Optimisation of the frequently sampled intravenous glucose tolerance test to reduce urinary glucose spilling in horses.

REASONS FOR PERFORMING STUDY: The frequently sampled i.v. glucose tolerance test (FSIGTT) is used to evaluate glucose and insulin dynamics in horses, but it has not been determined whether urinary glucose spilling (UGS) affects results. HYPOTHESIS: UGS occurs in horses during the FSIGTT and this problem can be minimised by adjusting the dextrose and insulin dosages used. METHODS: Six mature mares were included in this study. In the first phase, 6 FSIGTT procedures were performed in each horse to evaluate 6 different dextrose dosages. Six different insulin dosages were evaluated during the second phase of the study after administration of 300 mg/kg bwt dextrose. Area under the glucose (AUCg) and insulin (AUCi) curves were calculated and minimal model analyses performed. UGS was measured in the third and fourth phases of the study during the combined glucose insulin test and established FSIGTT. A new FSIGTT was developed and evaluated. RESULTS: Positive linear effects of dextrose dosage on AUCg, AUCi and acute insulin response to glucose were detected, with AUCg reaching a plateau at doses > or =200 mg/kg bwt. Insulin dosage had an inverse linear effect on AUCg, but other values remained unaffected. UGS occurred during all 3 tests and was the highest for the established FSIGTT and the lowest for the new FSIGTT. The type of FSIGTT performed did not affect minimal model results. CONCLUSIONS: Results indicate that the dextrose dosage of 300 mg/kg bwt used in the established FSIGTT is too high. UGS can be reduced by lowering the dextrose dosage to 100 mg/kg bwt. POTENTIAL RELEVANCE: A new FSIGTT involving the administration of 100 mg/kg bwt dextrose followed by 20 mu/kg bwt insulin 20 min later is recommended for use in horses because this test provides adequate data for minimal model analysis while minimising UGS.

Frequency of anticoagulation for atrial fibrillation and reasons for its non-use at a Veterans Affairs medical center.

Randomized clinical trials have led to guidelines for anticoagulation in atrial fibrillation (AF). However, it is unclear how successfully these guidelines are being implemented in clinical practice and there is concern that anticoagulation is underused. Therefore, we examined the rate of anticoagulation in 998 patients with AF who attended a Veterans Affairs Medical Center over a 2-year period. Warfarin was prescribed for 504 patients (51%) and not prescribed for 494 patients (49%). Of these 494 patients, 446 had sufficient data for further assessment. Warfarin was judged not indicated in 200 because AF was transient or lone. Warfarin was indicated in 246 patients, 63% having > or =3 risk factors for thromboembolism. However, 184 of these patients also had at least 1 contraindication to anticoagulation. Thus, warfarin was prescribed to 67% of patients with AF in whom anticoagulation was indicated and to 89% of such patients in whom it was indicated and who had no contraindications. However, 25% of AF patients with strong indications for anticoagulation had concomitant contraindications, which precluded its use. We conclude that the use of warfarin for AF in this setting is higher than previously reported and approaching ideal levels. However, there remains a large, problematic subgroup of patients with AF in whom indications for and contra-indications to anticoagulation coexist.

Declawing of neonatal rabbits destined for use in animal biosafety level 4 containment studies.

To protect personnel and protective outerwear from damage by scratching, rabbits to be housed in an Animal Biosafety Level 4 (ABSL4) facility are declawed routinely. The objective of the study presented here was to establish a procedure for declawing all four feet of neonatal rabbits in preparation for use in ABSL4 studies. Combining procedures conducted in private veterinary practice to remove dewclaws of canine pups with those used to declaw cats, we declawed rabbit kits at 3 to 8 days of age. Declawing neonates was believed to be advantageous because they are non-ambulatory, have soft, cartilaginous digits, and do not have extensive hair growth. These features resulted in decreased surgical preparation and surgery time, minimal bleeding, and minimal aftercare. The optimal age for declawing a litter was 6 or 7 days. Declawing of neonatal rabbits is relatively simple and efficient to perform and offers advantages over declawing of older animals. By using the method described, rabbits can be introduced into ABSL4 facilities by 12 weeks of age with confidence that nail regrowth will not occur.

The neck shaft-plate shaft angle in slipped capital femoral epiphysis.

We looked for structural differences between normal patients and those with slipped capital femoral epiphysis to explain shear failure of the growth plate in terms of mechanics. Hip radiographs of 50 normal adolescents were examined, and it was found that lines drawn along the axis of the femoral neck and perpendicular to the growth plate intersected at an average angle of 23 degrees (neck shaft-plate shaft angle). Radiographs of 50 patients with slipped capital femoral epiphysis were examined, and the femoral neck shaft-plate shaft angle was found to be between 10 degrees and 20 degrees in patients with unilateral slips and less than 10 degrees in patients with bilateral slips. These abnormalities in the femoral neck shaft-plate shaft angle suggest there are mechanical differences between normal hips and those that develop a slip of the capital femoral epiphysis that may predispose to shear failure of the growth plate.

Mechanical factors in slipped capital femoral epiphysis.

We performed three-dimensional force analyses on the hips of 50 normal patients and 50 patients with slipped capital femoral epiphysis to determine if mechanical factors alone could account for slips. We found that slipped epiphysis patients have reduced resistance to shear because of increased body weight and a decreased neck shaft-plate shaft angle. Slipped epiphysis patients have relative retroversion, and this generates increased sagittal plane shear stress at the proximal femoral growth plate. We suggest that, during running, these mechanical factors cause shear failure of the growth plate in obese adolescents.