Young horses are generally defined as those under five years of age, transitioning from foals to adults. Research in this area examines the study of equine development, behavior, and health across different life stages. This includes the physiological and anatomical changes that occur as horses mature from foals into adults. Additionally, understanding behavioral aspects such as socialization, learning, and adaptation to training is key to this field. This page gathers peer-reviewed research studies and scholarly articles that explore the developmental processes, health considerations, and management practices relevant to young horses and their transition into adulthood.
Muñoz A, Santisteban R, Rubio MD, Vivo R, Agüera EI, Escribano BM, Castejón FM.The fitness of 8 Andalusian horses between 3 and 4 years of age was analysed. The animals were subjected to an exercise test on a sandy track consisting of 2 stages of different intensities. The first stage was of submaximal intensity at 4 speeds which increased progressively (4.17, 5.56, 6.94 and 8.33 m/sec.) covering a distance of 1,000 m in each level. Between each of these speeds, the horses rested for 2 min. The second stage was a maximal speed test over the same distance carried out 2 min after the ending of the maximal phase. Data of heart rate, plasma lactate concentration, velocity, P...
Vulcano LC, Mamprim MJ, Muniz LM, Moreira AF, Luna SP.Monthly radiography was performed to study distal radial physeal closure in ten male and ten female Thoroughbred horses. The height, thoracic circumference and metacarpus circumference were also measured. Distal radial physeal closure time was sooner in females than males, and took 701 +/- 37 and 748 +/- 55 days respectively.
Wolff A, Hausberger M, Le Scolan N.Different tests were used to assess different aspects of the emotionality of 1-3 year-old horses: arena test; a `novel object' test; and a handling test. In reaction to the test situations no important differences were observed according to age or sex in the behaviour patterns, but clear individual differences were observed within these classes. The arena test seemed to reveal the degree of gregariousness of the animals whereas the results in the two other tests were correlated and seemed to reflect an inherent degree of fearfulness in the horse. Indices were developed that enabled to rank the...
Hawkins JF, Lescun TB.A 4-month-old Quarter Horse was admitted for evaluation of infection that developed following bilateral hemicircumferential periosteal transection and elevation. Sepsis of the common digital extensor tendon sheath was diagnosed. Treatment included lavage of the tendon sheath, placement of an indwelling drain for lavage after surgery, establishment of drainage, and administration of antimicrobial and anti-inflammatory drugs. Three months after treatment, the foal was clinically normal.
Ellis JA, Steeves E, Wright AK, Bogdan JR, Davis WC, Kanara EW, Haines DM.The objective of this study was to determine whether the administration of modified-live equine herpesvirus (EHV-1) to young horses with residual maternal antibodies stimulated EHV-specific cytolytic responses, and whether these responses were crossreactive between EHV-1 and EHV-4. Eighteen clinically normal Belgian cross-foals were used in the study and were commingled in two adjacent pens. Skin biopsies were harvested from 16 foals within 24 h of birth and fibroblast cultures were established, expanded and cryopreserved. Beginning at approximately 10 weeks of age, 10 randomly chosen foals we...
Kaseda Y, Ogawa H, Khalil AM.Misaki feral horses were separated into 2 herds and the difference between dispersal from natal group (natal dispersal) and dispersal from natal area (natal emigration) was studied. The causes of dispersal and emigration and their effects on harem formation were studied 1979-1994. The number of horses ranged from 73 (mature males: 8, mature females: 26, young males: 8, young females: 3, colt foals: 6, filly foals: 10 and geldings: 12) in 1979 and 86 (mature males: 14, mature females: 37, young males: 12, young females: 7, colt foals: 5, filly foals: 7 and geldings: 4) in 1994 when the present ...
Davis EW.The purpose of this study was to determine the feasibility of using laparoscopy to remove cryptorchid testes from standing horses. Methods: Prospective clinical study. Methods: Eleven client-owned horses ranging in age from 4 months to 2 years. Methods: Abdominal insufflation was initiated and maintained using a 20 F insufflation tube, attached via a stopcock, to the low pressure regulator on a standard carbon dioxide pressure tank. After trocar and laparoscope placement in the ipsilateral flank the testes were identified. Local anesthesia of the structures to be manipulated was administered t...
