Vancomycin kinetics in plasma and synovial fluid following intravenous administration in horses

Vancomycin hydrochloride was infused intravenously (i.v.) over a 30-min period in five horses at doses of 6.6, 11.0 and 15.4 mg/kg. Vancomycin concentration in plasma and synovial fluid samples was measured using a polarization immunoassay. A pharmacokinetic model was developed to accommodate the special features of the present study. The data were described by a two compartment open model with synovial fluid as an additional compartment in exchange with plasma. Minimum inhibitory concentration (MIC) and minimum bacterial concentration (MBC) were measured for Staphylococcus aureus and Enterococcus sp. using isolates from hospital patients. Based on the pharmacokinetic model and MIC/MBC data, a practical therapeutic protocol for vancomycin administration was established at doses of 4.3-7.5 mg/kg given as a 1-h infusion every 8 h.     

Effects of sodium acetate, bicarbonate and lactate on acid-base status in anaesthetized dogs

Equal doses of sodium acetate, bicarbonate and lactate (6.6 mEq/L) infused intravenously over 30 min into three groups of halothane-anaesthetized dogs caused changes in acid-base status. Arterial carbon dioxide tension (PaCO2), pHa, base excess (BE) and standard bicarbonate (SB) increased. Sodium bicarbonate caused the most rapid and greatest changes. The bicarbonate group was significantly different (P less than 0.05) from the other groups at 15 and 30 min after the start of infusion for pHa, BE and SB. The greater effects of bicarbonate are due to its production of alkalinization without a requirement for metabolism; acetate and lactate require oxidation to be effective. The acetate and bicarbonate groups were not statistically different at 45 min after the onset of drug infusion, but both had significantly higher SB and BE mean values than the lactate group. All measurements made after 45 min revealed no significant differences among groups. Thus, after the earlier differences noted above, the three alkalinizers caused similar effects on acid-base status. PaCO2 was elevated in all groups, but there were no differences among groups. Cardiovascular effects caused by infusion of the three drugs were minimal.     

A survey of neurological diseases in horses

SUMMARY: Case records of 450 horses with signs of neurological disease are reviewed. One hundred and nineteen horses with neurological disease due to trauma were examined, of which 60 were due to spinal cord trauma, 47 to brain or cranial nerve trauma and 12 to peripheral nerve trauma. Cervical vertebral fractures/trauma were the most common injury. Basisphenold/basloccipital bone fractures were the most common form of cranial trauma and facial nerve paralysis the most common cranial nerve injury. Eighty-nine horses with neurological disease due to malformation were examined. Cervical vertebral malformation occurred in 83 horses and congenital defects in 6 foals. Neurological disease due to inflammation or infection occurred in 30 horses. The most common disease of this type was meningitis, which occurred in 11 horses and foals. Neoplasms in the CNS caused neurological disease in 8 horses. The final category was miscellaneous neurological disease, which was diagnosed in 204 horses. Diseases in this category included neonatal (28 cases), toxic/metabolic (27 cases), idiopathic (133 cases), degenerative (3 cases) and other neurological diseases (13 cases). The most common condition was idiopathic laryngeal hemiplegia (116 cases).
Where possible, diagnosis relied on a thorough neurological examination with use of ancillary tests in selected cases including rhinolaryngoscopy, radiography, myelography, ophthalmoscopy and cerebrospinal fluid analysis when indicated. In many cases necropsy and histopathological confirmation or diagnosis was necessary.     

Dorsal Frontal Fractures of the First Phalanx in the Horse

Dorsal frontal fractures of the first phalanx in nine horses are described. All fractures were in hindlimbs, and two horses were affected bilaterally. Of the eleven fractures, seven were incomplete and nondisplaced, one was complete and nondisplaced, and three were complete and displaced. Two horses with complete displaced fractures had their fractures repaired with lag screw fixation combined with open reduction, and the other seven horses were treated nonsurgically.
All horses were sound on the injured limb within 3 to 6 months of the injury. Lag screw fixation was recommended for horses with complete, displaced dorsal frontal fractures in order to reduce the articular defect and help prevent secondary joint changes. Nonsurgical therapy in the form of stall rest with a heavy support wrap resulted in bony healing of the fracture in 4 to 6 months.
Follow-up was obtained on all nine horses: two were retired for breeding; five performed equal to or better than their previous level of racing performance; one was performing successfully as a combined training horse; and one returned to a lower level of performance due to an unrelated forelimb lameness.