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  • Author or Editor: Patrick D. Gerard x
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Objective—To evaluate the effects of pilot hole diameter and tapping on insertion torque and axial pullout strength of 4.0-mm cancellous bone screws in a synthetic canine cancellous bone substitute.

Sample—75 synthetic cancellous bone blocks (15 blocks/group).

Procedures—For groups 1 through 5, screw size-pilot hole diameter combinations were 3.5–2.5 mm (cortical screws), 4.0–2.5 mm, 4.0–2.5 mm, 4.0–2.0 mm, and 4.0–2.0 mm, respectively. Holes were tapped in groups 1, 2, and 4 only (tap diameter, 3.5, 4.0, and 4.0 mm, respectively). One 70-mm-long screw was inserted into each block; in a servohydraulic materials testing machine, the screw was extracted (rate, 5 mm/min) until failure. Mean group values of maximum insertion torque, axial pullout strength, yield strength, and stiffness were determined.

Results—Mean maximum insertion torque differed significantly among the 5 groups; the group 5 value was greatest, followed by group 3, 4, 2, and 1 values. Group 3, 4, and 5 axial pullout strengths were similar and significantly greater than the group 2 value; all values were significantly greater than that for group 1. Group 5 and 4 yield strengths were similar and significantly greater than the group 3, 2, and 1 values. Stiffness in group 3 was similar to group 4 and 2 values but significantly greater than the group 5 value; all values were significantly greater than that for group 1.

Conclusions and Clinical Relevance—These synthetic cancellous bone model findings suggested that tapping a 2.0-mm-diameter pilot hole when placing a 4.0-mm screw is the optimal insertion technique.

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in American Journal of Veterinary Research


OBJECTIVE To determine mortality rates for dogs undergoing cholecystectomy and variables associated with failure to survive to hospital discharge.

DESIGN Retrospective cohort study.

ANIMALS 70 dogs that underwent cholecystectomy for biliary tract disease at a companion animal referral hospital from 2009 through 2015.

PROCEDURES Medical records of dogs were reviewed and data collected; dogs with biliary diversion surgery were excluded. Included dogs were grouped by whether cholecystectomy had been elective (ie, dogs with no or mild clinical signs, with no indication of biliary obstruction, or that initially underwent surgery for a different procedure) or nonelective (ie, dogs with icterus and questionable patency of the biliary system). Mortality rates (proportions of dogs that failed to survive to hospital discharge) were compared between various groups.

RESULTS 45 (64%) dogs were included in the elective group and 25 (36%) in the nonelective group. Group mortality rates were 2% (1/45) and 20% (5/25), respectively, and differed significantly. Overall mortality rate was 9% (6/70). Serum albumin concentration was significantly lower and serum alanine aminotransferase activity and total bilirubin concentration were significantly higher in nonsurviving versus surviving dogs. Dogs with vomiting, signs of lethargy or anorexia, icterus, or azotemia were less likely to survive than dogs without these signs.

CONCLUSIONS AND CLINICAL RELEVANCE Dogs that underwent elective cholecystectomy had a considerably lower mortality rate than previously reported. Elective cholecystectomy may be an appropriate recommendation for dogs with early signs of biliary disease to avoid the greater mortality rate associated with more advanced disease and nonelective cholecystectomy.

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in Journal of the American Veterinary Medical Association


Objective—To assess the effects of electromagnetic (EM) field modification by use of Nufield EM field modification (NEFM) units on egg-laying hens in commercial flocks as indicated by production measures, including hen-day mortality rate (HDMR) and eggs per hen housed (EHH).

Animals—16 commercial flocks of egg-laying hens.

Procedure—5 caged commercial table egg layer flocks (Single Comb White Leghorns) successively housed at the same location during a 6-year period were exposed to NEFM. There were 7 hens/cage (317 cm2 of floor space/bird). At the same site, 11 concurrent non–NEFM-exposed flocks (4 genetically different strains) were sequentially housed. All 16 flocks underwent the same feed and management practices. For each NEFM- and non–NEFM-exposed flock, HDMR and EHH were compared with their respective national breeder goals (BG), defined as the reasonable genetic potential expressed under optimal management and environmental conditions. Furthermore, the HDMRs and EHHs of the NEFM- and non–NEFM-exposed flocks were compared.

Results—Mean HDMR and EHH of the NEFMexposed flocks was 36.9% less and 4.96% greater than the relevant BG, respectively. Mean HDMR and EHH of the non–NEFM-exposed flocks was 12.6% and 0.49% greater than the relevant BG, respectively. Compared with the 11 non–NEFM-exposed flocks, the NEFM-exposed flocks collectively had a 47.6% decrease in HDMR and 1.33% increase in EHH.

Conclusions and Clinical Relevance—Results strongly suggest that application of NEFM in commercial egg-layer flocks improves production measures, which has important welfare implications as well as gross economic advantage. (Am J Vet Res 2005;66:1425–1429)

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in American Journal of Veterinary Research