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in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE To identify risk factors for the development of aspiration pneumonia after unilateral arytenoid lateralization in dogs with laryngeal paralysis.

DESIGN Retrospective case series.

ANIMALS 232 client-owned dogs with a diagnosis of laryngeal paralysis treated with lef-tsided unilateral arytenoid lateralization.

PROCEDURES Medical records were reviewed. Signalment, medical history, surgical complications, and outcome data were collected. Follow-up was performed via review of medical records and by telephone interview with the owner, referring veterinarian, or both.

RESULTS At the 1-, 3-, and 4-year follow-up periods, aspiration pneumonia occurred in 18.6%, 31.8%, and 31.8% of dogs, respectively. The 1-, 3-, and 4-year survival rates for dogs with postoperative aspiration pneumonia were 83.1%, 51.5%, and 25.8%, respectively. None of the dogs with aspiration pneumonia before surgery developed clinical signs of aspiration pneumonia after surgery. Postoperative megaesophagus (hazard ratio [HR], 2.58; 95% confidence interval [CI], 1.56 to 3.93) and postoperative administration of opioid analgesics prior to discharge (HR, 1.69; 95% CI, 1.12 to 2.80) were significant risk factors for the long-term development of aspiration pneumonia in this study. Perioperative metoclopramide administration did not significantly decrease the risk for development of aspiration pneumonia (HR, 0.94; 95% CI, 0.67 to 1.37).

CONCLUSIONS AND CLINICAL RELEVANCE In the present study, aspiration pneumonia was the most commonly reported postoperative complication of unilateral lateralization in dogs treated for laryngeal paralysis; however, preexisting aspiration pneumonia was not associated with an increased risk for development of aspiration pneumonia after surgery. Megaesophagus was identified as an important risk factor for eventual development of aspiration pneumonia. Administration of an opioid analgesic may increase the risk of aspiration pneumonia in dogs treated surgically for laryngeal paralysis.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine whether kinematic changes induced by heel pressure in horses differ from those induced by toe pressure.

Animals—10 adult Quarter Horses.

Procedure—A shoe that applied pressure on the cuneus ungulae (frog) or on the toe was used. Kinematic analyses were performed before and after 2 levels of frog pressure and after 1 level of toe pressure. Values for stride displacement and time and joint angles were determined from horses trotting on a treadmill.

Results—The first level of frog pressure caused decreases in metacarpophalangeal (fetlock) joint extension during stance and increases in head vertical movement and asymmetry. The second level of frog pressure caused these changes but also caused decreases in stride duration and carpal joint extension during stance as well as increases in relative stance duration. Toe pressure caused changes in these same variables but also caused maximum extension of the fetlock joint to occur before midstance, maximum hoof height to be closer to midswing, and forelimb protraction to increase.

Conclusion and Clinical Relevance—Decreased fetlock joint extension during stance and increased head vertical movement and asymmetry are sensitive indicators of forelimb lameness. Decreased stride duration, increased relative stance duration, and decreased carpal joint extension during stance are general but insensitive indicators of forelimb lameness. Increased forelimb protraction, hoof flight pattern with maximum hoof height near midswing, and maximum fetlock joint extension in cranial stance may be specific indicators of lameness in the toe region. Observation of forelimb movement may enable clinicians to differentiate lameness of the heel from lameness of the toe. (Am J Vet Res 2000;61:612-619)

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in American Journal of Veterinary Research

Abstract

Objective—To determine disposition kinetics of amikacin in neonatal foals administered high doses at extended intervals.

Animals—7 neonatal foals.

Procedure—Amikacin was administered (21 mg/kg, IV, q 24 h) for 10 days. On days 1, 5, and 10, serial plasma samples were obtained for measurement of amikacin concentrations and determination of pharmacokinetics.

Results—Mean ± SD peak plasma concentrations of amikacin extrapolated to time 0 were 103.1 ± 23.4, 102.9 ± 9.8, and 120.7 ± 17.9 µg/mL on days 1, 5, and 10, respectively. Plasma concentrations at 1 hour were 37.5 ± 6.7, 32.9 ± 2.6, and 30.6 ± 3.5 µg/mL; area under the curve (AUC) was 293.0 ± 61.0, 202.3 ± 40.4, and 180.9 ± 31.2 (µg · h)/mL; elimination half-life (t1/2β) was 5.33, 4.08, and 3.85 hours; and clearance was 1.3 ± 0.3, 1.8 ± 0.4, and 2.0 ± 0.3 mL/(min · kg), respectively. There were significant increases in clearance and decreases in t1/2β, AUC, mean residence time, and plasma concentrations of amikacin at 1, 4, 8, 12, and 24 hours as foals matured.

