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1.
Vet Q ; 35(2): 76-81, 2015 Jun.
Article in English | MEDLINE | ID: mdl-25831401

ABSTRACT

BACKGROUND: Acylcarnitines play an important role in fuel metabolism in skeletal muscle. OBJECTIVE: To assess acylcarnitine ester utilization by the hindlimb of horses at rest and following low intensity exercise and carnitine supplementation. ANIMALS AND METHODS: Acylcarnitine ester uptake by the hindlimb was investigated using the arteriovenous difference technique. Blood from six warmblood mares (mean age 12 ± 3 (SD) years and weighing 538 ± 39 kg) was collected simultaneously from the transverse facial artery and from the caudal vena cava. Food was withheld for 12 hours prior to exercise. Exercise comprised a standardized treadmill protocol consisting of 5 minutes of walk, 20 minutes of trot and thereafter another 5 minutes of walk. At the end of the first exercise day, three horses were given carnitine supplementation (100 mg/kg bodyweight), whereas the other horses received saline. The next day the exercise was repeated and blood samples collected similarly. Free carnitine and acylcarnitines were analyzed as their butyl ester derivatives in heparinized plasma by electrospray tandem mass spectrometry. Statistical analysis was performed using a general linear mixed model. RESULTS: C3-carnitine, C6-carnitine and C14:1-carnitine showed the largest average extraction by the hindlimb at rest and C3-carnitine, C5:1-carnitine and C16-carnitine immediately after low-intensity exercise. Carnitine supplementation significantly increased free carnitine, C5-carnitine and C8-carnitine extraction. CONCLUSION: Carnitine supplementation altered the extraction of acylcarnitines by the hindlimb in horses exercising at low intensity. CLINICAL IMPORTANCE: Findings might aid in optimizing performance and myopathy prevention of the equine athlete.


Subject(s)
Carnitine/analogs & derivatives , Carnitine/administration & dosage , Hindlimb/metabolism , Horses/metabolism , Motor Activity/drug effects , Motor Activity/physiology , Animals , Carnitine/blood , Carnitine/metabolism , Dietary Supplements , Female , Horses/blood , Linear Models , Mass Spectrometry/veterinary , Rest
2.
Vet J ; 202(1): 26-32, 2014 Oct.
Article in English | MEDLINE | ID: mdl-25127376

ABSTRACT

Different head-and-neck positions (HNPs) are discussed in relation to potential welfare issues. To evaluate the effect on welfare, seven Royal Dutch Sport horses were studied in five predetermined HNPs: (1) unrestrained (HNP1); (2) neck raised, bridge of nose around the vertical (HNP2); (3) neck lowered and considerably flexed, bridge of nose pointing towards the chest (HNP4); (4) neck raised and extended, bridge of nose in front of the vertical (HNP5), and (5) neck lowered and flexed, bridge of nose pointing towards the carpus (HNP7). A standardised exercise test (SET) of 34 min consisted of trot, canter and walk. Behaviour was recorded with a pre-defined ethogram and R-R intervals measured using telemetry. Cortisol concentrations were taken at the start, 5 and 30 min after the SET. Behaviour around the SET was scored separately. Conflict behaviours increased significantly during HNP2 when compared with HNP1, HNP4 and HNP7 during the SET, and there was significant negative anticipation before HNP2 and HNP7. The heart rate variability (HRV) frequency domain for HNP2 showed a significantly increased low frequency peak (LFpeak) compared with other HNPs, and there was a decrease in very low frequency (VLF%) compared with HNP1. HNP4 showed a significant increase in LF% and decrease in VLF% compared with HNP1. Saliva cortisol concentrations were significantly increased in HNP2 at 5 and 30 min after exercise. Increased conflict behaviour was mostly observed in HNP2, but there was a raised HRV suggesting a sympathetic shift in HNP2 and HNP4, and increased cortisol concentrations during HNP2 indicated a stress response.


