Research in veterinary science.
Publisher:
British Veterinary Association. London : British Veterinary Association
Frequency: Bimonthly
Country: England
Language: English
Author(s):
British Veterinary Association.
Start Year:1960 -
ISSN:
0034-5288 (Print)
1532-2661 (Electronic)
0034-5288 (Linking)
1532-2661 (Electronic)
0034-5288 (Linking)
Impact Factor
2.4
2022
| NLM ID: | 0401300 |
| (DNLM): | R25920000(s) |
| (OCoLC): | 01644503 |
| Coden: | RVTSA9 |
| Classification: | W1 RE231 |
Improvement in arterial oxygen tension with change in posture in anaesthetised horses. Observations were made on horses spontaneously breathing oxygen, with halothane at a constant end tidal concentration. The horses were positioned in dorsal recumbency for the first 45 minutes of each anaesthetic episode during which the arterial oxygen tension (PaO2) was found to peak and then decline. The remaining 60 minutes of each anaesthesia was used to test the effect of various manoeuvres on PaO2. The PaO2 of horses decreased further both when remaining in dorsal recumbency and when repositioned in right or left recumbency. In contrast, placing the horses in sternal recumbency for these...
Effect of a respiratory gas collection mask on some measurements of cardiovascular and respiratory function in horses exercising on a treadmill. The effects of a respiratory gas collection mask on arterial blood gases, acid base values, oxygen content, respiratory frequency and heart rate, were investigated in standardbred horses during treadmill exercise at speeds up to 10 m sec-1 and a treadmill slope of 10 per cent. The mask had no significant effect on heart rates during exercise, but respiratory frequency was lower when the mask was used. The increase in respiratory frequency as treadmill velocity increased was also significantly slower with the mask operative. Arterial carbon dioxide tensions were significantly higher during exer...
In vitro and in vivo binding of phenylbutazone and related drugs to equine feeds and digesta. In vitro and in vivo studies of phenylbutazone binding to equine ingesta and digesta were undertaken. In vitro binding to chopped hay and powdered pony nuts in buffer solutions at 37 degrees C was found to be time-, concentration- and pH-dependent. Percentage binding generally increased with time, decreased with concentration and varied with buffer pH in an unpredictable manner. Other non-steroidal anti-inflammatory drugs (NSAIDs) also bound to hay, the degree of binding being less for meclofenamate and least for flunixin in comparison with phenylbutazone. Phenylbutazone became bound to digest...
Definition of 15 equine leucocyte antigens. Fifteen equine leucocyte antigens were defined by absorption and titration analysis of alloantisera obtained by natural sensitisation through pregnancy and by planned experimental immunisation. Definitive sera were tested on the cells of 90 unrelated horses and members of eight equine families. The family data suggested that 13 specificities were coded by a single locus (first locus) and one specificity (Eq 14) was coded by a second linked locus. The remaining specificity (Eq 7) was controlled by a third locus unlinked to the first or second loci. Tests on the cells of unrelated horses showed ...
Influence of arachidonic acid metabolites in vitro and in uterine washings on migration of equine neutrophils under agarose. The influence of arachidonic acid metabolites on migration of equine neutrophils under agarose was investigated. Leukotriene B4 (LTB4) was chemotactic at concentrations between 0.1 and 1000 ng ml-1 and prostaglandin E2 (PGE2) at 1 and 10 ng ml-1 but not at higher or lower concentrations. Prostaglandin F2 alpha (PGF2 alpha) was not chemotactic for equine neutrophils at any concentration. Random migration was significantly inhibited (P less than 0.05) by suspension of neutrophils in LTB4 (0.1 to 1000 ng ml-1) and PGF2 alpha (0.1 ng ml-1) but not at high concentrations. There was a significant po...
Effects of a specific thromboxane synthetase inhibitor in equine endotoxaemia. Thromboxane A2 may play a major role in circulatory shock. In some species, thromboxane synthetase inhibitors have a beneficial effect on shock induced by endotoxin, trauma, sepsis and administration of arachidonate. In some shock models, however, results with thromboxane synthetase inhibitors have been conflicting. The effect of UK-38,485, a selective thromboxane inhibitor, was evaluated in ponies injected with endotoxin intraperitoneally. Four groups of ponies were used to compare the effects of endotoxin alone, UK-38,485 alone, treatment with UK-38,485 before endotoxin challenge and treatme...
