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Abstract

OBJECTIVE To evaluate the effect of volume of IV regional limb perfusion (IVRLP) on amikacin concentrations in synovial and interstitial fluid of horses.

ANIMALS 8 healthy adult horses.

PROCEDURES Each forelimb was randomly assigned to receive IVRLP with 4 mL of amikacin sulfate solution (250 mg/mL) plus 56 mL (total volume, 60 mL) or 6 mL (total volume, 10 mL) of lactated Ringer solution. Horses were anesthetized, and baseline synovial and interstitial fluid samples were collected. A tourniquet was placed, and the assigned treatment was administered via the lateral palmar digital vein. Venous blood pressure in the distal portion of the limb was recorded. Additional synovial fluid samples were collected 30 minutes (just before tourniquet removal) and 24 hours after IVRLP began; additional interstitial fluid samples were collected 6 and 24 hours after IVRLP began.

RESULTS 30 minutes after IVRLP began, mean amikacin concentration in synovial fluid was significantly greater for the large-volume (459 μg/mL) versus small-volume (70 μg/mL) treatment. Six hours after IVRLP, mean concentration in interstitial fluid was greater for the large-volume (723 μg/mL) versus small-volume (21 μg/mL) treatment. Peak venous blood pressure after large-volume IVRLP was significantly higher than after small-volume IVRLP, with no difference between treatments in time required for pressure to return to baseline.

CONCLUSIONS AND CLINICAL RELEVANCE Study findings suggested that large-volume IVRLP would deliver more amikacin to metacarpophalangeal joints of horses than would small-volume IVRLP, without a clinically relevant effect on local venous blood pressure, potentially increasing treatment efficacy.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To evaluate the prophylactic efficacy of triclosan-coated (TC) suture in preventing surgical site infections (SSIs) in dogs and cats undergoing surgical procedures.

ANIMALS

862 animals (794 dogs and 68 cats).

PROCEDURES

Incidences of SSI of surgical wounds closed with TC suture and surgical wounds closed with non-TC suture occurring between the time of surgery and 1 month postoperatively were compared. Animals were randomly assigned to TC or non-TC suture groups. When TC suture was assigned, all suture available as TC material was used rather than non-TC suture. Presence of an SSI was determined by an owner questionnaire or direct examination.

RESULTS

Overall, 50 of 862 (5.8%) animals developed SSIs. Incidence of SSI was 6% (24/428) in the non-TC suture group and 6% (26/434) in the TC suture group. No significant difference was found in the incidence of SSI between groups. No significant difference was detected in the incidence of incisional problems (eg, redness, dehiscence, and seroma formation) between animals in which TC suture was used and those in which non-TC suture was used. On multivariable analysis, other factors were associated with increased SSI rates, including an incision length > 10 cm, surgery performed by the soft tissue surgery department, and anesthesia duration of > 240 minutes.

CONCLUSIONS AND CLINICAL RELEVANCE

No significant difference in incidence of SSI was detected between animals undergoing surgical procedures performed with non-TC versus TC suture.

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To estimate the probability of concurrently exceeding thresholds for plasma concentration of furosemide and urine specific gravity after IV administration of furosemide in horses.

Animals—12 mature healthy Thoroughbred (n = 6) or Quarter Horse (6) mares.

Procedure—Venous blood was collected from each horse prior to and 0.25, 0.5, 0.75, 1, 2, 3, 4, 4.5, 5, and 6 hours after IV administration of 250 mg (first experiment) or 500 mg (second experiment) of furosemide. Urine was collected hourly between 1 and 6 hours after administration of furosemide at both doses. Concentrations of furosemide were determined by use of an ELISA. Concentration of furosemide and urine specific gravity was modeled as a function of time, accounting for inter- and intrahorse variabilities. On the basis of pharmacokinetic and specific gravity data, the probability of exceeding a concentration of 100 ng of furosemide/ml as a function of time was determined, using a semiparametric smooth functional averaging method. A bootstrap approach was used to assess the inherent variation in this estimated probability.

Results—The estimated probability of exceeding the threshold of 100 ng of furosemide/ml and urine specific gravity < 1.012 was approximately 0% between 4.0 and 5.5 hours after IV administration of 250 mg of furosemide/horse, and ranged from 0 to 1% between 4 and 5.5 hours after IV administration of 500 mg of furosemide/horse. The probability of a horse being falsely identified as in violation of regulatory concentrations was inversely associated with time.

Conclusions and Clinical Relevance—Coupling plasma furosemide concentration with urine specific gravity testing will greatly reduce the chance that some horses are misclassified as being in violation of regulatory concentrations. (Am J Vet Res 2001;62:1349–1353)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To estimate the probability for exceeding a threshold concentration of furosemide commonly used for regulatory purposes after IV administration of furosemide in horses.