Simonsen U, Prieto D, Hernández M, Sáenz de Tejada I, García-Sacristán A.To study the influence of alpha-adrenergic stimuli on non-adrenergic non-cholinergic (NANC) neurogenic relaxation in isolated horse penile resistance arteries. Methods: Deep intracavernous penile arteries with an internal lumen diameter of 200-500 microns., isolated from the corpus cavernosum of young horses, were mounted in microvascular myographs for isometric tension recording and electrical field stimulation (EFS) of autonomic nerve terminals. Results: In the presence of guanethidine (10(-5) M) and atropine (10(-7) M) tone of the arteries was raised by the thromboxane analogue, U46619. EFS...
Santschi EM, Juzwiak JS, Moll HD, Slone DE.This clinical report describes surgical correction of diaphragmatic hernia in three young horses. Methods: Retrospective investigation of medical records and subsequent racing performance. Methods: Three young horses with diaphragmatic hernia. Results: Three young horses with signs of abdominal pain had diaphragmatic hernia causing small intestinal strangulation. The strangulated small intestine was resected and an end-to-end jejuno-jejunal (two horses) or a side-to-side jejuno-cecal anastomosis (one horse) was performed. Diaphragmatic hernias were closed with a continuous suture pattern. All ...
Holmström M, Drevemo S.The angular velocities of the hindlimb angles of 14 horses, including 6 Grand Prix dressage horses, 4 horses judged as good at the trot and 4 horses judged as poor, were analysed. The horse material was the same as previously used by Holmström (1994) in studies on conformation and trotting gaits in the Swedish Warmblood riding horse. Four consecutive strides of each horse and the corresponding pace were analysed and mean velocity curves (Xh) for each angle were calculated. Before calculation the data were filtered forwards and backwards with a Butterworth third order filter with a cut off fre...
Firth EC, Hodge H.The possible relationship between physeal diseases and physeal form prompted investigation of change in steepness of the physis in young foals. The distal and proximal aspects of the longbones were sawn sagittally in the right and frontally in the left bones. The slabs were washed to remove saw debris, arranged in order and inspected. The proximal physes had a flat or gently arched form, without obvious inclination. In the distal physes there were distinct inclinations. Inspection of an identical slab from the medial aspect of the distal radius of two series of foals of different breeds showed...
Trim CM.Hemorrhagic myelopathy or myelomalacia is an uncommon cause of failure to stand after general anesthesia. Affected horses are usually young and have been anesthetized for relatively short times in dorsal recumbency. Clinical signs involve the hind limbs and include loss of deep pain perception. Etiology of this condition is not known. Differentiation from other forms of neuropathy and myopathy is important to the prognosis.
Magee AA, Ragle CA, Hines MT, Madigan JE, Booth LC.Enlarged anorectal lymph nodes can cause colic in young horses by obstructing the caudal aspect of the rectum. Dyschezia and clinical signs consistent with abdominal pain were the predominant reasons for evaluation of the 5 young (3 to 15 month old) horses of this report. Digital transrectal palpation revealed a firm mass obstructing the caudal aspect of the rectum in each horse. Results of cytologic evaluation of the masses revealed a lymphoid population of cells in 4 of 5 horses. These nodes regressed over time or became abscesses and drained into the rectum. In 1 horse, detection of a matur...
Breit S.Ten horses, younger than 1 year, were used to investigate the articulatio interphalangea distalis of the pelvic limb. The expansion of the dorsal recess was compared to those of adult horses. The recessus dorsalis always formed a shape like the letter 'm' or like a triangle with oblique angles. Consequently the great proximo-distal expansion on the medial side of the dorsal recess very probably has nothing to do with the age of horses.
Ronéus N, Essén-Gustavsson B.To determine whether performance capacity in a group of young trained Standardbreds is related to skeletal muscle characteristics and metabolic response to exercise. Methods: 13 clinically normal 2-year-old Standardbreds. Methods: Venous blood and middle gluteal muscle biopsy samples were obtained from each horse within 1 to 2 minutes after trotting at high speed for 1,600 m. Results: There was a positive correlation between plasma lactate and muscle glucose-6-phosphate (G-6-P) concentrations and trotting speed. There was a negative correlation between muscle adenosine triphosphate concentrati...
