Equine health encompasses the study and management of diseases, disorders, and overall well-being of horses. It involves understanding various physiological systems, preventive care, and treatment strategies to maintain optimal health in equine populations. Common areas of focus include nutrition, infectious diseases, orthopedic conditions, and reproductive health. Research in equine health aims to advance knowledge on diagnostic methods, therapeutic interventions, and management practices that improve horse welfare and performance. This page collects peer-reviewed research studies and scholarly articles that explore the diverse aspects of equine health, offering insights into current findings and advancements in the field.
Nickels FA.Conditions of this portion of the respiratory tract are relatively uncommon. This article reviews these conditions and discusses the different modes of therapy. The conditions covered are redundant alar folds, diseases of the nasal septum, fungal infections, neoplasms, nasal polyps, and ethmoid hematomas. The different surgical approaches to the nasal cavity are reviewed, and surgery of removal of the nasal septum and the alar fold are described.
Kollias-Baker CA, Pipers FS, Heard D, Seeherman H.Pulmonary edema associated with transient airway obstruction was detected in 3 horses. The cause of obstruction was different in each horse, but after relief of the obstruction, clinical signs and radiographic abnormalities were indicative of pulmonary edema. In 2 of the 3 horses, pink frothy fluid was evident in the airways. The horses were treated with furosemide, nasal insufflation of O2, anti-inflammatory agents, and anti-biotics. Of the 3 horses examined, 1 horse died acutely, 1 horse recovered fully, and 1 developed pleuritis and was subsequently euthanatized.
Inoue J, Cerbito WA, Oguri N, Matsuzawa T, Sato K.The serum concentrations of testosterone and oestrogens were determined in stallions classified as geldings, normal (according to age) or infertile (azoospermic). There were significant differences in testosterone and oestrogen levels between the groups. Normal concentrations of testosterone and total oestrogens were attained after 16 months of age. Castrated and immature horses ( 4 years). The results suggest that serum levels of testosterone and total oestrogens may provide a sensitive index of the endocrine function of the testis in male horses.
Sager M.The aim of this article is to emphasize the need for analgesic medication in animals in possibly painful situations, especially in the postoperative period. The two large groups of compounds used as analgesics--the opiates and the nonsteroidal antiinflammatory drugs (NSAIDs)--are described with special reference to their pharmacokinetics, side-effects and toxicity, their mechanism of action, their indications and contraindications. Recommended doses of the different drugs available are given for the dog, the cat, the horse, the swine and the small and large ruminants.
Bogdan JR, Morley PS, Townsend HG, Haines DM.This study has tested the effect of using homologous or heterologous equine influenza A virus isolates to evaluate serum antibody levels to influenza A virus in vaccinated and naturally-infected horses. In addition, the potential effect of antigenic selection of virus variants in egg versus tissue culture propagation systems was studied. Serum antibody levels in samples from horses recently infected with a local influenza A virus isolate (A/equine 2/Saskatoon/1/90) or recently vaccinated with a prototype isolate (A/equine 2/Miami/1/63) were assessed by hemagglutination inhibition and by single...
MacDonald MH.Examination of the equine head should be a routine part of any complete physical examination. It can be performed rapidly and efficiently while providing important information about the health and function of several major body systems.
Aviles G, Bianchi TI, Daffner JF, Sabattini MS.It is shown here the WEE virus activity in ARgentina in 1983-1986 post-epizootic period. A surveillance system was established by the equine case notification and the sentinel animal method. Among the thirteen equine focus notified between September 1983-September 1985 in Córdoba and Santa Fe Provinces, 5 presumptive cases out of 16 sick horses were confirmed by the hemagglutination inhibition test for WEE epizootic virus. Twenty eight notified human cases were studied with negative results. The neutralizing antibody (Ac NT) prevalence among sentinel horses in Córdoba Province (4%) was lower...
Gaughan EM, DeBowes RM.Many questions concerning heritability arise when a veterinarian is asked to supervise and treat disease of congenital origin. Genetic counseling, ethics, and legality are often confronted in discussions between animal health professionals and laymen in animal industry. Guidelines have been offered as in the 1984 statement of the Judicial Council of the American Veterinary Medical Association: "Performance of surgical procedures in all species for the purpose of concealing genetic defects in animals to be shown, raced, bred, or sold as breeding animals is unethical. However, should the health ...