Animals—12 mature healthy horses (6 Thoroughbreds and 6 Quarter Horses).

Procedure—Venous blood was collected from each horse prior to and 0.25, 0.5, 0.75, 1, 2, 3, 4, 4.5, 5, and 6 hours after administration of 250 or 500 mg of furosemide. Concentrations of furosemide were determined, using an ELISA. Concentration of furosemide was modeled as a function of time, accounting for inter- and intrahorse variabilities. On the basis of pharmacokinetic data, the probability for exceeding a concentration of 100 ng/ml as a function of time was determined, using a semiparametric smooth functional averaging method. A bootstrap approach was used to assess inherent variation in this estimated probability.

Results—The estimated probability of exceeding the threshold of 100 ng of furosemide/ml ranged from 11.6% at 4 hours to 2.2% at 5.5 hours after IV administration of 250 mg of furosemide/horse and 34.2% at 4 hours to 12.3% at 5.5 hours after IV administration of 500 mg of furosemide/horse. The probability of a horse being falsely identified in violation of regulatory concentrations was inversely associated with time and positively associated with dose.

Conclusions and Clinical Relevance—Interhorse variability with respect to pharmacokinetics of furosemide will result in misclassification of some horses as being in violation of regulatory concentrations. (Am J Vet Res 2001;62:320–325)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the effect of an indwelling nasogastric tube on gastric emptying of liquids in horses.

Animals—9 healthy adult horses.

Procedure—A randomized block crossover design was used. For treatment group horses, a nasogastric tube was placed and 18 hours later, acetaminophen was administered; the nasogastric tube remained in place until the experiment was complete. For control group horses, a nasogastric tube was passed into the stomach, acetaminophen was administered, and the nasogastric tube was removed immediately. Serial blood samples were collected 15 minutes before and after administration of acetaminophen. Serum concentration of acetaminophen was determined by use of fluorescence polarization immunoassay. The variables, time to maximum acetaminophen concentration (Tmax) and the appearance constant for acetaminophen (Kapp), were determined. The values for Kapp and Tmax in horses with and without prolonged nasogastric tube placement were compared.

Results—No significant difference was found in Kapp between horses with and without prolonged nasogastric tube placement; the median difference in Kapp was 0.01 min–1 (range, –0.48 to 0.80 min–1). No significant difference was found in Tmax between horses with and without prolonged nasogastric tube placement; the median difference in Tmax was 5 minutes (range, –30 to 50 minutes). Reanalysis of data following the removal of possible outlier values from 1 horse resulted in a significant difference in Tmax between horses with and without prolonged nasogastric tube placement.

Conclusions and Clinical Relevance—Although no clinically important impact of 18 hours of nasogastric intubation was found on gastric emptying in healthy horses, considerable variability in Kapp and Tmax was found among horses. (Am J Vet Res 2005;66:642–645)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To characterize changes in lymphocyte subsets over time in foals from birth to 18 weeks of age, accounting for differences among individuals, and to determine the effect of overnight storage of blood samples on foal lymphocyte subset concentrations.

Animals—8 healthy Quarter Horse foals from birth to 18 weeks of age.

Procedure—Blood samples were collected longitudinally from birth to 18 weeks of age and a CBC performed on each sample. The samples were stained for lymphocyte markers, either immediately or after overnight storage and analyzed by flow cytometry.

Results—Total leukocytes, total lymphocytes, and the absolute concentrations of all lymphocyte subsets increased significantly with age. The proportions of B29A+, CD21+, and equine major histocompatability complex class-II molecule+ lymphocytes increased significantly with age. The proportion of equine (Eq) CD5+, EqCD8+, and EqWC4+ lymphocytes decreased significantly with age. Significant differences among foals were found with respect to initial concentrations with respect to initial concentrations, but not with respect to the rate of increase of the various subsets tested. Significant differences were not found in subset values when comparing blood samples stained on the day of collection or after overnight storage at room temperature (approx 21 C) or under refrigeration.

Conclusions and Clinical Relevance—These results are consistent with an increase in subset numbers and proportions over time, but with individual differences among foals. The observation of individual differences in subsets among foals suggests that there may be individual differences in susceptibility to infectious disease during the perinatal period. The absence of an effect of overnight storage makes field studies of lymphocyte subset concentrations more feasible. (Am J Vet Res 2002;63:531–537)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To quantify and compare geochemical factors in surface soils from horse-breeding farms with horses with pneumonia caused by Rhodococcus equi (affected farms) and horse-breeding farms with no history of pneumonia caused by R equi (unaffected farms).

Sample Population—Soil from 24 R equi-affected farms and 21 unaffected farms.

