The effect of nitrous oxide in accelerating the induction of and recovery from anesthesia was more evident for halothane than for sevoflurane or isoflurane. The cats recovered more rapidly from sevoflurane-oxygen than from either halothane- or isoflurane-oxygen. Heart rates did not significantly change during anesthesia with any of the anesthetics. Arterial blood pressures during sevoflurane-oxygen anesthesia were somewhat higher than those with either isoflurane- or halothane-oxygen. There were no significant differences in arterial blood pressures among sevoflurane, isoflurane, and halothane anesthesia when combined with nitrous oxide. The respiration rate during sevoflurane-oxygen was similar to that during halothane-oxygen. There were no significant differences in respiration rate among sevoflurane, isoflurane, and halothane anesthesia when combined with nitrous oxide. The degree of hypercapnia and acidosis during sevoflurane anesthesia was similar to that observed during isoflurane anesthesia and less than during halothane anesthesia. The three anesthetic regimens, with or without nitrous oxide, induced a similar degree of hyperglycemia and hemodilution during anesthesia. Serum biochemical examination did not reveal any hepatic or renal injuries after each anesthesia.     

Effects of Ketamine on the Equine Electroencephalogram During Anesthesia With Halothane in Oxygen

OBJECTIVE: To investigate the effects of ketamine on the electroencephalogram (EEG) of the horse. STUDY DESIGN: Prospective experimental study. ANIMALS: Eight Welsh mountain pony geldings weighing between 280 and 330 kg, 5 to 9 years old. METHODS: During halothane anesthesia at an end-tidal halothane concentration between 0.75 and 0.85%, the EEG frequency power spectrum and the auditory evoked potential were recorded while an infusion of ketamine was given. Ketamine 200 mg was infused over 5 minutes in 8 ponies. The effects of ketamine on the EEG were recorded continuously during the infusion and for a further 55 minutes. RESULTS: The ketamine infusion produced a plasma ketamine concentration that was significantly greater than the baseline until 7 minutes after the start of the infusion. The highest recorded ketamine concentration was 4.2+/-1.1 microg/ml recorded at 5 minutes after the start of the infusion. The spectral edge and median frequency of the EEG and the midlatency of the auditory evoked potential were compared with those recorded before the start of the infusion. The spectral edge, median frequencies and mid-latency of the auditory evoked potential were reduced by 21+/-13%, 31+/-20% and 19+/-36% respectively (mean +/- SD). Only the reduction in spectral edge frequency reached statistical significance. CONCLUSIONS: These results compared with those from other anesthetic and sedative agents suggest that the spectral edge frequency is an indicator of general central nervous system depression whereas the median frequency may be an indicator of antinociception.     

Development of a Colic Severity Score for Predicting the Outcome of Equine Colic

Thirty-two physical examination and laboratory variables were recorded during examination of 165 horses admitted for acute abdominal disease. Univariate analyses were performed to determine which of the variables were significantly different between horses that lived or died. Stepwise logistic regression was performed to identify variables with the best predictive value. Four variables (heart rate, peritoneal fluid total protein concentration, blood lactate concentration, and abnormal mucous membrane) remained significant when entered into the model. Histograms for each significant variable were used to set "cutting-points," establishing categories that were made into a table of assigned values from which a Colic Severity Score (CSS) for each horse was calculated. Seventy-one horses in a second group were used to validate the scoring chart. Case mortality rate was similar in both groups (20.6% in development group versus 21.1 % in validation group). All horses with a CSS > 7 died, whereas 75% of those with a score of 7 lived. For the validation group, use of the scoring table yielded a positive predictive value of 100%, negative predictive value of 91.8%, sensitivity of 66.7%, and specificity of 100%. The overall accuracy of the CSS was 93%. The CSS is a rapid and accurate method for predicting survival in cases of equine acute abdominal disease.     

Influence of Isoflurane General Anesthesia or Anesthesia and Surgery on Thyroid Function Tests in Dogs

Background: Anesthesia and surgery affect thyroid function tests in humans but have not been studied in dogs. Hypothesis: Anesthesia and anesthesia with surgery will affect thyroid function tests in dogs. Animals: Fifteen euthyroid dogs. Methods: Prospective, controlled, interventional study. Dogs were assigned to one of 3 groups: control, general anesthesia, and general anesthesia plus abdominal exploratory surgery. Dogs in the anesthesia and surgery groups were premedicated with acepromazine and morphine, induced with propofol, and maintained on isoflurane. Samples for measurement of serum thyroxine (T₄), free T₄ (fT₄) by equilibrium dialysis, triiodothyronine (T₃), reverse T₃ (rT₃), and thyroid‐stimulating hormone concentrations were collected from each dog immediately before premedication, at multiple times during anesthesia, surgery, 4, 8, 12, 24, 36, and 48 hours after anesthesia, once daily for an additional 5 days, and once 14 days after anesthesia. Sampling was performed at identical times in the control group. Results: Serum T₄ decreased significantly from baseline in the surgery and anesthesia groups compared with the control group at 0.33 (P= 0.043) and 1 hour (P= 0.018), and 2 (P= 0.031) and 4 hours (P= 0.037), respectively, then increased significantly in the surgery group compared with the control group at 24 hours (P= 0.005). Serum T₃ decreased significantly from baseline in the anesthesia group compared with the control group at 1 hour (P= 0.034). Serum rT₃ increased significantly from baseline in the surgery group compared with the control and anesthesia groups at 8 (P= 0.026) and 24 hours (P= 0.0001) and anesthesia group at 8, 12, 24, and 36 hours (P= 0.004, P= 0.016, P= 0.004, and P= 0.014, respectively). Serum fT₄ increased significantly from baseline in the surgery group compared to the control at 24 hours (P= 0.006) and at day 7 (P= 0.037) and anesthesia group at 48 hours (P= 0.023). Conclusions and Clinical Importance: Surgery and anesthesia have a significant effect on thyroid function tests in dogs.     

Equine Colic Associated with Sand Impaction of the Large Colon

In most cases the outcome of impaction of the colon is favourable and with mild purging and lubrication, the mass can be broken down and the horse returned to normal health. It is important to reevaluate impaction cases which neither deteriorate or improve in a 24 hour period and to perform a paracentesis to evaluate the etiology and prognosis. A decision of euthanasia or surgical correction should be made as early as possible. Though initially stable, vital signs will deteriorate rapidly without warning. A critical evaluation of the client's farm management can prevent many impaction colics and the service practitioners provide is not complete unless the necessary changes are made.     

七氟醚、氟烷、异氟醚对犬肝肾功能影响的临床比较

为评价七氟醚对肝肾功能的影响，并与氟烷和异氟醚作比较，对动物医院就诊的心肺功能正常，拟作手术治疗的61头患犬进行麻醉试验，所有犬均以l-美散痛和安定作为麻醉前给药。分别以1．5％七氟醚、1．0％氟烷、1．5％异氟醚维持手术麻醉，所有3组中无一组可见肝肾毒性副作用。至七氟醚麻醉后48h，GLDH，AST，ALT，γ-GT，总胆红素，AP，尿素氮和肌酐显示正常。