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Topic:Veterinary Research
Veterinary research in horses encompasses the study of diseases, health management, and medical treatments specific to equine species. This field investigates various aspects of horse health, including infectious diseases, metabolic disorders, and musculoskeletal conditions. Researchers focus on understanding the pathophysiology of equine ailments, developing diagnostic tools, and evaluating therapeutic interventions. The study of horse health also involves examining preventive measures such as vaccination protocols and nutritional management to promote overall well-being. This page collects peer-reviewed research studies and scholarly articles that explore the diverse areas of veterinary science related to horses, providing insights into disease mechanisms, treatment strategies, and advancements in equine healthcare.
Matrix metalloproteinases 2 and 9 in equine synovial fluids. Matrix metalloproteinases (MMPs) may be important in the destruction of cartilage seen in equine osteoarthritis and may be detectable in synovial fluid. Synovial fluids were obtained from normal equine joints and from joints of horses with aseptic and septic joint diseases. The total MMP gelatinase enzyme activities were measured by gelatin zymography and image analysis of the gels. The bioactivity of gelatinase in synovial fluid was determined by a gelatin degradation ELISA. Potential MMP-2 & MMP-9 monomer enzyme activities were significantly elevated in both septic and aseptic joint dise...
Failure of lipopolysaccharides to directly trigger the chemiluminescence response of isolated equine polymorphonuclear leukocytes. Divergent results have been reported on the effects of lipopolysaccharides (LPS) on the activation of equine polymorphonuclear leukocytes (PMN). We therefore attempted to determine whether LPS alone can stimulate equine PMN or whether plasma factors are necessary. PMN were isolated from citrated blood on a discontinuous density gradient of Percoll. The luminol (10(-3) mol/L)-enhanced chemiluminescence (CL) of 1.25 x 10(6) cells was measured after addition of Escherichia coli LPS (0.001-10 micrograms/ml) alone or after incubation in autologous plasma (1 h, 37 degrees C). After direct stimulatio...
Aerosol deposition in equine lungs following ultrasonic nebulisation versus jet aerosol delivery system. Therapeutic aerosols pay an increasing role in the treatment of equine respiratory disorders. This route of delivery permits concentration of significant amounts of drugs at the site of action without unwanted high systemic concentration and resultant side effects. The efficiency of such a topical therapy depends on the quantity of inhaled drugs deposited in the lungs and, for some drugs, on the proportion retained in specific parts of the lungs. The objective of this study was to define and to compare quantitative (dose deposited) and qualitative (regional distribution) deposition of an aeros...
Measurement of total body water content in horses, using deuterium oxide dilution. To measure total body water (TBW) content in horses, using deuterium oxide (D2O) dilution. Methods: Six 8- to 10-year-old healthy untrained mixed-breed horses, weighing (mean +/-SD) 503.4 +/- 64.0 kg. Methods: After a 12-hour nonfeeding period, 6 horses were given D2O (0.14 g/kg of body weight) via nasogastric tube. Blood samples were collected from a preplaced indwelling jugular vein catheter prior to and 1 to 8, 10, 12, 14, and 24 hours after administration of D2O. Blood samples were centrifuged immediately, and plasma was collected and stored at -70 C until analysis. The D2O content in plas...
An introduction to mammalian interspecific hybrids. Haldane's law states that in interspecific hybrids, it is the heterogametic sex that is likely to be absent, rare, or sterile. In mammals, there is increasing evidence to suggest that this may be due to the high mutation rate of male sex-determining genes on the Y chromosome. The mule, humanity's first successful attempt at genetic engineering, provides some support for this concept. Interspecific hybrids may also shed new light on the importance of the maternal transmission of mitochondrial DNA and the phenomenon of genomic imprinting.
Pharmacokinetics of enrofloxacin in horses after single intravenous and intramuscular administration. Pharmacokinetic behaviour of enrofloxacin was studied in 6 horses after intravenous (i.v.) or intramuscular (i.m.) administration of enrofloxacin (5 mg/kg bwt). Concentration of enrofloxacin and ciproflaxin were measured by high performance liquid chromatography in serum. Antimicrobial activity of the samples was determined with an agar-diffusion technique. Reactions at the site of i.m. injection were monitored clinically and by determination of serum creatine kinase (CK) activity. After i.v. administration, elimination half-life of enrofloxacin was 4.4 h and volume of distribution was 2.3 1/k...