Patterson-Kane JC, Firth EC, Goodship AE, Parry DA.To measure collagen fibril crimp angles and lengths as well as collagen fibril mass-average diameters in central and peripheral regions of the superficial digital flexor tendon of wild horses, to ascertain any age-related changes in either region in the absence of imposed galloping exercise. Methods: Measurements from a random cull of wild horses. Methods: Superficial digital flexor tendon samples were taken from 23 wild horses ranging in age from two to ten years. Methods: Horses were divided into 'young' (< 5 years, n = 10), 'middle-aged' (5 to < 10 years, n = 9) and 'ol...
Koskinen E, Katila T.The long-term effect of anabolic steroid was investigated in 3 experiments. In experiment I, 500 mg of 19-norandrostenololylaurate was given to 5 colts and a dose of 100 mg to another 5 colts every 3rd week. Six colts served as untreated controls. The animals were 12-16 months old at the start, and 24 months at the end of treatment. In experiment II, a dose of 1 mg/kg was given every 3rd week to 4 colts and 0.3 mg/kg every week to another 4 colts. Six colts served as controls. The colts were treated from 7 months to 12 months of age. In experiment III, 1 mg/kg of steroid was given every 3rd we...
Patterson-Kane JC, Parry DA, Birch HL, Goodship AE, Firth EC.The superficial digital flexor tendon is the most commonly injured tendon in the racing Thoroughbred. Despite the clinical significance of this structure, only limited data exist regarding normal age-related morphology of the tensile units, the collagen fibrils. The age at which these collagen fibrils become mature in composition and structure may be of importance. Consequently, the association of age and collagen fibril crosslink composition, diameter distribution and crimp morphology in the superficial and deep digital flexor tendons of Thoroughbreds up to and including three years of age ha...
Koskinen E, Andersson M, Katila T.The effect of anabolic steroid on testicular growth was investigated in 3 experiments. In experiment I, 500 mg of the anabolic steroid was given to 4 colts and 100 mg to another 4 colts, every 3rd week, starting at age 16 months and ending at age 24 months. Six colts served as controls. Both treatments decreased total scrotal width (TSW) within 6 weeks. Seasonal testicular growth during spring partly overcame the effect of steroid treatment. Cessation of anabolic steroid treatment was followed by testicular growth at the same time as TSW in untreated colts was decreasing by virtue of the effec...
Hendrickson DA.The determination of poor performance in the young or unproven horse can be a difficult experience for the practitioner. This article describes an incremental exercise test that may be helpful in determining the cause of poor performance in horses when a complete physical examination and a lameness examination fail to elucidate the causes of poor performance. Included are values from normal yearling and 2-year-old horses that have undergone the incremental exercise test.
Enbergs H, Karp HP, Schönherr U.The present study was aimed to determine the contents of calcium, inorganic phosphate, parathormon, 25-OH-D3 and the activity of alkaline phosphatase in the plasma of one- and two-years-old thoroughbred horses. Data were obtained monthly from 44 one-year-old thoroughbred of 4 different studs from May during grazing-season and from October during stable-, resp. training-season up to april of the following year. Calcium, inorganic phosphate and the activity of alkaline phosphatase were measured with a photometric method and the concentration of PTH and 25-OH-D3 were determined with a radioimmuno...
Borgsteede FH, van Beek G.The prevalence of tapeworm infestations was investigated in 70 horses slaughtered in the period February 1994-July 1994. Most horses were half-breed, young (1.5-3 years), and in good condition. They were bought for slaughter by dealers on local markets, and their treatment history was therefore unknown. Tapeworm infestations were seen in 16 horses (23%). Fifteen (21%) had an infection with Anoplocephala perfoliata. One horse had a single specimen of Paranoplocephala mamillana. The average number of A. perfoliata was 45 and the highest number was 508.
Malinowski K, Christensen RA, Hafs HD, Scanes CG.A survey with horses was conducted to determine whether plasma concentrations of triiodothyronine (T3), thyroxine (T4), insulin-like growth factor (IGF)-I and IGF binding proteins (IGFBP) change as horses grow, mature sexually, and age. Jugular blood was sampled from Standardbred fillies and mares at ages 0, 1, 7, and 14 d, at 1, 2, 4, 5, 6, and 9 mo, and at 5 to 8 and 16 to 22 yr (n = 5 to 18). In a second survey, we measured the same variables in eight breeds of horses with markedly different adult body sizes, from Miniatures to Friesians. Plasma T3, T4, and IGF-I were determined by radioimm...
