Selenium is an essential trace mineral that is important for various physiological processes in horses. It is a component of several enzymes and proteins, including glutathione peroxidase, which plays a role in protecting cells from oxidative damage. Selenium is also involved in thyroid hormone metabolism and immune function. Horses require selenium in their diet, but the required amounts can vary based on factors such as age, workload, and geographic location, as soil selenium content influences forage selenium levels. Both selenium deficiency and toxicity can lead to health issues in horses, with deficiency potentially resulting in muscle disorders and toxicity causing symptoms such as colic and neurological signs. This page compiles peer-reviewed research studies and scholarly articles that explore the metabolism, dietary requirements, and health implications of selenium in equine nutrition and management.
Higuchi T, Ichijo S, Osame S, Ohishi H.In order to clarify the cause of white muscle disease (W.M.D.) in foals, tocopherol and selenium concentrations in serum and glutathione peroxidase activities in blood were measured. Examination was made on the samples from horses affected with W.M.D., the foal kept with them in the same stable, the foals kept in the stables without affected foals, and respective mares. The heavy-breed horses in Fukuoka prefecture and Tokachi district were also examined for comparison. Serum tocopherol levels of these foals were normal because after intake of colostrum. Mares of affected foals showed lower toc...
Mullaney TP, Brown CM.Newborn Shetland foals died of acute hepatic failure following oral administration of approximately 16 mg/kg body weight ferrous fumarate. Lesions in these foals were indistinguishable from lesions in foals given an oral digestive inoculant containing ferrous fumarate and were also similar to the syndrome characterised as 'toxic hepatopathy' in foals in the United States in 1983. We conclude that foals are susceptible to toxicity from low doses of iron compounds in the first few days of life. Vitamin E and selenium deficiency may contribute to this susceptibility.
Rao PN, Somawardhana CW.4-Methoxyequilin and 2-methoxyequilin were synthesized from the corresponding 4-bromoequilin and 2-iodoequilin derivatives, respectively, by nucleophilic displacement of halogen with methoxide ion in the presence of copper (II) chloride and 15-crown-5-ether. 4-Bromoequilin was prepared by reacting equilin with one equivalent of N-bromoacetamide. 2-Iodoequilin was prepared by reductive dehalogenation of 2,4-diiodoequilin, which in turn was obtained by treatment of equilin with two equivalents of iodine in methanolic ammonium hydroxide solution. 4-Methoxy-equilenin and 2-methoxyequilenin were pr...
Junnila M, Korkeala H, Rahko T, Salmi A.The kidney cortex of 32 Finnish horses was analysed chemically for cadmium (Cd) and selenium (Se) content and by light microscopy for histopathological changes of the tissues. Cd concentrations in kidney cortex ranged from 6.9 to 91.6 mg/kg wet weight with an average of 31.9 mg/kg. Se concentrations ranged from 0.5 to 1.5 mg/kg with an average of 1.0 mg/kg. The age of the horses varied from 1.5 to 32 years; mean age was 16 years. Cd levels in kidney cortex seemed to increase linearly up to an age of about 16 years. In old (over 16 years) horses no such correlation could be found. Se concentrat...
Hosie BD, Gould PW, Hunter AR, Low JC, Munro R, Wilson HC.A myopathy of horses at grass in east and south east Scotland was recognised in the autumn and winter of 1984 and the spring of 1985. The clinical signs resembled those of paralytic myoglobinuria. Grossly increased creatine kinase activities and the passage of dark brown urine were consistent features. However, the horses were not in training, most of them died and the muscles affected were those of posture and respiration rather than movement. The condition may be unrelated to nutritional myopathy because all the cases had adequate levels of alpha-tocopherol although their selenium status var...
Baalsrud KJ, Overnes G.Fifteen horses used for serum production were maintained on low vitamin E and selenium diets. They were divided into four groups receiving: Group 1 no supplements, Group 2 vitamin E, Group 3 selenium and Group 4 both vitamin E and selenium. The humoral immune response to novel antigens, such as tetanus toxoid and equine influenza virus, was increased in groups receiving either vitamin E or selenium/vitamin E. No effects were recorded on the titres against Escherichia coli or the levels of immunoglobulin G.