Miyamoto C, Takashima I, Karaiwa H, Sugiura T, Kamada M, Hashimoto N.To investigate the overall prevalence of chlamydial infections in light (i.e. non-draught) horses in Japan, 599 sera obtained from 12 localities in 1991 were tested for complement fixation antibodies. The mean antibody positive rates of the all sera were 15.2% (91/599) and the regional positive rates were higher in Honshu (19.1%, 48/251) and Kyushu (20.0%, 20/100) than in Hokkaido (9.3%, 23/248). In Honshu, the highest rate (56.0%, 28/50) was observed in Utsunomiya. Analysis of the positive rate in different age groups showed that the 2-5 years age-group had the highest prevalence of chlamydia...
Mellor DJ.Physiological challenges facing the perinatal individual are huge. This is partly because of the marked and abrupt change from the intrauterine to the extrauterine environment, but also because the physiological responses to that change depend upon systems whose maturation is affected markedly by birth. Perinatal maturation appears, therefore, both to precede and accompany the physiological adaptations required for neonatal survival. This review does not provide a comprehensive coverage of perinatal physiology but directs attention towards evaluating constraints on foetal and neonatal thermoge...
Davicco MJ, Coxam V, Faulconnier Y, Dubroeucq H, Martin-Rosset W, Barlet JP.The present study was undertaken to assess GH secretory profiles in 12 light-breed foals and their dams during forty days after delivery, and the possible influence of GRF and TRH on plasma GH concentrations in these newborn foals. GH secretory pattern was pulsatile in one day- as well as in forty days-old foals. The number of secretory spikes (10 per 24 h) did not vary between days 1 and 40. In the same times, GH secretion did not show any circadian rhythm either in foals or in their dams. Mean daily plasma concentrations (measured through blood samples collected every 20 min for 24 h) were l...
Kai K, Tateyama S, Miyoshi N, Yamaguchi R, Uchida K, Rostami M.Genomic DNAs of cattle, horses, pigs, dogs, cats and chickens were surveyed using Southern blot hybridization analysis, with a human EGFR cDNA fragment. Several bands with different numbers and molecular weights were observed under the condition of low stringency in the individual animal species. The bands showing DNA polymorphism were observed among bovine genomic PstI-digested DNAs from 4 individuals and EcoRI-digested genomic DNAs from 4 chickens. These results may provide basic data which are useful for analysis of tumorigenetic mechanisms in domestic animals.
Cervantes CC, Brown MP, Gronwall R, Merritt K.Each of 5 healthy mares was given 5 consecutive IM injections of ceftiofur sodium (2 mg/kg of body weight; 50 mg/ml) at 12-hour intervals. Ceftiofur concentrations were measured serially in serum, synovial fluid, peritoneal fluid, and urine, and were measured in CSF and endometrial tissue after the fifth dose. Mean elimination rate constant was 0.354 +/- 0.101 h-1 and elimination half-life was 2.49 +/- 0.49 hour. Mean serum ceftiofur concentrations peaked approximately 1 hour after each injection. The highest mean ceftiofur concentration was 5.09 micrograms/ml at 1 hour after the fifth dose fo...
Troedsson MH, deMoraes MJ, Liu IK.The relationship between histologic lesions in endometrial biopsy specimens and susceptibility to chronic uterine infection (CUI) in mares was investigated. Mares were allotted to 4 groups on the basis of degree of endometrial lesions. Mares in group 1 (n = 6) had no pathologic changes, mares in group 2 (n = 5) had only mild pathologic changes, group-3 mares (n = 7) had moderate changes, and group-4 mares (n = 7) had severe inflammatory and fibrotic endometrial changes. Susceptibility to CUI was determined by the inflammatory response to intrauterine inoculation of 5 x 10(6) Streptococcus zooe...
McGorum BC, Dixon PM, Halliwell RE.Phenotypic analysis of lymphocytes in peripheral blood (PB) and bronchoalveolar lavage fluid (BALF) of control and chronic obstructive pulmonary disease (COPD) affected horses, both before and after 'natural (hay and straw) challenge', were performed using immunofluorescent labelling with monoclonal antibodies and flow cytometry. BALF lymphocytes were shown to be predominantly EqCD5+ cells, approximately half of which were also EqCD8+, with a smaller proportion of B cells. In comparison with PB, BALF contained higher proportions of EqCD5+ cells and EqCD8+ cells and a lower proportion of B cell...
