Effect of age on the pharmacokinetics of a single daily dose of gentamicin sulfate in healthy foals

ECEIM consensus statement on equine kidney disease

The aim of this consensus statement is to summarize and appraise scientific evidence and combine this with the clinical experience of a panel of experts to optimize recommendations on how to recognize and manage kidney disease in horses.

Potassium penicillin and gentamicin pharmacokinetics in healthy conscious and anesthetized horses

OBJECTIVE

To determine the effects of general anesthesia on the safety and efficacy of co-administered potassium penicillin G (PEN) and gentamicin (GENT) in horses.

STUDY DESIGN

Nonrandomized crossover.

ANIMALS

Six adult, Thoroughbred horses.

METHODS

Horses were administered PEN (22 000 IU/kg IV) and GENT (6.6 mg/kg IV). Plasma samples were collected over a 6 h period and synovial fluid was collected at 30 min and 6 h respectively. Drug administration and sample collection protocols were repeated after at least a 48 hour washout period and induction of anesthesia using xylazine/ketamine and maintenance with isoflurane gas. Drug concentrations were determined using ultrapressure liquid chromatography with mass spectrometry. A 2-compartment model was used to determine pharmacokinetics and differences were determined between conscious and anesthetized horses using paired t-tests (significance P < .05).

RESULTS

Potassium penicillin g and GENT had higher minimum plasma concentrations (PEN 0.44 vs. 0.11 μg/mL, P = .002; GENT 3.0 vs. 1.9 μg/mL, P = .009), longer half lives (PEN 71 vs. 59 min, P = .018; GENT 149 vs. 109 min, P = .038), and slower clearances (PEN 3.41 vs. 5.1 mL/kg/min, P = .005; GENT 1.18 vs. 1.48 mL/kg/min, P = .028) in anesthetized horses vs. conscious horses. The PEN concentrations remained above the breakpoint minimum inhibitory concentration (MIC, 0.5 μg/mL) for 332 min in anesthetized vs. 199 min in conscious horses. The GENT concentrations reached 10 times higher than the breakpoint MIC (2 μg/mL) in all horses and were maintained for 58 vs. 59 min in anesthetized and conscious states, respectively. Synovial fluid concentrations were higher in conscious horses vs. anesthetized horses at 30 min for PEN (7.0 vs. 0.93 μg/mL, P < .001) and 30 (5.3 μg/mL vs. 0.79 μg/mL, P < .001) and 360 min (3.4 vs. 1.82 μg/mL, P < .003) for GENT.

CONCLUSION

General anesthesia resulted in lower intrasynovial concentrations and delayed clearance of PEN/GENT in horses.

CLINICAL SIGNIFICANCE

Redosing healthy anesthetized horses with PEN prior to 4-5 h is not necessary. When administered to anesthetized horses, intravenous PEN/GENT may not reach adequate intrasynovial concentrations to treat or prevent common pathogens. The doses or dosing intervals of antimicrobials administered to horses undergoing anesthesia may need to be adjusted to ensure maintenance of safe and effective plasma concentrations.

Hernia formation after single‐stage umbilical vein marsupialization in three Percheron foals diagnosed with septic omphalophlebitis

Septic omphalophlebitis is a common disease process with a variety of morbidities and possible mortality. Affected umbilical remnant resection is highly successful but may not always be possible. Umbilical marsupialization can be implemented when total resection cannot be accomplished with minimally reported complications. Umbilical vein marsupialization was performed on three Percheron foals with extensive septic omphalophlebitis using the one‐stage paramedian translocation technique and prolonged postoperative antimicrobial therapy. Long‐term follow‐up revealed herniation at the marsupialization site in all foals. Two foals were subsequently treated with herniorrhaphy at the prior marsupialization site. One foal died due to septic peritonitis with hernia formation 3 months after marsupialization. This case series highlights hernia formation as a potential complication following one‐stage umbilical vein marsupialization in foals diagnosed with septic omphalophlebitis and should be considered as a possible postoperative complication.

