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Topic:Veterinary Medicine
Veterinary medicine for horses encompasses the study and application of medical practices to diagnose, treat, and prevent diseases in equine species. This field involves a comprehensive understanding of equine anatomy, physiology, pathology, and pharmacology. Veterinary practitioners employ a range of diagnostic tools and therapeutic interventions to address health issues in horses, including lameness, gastrointestinal disorders, respiratory conditions, and infectious diseases. Preventative care, such as vaccination and deworming programs, is also a significant aspect of equine veterinary medicine. This page gathers peer-reviewed research studies and scholarly articles that explore various aspects of veterinary medicine as it pertains to horses, including advancements in diagnostic techniques, treatment protocols, and preventive health strategies.
A rapid diagnostic assay for eastern equine encephalomyelitis viral RNA. Eastern equine encephalomyelitis virus (EEEV) has been a low-frequency, but serious human and veterinary health problem. Increased frequency of this mosquito-borne virus is anticipated as wetlands are maintained and re-established. Control of EEEV has depended on mosquito abatement in response to increasing frequency of EEEV in the environment. A coupled reverse transcription/polymerase chain reaction assay was designed to rapidly, sensitively, and specifically detect EEEV RNA. The assay successfully detected the viral RNA in a single-blind study of a set of field samples composed of either po...
[Narcolepsy in horses]. Narcolepsy is an incurable non-progressive disease of the central nervous system. In humans, narcolepsy causes excessive drowsiness during the day (sometimes a sleep-attack occurs), cataplexy (sudden loss of muscle tone), hallucinations, and sleep paralysis. In the horse and other mammals cataplexy is the most frequently observed symptom. Excessive drowsiness can occur but is harder to observe. Cataplexy is caused by a fragmentation of the REM sleep. The etiology of narcolepsy is still subject to debate, partly because normal sleeping patterns are poorly understood. In humans and certain breed...
Sedatives, tranquilizers, and stimulants. Drugs of relevance to equine practice that modify the central nervous system (CNS) can be broadly classified as depressants or stimulants. The pharmacologic mechanisms of action, uses, and side effects of selected CNS depressant and stimulant drugs in horses are reviewed. Knowledge of the way these CNS-modifying drugs may affect performance is limited.
Regulatory aspects of drug use in performance horses. The control of drug use in performance horses and the policing of rules and regulations to prevent unauthorized drug use are important tasks for agencies overseeing equestrian events. This article describes the roles of the American Horse Shows Association, the Federation Equestre Internationale, and the Association of Racing Commissioners International, Inc, in the policing of drug use in horses competing in events under their control.
Narcotics and local anesthetics. The recognition and alleviation of animal pain is a growing veterinary and public concern. Pain can be of an acute or chronic nature with different behavioral manifestations. Physiologically, pain is a dynamic and complex phenomenon that produces changes in the central and autonomic nervous systems as well as in the endocrine system. Horses and other animals appear to possess an endogenous pain-suppressing system involving the brainstem and spinal cord. This system can modulate pain perception and the responses to it. The recently discovered endogenous opioid peptides (endorphins and enkephali...
Equine plasminogen polymorphism: allelic frequencies in 23 breeds. A modified procedure for detection of the two alleles of equine plasminogen using Western blotting methods following polyacrylamide gel isoelectric focusing is described. Gene frequencies in 23 breeds and Equus przewalskii are provided.
Sonographic brightness of the flexor tendons and ligaments in the metacarpal region of horses. Sonographic observations were made of the image mean gray scale (MGS) of the flexor tendons and ligaments in the left and right metacarpal regions of each of 10 clinically normal horses. In images made in the dorsal and sagittal planes, the MGS was measured at multiple sites in the superficial digital flexor tendon (SDFT), deep digital flexor tendon (DDFT), accessory ligament (AL), and suspensory ligament (SL), and at single sites in the medial and lateral limbs of the SL, and the palmar ligament. Relative sonographic brightness of each tendon and ligament was calculated by dividing the value ...
Granulomatous enteritis and cutaneous arteritis in a horse. A 5-year-old Quarter Horse mare was examined because of weight loss of 2 months' duration. The horse was anemic and in poor body condition, and had several areas of cutaneous ulceration, including areas on the muzzle and distal portion of the limbs. Histologic examination of a rectal mucosa biopsy specimen revealed a lymphoplasmacytic infiltrate in the lamina propria mucosa. Results of a glucose absorption test were suggestive of malabsorption. Histologic examination of a biopsy specimen from the cutaneous lesions revealed pronounced arteritis, and weak, patchy immunofluorescent staining for i...