Sweeney CR, Freeman DE, Sweeney RW, Rubin JL, Maxson AD.Three horses were determined to have hemorrhage into a guttural pouch unassociated with mycosis, empyema, neoplasia, or foreign body. The source of the hemorrhage appeared to be the rupture of the longus capitis muscle and its associated vascular supply.
Small AC, Kelly WR, Seawright AA, Mattocks AR, Jukes R.A foal, small and jaundiced from birth, succumbed after two months to chronic hepatic damage which was characterised by fibrosis, biliary ductular hyperplasia and the presence of pleomorphic hepatocytes containing either a single large nucleus or multiple nuclei. The fixed liver contained sulfur-bound pyrroles, which are derived from pyrrolizidine alkaloids. During pregnancy the pasture was heavily infested with the pyrrolizidine alkaloid-containing plant, Senecio madagascariensis. The hepatic disease affecting the foal appears to have been initiated by consumption of the alkaloids by the mare...
Driesang I, Böhm D.Both hock joints were examined clinically, radiologically and scintigraphically in 80 horses with special regard to bone spavin. The positive x-ray and bone scan results corresponded in most cases. It was evident that there was no correlation between degree of lameness and/or extent of radiological findings and increased radioactive uptake in the joint. Scintigraphic evaluation may demonstrate early changes at the onset of bone spavin as well as the frequent bilateral nature of the condition.
McGorum BC, Dixon PM, Halliwell RE.A commercial radioimmunoassay kit was used to quantify histamine concentrations of plasma, bronchoalveolar lavage fluid (BALF) and pulmonary epithelial lining fluid (PELF) of normal horses and horses with chronic obstructive pulmonary disease (COPD), before and after 'natural (hay and straw) challenge' (NC). There were no significant changes in the concentrations of histamine in plasma or BALF at 0.5 or 5 h after NC, but the PELF histamine concentration of COPD affected horses was significantly increased at 5 h, but not at 0.5 h, following NC. As the histamine concentrations of whole BALF lysa...
Nicoll RG, Wood AK, Martin IC.Observations were made in dorsal and sagittal planes of the ultrasonographic mean gray scale of the flexor tendons and ligaments of the metacarpal regions of 5 Thoroughbred geldings, during weight bearing and nonweight bearing. In images made when the horses were nonweight bearing, the mean gray scale of the superficial and deep digital flexor tendons and accessory ligament was significantly reduced, but that of the interosseous medius muscle (suspensory ligament) was not. When relaxed, collagen fiber bundles in the tendons and ligaments acted as diffuse, rather than specular, reflectors of ul...
Trotter GW.Numerous conditions, including trauma, infection, neoplasia, and developmental problems, can affect the paranasal sinuses. Successful resolution of these problems is predicated upon a thorough diagnostic workup to ensure the most accurate presumptive diagnosis. Surgical intervention is enhanced by using approaches that allow wide access to sinus compartments. Rigorous postoperative management is also important to a successful outcome.
Yvorchuk-St Jean KE, Debowes RM, Gift LJ, Kraft SL, Sinha AK, Kennedy GA.A 5-week-old belgian colt was examined for colic of 12 hours duration after several episodes of diarrhea. Physical examination revealed signs of abdominal pain, mild dehydration and normal auscultable borborygmi in all abdominal quadrants. Distention of the cecum, large colon and small intestinal was evident on abdominal radiographs. The foal was treated medically as the owners declined surgery. The colt was euthanized because of continued deterioration and failure to respond to medical therapy. Post-mortem exam revealed the presence of a trichophytobezoar obstructing the distal part of the tr...
Jaeschke G, Lange W.In this paper three outbreaks of equine influenza in Berlin (Germany) in the years of 1988, 1989 and 1991 are discussed, reporting mainly clinical, hematological, virological and some epizootiological aspects. We have detected variations from the traditional pattern of equine influenza, whereby the main clinical symptoms like cough or fever were absent in several cases. If cough was found, it was moist. Furthermore a mucous nasal discharge was present in a number of cases for a period of 4-5 days. Extreme neutropenia, lymphocytosis and predominantly an unchanged level of monocytes were observe...