Procedure—Equine veterinary practitioners throughout Texas submitted surface soil samples from areas most frequented by foals, on R equi affected and unaffected horse-breeding farms in their practice. Soil samples were assayed for the following factors: pH, salinity, nitrate, phosphorus, potassium, calcium, magnesium, sodium, sulfur, zinc, iron, manganese, and copper. Median values for all factors were recorded, and differences between affected and unaffected farms were compared.

Results—Significant differences in soil factors were not detected between affected and unaffected farms; hence, there was no association between those factors and R equi disease status of the farms.

Conclusion and Clinical Relevance—The surface soil factors monitored in this study were not significant risk factors for pneumonia caused by R equi. As such, it is not possible to determine whether foals on a given farm are at increased risk of developing disease caused by R equi on the basis of these factors. Data do not support altering surface soil for factors examined, such as alkalinization by applying lime, as viable control strategies for R equi. (Am J Vet Res 2002;63:95–98)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate sensitivity and specificity of a multiplex polymerase chain reaction (PCR) assay for simultaneous detection of Rhodococcus equi and differentiation of strains that contain the virulence-associated gene (vapA) from strains that do not.

Sample Population—187 isolates of R equi from equine and nonequine tissue and environmental specimens and 27 isolates of bacterial species genetically or morphologically similar to R equi.

Procedure—The multiplex PCR assay included 3 gene targets: a universal 311-bp bacterial 16S ribosomal RNA amplicon (positive internal control), a 959-bp R equi-specific target in the cholesterol oxidase gene ( choE ), and a 564-bp amplicon of the vapA gene. Duplicate multiplex PCR assays for these targets and confirmatory singleplex PCR assays for vapA and choE were performed for each R equiisolate. An additional PCR assay was used to examine isolates for the vapB gene.

Results—Results of duplicate multiplex and singleplex PCR assays were correlated in all instances, revealing high specificity and reliability (reproducibility) of the vapA multiplex assay. Of the pulmonary isolates from horses with suspected R equi pneumonia, 97.4% (76/78) yielded positive results for vapA. Seven of 50 (14%) human isolates of R equi yielded positive results for vapA. Six human R equi isolates and 1 porcine isolate yielded positive results for vapB. No isolates with vapA and vapB genes were detected.

Conclusions and Clinical Relevance—The multiplex PCR assay is a sensitive and specific method for simultaneous confirmation of species identity and detection of the vapA gene. The assay appeared to be a useful tool for microbiologic and epidemiologic diagnosis and research. (Am J Vet Res 2005;66:1380–1385)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate fecal concentrations of selected genera of colonic bacteria in healthy dogs, and to investigate effects of dietary fructooligosaccharides (FOS) on those bacterial populations.

Animals—6 healthy adult Beagles.

Procedure—Dogs were randomly assigned to 2 groups of 3 and fed an unsupplemented diet for 370 days. After 88 days, fecal samples were collected. Another fecal sample was collected from each dog 282 days later. Group A then received a diet supplemented with FOS, and group B continued to receive the unsupplemented diet. Twenty-eight to 29 days later, fecal samples were collected. Diets were switched between groups, and fecal samples were collected 31 and 87 days later. Concentrations of Bifidobacterium spp, Lactobacillus spp, Clostridium spp, Bacteroides spp, and Escherichia coli in freshly collected feces were determined. Effects of diet and time on bacterial concentrations were compared between groups.

ResultsBifidobacterium spp and Lactobacillus spp were inconsistently isolated from feces of dogs fed either diet. Sequence of diet significantly affected number of Bacteroides spp subsequently isolated from feces, but diet had no effect on numbers of Clostridium spp or E coli.

Conclusions and Clinical Relevance—Some genera of bacteria (eg, Bifidobacterium) believed to be common components of colonic microflora may be only sporadically isolated from feces of healthy dogs. This deviation from expected fecal flora may have implications for the effectiveness of supplementing diets with prebiotics. (Am J Vet Res 2000;61: 820–825)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the chemoprophylactic effect of gallium maltolate on the cumulative incidence of pneumonia caused by Rhodococcus equi infection in foals.

Animals—483 foals born and raised on 12 equine breeding farms with a history of endemic R equi infections.

Procedures—Group 1 foals were treated with a placebo and group 2 foals were treated with gallium maltolate (approx 30 mg/kg, PO, q 24 h) during the first 2 weeks after birth. Foals were monitored for development of pneumonia attributable to R equi infection and for adverse effects of gallium maltolate.

Results—There were no significant differences in the cumulative incidence of R equi pneumonia among the 2 groups.

Conclusions and Clinical Relevance—Chemoprophylaxis via gallium maltolate administered orally at approximately 30 mg/kg daily for the first 2 weeks after birth failed to reduce the cumulative incidence of pneumonia attributable to R equi infection among foals on breeding farms with endemic R equi infections. Further investigation is needed to identify strategies for control of R equi infections.

Full access
in American Journal of Veterinary Research