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Abstract

Objective

To determine pharmacokinetic variables that describe disposition of ketoprofen after its IV administration to foals < 24 hours old.

Animals

6 healthy foals (1 male and 5 females); mean age, 12.5 (range, 8.5 to 17) hours at time of dose administration.

Procedure

Ketoprofen was administered IV to foals at a dosage of 2.2 mg/kg of body weight. Ketoprofen concentration in plasma samples was analyzed, using high-performance liquid chromatography. Concentration versus time profiles were analyzed according to standard pharmacokinetic techniques. Blood samples were obtained from foals by jugular venipuncture at defined times during a 48-hour period. Samples were centrifuged, and plasma was frozen at −70 C until analyzed. One-, two-, and three-compartment analyses were conducted. The most appropriate model was determined by use of Akaike's information criterion analysis.

Results

Plasma concentration versus time profiles were best described, using a two-compartment open model. Clearance (normalized for body weight) was significantly lower than that determined for adult horses. Volume of distribution (normalized for body weight) was larger than that determined for adult horses. Mean (harmonic) plasma half-life for healthy foals < 24 hours old was 4.3 hours.

Clinical Relevance

Although additional factors, such as dehydration or sepsis, must be considered on a case-by-case basis, the dose of ketoprofen administered to foals < 24 hours old should be different from the dose administered to adult horses. Under similar clinical circumstances, doses in foals should be increased by as much as 1.5 times to produce comparable therapeutic concentrations; longer dose intervals, based on clinical response, would be necessary to avoid drug toxicity. (Am J Vet Res 1998;59:290–292)

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

Abstract

Objective—To describe the anatomic features of the pituitary gland region in horses via computed tomography (CT) and determine the accuracy of CT for estimating normal equine pituitary gland dimensions.

Animals—25 adult horses with no clinical signs of pituitary disease.

Procedure—Transverse CT images and gross transverse tissue sections were compared in 2 horses. Contrast-enhanced CT of the pituitary gland region was performed postmortem in 23 horses with 4 slice thickness and interval settings (10-mm contiguous or overlapping slices and 4-mm contiguous or overlapping slices). Gross and CT estimates of pituitary gland dimensions were compared via ANOVA. Accuracy of CT estimates was calculated with gross pituitary gland measurements as the known value.

Results—Pituitary glands were located between the temporomandibular joints and had contrast enhancement. Mean gross dimensions were length, 2.11 cm; width, 2.16 cm; height, 0.98 cm; and volume, 2.66 cm3. Gross measurements and CT estimates of pituitary gland length from 10-mm contiguous and overlapping slices did not differ. Gross measurements and CT estimates of pituitary gland width from 4-mm contiguous and overlapping slices did not differ. Estimates of height and volume from all CT techniques differed from gross measurements. Accuracies for CT estimates were length, 88 to 99%; width, 81 to 92%; height, 58 to 71%; and volume, 43 to 55%.

Conclusions and Clinical Relevance—Accuracy of estimates of pituitary gland dimension in horses varied with CT scanning technique; via CT, estimates of length and width of glands were more accurate than estimates of height or volume. (Am J Vet Res 2003;64:1387–1394)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether a limited sampling time method based on serum iohexol clearance (Cliohexol) would yield estimates of glomerular filtration rate (GFR) in clinically normal horses similar to those for plasma creatinine clearance (Clcreatinine).

Animals—10 clinically normal adult horses.

Procedures—A bolus of iohexol (150 mg/kg) was administered IV, and serum samples were obtained 5, 20, 40, 60, 120, 240, and 360 minutes after injection. Urinary clearance of exogenous creatinine was measured during three 20-minute periods. The GFR determined by use of serum Cliohexol and plasma Clcreatinine was compared with limits of agreement plots.

Results—Values obtained for plasma Clcreatinine ranged from 1.68 to 2.69 mL/min/kg (mean, 2.11 mL/min/kg). Mean serum Cliohexol was 2.38 mL/min/kg (range, 1.95 to 3.33 mL/min/kg). Limits of agreement plots indicated good agreement between the methods.

Conclusions and Clinical Relevance—Use of serum Cliohexol yielded estimates of GFR in clinically normal adult horses similar to those for plasma Clcreatinine. This study was the first step in the evaluation of the use of serum Cliohexol for estimating GFR in adult horses.

Full access
in American Journal of Veterinary Research