Influence of chemotactic agents on the locomotion of equine polymorphonuclear and mononuclear leucocytes. Subpopulations of equine leucocytes, polymorphonuclear and mononuclear cells, were separated from whole blood on a discontinuous Percoll gradient and used in studies of chemokinesis and chemotaxis. Polymorphonuclear cells responded to the chemo-attractant properties of zymosan-activated plasma in Boyden chamber and agarose microdroplet assays but they responded only slightly (Boyden chamber) or not at all (agarose microdroplet) to the peptide N-formyl-methionyl-leucyl-phenylalanine (FMLP). Equine mononuclear cell movement was increased by FMLP in both assay systems and these cells also respond...
HPLC determination and pharmacokinetics of thiabendazole and its major metabolite 5-OH thiabendazole in equine plasma. Separate high performance liquid chromatographic methods were developed for thiabendazole (TBZ) and 5-hydroxy thiabendazole (5-OH-TBZ) determination in horse plasma using 1-methyl-2-phenyl benzimidazole (MPBZ) as an internal standard. In both methods TBZ and 5-OH-TBZ were extracted from plasma using organic solvents, injected on to a C-18 column, and eluents monitored by a fluorescence detector. However, mobile phase composition, extraction solvent as well as detector wavelength differed in the two methods. The linear range for TBZ was 0.02 to 0.77 microgram ml-1 while that for 5-OH-TBZ was 0....
Responses of horses to acepromazine maleate administered orally in a paste. The effects of acepromazine maleate (ACP), given orally in a paste form, were examined in six standard-bred geldings over a 12 hour period. Three dose rates, zero (placebo paste), 0.13 mg kg-1 and 0.26 mg kg-1, given before or after feeding, were investigated. The data were divided into two sampling periods for analysis, one from zero to 120 minutes and the other from four to 12 hours. Sedation was assessed by a score (TS score) based on general appearance, anal sphincter relaxation and penile protrusion. This TS score was significantly elevated 40 minutes after dosing with ACP, irrespective o...
Development of an enzyme-linked immunosorbent assay for the detection of phenothiazine tranquillisers in horses. An acepromazine (ACP) hapten was synthesised, coupled to bovine serum albumin and injected into a horse to produce antibodies to the drug. A competitive ELISA was developed whereby ACP attached to the solid phase via lysozyme competed with free ACP present in phosphate buffered saline, horse serum or horse urine for limiting amounts of antibody. The assay could detect the presence of ACP and, or, some of its metabolites in horse urine for at least 25 hours after intravenous injection of 0.1 mg kg-1 ACP maleate, but because of non-specific interference, horse serum could not be used. As little ...
Pharmacokinetics of intravenously administered ketamine in the horse. The metabolism and distribution of ketamine and its two major metabolites (norketamine and dehydronorketamine) was investigated in 10 horses undergoing airway surgery. Following premedication with xylazine (1.1 mg kg-1 intravenously) anaesthesia was induced by the rapid injection of ketamine at a dose of 2.2 mg kg-1 intravenously. Anaesthesia was maintained with halothane vaporized in oxygen and nitrous oxide (50:50). Serially collected blood samples were analysed by a sensitive gas liquid chromatographic technique. Plasma ketamine concentrations declined biexponentially with a rapid initial d...
Radioimmunoassay of thromboxane B2 in horse plasma. A radioimmunoassay for thromboxane B2 (TXB2) in unextracted horse plasma was evaluated. Sensitivity of the assay was 14.0 (SD 5.6) pg ml-1 of plasma. Interassay and intra-assay variation were 21.3 per cent and 4.3 per cent, respectively. The percentage of tracer bound in unextracted plasma in the absence of TXB2 was often higher than that in buffer. Therefore standard curves were obtained using standards diluted in plasma from horses treated with aspirin or in charcoal treated TXB2-free plasma. Standard curves determined in plasma and buffer were parallel. This assay was used to determine the ...
Cartilage thickness measurement in foals. The talus and proximal and distal epiphysis of the humerus, radius, femur, tibia and distal metacarpus of 20 foals aged 0 to 150 days were obtained at necropsy and sawn sagittally into slabs 4 to 8 mm thick. The thickness of the cartilage (articular cartilage and unossified epiphyseal cartilage) was measured in three to five places in each slab, using a sliding calliper. In most epiphyses, the site, or sites, of thickest cartilage was constant in all foals examined. The difference between thickest and thinnest cartilage within one epiphysis was greatest in distal femora and least in distal met...
Demonstration of the carrier state in naturally acquired equine arteritis virus infection in the stallion. The chronic carrier state was virologically confirmed in 15 thoroughbred stallions naturally infected with equine arteritis virus based on the results of test matings and, or, isolations of the virus from semen. Carrier stallions were shown to shed equine arteritis virus in the semen for at least one to two years. Existence of a short-term or convalescent carrier state was also demonstrated in five additional stallions. The frequency of the long-term carrier state in stallions naturally infected with equine arteritis virus was 35 per cent; it varied considerably between groups of stallions on ...