Ruggles AJ, Moore RM, Bertone AL, Schneider RK, Bailey MQ.To determine clinical signs, radiographic and scintigraphic findings, and performance outcome of racing Standardbreds with tibial stress fractures. Methods: Retrospective case series. Methods: 13 racing Standardbreds with tibial stress fractures. Methods: Information concerning clinical signs, diagnostic evaluation, and recommendations was obtained by review of the medical records. Performance information before and after diagnosis of the fracture was collected from racing records, and follow-up information was obtained from the owners or trainers by use of a telephone questionnaire. Results: ...
Krzywanek H, Mohr E, Mill J, Scharpenack M.Until the age of about 2 years, trotters normally grow up on pasture without any kind of training. In the stud farm Lindenhof (Templin, Germany), however, these first 2 years are used for a special fitness training for the young animals: 2-3 times a week, a group of the yearlings is forced to run a distance of about 1700 m on a track at an average speed of up to 10 m/s. Until now, little was known about changes of blood parameters which may occur during such special exercise. This study therefore investigated the activity of selected serum enzymes (aspartate-amino-transferase (AST), alanine-am...
Murray RC, Debowes RM, Gaughan EM, Bramlage LR.Closed fractures of the proximal aspect of the ulna were repaired in 10 horses younger than or equal to 6 months of age by application of a hook plate using a tension band principle. Ulnar fractures were classified as type 1A (2 horses), type 1B (4 horses), type 2 (1 horse), type 3 (1 horse), and type 4 (2 horses); all fractures had displacement of a proximal fragment. Complications were implant deformation (4 horses), screw pullout (1 horse), osseous sequestration (1 horse), ulnar fracture through a hole used to apply a tension device (1 horse), and metacarpophalangeal deformity associated wi...
Ray CS, Baxter GM, McILWRAITH CW, Trotter GW, Powers BE, Park RD, Steyn PF.The objective of this study was to determine if damage to the articular cartilage alone or articular cartilage plus subchondral bone of the distal medial femoral condyle of young, exercised horses resulted in the formation of subchondral cystic lesions. Twelve Quarter Horses (age 1-2 years), free of clinical and radiographic signs of osteochondrosis and lameness were used. In 6 horses (Group 1), a 15 times 1 mm linear full thickness defect in the articular cartilage was made arthroscopically on the weightbearing surface of the distal aspect of the medial femoral condyle. In the other 6 horses ...
Boersema JH, Eysker M, Maas J, van der Aar WM.The reappearance of strongyle eggs in faeces after treatment with ivermectin or pyrantel embonate was investigated in 22 foals, 36 yearlings, and 45 adult horses on five Dutch horse farms. The results confirmed earlier studies which showed an egg reappearance period of 9 and 6 weeks after ivermectin and pyrantel treatment, respectively. There were no differences between the egg reappearance periods of foals, yearlings, and adult horses. The mean egg counts of the yearlings were, however, consistently higher than the mean egg counts of the adult horses and foals in both ivermectin- and pyrantel...
Davern AJ, Peloso JG, Hawkins JF, Moore GE, Morehead JP.OBJECTIVE To evaluate 2- and 3-year-old and career race performance of Thoroughbred racehorse prospects with and without osteochondral fragmentation of the accessory carpal bone (ACB) identified on yearling presale radiographs. DESIGN Retrospective, matched cohort study. ANIMALS 47 nonlame Thoroughbreds with (exposed cohort) and 94 nonlame Thoroughbreds without (unexposed cohort) osteochondral fragmentation of ACB facture identified on yearling sales repository radiographs. PROCEDURES Repository radiographic interpretation reports for September yearling sales of a large Kentucky auction house ...
Vergnano D, Bergero D, Valle E.Nutrition plays a very important role in the healthy and in the ill horse. Although research in this field clearly shows that incorrect nutritional practices may lead to severe pathologies, inappropriate feeding plans often continue to be used. A clinical nutrition counselling (CNC) service could thus be of great use to both horse owners and veterinarians. The aim of this study was to provide information on equine patients referred to the CNC service of the University of Turin and to provide standard dietary protocols as used in our Veterinary Teaching Hospital for the most common nutrition-re...