Extraction and quantification of acrosin, beta-N-acetylglucosaminidase, and arylsulfatase-A from equine ejaculated spermatozoa. Acrosin, Arysulfatase A, and beta-N-acetylglucosaminidase are three key enzymes localized within the mammalian acrosome that play a pivotal role in the penetration of the oocyte. The objectives of this study were to compare two methods of enzyme extraction based on the activities of these enzymes from equine spermatozoa. Method A utilized a 0.5 M Tris-maleate buffer containing 0.1% Triton X-100 and Hyamine 2389. Method B used 0.05 M Tris-HCl, 0.05 M MgCl2 in 0.05 M Tris-maleate, followed by 0.05 M Tris-maleate containing 0.1% Triton X-100. Results indicated that acrosin was initially bound in ...
Flow cytometric method for detecting thiazole orange-positive (reticulated) platelets in thrombocytopenic horses. To evaluate a method for detecting thiazole orange-positive (TO+, reticulated) platelets in equine blood, using flow cytometry. Methods: 16 healthy, equine infectious anemia virus (EIAV)-negative horses and ponies; 9 thrombocytopenic, EIAV-positive horses and ponies; and 2 thrombocytopenic, EIAV-negative horses. Methods: Blood from healthy and thrombocytopenic horses was collected by jugular venipuncture. Appropriate sample requirement and incubation time for the assay were evaluated, using blood anticoagulated with EDTA or sodium citrate, or platelet-rich plasma in sodium citrate. The sample ...
The effect of pulsatile gonadotropin-releasing hormone and estradiol administration on luteinizing hormone and follicle-stimulating hormone concentrations in pituitary stalk-sectioned ovariectomized pony mares. Hourly pulses of gonadotropin-releasing hormone (GnRH) or bi-daily injections of estradiol (E2) can increase luteinizing hormone (LH) secretion in ovariectomized, anestrous pony mares. However, the site (pituitary versus hypothalamus) of positive feedback of estradiol on gonadotropin secretion has not been described in mares. Thus, one of our objectives involved investigating the feedback of estradiol on the pituitary. The second objective consisted of determining if hourly pulses of GnRH could re-establish physiological LH and FSH concentrations after pituitary stalk-section (PSS), and the th...
Cartilage canals in equine articular/epiphyseal growth cartilage and a possible association with dyschondroplasia. Cartilage canals have been described in most mammals and contain the vascular elements necessary for the maintenance of epiphyseal growth cartilage. The presence and longevity of cartilage canals in developing articular/epiphyseal cartilage of horses is described for the first time. Growth cartilages from 30 normal horses (from 130 days gestation to age 2 years) and 6 cases of dyschondroplasia (age 6 months. Cartilage canals were associated with retained cartilage of dyschondroplastic lesions found in animals age < 15 months. The presence of cartilage canals in association with dyschondrop...
Preliminary study of ovarian activity in fillies treated with a GnRH vaccine. To investigate the effects of two doses (200 and 400 mg) of a water-soluble gonadotrophin-releasing hormone vaccine on the ovarian activity of 2-year-old fillies. Methods: A controlled vaccination dose rate experiment. Methods: Six 2-year-old Australian Stock Horse fillies were randomly allocated to three treatment groups; unvaccinated controls, those receiving 200 mg of the vaccine and those receiving 400 mg of the vaccine. Results: Ovarian activity of the treated fillies was suppressed at the peak of breeding season while that of untreated controls continued normally. The control fillies dis...