Cardiopulmonary and behavioral responses to computer-driven infusion of detomidine in standing horses. Cardiopulmonary and behavioral responses to detomidine, a potent alpha 2-adrenergic agonist, were determined at 4 plasma concentrations in standing horses. After instrumentation and baseline measurements in 7 horses (mean +/- SD for age and body weight, 6 +/- 2 years, and 531 +/- 48.5 kg, respectively), detomidine was infused to maintain 4 plasma concentrations: 2.1 +/- 0.5 (infusion 1), 7.2 +/- 3.5 (infusion 2), 19.1 +/- 5.1. (infusion 3), and 42.9 +/- 10 (infusion 4) ng/ml, by use of a computer-controlled infusion system. Detomidine caused concentration-dependent sedation and somnolence. The...
Effects of atropine on the arrhythmogenic dose of dobutamine in xylazine-thiamylal-halothane-anesthetized horses. We investigated the influence of parasympathetic tone on the arrhythmogenic dose of dobutamine in horses premedicated with xylazine, anesthetized with guaifenesin and thiamylal, and maintained on halothane in oxygen. Six horses were used in 12 randomized trials. In each trial, after end-tidal halothane concentration was stabilized at 1.1% (1.25 times minimum alveolar concentration [MAC]) in oxygen, either saline solution (0.02 ml/kg of body weight) or atropine (0.04 mg/kg) was administered IV. Five minutes later, dobutamine infusion was started at dosage of 2.5 micrograms/kg/min, IV. The dobut...
Kinetic analysis of D-xylose absorption after its intragastric administration to mares deprived of food. Multicompartmental analysis was applied to study the kinetics of D-xylose distribution after its intragastric administration to healthy mares deprived of food for 12, 36, 72, and 96 hours. Disposition of D-xylose was described by a 5-compartment model. Maximal plasma D-xylose concentration was similar for 12 and 36 hours of food deprivation and was greater (P = 0.0001) than the values for 72 and 96 hours. Peak concentration of D-xylose appeared progressively later as food deprivation proceeded (P = 0.0001). Fractional rate of transfer (k1,6) was less after 96 hours of food deprivation, compare...
Pharmacokinetics of metronidazole after rectal administration in horses. Five healthy adult mares and 1 gelding were given a single dose (15 mg/kg of body weight) of metronidazole per rectum. After manual evacuation of feces from the rectum, a suspension of crushed tablets and water (40 ml) was administered via a 28-F catheter advanced 30 cm into the rectum. Blood samples were obtained by jugular venipuncture, and metronidazole concentration was measured serially for the 14 hours after drug administration. Mean serum concentration of metronidazole peaked at 4.5 micrograms/ml, 0.83 hour after administration, and decreased to 0.38 microgram/ml, 14 hours after adminis...
Pharmacokinetics of phenylbutazone in neonatal foals. Single doses (2.2 mg/kg of body weight) of phenylbutazone (PBZ) were administered IV to 6 neonatal horses (5 to 17 hours old at time of dosing). Plasma concentrations of PBZ and its metabolite oxyphenbutazone were monitored serially for 120 hours after drug administration. Pharmacokinetic variables were calculated, using 1- and 2-compartment open models. Descriptive equations from the best model for each foal were then used to derive model-independent variables describing PBZ disposition. Median volume of distribution at steady-state was 0.274 L/kg (range, 0.190 to 0.401 L/kg). Median terminal...
Pharmacokinetics of and serum thromboxane suppression by flunixin meglumine in healthy foals during the first month of life. Age and species reportedly affect the pharmacokinetic variables of nonsteroidal anti-inflammatory drugs. We determined the effect of age on flunixin pharmacokinetic variables in foals during the first month of life. We also estimated the physiologic activity of the drug in neonatal foals by determining the effect of flunixin on thromboxane production during clotting of blood taken from the foals. Flunixin disposition and clearance were determined after IV administration of 1.1 mg of drug/kg of body weight to 5 healthy foals when they were 24 to 28 hours, 10 to 11 days, and 27 to 28 days old. T...
Effects of sympathomimetic and sympatholytic drugs on exercise performance. This article has presented information on the importance of the sympathetic nervous system in the response to exercise. The authors have reviewed the very limited information on the effects of sympathomimetic and sympatholytic drugs on exercise performance in the horse. Most of these drugs are specifically prohibited under the rules of racing, and they have significant side effects that either decrease performance or make their use dangerous to both the horse and horse-man. Additionally, all of these drugs or their metabolites are readily detected by current drug testing protocols. Further inf...