Naddaf H, Sabiza S, Kavosi N.A 3-year-old Arabian colt was presented for a major gingiva wound at the right rostral part of mandible. After clinical assessments, rostral mandibular fracture was determined. Stabilization of fractured region was achieved via cerclage wire application under general anesthesia. Fixation wires were left in place for 6 weeks. A 3 -month follow up revealed complete fracture healing. The purpose of this case report was to give clinical information about rostral mandibular fractures and treatment of these fractures and nutrition protocol in a horse, as this fracture is of the most common type of j...
Zamos DT, Parks AH.Medical records of 22 horses with humeral fractures were reviewed. The horses were from 2 to 144 months old (mean, 25.8 +/- 37.3 months). Ten horses were treated with stall confinement, 3 were treated surgically, and 9 were euthanatized at the time of diagnosis. Seven of 10 horses treated nonsurgically (stall confinement) were able to be ridden 5 to 12 months after the diagnosis was made (mean, 7.5 +/- 2.6 months). One horse treated nonsurgically was euthanatized 6 months after diagnosis because of laminitis in the contralateral limb. Two horses treated nonsurgically were lost to follow-up eva...
Bigot G, Bouzidi A, Rumelhart C, Martin-Rosset W.Two specimens (70.0 x 4.5 x 1.8 mm) (proximal and distal) of cortical bone were taken from each of the cranial, caudal, lateral and medial quadrants at mid-diaphysis of the third metacarpus and metatarsus of French saddle horses (12 males and seven females) aged from 1 day to 4 years. The mechanical properties (bending strength, Young's modulus, yield stress and ultimate specific deflection) were determined by a 4-point bending test, loading at a rate of 166 x 10(-6) ms-1. During growth, the mechanical properties of the cortical bone were not significantly different (p > 0.05) between metacarp...
Ott EA, Asquith RL.Thirty-three Thoroughbred and Quarter Horse yearlings were used in two experiments (18 in Exp. 1 and 15 in Exp. 2) to determine the influence of trace mineral (TM) supplementation on growth and bone mineral content in young growing horses from 340 to 452 d of age. In each experiment the yearlings were assigned at random within breed and sex outcome groups to one of three treatments. Horses were fed assigned concentrates individually to appetite for two 1.5-h feeding periods, daily and group-fed Coastal bermudagrass (Cynodon dactylon) hay in drylot paddocks at a rate of 1.0 kg/100 kg BW daily. ...
Houpt KA, Parsons MS, Hintz HF.The maze learning ability of six pony foals that had been weaned at birth was compared to that of six foals reared normally. The foals' learning ability was also compared to their mothers' learning ability at the same task; the correct turn in a single choice point maze. The maze learning test was conducted when the foals were 6 to 8 mo old and after the mothered foals had been weaned. There was no significant difference between the ability of orphaned (weaned at birth) and mothered foals in their ability to learn to turn left (6 +/- .7 and 5.1 +/- .1 trials, respectively) or to learn the reve...
Vera L, Muylle S, Van Steenkiste G, Segers P, Decloedt A, Chiers K, van Loon G.Arterial rupture is a well-recognized cause of sudden death in horses, which mainly affects older horses. The arterial wall is known to stiffen with age, although the underlying age-related histological and biomechanical changes remain unclear. The purpose of this study was to investigate the effect of aging by histological analysis of the arterial wall and examination of the arterial wall biomechanical properties using an inflation-extension test. Entire circular samples of the proximal and distal aorta, cranial and caudal common carotid, external iliac, femoral and median artery were collect...
Dahn M, Ueltschi G.Normal radiographs of hocks were analyzed for 270 horses (3 views for each hock). They were mainly from young and sound horses. For such animals, the mean number of abnormalities found was 2 to 4.5 for each picture. The mean dimension of certain tarsal bones was measured; geldings had greater bones than mares. An increase of reactions at the origin of the M. interosseus was seen with the age. It was possible to demonstrate that Medichrome films increase the number of discrete abnormalities to be found; this is of particular value for purchase examinations of young horses. The direction of the ...
