Search Results

You are looking at 1 - 10 of 14 items for

  • Author or Editor: Michael W. Thomas x
  • Refine by Access: All Content x
Clear All Modify Search

Summary

Epidural analgesia was achieved at weekly intervals in 6 adults llamas by injection of 2% lidocaine, 10% xylazine, and a combination of 2% lidocaine/10% xylazine at the sacrococcygeal junction. Analgesia was determined by lack of response to pin prick or hemostat pressure in the perineal area. Ataxia could not be accurately evaluated because of the llamas’ tendency to assume sternal recumbency when restrained. Time to onset of analgesia was not different between lidocaine (3.16 ± 0.31 minutes) and lidocaine/xylazine (3.50 ± 0.56 minutes), but results for both groups were different than those for xylazine (20.67 ± 3.37 minutes). Duration of analgesia was different among all groups (lidocaine, 71.0 ± 6.15 minutes; xylazine, 186.83 ± 14.86 minutes; lidocaine/xylazine, 325.83 ± 29.39 minutes). Mild sedation developed in 4 llamas given xylazine alone. Lidocaine/xylazine caused mild sedation in 2 llamas and moderate sedation in 1 llama. Significant changes in pulse or respiratory rates were not observed among drugs, but changes were observed over time with all drugs. As has been reported in other species, lidocaine/xylazine provided rapid onset and prolonged duration of analgesia.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To devise and test an IV methohexital infusion regimen for induction and maintenance of surgical anesthesia in dogs from which they would rapidly recover.

Design

Dose-response and plasma concentration-effect study.

Animals

11 clinically normal dogs.

Procedure

Bolus methohexital pharmacokinetic variables were determined in ketamine- and pentobarbital-anesthetized dogs. Plasma methohexital concentrations required to inhibit purposeful movement in response to painful stimuli were determined during a stepped methohexital infusion in the same dogs on a second occasion. These pharmacokinetic/pharmacodynamic data were next used to design a bolus and two-stage infusion regimen that would result in stable plasma methohexital concentrations with prolonged infusion. This regimen was tested in a second group of dogs.

Results

Mean steady-state volume of distribution of methohexital in the anesthetized dogs was 1.50 L/kg of body weight and mean elimination clearance was 10.2 ml/kg/min. Mean plasma concentrations required to prevent movement response to a noxious stimulus and at which the dogs could be extubated were 11.8 and 6.9 μg/ml, respectively. After a 6-hour infusion, recovery of airway reflexes sufficient to allow extubation required 67 minutes.

Conclusions

An easily implemented IV methohexital infusion regimen for induction and maintenance anesthesia in dogs was developed. During a 6-hour infusion, hemodynamic variables did not change. Use of this regimen resulted in anesthesia of sufficient depth to prevent withdrawal in response to noxious stimuli and in reliable and acceptable emergence times for use in canine survival studies in a cost-effective manner. (Am J Vet Res 1996;57:1044–1049)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate skeletal characteristics of pelvic limbs with and without cranial cruciate ligament (CCL) deficiency in Labrador Retrievers.

Animals—30 adult purebred Labrador Retrievers.

Procedures—Pelvic limbs (n = 28) of 14 dogs without CCL deficiency were classified as control limbs, whereas the limbs of 16 dogs with CCL deficiency were considered affected by (18 limbs) or predisposed to (10 contralateral limbs of dogs with 1 affected limb) CCL deficiency. Skeletal characteristics were evaluated via physical examination, radiography, and computed tomography. Radiographic and computed tomographic variables were compared among limb groups by use of a mixed-model ANOVA.

Results—The tibial plateau slope was steeper in CCL-deficient limbs but not in predisposed limbs, compared with the slope in control limbs. The angle between diaphyseal and proximal tibial axes was increased in both CCL-deficient and predisposed limbs. The relative width of the proximal portion of the tibia and the inclination of the patellar ligament did not differ among limb groups. The overall and distal femoral anteversion angles were greater in CCL-deficient and predisposed limbs, whereas the femoral condyle trochanteric angle was decreased in those limb groups, compared with findings in control limbs.

Conclusions and Clinical Relevance—Cranial angulation of the proximal portion of the tibia, excessive steepness of the tibial plateau, and distal femoral torsion appeared more likely to be associated with CCL deficiency than femoral angulation, tibial torsion, intercondylar notch stenosis, and increased inclination of the patellar ligament.