A comparison of the reduction in immunoglobulin (IgG) concentration of frozen equine plasma treated by three thawing techniques. The IgG concentration of plasma from 13 mares was measured by radial immunodiffusion when fresh and after storage at -4 degrees C and thawing by 3 methods. There was no significant (P > 0.05) reduction in the IgG concentration when plasma was thawed over 6 hours at 22 degrees C (1352.9 +/- 101.6 mg/dL) (mean +/- SEM) compared with the fresh sample (1369.5 +/- 88.1 mg/dL). In contrast, there was a significant (P < 0.05) reduction in the IgG concentration of plasma that was rapidly thawed at 57 degrees C over 50 minutes (1142.9 +/- 66.2 mg/dL), or placed in a microwave oven for 20 to 25 minutes ...
Ischemia/reperfusion injury of the ascending colon in ponies: a correlative study utilizing microvascular histopathology and corrosion casting. Volvulus of the ascending colon (ACV) in the horse results in microvascular injury and necrosis of the intestinal mucosa. This study investigated the site and type of microvascular injury which occurs within the mucosa and submucosa following ACV. Histopathology of volvulus treated ponies demonstrated mucosal necrosis with microvascular hemorrhage and thrombosis. Thrombi occurred within the subepithelial capillaries and edema and hemorrhage developed throughout the mucosa and submucosa. Vascular casts allowed 3-D viewing of samples obtained from the entire pelvic flexure and demonstrated two d...
Factors affecting drug withholding time estimates in horses. Although all the factors discussed in this article may have an effect on drug withholding time estimates, the factors that have the potential for the greatest effect or that have been found to cause positive tests in the past are 1. Dosage: Increasing the drug dosage will require a longer withholding time. 2. Dosing interval: Narrowing the dosing interval will require a longer withholding time. 3. Administration route: In general, oral administration results in lower peak plasma concentrations but may result in longer excretion in the urine and therefore longer withholding time. 4. Drug intera...
[Cryopreservation trial with semen of purebred Arabian and Haflinger stallions in the Turkish national stud in Karacabey]. Within a German-Turkish university partnership deep freezing preservation of stallion semen was performed as a part project of the cooperation contract. In this study a modification of the introduced Makrotüb method was used for semen freezing. The investigated characteristics of fresh semen of the Arab stallions were in the normal range cited in the international literature. However, the semen data obtained from the Haflinger stallions were markedly and partially significantly in lower range than measured for the Arab stallions. This may reflect an incomplete adaptation process of the import...
Myocarditis following envenoming with Vipera palaestinae in two horses. Cardiac disease developed several days to weeks after resolution of local inflammation caused by envenoming by Vipera palaestinae in two horses. In one horse (case A), referred to the hospital for recurrent abdominal pain 8 days after envenoming, a tachyarrhythmia was detected; ventricular premature depolarizations were diagnosed by ECG. A second horse (case B) was found dead without premonitory signs 60 days after envenoming. In both horses, there was extensive necrosis of cardiac ventricular tissues.
Aromatase activity in the mare ovary during estrous cycle. Measurement of endogenous steroids and of their in vitro inhibitory effect. This present study was undertaken to clarify estrogen synthesis in the mare ovary. First of all, an evaluation of endogenous steroid contents was carried out in the follicular fluid and in the luteal tissue at different stages of the luteal phase. Radioimmunoassays were performed after separation and purification of each hormone by chromatography. High amounts of conjugated (0.9 mg/l) and unconjugated (4 mg/l) estradiol-17 beta were found in the follicular fluid of the large follicules (50 mm). These concentrations of estrogens decreased drastically in the luteal tissue, and only low levels of...
Evaluation of serum amyloid A protein as an acute-phase reactive protein in horses. Serum amyloid A protein (SAA) was isolated from equine acute-phase serum by repeating Sephadex G-75 gel filtration 3 times. Quantitative measurement of equine SAA was performed by the single radial immunodiffusion technique with rabbit anti-equine SAA serum. In clinically normal horses, the SAA concentration remained relatively high from immediately after birth up to 1 week of age. After this the concentration showed periodic fluctiation in the range of approximately 13 to 30 micrograms/ml. The mean (+/- SD) concentration of SAA in foals ( or = 18 months old) was 19.37 +/- 9.41 and 21.53 +/- 9...