Ruggles AJ, Moore RM, Bertone AL, Schneider RK, Bailey MQ.To determine clinical signs, radiographic and scintigraphic findings, and performance outcome of racing Standardbreds with tibial stress fractures. Methods: Retrospective case series. Methods: 13 racing Standardbreds with tibial stress fractures. Methods: Information concerning clinical signs, diagnostic evaluation, and recommendations was obtained by review of the medical records. Performance information before and after diagnosis of the fracture was collected from racing records, and follow-up information was obtained from the owners or trainers by use of a telephone questionnaire. Results: ...
Stewart AJ, Hardy J, Kohn CW, Toribio RE, Hinchcliff KW, Silver B.To evaluate the diagnostic value of serum concentrations of total magnesium (tMg) and ionized magnesium (iMg), concentrations of magnesium (Mg) in muscle, intracellular Mg (icMg) concentrations, urinary Mg excretion (EMg), Mg clearance (CMg), and fractional clearance of Mg (FCMg) in horses fed diets with Mg content above and below National Research Council recommendations. Methods: 9 young female horses. Methods: 6 horses were fed a reduced-Mg diet for 29 days followed by an Mg-supplemented diet for 24 days. Control horses (n = 3) were fed grass hay exclusively. Blood, urine, and tissue sample...
Soma LR, Uboh CE, Rudy J, Fegely J.The effects of the intravenous (i.v.) administration of 1.1 mg/kg of flunixin meglumine on thromboxane B2 (TxB2) concentrations were studied in sedentary and 2-year-old horses in training. The baseline TxB2 serum concentrations generated during clotting were 2.89 +/- 0.81, 2.19 +/- 0.25 and 0.88 +/- 0.12 ng/ml for the 2-year-old Thoroughbreds in training, sedentary horses under 10 and over 10 years old, respectively. There was a significant difference in baseline TxB2 concentrations between older and younger horses (P less than 0.005). Significant reduction in TxB2 production from baseline wer...
Roberts MC, Kelly WR.Granulomatous enteritis was diagnosed in a 4-year-old Standarbred mare suffering from chronic weight loss, depression, dependent oedema but not diarrhoea. There was hypoproteinaemia (hypoalbuminaemia), lymphocytopaenia and neglibible carbohydrate absorption from the small intestine. Pathological changes in almost the entire small intestine included proprial infiltration resulting in partial villous atrophy, and granuloma formation beneath the muscularis which was most severe in the ileum. Slight infiltration occurred in the stomach and the colon. The cells were predominantly lymphocytes and hi...
Kim W, Kawcak CE, McIlwraith CW, Firth EC, McArdle BH, Broom ND.To investigate the influence of early conditioning exercise on the development of gross cartilage defects and swelling behavior of cartilage extracellular matrix (ECM) in the midcarpal joint of horses. Methods: 12 Thoroughbreds. Methods: 6 horses underwent early conditioning exercise from birth to 18 months of age (CONDEX group), and 6 horses were used as control animals (PASTEX group). The horses were euthanized at 18 months of age, and the midcarpal joints were harvested. Gross defects of the cartilage surface were classified and mapped. Opposing surfaces of the third and radial carpal bones...
Sloan PB, White B, Santschi EM.Osteochondrosis dissecans (OCD) is common in the femoropatellar joint in Thoroughbred yearlings for sale at auction and there is no consensus on the effect on racing outcomes. Objective: Describe femoropatellar OCD in juvenile Thoroughbreds and compare the racing performance of affected Thoroughbred horses to siblings and unaffected horses from the same sale. Methods: Retrospective case-control study of juvenile horses born 2010-2016. Methods: Radiographic reports from 27 Thoroughbred auctions of weanling (5-11 months of age) and yearling (12-22 months of age) horses were reviewed to ident...
Dicht S, Del Chicca F, Fürst A.Ectopic teeth occur because of failure of the first branchial cleft to close during development and are found mostly in young horses. Such dentigerous cysts are often located at the base of the ear, forming a notable swelling with a fistula, as it was the case with the two year old Iceland mare «Runa». In order to confirm the diagnosis, x-ray images were taken, which is also necessary to locate the ectopic tooth correctly. While operating, the whole cystic membrane should be removed and it is important to prevent adjacent nerves and blood vessels from damage. Prognosis for complete healing a...