Subject(s)
Heart Rate/physiology , Horses/physiology , Hydrocortisone/blood , Physical Conditioning, Animal/physiology , Animals , Biomechanical Phenomena , Female , Gait , Head , Male , Neck , Posture
3.
Vet Q ; 33(1): 20-4, 2013.
Article in English | MEDLINE | ID: mdl-23594165

ABSTRACT

BACKGROUND: In particular branched-chain amino acids might limit muscle protein loss in pathological conditions. Little is known on basic amino acid utilization of muscle in horses. OBJECTIVE: To assess amino acid utilization by the hindlimb of horses at rest and following low intensity exercise. ANIMALS & METHODS: Amino acid uptake by the hindlimb was investigated using the arteriovenous difference technique. Blood from six warmblood mares (mean age 12 ± 3 (SD) years and weighing 538 ± 39 kg) was collected simultaneously from the (transverse) facial artery and from the caudal vena cava. Food was withheld for 12 hours prior to exercise. Exercise comprised a standardized treadmill protocol consisting of 5 minutes of walk, 20 minutes of trot, and thereafter another 5 minutes of walk. Amino acids were determined quantitatively by means of anion exchange chromatography. Statistical analysis was performed using a general linear mixed model. RESULTS: Amino acids with the largest average extraction at rest were citrulline (11.1 ± 9%), cystine (8.3 ± 36%), serine (7.9 ± 11%), and leucine (5.9 ± 9%). Of the 25 amino acids studied, none showed a significant difference following exercise. Glycine (485 ± 65 µmol/L), glutamine (281 ± 40 µmol/L), valine (183 ± 26 µmol/L), and serine (165 ± 22 µmol/L) showed highest plasma concentrations. The average extraction for α-aminobutyric acid at rest was 18.2 ± 26%. Arterial plasma citrulline concentration was higher than venously. CONCLUSION: Citrulline, cystine, serine, and leucine might be regarded as most important amino acids at rest in warmblood mares. CLINICAL IMPORTANCE: Further investigation is necessary into the specific role of leucine supplementation to preserve or restore body protein in horses.


Subject(s)
Amino Acids/blood , Amino Acids/metabolism , Hindlimb/metabolism , Horses/physiology , Physical Conditioning, Animal , Aminobutyrates/blood , Animals , Chromatography, Ion Exchange/veterinary , Female
4.
Equine Vet J Suppl ; (41): 52-6, 2012 Feb.
Article in English | MEDLINE | ID: mdl-22594027

ABSTRACT

REASONS FOR PERFORMING STUDY: To compare the pharmacokinetics of the fourth generation cephalosporin, cefquinome, in neonatal foals, 6-week-old foals and mature New Forest ponies in order to recommend appropriate dosage regimens for use of this drug. METHODS: Cefquinome was administered i.v. at 1 mg/kg bwt twice a day (q. 12 h), 1 mg/kg bwt 3 times a day (q. 8 h) or 4.5 mg/kg bwt q. 12 h to each age group (n = 6). Plasma cefquinome concentrations were analysed using high-performance liquid chromatography combined with electrospray tandem mass spectrometry. RESULTS: Both foal age groups had comparable pharmacokinetic data except for the volume of distribution at a steady-state (Vss), total body clearance (ClB) and mean residence time (MRT). Both ClB and MRT decreased as the age of the foals increased. Values of area under the curve increased, in a dose dependent manner, with significant increases for all age groups following administration of 4.5 mg/kg bwt q. 12 h. Total body clearance did not have comparable dose dependency. CONCLUSIONS: Cefquinome can be given at a dose of 1 mg/kg bwt q. 12 h for the treatment of infections caused by susceptible pathogens with MIC < 0.125 microg/ml. A higher dose of 4.5 mg/kg bwt q. 12 h is recommended for the treatment of bacterial pathogens with minimal inhibitory concentration (MIC) 0.125-0.5 microg/ml POTENTIAL RELEVANCE: Commonly used dosing regimens should be critically evaluated in neonatal foals due to the higher volume of distribution of less lipophilic drugs in this age group.


Subject(s)
Aging/physiology , Anti-Bacterial Agents/pharmacokinetics , Cephalosporins/pharmacokinetics , Horses/blood , Animals , Animals, Newborn , Anti-Bacterial Agents/administration & dosage , Anti-Bacterial Agents/blood , Area Under Curve , Cephalosporins/administration & dosage , Cephalosporins/blood , Chromatography, High Pressure Liquid/veterinary , Dose-Response Relationship, Drug , Female , Half-Life , Microbial Sensitivity Tests
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