Observational studies in horses involve systematically assessing and recording behaviors, conditions, or other characteristics without manipulating the study environment. These studies provide insights into natural equine behaviors, health conditions, and interactions with their environment. Researchers often focus on aspects such as herd dynamics, feeding patterns, or responses to environmental changes. The data collected can help identify trends, correlations, and potential risk factors for certain conditions. This page compiles peer-reviewed research studies and scholarly articles that explore various observational methodologies and their applications in understanding equine behavior and health.
Coombs SL, Webbon PM.The rate of movement up the mucociliary escalator of Technetium99m tagged to macroaggregated albumin was measured in 7 normal horses and 8 with respiratory disease. The activity at 2 sites in the neck, separated by 12-15 cm, was measured using a hand held scintillation counter and rate meter. In normal horses the Technetium complex moved as a bolus up the neck with a mean rate of 1.58 cm/min. In the horses with respiratory disease the Technetium complex was less likely to move as a discrete bolus and in three horses it was not possible to measure the transport rate. The remainder had a mean tr...
Kosiniak K, Bittmar A.Physiological processes connected with sexual maturation of stallions were observed on 10 half-breed Anglo-Arab stallions beginning from 8 months of age, until 4.5 years of age. It was found that there is full somatic and sexual development in the stallion reached around the age of 3.5 years, and the sperm morphology stabilized in the range of the physiological norm around 3.0 years of age. On the other hand biochemical components of the semen plasma such as glycerylphosphorylcholine (GPC), ergothioneine (EGT), total protein (PRT), up to age 4.5 years, reach significantly lower value than in m...
Petzoldt K, Merkt H, Müller E, Kirpal G.Over the last years the percentage of foals lost by EHV at term or close to term seems to be higher than in former years. Furthermore, the pathological findings seem to shift from liver to lung. So far there has been no explanation for this phenomenon.
Martin BB, Klide AM.Fourteen horses that could not perform at their expected standards due to chronic back pain of 4 to 48 months duration, and had not obtained lasting improvement from other forms of therapy, were treated by stimulating nine acupuncture points using a low powered infrared laser (300 microW, 904 nm). The treatments were performed weekly, and consisted of stimulating each point for 2 minutes with a pulse frequency of 360 pulses per second. After completion of a mean of 11 treatments, clinical signs of back pain were alleviated in 10 of the 14 horses, there was no change in three, and one was lost ...
Ellis DR, Simpson DJ, Greenwood RE, Crowhurst JS.A retrospective study of 119 cases of fracture of the proximal phalanx is described. The short incomplete sagittal fracture (split pastern) was most common and carried a good prognosis for a return to racing following conservative treatment. Longer incomplete fractures also had a good prognosis but complete fractures, either through the lateral cortex of the proximal phalanx or through the bone into the proximal interphalangeal joint, required internal fixation. Careful assessment of these and comminuted fractures was essential before surgery was undertaken. Most comminuted fractures were trea...
Voith VL.This article discusses some general principles of learning as well as possible constraints and how such principles can apply to horses. A brief review is presented of experiments that were designed to assess learning in horses. The use of behavior modification techniques to treat behavior problems in horses is discussed and several examples of the use of these techniques are provided.
Crowell-Davis SL, Houpt KA.A thorough behavioral history is essential for adequate assessment of a given case. In reviewing the chief complaint, a description of what actually happened, rather than the owner's interpretation of what happened, is required. Other behavior problems, environment, rearing history, and training need to be reviewed. Sample question sets for some common problems are given.
Boyd L.Behavior problems in zoo equids commonly result from a failure to provide for needs basic to equine nature. Equids are gregarious, and failure to provide companions may result in pacing. Wild equids spend 60 to 70 per cent of their time grazing, and failure to provide ad libitum roughage contributes to the problems of pacing, cribbing, wood chewing, and coprophagia. Mimicking the normal processes of juvenile dispersal, bachelor-herd formation, and mate acquisition reduces the likelihood of agonistic and reproductive behavior problems. Infanticide can be avoided by introducing new stallions to ...
Keiper RR.Socially feral horses live in stable social groups characterized by one adult male, a number of adult females, and their offspring up to 2 years of age. Extra males either live by themselves or with other males in bachelor groups. The bands occupy nondefended home ranges that often overlap. Many abnormal behaviors seen in domestic horses occur because some aspect of their normal social behavior cannot be carried out in captivity.