Rose RJ, Davis PE.Three young Standardbred pacers with atrial fibrillation were treated with quinidine sulphate (QS) by stomach tube. They were given 10g QS every 2 hours until cardioversion was achieved. Total doses varied between 20 and 30 g. No premedication was given nor any follow up treatment after return to sinus rhythm. All horses were given 3 months rest after the treatment, and when electrocardiographed then, and at 6 months, showed normal sinus rhythm. As all 3 horses won races after cardioversion and showed subsequent normal electrocardiograms it seems likely that atrial fibrillation can occur witho...
Baker WT, Slone DE, Lynch TM, Johnson CR, Baker WA.To evaluate the racing and sales performance of Thoroughbred horses with varus angular limb deformities of the carpus treated by unilateral or bilateral single transphyseal screw (STS) placement. Methods: Case series. Methods: Thoroughbred horses (n=53). Methods: Medical records (January 1, 2005-December 31, 2006) of yearling Thoroughbreds treated for carpal angular limb deformity by transphyseal screw insertion in the distal aspect of the radius were reviewed. Retrieved data were sex, surgery, and screw removal dates, surgical site, appearance, limb(s) affected, type of angular limb deformity...
Lescun TB, Hawkins JF, Siems JJ.A 6-month-old warmblood filly had traumatic rupture in the gastrocnemius and superficial digital flexor muscles of the left hind limb. A modified Thomas splint-cast combination, which was custom fitted to the limb, was placed to prevent further disruption of the caudal reciprocal apparatus. The external coaptation device was removed after 21 days. The horse developed lesions consistent with osteochondrosis of the femoropatellar articulation within 8 weeks of the initial injury. Examination of the horse 6 months after injury revealed fibrous healing of the muscles and restoration of caudal reci...
Cook AG, Buechner-Maxwell V, Morrow JK, Ward DL, Parker NA, Dascanio JJ, Ley WB, Cooper W.Horses that are exposed to Sarcocystis neurona, a causative agent of equine protozoal myeloencephalitis, produce antibodies that are detectable in serum by western blot (WB). A positive test is indicative of exposure to the organism. Positive tests in young horses can be complicated by the presence of maternal antibodies. Passive transfer of maternal antibodies to S. neurona from seropositive mares to their foals was evaluated. Foals were sampled at birth (presuckle), at 24h of age (postsuckle), and at monthly intervals. All foals sampled before suckling were seronegative. Thirty-three foals f...
Textor JA, Nixon AJ, Lumsden J, Ducharme NG.To determine clinical and radiographic features of subchondral cystic lesions (SCL) of the proximal extremity of the tibia in horses that could be used to classify these lesions as being related to osteochondrosis or osteoarthritis and to evaluate results of surgical debridement. Methods: Retrospective study. Methods: 12 horses with 14 SCL. Methods: Medical records and radiographs obtained before and after treatment were reviewed. Results: In 6 young horses (8 lesions), SCL were considered to be related to osteochondrosis; all involved the lateral tibial condyle. The remaining 6 horses were ma...
Fjordbakk CT, Strand E, Milde AK, Ihler CF, Rorvik AM.To determine clinical and diagnostic imaging findings in young horses with osteochondral fragments involving the dorsomedial aspect of the proximal interphalangeal (PIP) joint. Methods: Retrospective case series. Methods: 6 horses. Methods: Medical records were reviewed. Follow-up information was obtained through telephone conversations with owners or trainers or by examining race records. Results: Horses were between 1 and 4 years old. Three had bilateral osteochondral fragments in the forelimbs (n = 2 horses) or hind limbs (1). Radiographically, all but 1 fragment seemed to originate from th...
Kondo T, Sato F, Tsuzuki N, Yamada K.Cervical vertebral stenotic myelopathy (CVSM), a common cause of cervical spinal cord compression, is a neurological disease characterized by general proprioceptive ataxia and weakness of hindlimbs that tends to develop in young adult Thoroughbred horses. Although male horses seem to be at increased risk for CVSM, the mechanism for the occurrence of sex differences in the prevalence of CVSM is still poorly understood. Hence, we hypothesized that sex differences in the development of cervical spinal cord and spinal canal would affect the development of CVSM. This study aimed to evaluate sex dif...