Foreman JH, Potter KA, Bayly WM, Liggitt HD.A 7-month-old male Quarter Horse was examined because of severe cachexia, which had begun 2 months earlier. The foal was emaciated and weak despite an excellent appetite. Percutaneous biopsy revealed multiple areas of subcutaneous steatitis with mineralization. Radiography demonstrated calcification of the nuchal ligament. The foal died 9 days after admission. Necropsy revealed mineralized lesions throughout the fascial planes and adipose tissues of the thorax, abdomen, and skeletal muscles, with little to no involvement of muscular tissue. Serum magnesium, copper, and thyroxine concentrations...
Ekfalck A, Funkquist B, Jones B, Obel N.An in vitro method has been designed and used to study the incorporation of 75Se-cystine into matrix fragments from hooves and claws of healthy horses and cattle. Tissue fragments from the zone of keratinisation were incubated with L-75Se-cystine in a tissue culture medium for 4 to 6 h, during which time there was continuous incorporation of the labelled selenocystine. The incorporation was greatly decreased by adding L-cystine to the incubation mixture. It is concluded that the incorporation of 75Se-cystine depends on the presence of a specific receptor for cystine in the tissue fragments stu...
Shellow JS, Jackson SG, Baker JP, Cantor AH.Twenty mature geldings, averaging 535 kg, were used to determine the influence of dietary selenium (Se) on the blood levels of Se and Se-dependent glutathione peroxidase (SeGSH-Px) activity in the horse. Horses were randomly assigned within breed to four treatments consisting of five horses each and fed a basal diet containing .06 ppm of naturally occurring Se. Diets were supplemented with .05, .10 and .20 ppm Se, as sodium selenite. Blood was drawn for 2 wk before, and for 12 wk following, the inclusion of supplement Se in the diets. Whole blood and plasma Se concentrations and plasma SeGSH-P...
Teilmann AM, Hansen JC.The content of cadmium and selenium in horse kidneys from Jutland , Denmark, in relation to age, local geographical variation and possible relationship between the two elements has been investigated. During the winter of 1982-1983 kidneys from 50 horses were sampled and analysed for cadmium and selenium. The cadmium content of the horse kidneys was recorded in connection with the age of the horses. The cadmium level increases until the animal has reached approximately 7 years of age. At this age the cadmium concentration levels off. A significant regional difference was shown. The cadmium cont...
Ronéus B, Lindholm A.Glutathione peroxidase (GSH-px) activity in the blood is correlated to the amount of selenium which was given to the horse. Currently recommended doses of selenium seem to be sufficient in order to prevent selenium deficiency. The blood GSH-px in foals reflects the amount of selenium given to the mare during pregnancy.
Ronéus B.When blood selenium concentrations and glutathione peroxidase activity was measured in 30 standardbred horses a significant correlation was found (r = 0.97). A comparison between blood GSH-px activity in clinically healthy foals, foals affected by muscular dystrophy (MD) and their respective mares was also done. There was no difference in GSH-px activity between the healthy foals and the MD foals or between the corresponding mares.
Blackmore DJ, Campbell C, Dant C, Holden JE, Kent JE.The activity of glutathione peroxidase (GSH-Px) was measured in the erythrocytes of 600 Thoroughbred horses in training; the selenium concentrations in whole blood and serum was measured in over 80 of these Thoroughbreds. A quadratic relationship was demonstrated between erythrocyte GSH-Px and whole blood or serum selenium concentration. There was no significant difference in the activity of aspartate aminotransferase, creatine kinase, or gamma-glutamyl transferase in the serum of Thoroughbreds with high erythrocyte GSH-Px activity (more than 25 u/ml) when compared with those with low erythroc...
Hintz HF, Kallfelz FA.The effects of overfeeding, calcium-phosphorus imbalance, misuse of supplements and false advertising on equine nutrition are discussed. Overfeeding is known to cause disorders in several species but, although a similar relationship has been suggested on clinical evidence, no controlled trials on horses have been reported. It has also been suggested that overfeeding is a problem only for those horses with a genetic predisposition to skeletal problems. The importance of adequate calcium and phosphorus levels has been known for many years but severe cases of calcium deficiency still occur. Clien...