Full access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association

Objective

To determine whether results of the Ortolani method of hip joint palpation in dogs were related to distraction index (DI), Norberg angle, or radiographic hip score.

Design

Cross-sectional study.

Animals

459 clinically normal dogs.

Procedure

Dogs were sedated for radiography and palpation of the hip joints. Results of hip joint palpation were classified as negative, mild positive, moderate positive, or severe positive. Distraction indices were measured for all dogs. Norberg angles were measured for 380 dogs for which ventrodorsal hip-extended radiographic projections were available. Hip scores assigned by the Orthopedic Foundation for Animals (OFA) were available for 95 dogs.

Results

Age, weight, and sex were not significantly associated with results of hip joint palpation. There was moderate correlation between results of hip joint palpation and DI (r = 0.636), low-moderate correlation between results of hip joint palpation and OFA hip scores (rs = 0.437), and weak negative correlation (r = -0.236) between results of hip joint palpation and Norberg angle. For joints without degenerative joint disease (DJD), there was a significant linear relationship between results of hip palpation and DI; however, for joints with DJD, there was not. Results of hip joint palpation were 5.3-fold as likely to be negative for dogs with DJD as for dogs without.

Clinical Implications

Results of hip joint palpation were at best moderately correlated with radiographic measures of hip joint laxity. Therefore, hip joint palpation should be combined with hip-extended and stress radiography when assessing hip joint quality. (J Am Vet Med Assoc 1999;214:497–501).

Free access
in Journal of the American Veterinary Medical Association

Summary

To provide long-term gastric fistulas for collection of third-compartment gastric contents, Janeway mucosal tube gastrostomy was performed, using a gastrointestinal stapling instrument, in 6 castrated adult male llamas. Mean operative time (±sem) was 65 ±4.16 minutes. All llamas survived the 6-week study period. Of the 6 llamas, 5 did not have signs of abdominal pain and returned to preoperative food consumption amounts within 36 hours. One llama had mild intermittent signs of abdominal pain daily for 7 days before returning to preoperative amount of food consumption. All gastrostomies leaked small amounts of gastric contents around indwelling 6- to 8-mm cannulas at the skin surface. Gastric contents did not leak when cannulas were dislodged from gastrostomy stomas. Replacement of cannulas was rapid and easy. Gravity-flow sample collection was best accomplished through 8-mm cannulas. Mean (±sem) weight loss was detected in all llamas (15 ± 3 kg) and was associated with frequent nonfeeding and stress of sample collection.

Gross necropsy findings were unremarkable in 5 of 6 llamas. All mucosal tube gastrostomies were patent, and there was no evidence of peritonitis. One llama had a single fibrous adhesion connecting the operative site with the ascending colon. Histologically, small (2.5- to 15-mm diameter) partial-thickness mucosal erosions identified at the tube gastrostomy-gastric wall junctions may have been associated with indwelling gastric cannulas. The Janeway gastrostomy was generally well tolerated in the llamas and should be considered as a useful long-term fistulation technique.

Free access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the epidemiologic plausibility of a sylvatic transmission cycle for Neospora caninum between wild canids and beef cattle.

Design—Spatial analysis study.

Animals—1,009 weaned beef steers from 94 beef herds in Texas.

Procedure—Calves were grouped on the basis of seroprevalence for N caninum and ecologic region in Texas. The Morans I test was used to evaluate spatial interdependence for adjusted seroprevalence by ecologic region. Cattle density (Number of cattle/259 km2 [Number of cattle/100 mile2] of each ecologic region) and abundance indices for gray foxes and coyotes (Number of animals/161 spotlight-transect [census] km [Number of animals/100 census miles] of each ecologic region) were used as covariates in spatial regression models, with adjusted seroprevalence as the outcome variable. A geographic information system (GIS) that used similar covariate information for each county was used to validate spatial regression models.

Results—Spatial interdependence was not detected for ecologic regions. Three spatial regression models were tested. Each model contained a variable for cattle density for the ecologic regions. Results for the 3 models revealed that seroprevalence was associated with cattle density and abundances of gray foxes, coyotes, or both. Abundances of gray foxes and coyotes were collinear. Results of a GIS-generated model validated these spatial models.

Conclusions and Clinical Relevance—In Texas, beef cattle are at increased risk of exposure to N caninum as a result of the abundance of wild canids and the density of beef cattle. It is plausible that a sylvatic transmission cycle for neosporosis exists. (J Am Vet Med Assoc 2000;217:1361–1365)

Full access
in Journal of the American Veterinary Medical Association