Causes of equine perinatal mortality

The peripartum period is critical in equine medicine for maintaining healthy mares, and ensuring the delivery of healthy neonatal foals. The field of perinatal mortality in horses is continuously evolving, with several advances being recently made in causes of perinatal fetal and foal loss. This review details the main causes of perinatal loss in horses, through late pregnancy, parturition and the neonatal period. Recent advances in identification of infectious organisms and indicators of survival in neonatal foals will be discussed. Continued advances in reproductive and neonatal medicine will aid improved survival of foals through fewer pregnancy losses, and improved management of high-risk pregnancies and critically ill neonatal foals.

Antimicrobial dosing for common equine drugs: a content review and practical advice for veterinarians in Australia

BACKGROUND

Appropriate dosing with antimicrobial agents is critical for effective treatment and to prevent the development of antimicrobial resistance.

METHODS

A review was undertaken of equine journal articles (Equine Veterinary Journal, Equine Veterinary Education, Australian Veterinary Journal, Australian Equine Veterinarian, Journal of Veterinary Internal Medicine and Journal of Equine Veterinary Science) between January 2015 and August 2018. Those with dosing regimens for procaine penicillin G, gentamicin or trimethoprim-sulfonamide in adult horses were examined and evaluated. Pharmacokinetics and -dynamics of these drugs were also reviewed.

RESULTS & CONCLUSION

The most frequently reported doses for penicillin, gentamicin and trimethoprim-sulfonamide were 20-25,000 IU/kg, 6.6 mg/kg and 30 mg/kg, respectively. Veterinarians treating equine patients in Australia should be aware of the current recommended doses and inter-dosing intervals to ensure efficacy in therapy and to preserve the usefulness of these antimicrobials for the future.

Antimicrobial use in critically ill horses

OBJECTIVE

To discuss controversies surrounding antimicrobial use in critically ill horses.

DATA SOURCES

PubMed searches from 1970-present for terms including, but not limited to: "horse," "foal," "antimicrobial," "prophylaxis," "infection," "surgery," "sepsis," and "antimicrobial resistance."

HUMAN DATA SYNTHESIS

Increasing bacterial antimicrobial resistance has changed first-line antimicrobial choices and prompted shortening of the duration of prophylactic and therapeutic treatment. The need to decrease bacterial resistance development to critically important antimicrobials has been highlighted.

VETERINARY DATA SYNTHESIS

Veterinary medicine has followed a similar trend but often without a high-level evidence. Common dilemmas include diseases in which the theoretically most effective drug is a reserved antimicrobial, the inability to differentiate infectious from noninfectious disease, the duration and necessity of prophylactic antimicrobials and use of antimicrobials in primary gastrointestinal disease. These problems are illustrated using examples of purulent infections, neonatal sepsis, colic surgery, and treatment of colitis. Although enrofloxacin, cephalosporins, and doxycycline, in contrast to gentamicin, reach therapeutic concentrations within the lungs of healthy horses, the first two should not be used as first line treatment due to their reserved status. Due to the high risk of bacterial sepsis, antimicrobial treatment remains indispensable in compromised neonatal foals but shortening the length of antimicrobial treatment might be prudent. One prospective randomized study demonstrated no difference between 3 and 5 days of perioperative antimicrobial treatment in colic surgery but shorter durations were not evaluated. High-level evidence to recommend antimicrobial treatment of adult horses with undifferentiated diarrhea does not exist.

CONCLUSIONS

Few evidence-based recommendations can be made. Commonly used antimicrobial combinations remain the mainstay for treating purulent infections. Antimicrobial treatment for compromised foals should not extend beyond recovery. Continuation of prophylactic antimicrobials >3 days is likely unnecessary after colic surgery; shorter durations might be equally effective. Antimicrobial prophylaxis in adult horses with diarrhea is unlikely to be beneficial.