Absorption of phenylbutazone from a paste formulation administered orally to the horse. The absorption pattern of phenylbutazone was studied in five horses during administration of the drug in a paste formulation on days 1, 5, 8 and 12 of a 12-day dosing schedule. Since two or more plasma concentration peaks were usually obtained following each oral dose, it was concluded that phasic absorption was a particular feature of the oil:water formulation of the product. Possible causes of this unusual absorption pattern are discussed and the therapeutic implications of both phasic absorption and the recorded values of Cmax, tmax and AUC024 for phenylbutazone and its active metabolite ox...
Variations in cross-sectional area and composition of equine tendons with regard to their mechanical function. The cross-sectional area, collagen content, dry weight as a percentage of the wet weight and the tendon fibre percentage of the cross-sectional area of the equine hindlimb were determined in the superficial and deep digital flexor tendons and the suspensory ligament at 10, 12 and six sites between tarsus and insertion respectively. The values of each of the four parameters varied between different sites in the same tendon, between different tendons within a horse and between analogous tendons of different horses. Within a tendon the cross-sectional area was inversely proportional to the collag...
Sex variation in the prevalence of exercise-induced pulmonary haemorrhage in racing quarter horses. Post race endoscopy was carried out on 255 two-year-old quarter horses and exercise-induced pulmonary haemorrhage (EIPH) was diagnosed in 166 (65 per cent) of them. Visible epistaxis was seen in a higher proportion of geldings than in either mares or stallions. The prevalence of EIPH was similar in mares (73 per cent) and in geldings (74 per cent). A significantly lower prevalence (49 per cent) was noted in stallions (P less than 0.01). It was concluded that a sex variation in the prevalence of EIPH exists in two-year-old quarter horses.
Crystalline composition of equine urinary calculi. X-ray diffraction crystallography was used to determine the crystalline composition of 18 equine urinary calculi, including stones originating in the kidney, bladder and urethra. Calcium carbonate in the form of calcite was found to be the major component in all calculi examined. Other components commonly found included weddellite and substituted vaterite. Urine deposits from a number of normal horses were also examined. The significance of these findings, as well as those from a number of previous reports, are discussed in relation to the possible aetiology of urolithiasis in the horse.
Effects of warfarin on blood rheology in navicular disease. A preliminary investigation has been undertaken of blood rheology in horses and ponies, its variation in navicular disease and the changes following treatment with warfarin. Erythrocyte flexibility, measured by a centrifuge packing technique, is higher in horses (30 per cent min-1) than in ponies (23.8 per cent min-1). There are corresponding differences in blood viscosity. The high erythrocyte flexibility in horses is caused by an unknown factor present in plasma. The erythrocyte flexibility in horses with navicular disease is even higher, at 38.5 per cent min-1. Treatment with warfarin reduc...
Effects of flunixin meglumine, phenylbutazone and a selective thromboxane synthetase inhibitor (UK-38,485) on thromboxane and prostacyclin production in healthy horses. The efficacy of three agents which alter the metabolism of arachidonic acid was investigated in normal, conscious horses. A dose response evaluation was made of flunixin meglumine and phenylbutazone, two cyclo-oxygenase inhibitors, and of a selective thromboxane synthetase inhibitor, UK-38,485. Radioimmunoassay of thromboxane B2 (TxB2) and 6-keto prostaglandin F1 alpha (PGF1 alpha) was used to assess the concentrations of thromboxane A2 (TxA2) and prostacyclin (PGI2) respectively, in serum. Flunixin was the most potent inhibitor of serum TxB2 and 6-keto PGF1 alpha production. UK-38,485 also de...
Specific antibody in the equine genital tract following local immunisation and challenge infection with contagious equine metritis organism (Taylorella equigenitalis). Antibody in serum, uterine and vaginal secretions was measured following local immunisation and experimental infection with the organism of contagious equine metritis (Taylorella equigenitalis). Intrauterine immunisation with killed T equigenitalis stimulated a systemic IgG titre and a uterine IgA and IgM response. Subsequent challenge with the organism, however, resulted in a characteristic metritis in both control and vaccinated mares. Antibody in serum and secretions was increased following challenge infection, dwarfing the response to immunisation. The local response was restricted to the ...
Effects of verapamil on the smooth muscle of the horse urinary tract. The effects of verapamil, a calcium antagonist agent, were studied on smooth muscle preparations of the lower urinary tract of horses. Verapamil (2 X 10(-4) to 2 X 10(-8) M) relaxed the ureter, urethra and urinary bladder preparations contracted by potassium (127 mM), L-noradrenaline (2 X 10(-5) M), histamine (2 X 10(-5) M) and acetylcholine (2 X 10(-5) M). These results allow the conclusion that verapamil has a dose-dependent relaxing effect on smooth muscle of the lower urinary tract.