Role of endothelium and nitric oxide in the in vitro response of equine colonic venous rings to vasoconstrictor agents. To determine in vitro contractile responses of equine colonic veins to various vasoconstrictor agents. Methods: Colonic veins collected from 8 adult horses. Methods: Veins were cut into 4-mm-wide rings, placed in organ baths at 37 C, and attached to a force-transducer interfaced with a polygraph; 2 g of tension was applied, and rings were allowed to equilibrate for 45 minutes. Bath solution was replaced, and tension was reapplied at 15-minute intervals. Cumulative concentration responses (10(-8) to 10(-4) M) were determined for each agent, using separate rings (n = 8). Three vein groups were e...
Clinical features of blister beetle poisoning in equids: 70 cases (1983-1996). To document clinical signs and gross pathologic changes associated with naturally acquired cantharidiasis (blister beetle poisoning) in equids. Methods: Retrospective study. Methods: 70 equids with laboratory-confirmed blister beetle poisoning. Methods: Medical records were reviewed to obtain history, physical examination findings, feeding practices, and diagnostic test and necropsy results. Results: 32 horses and 2 donkeys died from exposure to cantharidin, whereas 36 horses survived. Diet content varied, but alfalfa hay was the common component. Onset of signs of disease was rapid. Most equi...
Brodifacoum toxicosis in two horses. Increased popularity during the past decade of brodifacoum, an anticoagulant rodenticide, has led to an increase in cases of accidental poisoning in nontarget species, including pets and farm animals. Pharmacokinetics of second-generation anticoagulant rodenticides such as brodifacoum are substantially different from those of first-generation anticoagulant rodenticides such as warfarin. This difference dramatically influences management of exposure in terms of duration and cost of treatment and may affect outcome. The National Poison Control Center reports that approximately 50 cases of brodif...
Vitamin A repletion in thoroughbred mares with retinyl palmitate or beta-carotene. Forty-five Thoroughbred mares used in an 8-mo depletion study were kept for an additional 20 mo on the same three forage diets (15 mares each): 2-yr-old orchardgrass hay and vitamin A-free concentrate on a drylot (HC); pasture, orchardgrass/alfalfa hay, and vitamin A-free concentrate (PHC); or pasture and orchardgrass/alfalfa hay only (PH). Each diet group was divided into three subgroups, and mares (n = 5) in each group were given either retinyl palmitate (A) at twice the NRC (1989) recommended daily intake, the equivalent amount of vitamin A in the form of water-dispersible beta-carotene (B)...
The soft-tissue components of the vomeronasal organ in pigs, cows and horses. The soft-tissue components of the vomeronasal organ of the pig, the cow and the horse were studied with the aid of dissection, microdissection, and light microscopy and immunohistochemistry of series of transverse sections. In horses, the rostral end of the incisive duct was blind: thus, unlike in pigs and cows, there was no communication between the vomeronasal organ and the oral cavity. In all three species, the central part of the vomeronasal duct bore the 'typical' respiratory/ receptor epithelium lining on its lateral and medical walls. The rostral part of the duct was characterized by st...
Evaluation of the variably ossified collateral cartilages of the distal phalanx and adjacent anatomic structures in the Finnhorse with computed tomography and magnetic resonance imaging. Six Finnhorse cadaver forefeet were selected to represent radiographically different types and grades of ossification of the collateral cartilages of the distal phalanx. These cartilages and adjacent tissues were evaluated with computed tomography (CT) and high field magnetic resonance imaging (MRI). In CT the internal structure of the cartilages was consistent, but in MRI some differences were noted. The shape of the collateral cartilages and their ligamentous attachments varied. The border between ossified and non-ossified cartilage appeared distinct, with considerable variation in the exten...
Antigenic diversity of granulocytic Ehrlichia isolates from humans in Wisconsin and New York and a horse in California. The agent of human granulocytic ehrlichiosis (HGE), Ehrlichia phagocytophila, and Ehrlichia equi are very similar. HGE is of variable severity. Genetic and antigenic differences among 3 human isolates (Webster, Spooner, and NY-8) and 1 horse isolate (MRK) were evaluated. The 16S rRNA gene sequences were identical in all human isolates. By use of 5 homologous antisera from these 3 humans and 1 horse and an additional 5 antisera in heterologous reactions, the immunodominant antigens of each isolate were noted to differ in molecular size: 43 kDa in the Webster (Wisconsin) isolate, 46 kDa in the S...