Freestone JF, Seahorn TL.Nutritional secondary hyperparathyroidism is associated with horses that are fed diets with an imbalance of calcium and phosphorus or diets containing oxalates. Clinical signs include a shifting lameness, with tenderness of the joints, reluctance to move, or a stiff, stilted gait. Some horses may have broadening of the nasal bones, enlargement of the maxilla and/or the mandible, or a ridge over the nasal bones. Diagnosis may include physical examination findings; analysis of feed; and clinical pathologic data, which may include normocalcemia, normal to increased serum phosphorus, and increased...
Park RD.Radiographic examinations of the equine head can be performed with portable x-ray machines. The views comprising the examination depend on the area of the head being examined. With a knowledge of radiographic anatomy and radiographic signs of disease, valuable diagnostic information can be obtained from the radiographic examination. In addition, the radiographic information can also be used to develop a prognosis and determine the most appropriate therapy.
Tulleners EP, Donawick WJ.Infected abdominal incisions in 7 cattle and 3 horses were resutured with monofilamentous stainless steel retention sutures. After debridement of devitalized and infected tissue, wound edges were apposed with simple interrupted vertical (5 cattle, 3 horses) or horizontal (2 cattle) mattress sutures, placed through all layers of the body wall. Sutures were placed 2 to 3 cm apart over rubber tubing, 3 to 5 cm from wound edges. In 5 of the 10 operations, skin and subcutaneous tissue were left unsutured. The repaired wounds were supported with an encircling elastic roll bandage and sterile compres...
Arroyo-Salvo C, Sanhueza F, Fuentes F, Treulén F, Arias ME, Cabrera P, Silva M, Felmer R.Conventional in vitro fertilization has not yet been implemented in the equine species. One of the main reasons has been the inability to develop a culture medium and incubation conditions supporting high levels of stallion sperm capacitation and hyperactivation in vitro. Although different culture media have been used for this purpose, human tubal fluid (HTF) medium, widely used in the manipulation of human and mice gametes, has not been reported so far in stallion sperm culture. The first part of this study aimed to compare HTF and Whitten's media on different stallion sperm quality and capa...
Ross MW.Safe, effective surgery can be performed in the standing, conscious horse using a combination of mechanical and chemical restraint. Clear indications for performing standing abdominal surgery exist, but many procedures are best performed under general anesthesia. The preferred approach involves a modified grid incision of the left paralumbar fossa. Flank celiotomy allows the surgeon to thoroughly explore the abdominal cavity, but few structures can be exteriorized, and visibility of abdominal contents is poor. Indications for standing abdominal surgery include diagnosis of abdominal masses, dr...
The Journal of hygieneJune 1, 1971
Volume 69, Issue 2 201-207 doi: 10.1017/s0022172400021434
Sinclair IS, McCormick JS, Clark JG.The three heterologous anti-sera currently provided for tetanus prophylaxis have been compared with reference to the production of untoward reactions in 498 patients, and to the blood antitoxin concentrations produced in 76 patients. Equine serum, although giving rise to more reactions, was the only effective agent in terms of the levels and duration of serum antitoxin concentration produced. The local response to a test dose of any of the three sera is not a reliable guide to immediate or late general reactions.
Gentry LR, Thompson DL, Stelzer AM.Seventeen seasonally anovulatory light horse mares were treated daily, starting January 5 (d 1), for 28 d with GnRH analog (GnRH-A; 50 ng/kg BW) and(or) thyrotropin-releasing hormone (TRH; 5 microg/kg BW) in a 2 x 2 factorial arrangement of treatments to test the hypothesis that combined treatment may stimulate follicular growth and development. Ovaries were examined via ultrasonography and jugular blood samples were collected every 3 d. Frequent blood samples were collected after treatment injections on d 1, 2, 4, 7, 11, 16, and 22; on d 29, all mares received an i.v. mixture of GnRH, TRH, su...
Andrade DGA, Basso RM, Castiglioni MCR, Silva JP, Machado VMV, Laufer-Amorim R, Borges AS, Oliveira-Filho JP.Four causative mutations (D1, D2, D3*, and D4) of chondrodysplastic dwarfism have been described in the equine () gene. Homozygotes for one of these mutations and heterozygotes for any combination of these mutations exhibit the disproportionate dwarfism phenotype. However, no case description of homozygotes for D4 (D4/D4) has been reported in the literature, to our knowledge. We report 2 Miniature horses with the genotype D4/D4 in the gene. Clinically, the 2 dwarfs had a domed head that was large compared to the rest of the body, mandibular prognathism, and short and bowed limbs, mainly in t...