Clinical use and characteristics of the corticosteroids. Corticosteroids possess potent anti-inflammatory activity and are commonly injected intra-articularly for local relief of inflammatory lesions in performance horses. However, the suppression of anabolic activity in the joint may lead to an increased rate of joint breakdown. Complications associated with intra-articular corticosteroid therapy include septic arthritis, which is usually due to inadvertent joint contamination at the time of corticosteroid injection, and steroid arthropathy, which is characterized by an accelerated rate of joint destruction and radiographic evidence of severe degen...
Duration of antigen-induced hyperresponsiveness in horses with allergic respiratory disease and possible links with early airway obstruction. Antigen-induced airway hyperresponsiveness in allergic horses has previously been demonstrated when clinical signs of acute airway obstruction were apparent, as a consequence of exposure of animals to hay and straw for variable periods of time, and repeat measurements of hyperresponsiveness have been made no earlier than 1 week after challenge. In the present study airway responsiveness to methacholine has been measured in normal horses and allergic horses in clinical remission before and 24, 48 and 72 h after a hay and straw challenge of fixed, short, duration (7 h). Correlations between earl...
Eastern equine encephalitis (EEE): a description of the 1989 outbreak, recent epidemiologic trends, and the association of rainfall with EEE occurrence. An Eastern equine encephalitis (EEE) outbreak in 1989 led to nine human and 196 equine cases, chiefly in coastal Atlantic and Gulf Coast counties. In the past two decades, EEE age-specific incidence and mortality rates have declined compared with earlier years. Analysis of rainfall patterns in areas where human EEE cases occurred between 1983 and 1989 revealed an association between occurrence of human cases and excess rainfall. The association was stronger with data from local weather stations than from statewide rainfall averages and the predictive models were best when applied to northern s...
Pharmacokinetic values of drugs frequently used in performance horses. Tables of values of pharmacokinetic variables (volume of distribution, total body clearance, and plasma elimination half-life) of drugs frequently administered to performance horses are accompanied by explanatory notes. Drugs described include the nonsteroidal anti-inflammatory drugs, corticosteroids, anabolic steroids, central nervous system-modifying drugs, respiratory system drugs, diuretics, local anesthetics, and antibacterial drugs.
Anabolic steroids. Anabolic steroids have been employed extensively in equine practice over the past 25 years. Their usefulness is largely dependent on subjective opinions, as only minimal studies have been carried out in horses. Therefore, their use will vary markedly between practitioners depending on their personal experiences and pressures by trainers to use them. They form part of rational therapy in a variety of conditions. In addition to use for increasing muscle mass, they are used to a varying extent in the raising of yearlings and in the training and racing of horses with the view of improving performa...
Effects of single intravenously administered doses of omeprazole and ranitidine on intragastric pH and plasma gastrin concentration in nonfed ponies. We investigated the effects of a range of IV administered doses of omeprazole (0.125 to 2.0 mg/kg of body weight) on gastric pH (monitored by indwelling electrode) and plasma gastrin concentration, compared with those of IV administered ranitidine (1.0 mg/kg) in 4 Welsh mountain-type ponies. Pharmacokinetic variables of IV administered omeprazole also were examined. Episodes of high gastric pH in the basal state obscured the effect of acid suppression on intragastric pH; however, omeprazole induced dose-dependent increase in mean gastric pH (P < 0.01) during the 11 hours after its administr...
Effect of furosemide on physiologic variables in exercising horses. Twelve horses (6 Standardbreds and 6 Thoroughbreds) received IM injections of furosemide (250 mg) or physiologic saline solution and performed standard exercise tests, to assess the effects of furosemide and breed on blood gas values, PCV, plasma lactate concentration, and heart rate during exercise. After furosemide administration, arterial and venous blood pH values were significantly (P < 0.05) increased. Partial pressures of O2 and CO2 in arterial blood and of CO2 in venous blood (PaO2, PaCO2, and PVCO2, respectively) were unaffected by furosemide treatment, whereas venous partial press...
Fluids, electrolytes, and bicarbonate. In an attempt to enhance performance, primarily by delaying the onset of fatigue, a variety of formulations of fluids, electrolytes, and sodium bicarbonate are administered to performance horses. Some current practices of fluid and electrolyte supplementation are well justified; others have no basis to support their use. In addition, occasional combined administration of certain agents (i.e., furosemide and sodium bicarbonate) can have detrimental effects on performance.