In vitro comparison of cytochrome P450-mediated metabolic activities in human, dog, cat, and horse. As domestic animals such as cat, horse, and dog increasingly become the clinical targets for drug discovery programs, the need to understand how these animals metabolize xenobiotics becomes more important. In the present study, substrates and inhibitors that were reported to be selective for particular P450 isozymes were used as probes to study in vitro metabolism in horse, dog, cat, and human liver microsomes. Seven selective catalytic activity markers for cytochrome P450-mediated reactions were measured: phenacetin O-deethylase (P4501A1/2), coumarin 7-hydroxylase (P4502A6), tolbutamide hydro...
Airway response of horses with COPD to dry powder inhalation of ipratropium bromide. To determine the effects of the dry powder inhalation (DPI) of ipratropium bromide (ipratropium) on the airways of health horses and the dose-response curve in horses suffering from chronic obstructive pulmonary disease (COPD) by means of pulmonary function tests, five healthy horses were first studied. Ipratropium (2400 micrograms ipratropium horse-1) was contained in gelatine capsules and administered using a dry powder device connected to an adapted face mask. Pulmonary function tests were recorded before inhalation and 15 and 60 min after inhalation. No modification of pulmonary function w...
The intercarpal ligaments of the equine midcarpal joint, Part 2: The role of the palmar intercarpal ligaments in the restraint of dorsal displacement of the proximal row of carpal bones. To determine the relative contributions of the palmar intercarpal ligaments in the midcarpal joint to the restraint of dorsal displacement of the proximal row of carpal bones. Methods: A biomechanical study of cadaver equine carpi. Methods: Eight equine forelimbs from six thoroughbred horses. Methods: With joints in full extension, the radius was dorsally displaced while midcarpal joint displacement was measured. The restraining force at a joint displacement of 1.5 mm was determined from the load-displacement curve. A ligament or pair of ligaments was then cut and the testing procedure repeate...
The intercarpal ligaments of the equine midcarpal joint, Part 1: The anatomy of the palmar and dorsomedial intercarpal ligaments of the midcarpal joint. To describe in detail the structure of the medial palmar intercarpal ligament (MPICL), the lateral palmar intercarpal ligament (LPICL), and a dorsomedial intercarpal ligament (DMICL) of the equine midcarpal joint. Methods: Dissections of equine midcarpal joints. ANIMALS AND SAMPLE POPULATION: Ten carpal joints from eight thoroughbred horses. Methods: Detailed dissections of the midcarpal joint were performed, with particular attention paid to the MPICL, the LPICL, and the DMICL. The attachments and dimensions of these structures were recorded, as well as their behavior during joint movement. R...
Effect of alpha-phenyl-tert-butylnitrone on endotoxin toxemia in horses. Lipopolysaccharide (LPS), or endotoxin, is a component of the cell wall of gram-negative bacteria and is toxic to humans and animals. The GI tract of horses contains large numbers of endotoxins which may cause disease if gut wall integrity is compromised. The objective of this study was to develop a unique therapeutic approach to the treatment of endotoxemia with a sulfonyl analog of the alpha-phenyl-N-tert-butyl-nitrone (PBN) spin-trap molecule which may prevent the LPS-induced cytokine cascade. Following challenge with 55 mg/kg LPS, the survivability of ICR Swiss mice was significantly impro...
IL-1 beta induces the degradation of equine articular cartilage by a mechanism that is not mediated by nitric oxide. Proteoglycan degradation was induced in young equine articular cartilage explants cultured for eight days in the presence of 50 ng/ml recombinant human interleukin-1 beta. Degradation was initiated after 6 hours of exposure to the cytokine. This was accompanied by an induction of nitric oxide synthesis and a decrease in the incorporation of [36S]sulphate into the glycosaminoglycan chains of proteoglycans. The addition of 1mM N-iminoethyl-L-ornithine (an inhibitor of nitric oxide synthase) to the explant cultures in the presence of rhIL-1 beta suppressed the synthesis of NO and restored proteog...
