Pharmacokinetics of regional limb perfusion using a combination of amikacin and penicillin in standing horses.

The objectives of this study were to evaluate the compatibility and the pharmacokinetic properties of combined amikacin and penicillin administration by intravenous regional limb perfusion (IVRLP) in horses. A tourniquet was applied proximal to the carpus of 7 clinically healthy adult horses and 2 g of amikacin and 10 × 106 IU of penicillin (100 mL total volume) were sequentially injected into the cephalic vein just distal to the tourniquet. Synovial samples were collected from the joint at several times after injection. All samples were analyzed for amikacin and penicillin concentration. The mean maximum concentration (Cmax) of both amikacin and penicillin was over 10-fold the relevant minimal inhibitory concentration (MIC) for all horses and remained above those MICs for at least 24 hours. The results of this study indicate that combining amikacin with penicillin during IVRLP in normal horses delivers high therapeutic synovial concentrations of both drugs.

Pharmacocinétique de la perfusion régionale des membres en utilisant une combinaison d'amikacine et de pénicilline chez des chevaux debout. Les objectifs de cette étude consistaient à évaluer la compatibilité et les propriétés pharmacocinétiques de l'administration combinée d'amikacine et de pénicilline par perfusion intraveineuse régionale des membres (PIRM) chez les chevaux. Un tourniquet a été appliqué proximalement au carpe de sept chevaux adultes en bonne santé clinique et 2 g d'amikacine et 10 × 106 UI de pénicilline (volume total de 100 ml) ont été injectés en séquence dans la veine céphalique légèrement distale au tourniquet. Des échantillons synoviaux ont été prélevés de l'articulation plusieurs fois après l'injection. Tous les échantillons ont été analysés pour la concentration d'amikacine et de pénicilline. La concentration maximale moyenne (Cmax) de l'amikacine et de la pénicilline était plus de 10 fois supérieure à la concentration inhibitrice minimale (CIM) pertinente pour tous les chevaux et est demeurée au-dessus de ces CIM pendant au moins 24 heures. Les résultats de cette étude indiquent que la combinaison de l'amikacine avec la pénicilline durant la PIRM chez des chevaux en santé offre des concentrations synoviales thérapeutiques élevées des deux médicaments.(Traduit par Isabelle Vallières).

Pharmacokinetics of ceftazidime after regional limb perfusion in standing horses.

OBJECTIVE: To determine the metacarpophalangeal joint fluid concentrations of ceftazidime administered via regional limb perfusion (RLP). ANIMALS: Eight healthy horses. METHODS: RLP was performed by injecting 2 g of ceftazidime and 60 mL of perfusate volume in the cephalic vein of standing, sedated horses. Serum and synovial fluid from the metacarpophalangeal joint were collected before perfusion and at 0.5, 2, 6, 12, 24 hours postperfusion. Ceftazidime concentrations were measured via liquid chromatography. Maximal concentration (Cmax ), area under the curve (AUC), half-life of the drug (T ½), and the timing of Cmax (Tmax ) were determined to assess ceftazidime as a candidate drug for RLP. Continuous parameters were compared with the Mann-Whitney U test. P value ≤ .05 was considered statistically significant. RESULTS: The Cmax of ceftazidime in synovial fluid (235 µg/mL) was 15 times higher than the minimal inhibitory concentration (MIC) for most bacteria involved in orthopedic infections, including resistant pathogens such as Pseudomonas aeruginosa (MIC = 16 µg/mL). However, synovial concentrations decreased quickly and remained above the MIC in only 1 horse by 6 hours postperfusion. CONCLUSION: RLP generated high synovial fluid concentrations of ceftazidime in the distal limb, but these concentrations decreased rapidly below the deliberately high MIC selected. CLINICAL RELEVANCE: Once daily RLP, as applied in our study, with 2 g ceftazidime in standing horses, cannot be recommended for use in a clinical setting.

Surgical management and long-term outcome of umbilical infection in 65 foals (2010-2015).