Hedberg Y, Dalin AM, Santesson M, Kindahl H.Strong oestrous symptoms in the mare can cause problems with racing, training and handling. Since long-acting progesterone treatment is not permitted in mares at competition (e.g. according to FEI rules), there is a need for methods to suppress unwanted cyclicity. Spontaneous dioestrous ovulations in the late luteal phase may cause a prolongation of the luteal phase in mares. Methods: In this preliminary study, in an attempt to induce ovulation during the luteal phase, human chorionic gonadotropin (hCG) (3000 IU) was injected intramuscularly in four mares (experimental group) in the luteal pha...
Wenzel RG, Major D, Hesp KF, Hall E, Doble P.To monitor cobalt concentrations in urine, red blood cells and plasma after chronic parenteral administration of cobalt chloride evaluate these results against the current International Federation of Horseracing Authorities thresholds for detecting cobalt misuse. Methods: Eight mares were randomly assigned to four treatment groups, with two mares in each group: Group 1 - control group, Group 2 - 25 milligrams cobalt intravenously as CoCl weekly, Group 3 - 50 milligrams cobalt intravenously as CoCl weekly, and Group 4 - 25 milligrams cobalt intravenously mid-week and at the end of the week. Uri...
Poonacha KB, Gregory CR, Vickers ML.The primary lesions of eastern equine encephalomyelitis (EEE) virus infection in the horse are limited to the brain and spinal cord. Intestinal lesions in addition to the changes in the central nervous system were found in a 6-month-old male Tennessee Walking Horse. One week prior to death, this colt was vaccinated for EEE virus, western equine encephalomyelitis virus, influenza virus, equine rhinopneumonitis virus, and tetanus. The clinical signs consisted of ataxia and rear-end weakness, with a body temperature of 102.8 F. Gross lesions consisted of yellowish discoloration, swelling, edema, ...
Davies JV.Perhaps because of the inherent difficulty in using horses as experimental animals, only a relatively small amount of data is as yet available regarding normal equine gut motility. However, it is clear that the horse is fundamentally similar to other mammalian species studied. The neural and humoral control of gut activity requires much exploration; it is likely that, in the horse, some of this information will be derived during the investigation of the effects of various substances that might have clinical relevance. This is alluded to in the chapter that follows (The Effects of Pharmacologic...
Vitums A, Bayly WM.Three Arabian males foals were presented with cyanosis, heart murmur, and exercise intolerance, Results of clinical evaluation suggested a tentative diagnosis of ventricular septal defect in conjunction with malformations of the great arteries. Each foal had a poor prognosis and was killed at the owners' requests. At necropsy, the malformed hearts of the three foals were virtually identical. Each heart had a large defect in the upper interventricular septum. The aorta originated from the hypertrophied right ventricle and partially overrode the ventricular septal defect. The aortic ostium was g...
Jacob RJ, Price R, Bouchey D, Davis T, Borchelt J.This article reviews the findings on temperature sensitivity of equine herpesvirus isolates with an emphasis on equine herpesvirus 3, etiological agent of equine coital exanthema. The hypothesis is presented that the relative apathogenic nature of this herpesvirus may be an indirect result of its inability to synthesize and/or process glycoproteins needed by the virus to produce infectious virions at the normal body temperature of its natural host. It is suggested that equine herpesvirus 3 is the more evolved and naturally attenuated member of the equine herpesviruses.
Lefebvre RA, Callens C, Van Colen I, Delesalle CJG.Postoperative ileus (POI) remains an important cause of death in horses. The recently developed selective 5-HT receptor agonists such as prucalopride target 5-HT receptors on myenteric cholinergic neurons to enhance acetylcholine release and GI motility. No clearcut in vitro evaluation whether highly selective 5-HT receptor agonists enhance submaximal cholinergic neurotransmission towards the muscle layer has been performed in horses. Objective: To identify functional 5-HT receptors in equine jejunum. Methods: In vitro experimental study. Methods: Circular and longitudinal smooth muscle strips...