Back W, Smit LD, Schamhardt HC, Barneveld A.To study the influence of different exercise regimens on the development of locomotion, 40 Warmblood foals aged 1 week were subdivided into 3 groups: box-rest, training and pasture exercise. The box-rest group remained for 24 h a day in a box stall while the training group was housed similarly, but additionally received a 30 min workout with gallop sprints 6 times a week. The pasture group served as a control group and was kept at pasture for 24 h a day. After 5 months, the locomotion pattern at the trot of every foal was recorded overground with a 2-D MacReflex gait analysis system. A randoml...
Warren-Smith AK, McGreevy PD.Recently, training horses within round-pens has increased in popularity. Practitioners often maintain that the responses they elicit from horses are similar to signals used with senior conspecifics. To audit the responses of horses to conspecifics, 6 mare-young-horse dyads, this study introduced them to each other in a round-pen and videoed them for 8 min. These dyads spent significantly more time farther than 10 m apart than they did less than 1 m apart (p < .001). The time they spent less than 1 m apart decreased over the 8-min test period (p = .018). Mares occupied the center of the roun...
Siciliano PD, Wood CH.Fourteen 2-yr-old Quarter Horses and Quarter Horse x Thoroughbreds were randomly assigned to either a control (CTRL) diet or a diet supplemented with 6.4% soybean oil (SBO). The amounts of both diets that were fed met current NRC nutrient requirements and were isoenergetic with similar nutrient:energy ratios. Venous blood samples (20 mL) were taken at d 0, 30, 60, and 90 of the experiment and analyzed for serum alpha-tocopherol, serum cholesterol, and serum triglyceride. The sum of serum cholesterol and serum triglyceride values was used as an estimate of serum total lipid. The ratio of serum ...
McCoy AM, Scolman KN.The aim of this study was to identify the radiographic prevalence of periarticular osteophytes of the distal tarsus in nonlame yearling Standardbred horses, and to evaluate its potential impact on race performance. Methods: Cross-sectional cohort study. Methods: Client-owned yearling Standardbred horses (n = 416). Methods: Bilateral tarsal radiographs were available from all horses for review. Osteophytes were measured on radiographs using clinical visualization software and categorized by size. Racing records were obtained from the United States Trotting Association. Regression analysis w...
Kobrina Y, Isaksson H, Sinisaari M, Rieppo L, Brama PA, van Weeren R, Helminen HJ, Jurvelin JS, Saarakkala S.The collagen phase in bone is known to undergo major changes during growth and maturation. The objective of this study is to clarify whether Fourier transform infrared (FTIR) microspectroscopy, coupled with cluster analysis, can detect quantitative and qualitative changes in the collagen matrix of subchondral bone in horses during maturation and growth. Equine subchondral bone samples (n = 29) from the proximal joint surface of the first phalanx are prepared from two sites subjected to different loading conditions. Three age groups are studied: newborn (0 days old), immature (5 to 11 months ol...
Gorissen BMC, Serra Bragança FM, Wolschrijn CF, Back W, van Weeren PR.Foals can follow the herd within hours of birth, but it has been shown that kinetic gait parameters and static balance still have to mature. However, development of dynamic balance has not been investigated. Objective: To objectively quantify landing and pressure pattern dynamics under the hoof during the first half year of life. Methods: Prospective, cohort study performed at a single stud farm. Methods: Pressure plate measurements at walk and trot from ten Dutch warmblood foals during the first 24 weeks of life were used to quantify toe-heel and medial-lateral hoof balance asymmetry indexes ...
Cymbaluk NF, Christison GI.Growth and clinical biochemistry were examined over 30 wk in 42 light horse weanlings fed high-forage diets (73 to 77% alfalfa) or high-concentrate diets (63 to 65% grain and grain by-products) that were either low (.24 to .35%), normal (.68%) or high (.95 to 1.06%) in P. Body weights and blood samples were taken every 2 wk. Forage and concentrate diets contained 2.65 and 3.09 Mcal digestible energy/kg DM, respectively. Calcium and P digestibilities were highest (P less than .01) in those horses fed the low P diets, but only horses fed forage-low P diets may have absorbed insufficient P. Serum...