In vitro mechanical properties of equine tendons in relation to cross-sectional area and collagen content. The mechanical properties of the deep digital flexor tendon (DDFT), the superficial digital flexor tendon (SDFT) and the suspensory ligament (SL) of the hindlimb of the horse were studied in vitro. The tendons were observed at several morphologically distinct sites. The loaded tendon is homogeneously strained, in spite of large variations in cross-sectional area. Consequently the modulus of elasticity was inversely proportional to the corresponding cross-sectional area and ranged from 738 MPa (megaPascal, N mm-2) to 1398 MPa within the DDFT, from 1000 MPa to 1282 MPa within the SDFT and from 5...
In vivo bone strain in the equine tibia before and after transection of the peroneus tertius muscle. The present study was undertaken to determine the influence of the peroneus tertius muscle on the loading regime of the tibia in the horse. Strain gauge rosettes were bonded to the cranial and caudal cortices of the left and right tibiae in six Shetland ponies. In vivo bone strain recordings were made before and after unilateral transection of the peroneus tertius muscle. Relatively large individual variations in response to transection were observed in both the experimental and the contralateral control limbs. The principal strain values on the cranial and caudal cortices increased during the...
Spirochaetes in the equine caecum. Two morphological types of spirochaete were found in the horse caecum measuring 4 to 6 micron by 0.3 to 0.4 micron and 6 to 8 micron by 0.1 to 0.2 micron. Attempts were made to culture the organisms but none survived subculture beyond the primary isolate. Electron microscopy revealed that many of the organisms were infected by bacteriophages.
Unusual compound of small molecular weight in the serum of horses with acute grass sickness. An unusual compound of small molecular weight has been detected in serum from horses with acute grass sickness by solvent extractions and thin-layer chromatography. The substance has not been detected in the serum of normal horses or cases of equine colic and apparently disappears from grass sickness serum after two to three days of clinical illness. Although this compound is found in sera which are known to possess in vivo neurotoxicity, this property could not be demonstrated in either the total chloroform extract which contains the compound or in the hydrophilic serum components remaining a...
Breed and species comparison of amino acid transport variation in equine erythrocytes. The amino acid permeability of red blood cells from Equus caballus (thoroughbred, Arab, shire and pony), E przewalskii (Przewalski's horse), E asinus (donkey and mule) and E burchelli (common or plains zebra) was measured. Individual animals exhibited stable but widely differing rates of L-[U-14C]alanine uptake in the range 5 to 1554 mumol (litre cells)-1 h-1 (0.2 mM extracellular L-alanine, 37 degrees C). Of the thoroughbreds tested, 30 per cent had red blood cells which were essentially impermeable to L-alanine (5 to 10 mumol (litre cells)-1 h-1, giving transport rates similar to those found...
Transformation of cultured equine fibroblasts with a bovine papillomavirus. Fetal equine fibroblasts exposed to bovine papillomavirus became transformed by the criteria of morphological alterations and the acquisition of an increased life span, although they failed to grow in soft agar. Papillomavirus genome persisted in the transformed fibroblasts and was apparently not integrated with the cellular genome. These findings support the notion that bovine papillomaviruses are involved in the production of equine sarcoids.
Production and biological properties of M-protein of Streptococcus equi. The production of M-protein antigen of Streptococcus equi was studied during in vitro growth in equine blood and in various media. Of 11 S equi strains studied, seven which had initially possessed 0.04 mg or less M-protein per 10 mg of streptococcal cell extract showed an increase in M-protein content after successive culture in heparinised horse blood. Maximum proliferation occurred in Todd-Hewitt (TH) medium with added 0.2 per cent w/v glucose when compared with TH medium alone or TH medium with 2 per cent w/v sucrose, starch, neopeptone or normal horse serum. The M-protein of these strains ...
Immunohistological studies of the local immune system in the reproductive tract of the mare. The immunoperoxidase technique was adapted for the identification of free immunoglobulin and immunoglobulin producing cells in equine tissues. Staining specific for free IgG, IgA and IgM was detected at all levels of the reproductive tract, and secretory component staining was present in the uterine epithelium but not in the oviduct, cervix or vagina. Immunoglobulin producing cells were present at all levels of the tract, with IgG and IgA cells at equivalent concentrations, but with fewer IgM cells. There was no cyclical trend in free immunoglobulin staining, or plasma cell numbers. IgG and Ig...