Stowe HD.Thirty-four adult ponies were used to determine the effects of single oral doses of copper (Cu) supplements (0, 20, and 40 mg of Cu/kg of body weight) on the toxicity of oral doses of selenium (Se) supplements (0, 2, 4, 6, and 8 mg of Se/kg of body weight) administered 24 hours after the copper was given. Signs of Se toxicosis-sweating, diarrhea, tachycardia, tachypnea, mild pyrexia, lethargy, and colic-developed in ponies given 6 and 8 mg of Se/kg of body weight without Cu pretreatment. Two of 4 ponies given 6 mg of Se/kg and both ponies given 8 mg of Se/kg without Cu pretreatment died within...
Gallagher K, Stowe HD.Blood samples were obtained from 45 racing Standardbred horses immediately before and immediately after a training jog at a commercial race track to establish reference values for serum selenium and related values of the peroxide reduction system of racing horses. Hemoglobin, hematocrit, and serum selenium increased significantly (P < 0.001), whereas RBC-reduced glutathione decreased significantly (P < 0.01) immediately after exercise. Glutathione peroxidase and glutathione reductase were not altered by exercise. Serum copper and magnesium were significantly increased (P < 0.01) after exercise...
Maylin GA, Rubin DS, Lein DH.A survey of selenium and vitamin E concentrations in horses was conducted at four breeding farms in New York. There were no significant changes in mean blood selenium concentrations in horses at the three sampling dates whereas vitamin E concentrations underwent seasonal fluctuations. The mean blood selenium concentration in this survey for horses fed local feed was 7.7 microgram/dl. Horses fed commercial feed had a mean blood selenium concentration of 15.6 microgram/dl. A 0.94 correlation coefficient was found between blood glutatione peroxidase activity and blood selenium concentrations in h...
Blackmore DJ, Willett K, Agness D.Selenium and gamma-glutamyl transferase activity has been measured in the serum of clinically health thoroughbreds. The thoroughbreds, whose performance was reported to be unsatisfactory, had consistently low concentrations of selenium and high activity of gamma-glutamyl transferase in the serum when compared with those whose performance was as expected. Vitamin E levels in the serum showed no such difference. The only other biochemical and haematological abnormality was lower serum phosphate concentrations in the unsatisfactory group. These results suggest that low concentrations of selenium ...
Caple IW, Edwards SJ, Forsyth WM, Whiteley P, Selth RH, Fulton LJ.The activity of glutathione peroxidase, a selenium containing enzyme, was measured in the blood of horses to determine its usefulness as an indicator of selenium status. In 15 horses the enzyme activity was positively related to the blood selenium concentration (P less than .001, r-0.98) over the range of enzyme activities of 8.2 to 140 units (mumoles NADP-oxidised/min/gHb) and selenium concentrations of 0.24 to 2.74 mumol/l. In a group of 8 horses which 2 foals had died with lesions of muscular dystrophy the enzyme activity increased from a mean of 11.8 units before treatment with selenium to...
Pearson EG, Snyder SP, Saulez MN.The medical records of eight horses with histological evidence of myodegeneration of the masseter muscles were examined. While they were alive their most common clinical signs had included difficulty in eating or opening their mouths, weight loss, difficulty in moving, and noticeable atrophy of the masseter muscles. The serum activities of muscle enzymes were abnormally high in all of the horses. Whole blood and/or liver selenium and vitamin E concentrations were less than the reference ranges in some of the horses. The lesions varied with the stage of the disease and consisted of swelling and...
Deficiency of the necessary complex of micronutrients under abnormal nutrition structure creates a problem for the preservation of health and performance of the population. In this regard, it is very relevant to develop a science-based strategy for the consumption of traditional Yakut national food that have a high nutritional value and are able to satisfy the requirements of the human body in micronutrients. of the research was to investigate the content of selenium and zinc in the local foods which are most commonly consumed by the population of Yakutia. . The objects of study were meat (7-...
Zentek J.In this case report on myopathies in 6 saddle-horses, a combined dietary vitamin E and selenium deficiency is presumed. Other disorders, such as exertional myopathy ("Monday morning disease") due to excessive energy intake or ionophore intoxication could be excluded by calculating the energy supply or by a simple colour test. The selenium requirement of horses is estimated to 0.1-0.2 mg/kg dry matter (Meyer 1986). If natural feed compounds are low in selenium, adequate amounts of this trace element can be supplied by means of supplemental feeds, sodium selenite (20 mg/500 kg BW/week) or bruise...