Rose RJ.Many factors can influence electrolytes in the horse. With the major electrolytes (sodium and potassium), alterations in serum or plasma values do not reflect changes in total body status. However, estimates of electrolyte alterations may be made by combining assessments of body weight changes with plasma sodium values by using the formula of Edelman et al. In planning electrolyte therapy, it has to be remembered that access to green feed or hay is important in correcting any total body potassium depletion and that diets marginal in sodium may interfere with exercise capacity by limiting sweat...
Martín-Cuervo M, Gracia LA, Vieitez V, Jiménez J, Durán E, Ezquerra LJ.A 16-year-old, Lusitanian stallion was admitted to the Veterinary Teaching Hospital with a 12-hour history of signs of abdominal pain. Exploratory celiotomy was performed due to an inguinal hernia, and a second celiotomy was performed in response to the abdominal pain. The horse was euthanized and mesenteric venous thrombosis was diagnosed and considered likely due to peritonitis and systemic inflammatory response syndrome (SIRS). Un étalon Lusitanien âgé de 16 ans a été admis à l’hôpital d’enseignement vétérinaire avec une anamnèse de 12 heures de douleurs abdominales. Une coel...
Prokop O, Geserick G, Patzelt D, Meier F.The immunological comparison of human and equine Gc proteins showed partial identical reactions between both species. Immunizations of goats and rabbits with horse serum produced antisera able to recognize human Gc proteins.
Carneiro FP, Alonso MA, Redoan MA, Henriques DA, Lima FM, Oliveira RM, Cogliati B, Canisso IF, Fernandes CB.Nocardioform placentitis is a pathologically unique form of placental disease first diagnosed in central Kentucky in the mid-80s. Since then, the occurrence of nocardioform placentitis in the region has varied over the years, from sporadic cases to outbreaks. The disease has been sporadically detected in other countries and has not been confirmed in South America. A 13-year-old multiparous Mangalarga delivered a healthy filly at 340d gestation. The mare passed the fetal membranes 33 minute after foaling. Gross examination of the fetal membranes identified two focal lesions on the chorionic sur...
Nunn FG, Pirie RS, McGorum B, Wernery U, Poxton IR.There is much evidence to suggest that group III Clostridium botulinum (types C and D) are involved in the aetiology of equine grass sickness (EGS). Antibodies have been detected previously in the blood and high levels associated with resistance to disease. Specific mucosal antibodies in the gastrointestinal (GI) tract are likely to be important in protection, and this study was performed to ascertain if such antibodies could be detected and if their levels were related to disease state. Objective: To develop a method for quantifying IgA antibodies to C. botulinum types C and D in the GI tract...
Colahan PT, Bailey JE, Chou CC, Johnson M, Rice BL, Jones GL, Cheeks JP.Twelve clinically sound, healthy, athletically conditioned Thoroughbred horses were subjected to an incremental exercise stress test to determine the effects and period of detection of a single dose of flunixin meglumine (1.1 mg/kg by intravenous injection) in serum and urine by ELISA. Flunixin concentrations, performance, and hematologic and clinical chemical parameters were measured. All horses were rotated through four treatment groups of a Latin-square design providing for each horse to serve as its own control. Flunixin meglumine reduced prostaglandin F(1alpha) and thromboxane concentrati...
Gao KX, Chen NB, Liu WJ, Li R, Lan XY, Chen H, Lei CZ, Dang RH.Gray horses are born colored, and they then gradually lose their hair pigmentation. Tremendous progress has been made in identifying the genes responsible for graying with age in horses in recent years. Results show that gray coat color in horses is caused by a 4.6-kb duplication in intron 6 of the syntaxin 17 gene (STX17), which constitutes a cis-acting-regulatory mutation. However, little is known about the gray phenotype in native Chinese horses. This study was conducted to explore the frequency distribution of the gray mutation in native Chinese horse breeds. A total of 489 samples from 14...
Beech J, Fletcher JE, Tripolitis L, Lindborgh S.The effects of phenytoin treatment were evaluated in 2 myotonic horses with hyperkalemic periodic paralysis (HPP). Phenytoin treatment abolished the clinical signs of muscle fasciculations following oral potassium challenge and decreased or abolished repetitive firing and myotonic discharges found on electromyographic examination. In both horses, an abnormally low threshold for calcium-induced calcium release was measured in heavy sarcoplasmic reticulum fractions from skeletal muscle, and this threshold increased with phenytoin treatment. Results suggest phenytoin is useful in modifying disord...