Oral administration of tepoxalin in the horse: a PK/PD study

Tepoxalin is a non-steroidal anti-inflammatory drug with analgesic, anti-inflammatory, and antipyretic properties and has been recently introduced into veterinary medicine. The aim of this study was to evaluate the pharmacokinetic/pharmacodynamic (PK/PD) profile of tepoxalin to assess whether it would be suitable for clinical use in horses. Six female fasting/fed horses were given 10mg/kg tepoxalin orally in a cross-over study. After administration, tepoxalin underwent rapid and extensive hydrolytic conversion to its carboxylic acid metabolite RWJ-20142. In animals that had been fed, the plasma concentrations of tepoxalin were undetectable, whereas in fasting animals they were close to the limit of quantification of the method. No differences between the fasting/fed groups in RWJ-20142 plasma concentrations were shown. Tepoxalin showed a strong and long-lasting ex vivo inhibitory activity against cyclooxygenase (COX)-1, mainly due to its main metabolite RWJ-20142. Tepoxalin and RWJ-20142 do not seem to possess either COX-2 or 5-lipoxygenase inhibitory activity in the horse. These features suggest that the drug is a selective COX-1 inhibitor in horses, with no significant anti-inflammatory activity. Thus, its long term use in equine practice could be of concern.     

The effects of restriction of movement on the reliability of heart rate variability measurements in the horse (Equus caballus)

Analysis of heart rate variability (HRV) is a noninvasive approach for investigating the sympathovagal balance of the autonomic nervous system. In recent years, HRV has been increasingly evaluated in animal research. In horses, it has been suggested that basal resting conditions can be achieved by restraining them. The aim of this study was to verify how restriction of movement influences HRV i2n horses. Ten healthy standardbred mares were used to measure the electrocardiographic signal under 2 conditions: free to move in the stall and restrained in the stock. Results indicate that the restriction of movement is associated with increased nervous system sympathetic activity not consistent with resting conditions.     

Conjunctival fungal flora in healthy donkeys

OBJECTIVE: To identify and quantify ocular fungi from healthy donkeys living in the center of Italy. ANIMALS STUDIED: One hundred and two Amiata donkeys were examined. PROCEDURES: Conjunctival swabs from both eyes were seeded onto Sabouraud dextrose agar (SDA) and malt extract agar (MEA), and incubated at 25 degrees C over a 10-day period. Filamentous fungi identification was achieved to the genus level; yeast colonies were identified for macro-micromorphologic and physiological characteristics. RESULTS: Eighty-one donkeys out of 102 (79.4%) were positive for fungi; 47/102 (46.1%) had positive cultures from both eyes. Most frequently recovered fungal genera were Aspergillus spp., Penicillium spp., Cladosporium spp., Acremonium spp. Different fungal genera and/or species were recovered from the same donkey in 43 cases (42.1%). Yeasts were isolated from five subjects; the yeasts were never associated with molds. The number of colony forming units (CFU) ranged from 1 to 100. CONCLUSIONS: Aspergillus was the most commonly isolated fungal genus (33%). This result agrees with the findings of similar surveys carried out in horses. There was a remarkable presence of fungi and perfect forms. These observations may be explained by the optimal conditions for presence and development of fungi in the conjunctival fornix microenvironment in Amiata donkeys.     

Early Evidence of the Anticipatory Response of Plasma Catecholamine in Equine Exercise

Catecholamines seem to play a role in equine exercise physiology that is somewhat different from their role in human beings. In sport horses, a greater increase in plasma adrenaline (ADR) levels occurs in response to strenuous exercise as compared with human beings. However, it is not known whether this is true for breeds not specifically bred for sport. The aim of this study was to gather data on plasma catecholamine kinetics during exercise in a nonracing breed. We also attempted to evaluate the influence of the phases preceding the start of the exercise on the kinetics of these molecules. Four 2-year-old female Esperia ponies were made to perform a four-step exercise test on a treadmill. Blood samples were collected in the box (basal 1), in the treadmill room (basal 2), and at the conclusion of each step, using an automatic system. ADR and noradrenaline (NOR) levels were determined by high-pressure liquid chromatography. Results were analyzed using analysis of variance and the Student-Newman-Keuls test. As compared with basal 1, basal 2 showed a significant 19.6-fold increase for ADR and a 6.7-fold increase for NOR. The highest concentration was observed for both molecules at the end of the fourth step, with a significant 1.2-fold increase as compared with blood samples collected at basal 2 for ADR and a 2.4-fold increase for NOR. Therefore, in Esperia ponies, catecholamine showed a trend similar to that of Standardbreds and Thoroughbreds. The results reported in this study also revealed a marked increase in ADR in the phases preceding the beginning of physical activity. Therefore, the greater adrenergic activity in horses in response to exercise could be because of an anticipatory response.     

Plasma Procalcitonin Concentration in Healthy Horses and Horses Affected by Systemic Inflammatory Response Syndrome

Background

The diseases most frequent associated with SIRS in adult horses are those involving the gastrointestinal tract. An early diagnosis should be the goal in the management of horses with SIRS.

Objective

The objective of this study was to evaluate the plasma procalcitonin (PCT) concentration in healthy and SIRS horses to assess differences between the two groups.

Animals

Seventy‐eight horses (30 healthy and 48 SIRS).

Methods

Prospective in vivo multicentric study. Horses were classified as SIRS if at least 2 of the following criteria were met: abnormal leukocyte count or distribution, hyperthermia or hypothermia, tachycardia, tachypnea. Healthy horses showed no clinical or laboratory signs of SIRS. Plasma PCT concentrations were measured with a commercial ELISA assay for equine species. Results were expressed as mean±standard deviation. T‐test for unpaired data was performed between healthy and SIRS group. SIRS group was divided in 4 subgroups and t‐test was performed between healthy versus each subgroup.

Results

PCT concentrations in healthy and SIRS horses were 18.28 ± 20.32 and 197.0 ± 117.0 pg/mL, respectively. T‐test showed statistical differences between healthy versus SIRS group and between healthy versus all subgroups.

Conclusions and Clinical Importance

Results showed an increase in PCT concentration in SIRS horses as previously reported in humans and dogs. PCT could be used as a single assay in equine practice for detection of SIRS.