Busse NI, Uberti B.A 12-year-old, multiparous, parturient show jumper embryo-recipient mare presented at a veterinary hospital, seven days past her due date and with a dilated cervix, for evaluation of mild colic. Gastrointestinal or metabolic abnormalities and fetal maldispositions were excluded as causes of dystocia, and a diagnosis of uterine inertia was made. There was no uterine response to oxytocin treatment. A live filly was delivered via C-section, and severe selenium deficiency was eventually confirmed in the mare, her offspring, and in the herd of origin. The filly was born with severe white muscle dis...
Millican AA, Leatherwood JL, Coverdale JA, Arnold CE, Bradbery AN, Larson CK, Lamprecht ED, White SH, Paulk CB, Welsh TH, Wickersham TA.Sixteen weanling Quarter Horses (255 ± 22 kg) were utilized in a 56-d trial to evaluate the effects of trace mineral (TM) source on intra-articular inflammation following a single acute inflammatory insult. Horses were stratified by age, sex, and BW and then randomly assigned to dietary treatment: concentrate formulated with Zn, Mn, Cu, and Co as inorganic sources (CON; n = 8) or complexed TMs (CTM; n = 8). Added TM were formulated at iso-levels across treatments and intakes met or exceeded NRC requirements. Horses were offered 1.75% BW (as-fed) of treatment concentrate and 0.75% BW (as-fed) ...
Hintz HF, Kallfelz FA.The effects of overfeeding, calcium-phosphorus imbalance, misuse of supplements and false advertising on equine nutrition are discussed. Overfeeding is known to cause disorders in several species but, although a similar relationship has been suggested on clinical evidence, no controlled trials on horses have been reported. It has also been suggested that overfeeding is a problem only for those horses with a genetic predisposition to skeletal problems. The importance of adequate calcium and phosphorus levels has been known for many years but severe cases of calcium deficiency still occur. Clien...
Waheed MM, Meligy A, Alhaider AK, Ghoneim IM.Seminal plasma contains several microelements like Zn, Fe, Se, and Cu that affect sperm motility and male fertility. Biochemical evaluation of seminal plasma trace elements is important for assessing fertility and diagnosing male infertility. Unassigned: The present study was designed to evaluate the effect of seminal fluid trace elements on sperm parameters and fertility in Arabian horses. Unassigned: Ninety-four ejaculates from 25 Arabian stallions (4-27 years old) were used to investigate the effect of seminal fluid trace elements on semen parameters and fertility. Data divided according to...
Stahl LT, Müller A, Krohn J, Büttner K, Wehrend A.An adequate supply of trace elements is very important for equine neonates, as deficiencies can lead to health problems and even death. Unassigned: This study investigated serum concentrations of selenium (Se), copper (Cu), and zinc (Zn) in neonatal foals up to the 8th day of life. The influences of disease, age, and failure of passive transfer (FPT) on these concentrations were analyzed. Unassigned: Serum concentrations of Se, Cu, and Zn were determined from blood samples of 93 foals by means of inductively coupled plasma mass spectrometry. The foals were divided into 2 groups based on health...
Step DL, Divers TJ, Cooper B, Kallfelz FA, Karcher LF, Rebhun WC.A 6-year-old Quarter Horse was examined because of acute, severely swollen masseter muscles (palpation of which elicited pain response), exophthalmos, severe chemosis, and protrusion of the third eyelids. Blood selenium and vitamin E concentrations, and results of feed analysis and muscle biopsy supported a diagnosis of nutritional myopathy. The horse was treated and was clinically normal 2 weeks after discharge from the hospital.
Foreman JH, Potter KA, Bayly WM, Liggitt HD.A 7-month-old male Quarter Horse was examined because of severe cachexia, which had begun 2 months earlier. The foal was emaciated and weak despite an excellent appetite. Percutaneous biopsy revealed multiple areas of subcutaneous steatitis with mineralization. Radiography demonstrated calcification of the nuchal ligament. The foal died 9 days after admission. Necropsy revealed mineralized lesions throughout the fascial planes and adipose tissues of the thorax, abdomen, and skeletal muscles, with little to no involvement of muscular tissue. Serum magnesium, copper, and thyroxine concentrations...