Conclusions and Clinical Relevance—Once-daily administration of high doses of amikacin to foals resulted in high peak plasma amikacin concentrations, high 1-hour peak concentrations, and large values for AUC, consistent with potentially enhanced bactericidal activity. Age-related findings suggested maturation of renal function during the first 10 days after birth, reflected in enhanced clearance of amikacin. High-dose, extended-interval dosing regimens of amikacin in neonatal foals appear rational, although clinical use remains to be confirmed. (Am J Vet Res 2004;65:473–479)

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

Summary

Fifteen isolates of Escherichia coli obtained from the blood and tissues of septic foals had plasmid dna of size ranging from 2.5 to 93 megadaltons. These isolates grew in normal equine serum (serum resistant), a trait previously documented to be expressed by isolates obtained from blood and tissues of septic foals, but not by isolates obtained from the feces of clinically normal horses. Of these isolates, 3 contained conjugal plasmids that encoded resistance to multiple antimicrobial agents linked to serum resistance and, in 1 isolate, to production of aerobactin as well. Serum resistance and production of aerobactin are related to virulence of septicemic E coli from non-equine sources.

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in American Journal of Veterinary Research

Abstract

Objective

To determine pharmacokinetics and bioavailability of erythromycin base after intragastric administration and erythromycin lactobionate after IV administration to healthy foals and to compare a microbiologic assay with a high-performance liquid chromatography (HPLC) method to determine plasma concentrations of erythromycin A.

Animals

6 healthy foals that were 2 to 4 months old.

Procedure

Foals were given single doses of erythromycin (10 mg/kg of body weight, IV, and 25 mg/kg, intragastrically) in a crossover study. Venous blood samples were obtained at specific times after drug administration, and plasma was harvested for determination of erythromycin concentrations by microbiologic assay and a HPLC method. Pharmacokinetic analysis of plasma concentration-time data was performed, and results derived from each method were compared.

Results

Concentration-time profiles for IV administration were best described by a two-compartment open model. Comparing pharmacokinetic data obtained by the 2 methods revealed substantial differences in results. Values for area under the plasma concentration-time curve and area under the first moment of the curve were substantially higher when determined by the bioassay, indicating overestimation of plasma concentration-time data by this method. The derived rate transfer constants (K21 and Ke1) and mean residence time were significantly different, when determined by the bioassay. Systemic bioavailability of erythromycin base was low in all foals.

Conclusions and Clinical Relevance

The bioassay method overestimated plasma concentrations of erythromycin, compared with the HPLC method. Despite low systemic bioavailability of erythromycin base administered intragastrically, plasma concentrations of erythromycin exceeded, for at least 4 hours, the minimum inhibitory concentration of most Rhodococcus equi isolates. (Am J Vet Res 1999;60:414-419)

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in American Journal of Veterinary Research

Summary

The medical records of 25 horses with intra-abdominal neoplasms and 15 horses with intra-abdominal abscesses were reviewed. Common clinical signs of disease observed by owners of horses in both groups included anorexia, weight loss, fever, signs of colic, and depression. Clinical laboratory abnormalities included leukocytosis, hyperfibrinogenemia, hypoalbuminemia, and hypocalcemia. There was considerable overlap of laboratory test results within and between the 2 groups of horses. Peritoneal fluid was classified as an exudate in 12 of 15 horses with intra-abdominal abscesses and in 14 of 25 horses with intra-abdominal neoplasms. Cytologic examination of peritoneal fluid yielded an accurate diagnosis in 11 of 25 horses with neoplasia and in 3 of 15 horses with abscesses. A mean number of 1.45 cytologic analyses/horse was needed to diagnose neoplasms in the 11 horses in which the analysis was successful in definitively diagnosing the condition.

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in Journal of the American Veterinary Medical Association