OBJECTIVE: To report the short- and long-term outcomes of surgical management of umbilical infection in foals. STUDY DESIGN: Retrospective case series. ANIMALS: Foals (n = 65). METHODS: Medical records (2010-2015) of foals up to 1 month of age, surgically treated for an umbilical infection were reviewed. Short-term (at the time of discharge from hospital) and long-term (1 year after surgery) survival rates were obtained. Clinical variables influencing survival were assessed. Chi-square or Fisher's exact test were used to evaluate the relationship between the data retrieved and outcome. P ≤ .05 was considered statistically significant. RESULTS: Sixty-five foals were included in the study, representing 17.2% of all foals admitted to the hospital. Fifty foals were discharged from hospital (77%) and 43 foals (66%) were alive 1 year after surgery. Lower long-term survival rates were associated with: younger age at presentation, septic joints, multiple pathologies, higher creatinine level, higher heart rate, umbilical infection diagnosed at the hospital rather than prior to referral, prolonged hospitalization, longer period between arrival and surgery, and postoperative complications. The most common surgical findings were urachal enlargement followed by right arterial enlargement. CONCLUSION: Younger foals with worse systemic condition and concurrent disorders are at higher risk for treatment failure. Early diagnosis improves the outcome. Surgical treatment yields good results and should be considered upon diagnosis, after taking into account the clinical situation. CLINICAL SIGNIFICANCE: Based on the results of this study, diagnosis and surgical management of umbilical infection in neonatal foals should be performed as early as possible, and a good outcome can be expected after surgery.

The Effect of Perfusate Volume on Amikacin Concentration in the Metacarpophalangeal Joint Following Cephalic Regional Limb Perfusion in Standing Horses.

OBJECTIVE: To determine the influence of 3 perfusate volumes on amikacin concentration in the metacarpophalangeal joint following cephalic regional limb perfusion (RLP) in standing horses. ANIMALS: Seven healthy horses. METHODS: Three perfusate volumes (100, 60, and 30 mL), containing 2 grams of amikacin, were tested during intravenous RLP at the cephalic vein, placing the tourniquet at mid antebrachium, in standing sedated horses. Synovial fluid was collected from the metacarpophalangeal joint before perfusion and at 30 and 120 minutes after perfusion. Serum samples were taken from the jugular vein at the same time points. Samples were analyzed for amikacin concentrations and a repeated measures ANOVA, followed by least squares difference pairwise comparisons to identify differences in amikacin concentration across perfusate volumes. Differences were considered significant at P<.05. RESULTS: The mean amikacin concentration in synovial fluid at 30 minutes after perfusion was significantly higher following perfusate volume of 100 mL (579 µg/mL), compared to volumes of 60 mL (227 µg/mL) or 30 mL (282 µg/mL) (P<.05). When a threshold of 160 µg/mL was used, more horses reached the synovial therapeutic threshold following perfusate volume of 100 mL (100%), than horses receiving 60 mL (43%) and 30 mL (57%) at 30 minutes after injection. CONCLUSION: The use of 100 mL volume for RLP at the cephalic vein in standing horses resulted in higher concentration of amikacin in the synovial fluid and is recommended for use in clinical cases.

Removal of sialoliths using the intraoral approach in 15 horses.

This study describes the use of an intraoral approach for sialolith removal in horses. All horses resumed their previous activity after surgery. Sialoliths were composed mainly of calcium carbonate, containing a nidus of plant material. The removal of sialoliths via an intraoral approach results in a high success rate with minimal complications.

Enlèvement des sialolithes en utilisant une approche intraorale chez 15 chevaux. Cette étude décrit l'utilisation d'une approche intra-orale pour l'enlèvement des sialolithes chez les chevaux. Tous les chevaux ont repris leurs activités antérieures après la chirurgie. Les sialolithes étaient principalement composés de carbonate de calcium contenant un nidus de matériau végétal. L'enlèvement des sialolithes par une approche intra-orale se traduit par un taux de succès élevé avec un minimum de complications.(Traduit par Isabelle Vallières).