Menzies-Gow NJ, Patterson-Kane JC, McGowan CM.The clinical signs of chronic nodular panniculitis in a three-year-old mare were consistent with a diagnosis of sterile nodular panniculitis, but the mare had histopathological signs of both generalised steatitis and sterile nodular panniculitis. The mare was deficient in vitamin E and selenium.
Gallagher K, Stowe HD.Blood samples were obtained from 45 racing Standardbred horses immediately before and immediately after a training jog at a commercial race track to establish reference values for serum selenium and related values of the peroxide reduction system of racing horses. Hemoglobin, hematocrit, and serum selenium increased significantly (P < 0.001), whereas RBC-reduced glutathione decreased significantly (P < 0.01) immediately after exercise. Glutathione peroxidase and glutathione reductase were not altered by exercise. Serum copper and magnesium were significantly increased (P < 0.01) after exercise...
Sill S, Zhao L, Houpt K.Salt (NaCl) is an essential nutrient for horses because their diet is low in sodium and they lose salt in sweat. Given the many types of salt block available, 342 horse owners were surveyed to see what type they offered their horses. The owners most often offered plain(30%) mineralized (29%) or Himalayan salt blocks. Next, adult mares were given two choice preference tests between plain (white) and mineralized (red) salt blocks, between mineralized and selenium (green) blocks, between plain and selenium, between Himalayan (pink) and plain and between Himalayan and selenium salt blocks. The hor...
Pagan JD, Valberg SJ.Many myopathies in horses can be managed by exercise regimes and dietary modifications. This includes modifying the amount of nonstructural carbohydrate, fat, amino acids, vitamin E, and selenium based on the horse's specific myopathy, metabolic status, exercise program, and optimal body weight. Because dietary recommendations differ substantially between myopathies, it is imperative to establish a specific diagnosis. A nutritionist will help practitioners select from the myriad of offered products to ensure a balanced diet. This article provides detailed recommendations for a variety of myopa...
Witte ST, Will LA, Olsen CR, Kinker JA, Miller-Graber P.Chronic selenosis (alkali disease) was diagnosed in horses of western Iowa, a region associated with marginal to adequate soil selenium. Two locally produced alfalfa hays (Medicago sativa L) were identified as the primary source. Difficulty in selecting diagnostic specimens to evaluate potential chronic selenosis cases is complicated by the wide range of tissue concentrations reported in previous cases, conflicting correlation of sample selenium concentrations in the literature, and different recommendations on specimen selection and diagnostic value. These problems arise form the similarity i...
Kósa CA, Nagy K, Szenci O, Baska-Vincze B, Andrásofszky E, Szép R, Keresztesi Á, Mircean M, Taulescu M, Kutasi O.A severe form of recurrent exertional rhabdomyolysis occurs enzootically in a well-defined region of Transylvania, Harghita county. At the highest lying two settlements (more than 800 m above sea level), the prevalence of equine rhabdomyolysis is between 17 and 23%, while in the neighbouring villages in the valley it is less than 2%. The objective of our study was to clarify the role of selenium and vitamin E in the high prevalence of rhabdomyolysis in that region. Soil and hay samples were collected from each area to evaluate mineral content. Ten horses from the non-affected and 20 horses fro...
Langner K, Hörügel U, Donat K, Vervuert I.Screening of commercial mineral feeds and mineral licks on the German market containing selenium (Se) in relation to the Se status in equines in Thuringia with different forms of Se supplementation. Methods: Commercially available Se-containing minerals for horses identified by an online research were evaluated for their Se concentration, Se source, flavour carrier and recommended dosage according to the manufacturer's labelling. Furthermore, serum Se status in 8 equine farms was regularly monitored over the period of one year. The sampled horses either received no Se supplement or Se was supp...
Pilarczyk B, Tomza-Marciniak A, Stankiewicz T, Błaszczyk B, Gaczarzewicz D, Smugała M, Udała J, Tylkowska A, Kuba J, Cieśla A.The aim of this study was to determine serum selenium concentrations in Polish Konik horses residing in the Odra Delta Nature Park (Poland) and to evaluate the activity of glutathione peroxidase and Se content in testes of this horse breed. In over 95% of cases, serum Se concentration was below the optimal range, and none of the horses examined was deficient in this trace element. The lack of Se deficiency in the animals examined suggests however, that the Polish Konik horses have a natural ability to the optimal use of nutrients available in their life area. Testicular content of Se and GSHPx...