Baker SM, Drummond WH, Lane TJ, Koterba AM.A follow-up study was conducted on 131 foals that were less than 7 days old when admitted to the University of Florida Veterinary Medical Teaching Hospital between 1981 and 1983. Of the 71 foals (54%) that survived to be discharged, 39 (55%) were alive at follow-up evaluation, 19 (27%) could not be located, and 13 (18%) had died. The owners of surviving foals were sent questionnaires and 72% responded. The horses were visited and examined, if geographically possible, and an age-matched stablemate or a sibling also was evaluated and used as a control. Thirteen foals (10% of total admitted) died...
Crowell-Davis SL.Examination of the developmental changes that occur in the behavior of foals reveals three major periods that can be characterized by certain types of behavior. Although the beginnings and endings of these periods are not definitive, these periods may be conceptually useful in evaluating a foal's behavior. Period of Dependence. During the first 4 weeks of life, a foal is maximally dependent on its mother for sustenance, remains near her, and has little contact with other horses or ponies of any age. Period of Socialization. During the second and third months of life, foals have rapidly increas...
Hill T, Carmichael D, Maylin G, Krook L.The incidences of fractures and soft tissue injuries during 68397 starts of thoroughbred horses at New York Racing Association tracks were analyzed concerning track condition, dirt and turf tracks, environmental conditions, length of races, location of fractures on the track, and age of horses. It was concluded that the conditions evaluated are of no importance in the occurrence of racing injuries to thoroughbred horses.
Webbon PM.A series of experimental tendon biopsies is described. Three biopsies were taken from the lateral digital extensor tendon (LDET) and three from the superficial flexor tendon (SFT). The LDET biopsies resulted in little discomfort whereas the SFT biopsies led to temporary lameness. The tendons were examined histologically up to 99 days after the biopsies were removed. In all of the tendons the defect filled with granulation tissue which subsequently became organised as a longitudinally orientated collagenous scar tissue. In this small series of biopsies the histological effects of the biopsy per...
MacMillan AP, Cockrem DS.Five mares and a stallion were studied from three to 30 months after experimental infection with Brucella abortus strain 544. The mares bred normally. No organisms were recovered from horses or from pregnant Friesian heifer contacts. Titres of serum antibody in the antiglobulin (Coombs) and complement fixation tests fell more slowly than those assessed by other tests. The serum of one foal yielded maternal antibody. An intradermal test was positive in infected adults only, and negative in all foals.
Yovich JV, Stashak TS, DeBowes RM, Ducharme NG.Fractures of the distal phalanx of the forelimb were diagnosed in 5 colts and 3 fillies ranging in age from 2 weeks to 5 1/2 months at the time of fracture. Three fractures entered the distal interphalangeal joint and 6 fractures (one foal had bilateral fractures) were nonarticular. All foals with articular fractures became sound with conservative treatment. Four of 5 foals with nonarticular fractures became sound with conservative treatment and 1 foal developed separation of the hoof at the coronary band after application of acrylic around the hoof. On the basis of our observations in these f...
McDonnell SM, Garcia MC, Blanchard TL, Kenney RM.Ten pony mares that had developed stallion-like sexual behavior as the result of anabolic steroid treatment (boldenone undecylenate, 0.55 mg/kg intramuscularly (i.m.), once weekly for 12 injections) were evaluated for ability to aid in detecting estrus in cycling mares. In across-the-fence estrus detection trials, androgenized mares failed to elicit signs of estrus or diestrus. In 10-min pasture trials, in which each androgenized mare was placed in a group of 10 cycling mares (six of which were estrous), seven of the 10 androgenized mares elicited estrous behavior from one or two mares. Observ...
Hammond CJ, Mason DK, Watkins KL.Routine post mortem examination of 195 Thoroughbreds in Hong Kong revealed that 66 per cent suffered from gastric ulceration. Racehorses killed straight out of training suffered a significantly greater incidence of ulceration (80 per cent) than those having been retired for a month or more (52 per cent). The macroscopic findings post mortem enabled a classification of equine gastric ulceration to be suggested (Types 1, 2, 3), according to severity. Severe lesions (Types 2 and 3) were present in 45 per cent of horses put down from training and 5 per cent of retired horses. This difference was s...
Despite some views to the contrary the working party of the Association of Veterinary Teachers and Research Workers considers that it has been demonstrated that it is possible to prepare guidelines for the recognition and assessment of pain in experimental animals. The detailed information readily available on species specific signs is limited and it has been particularly difficult to obtain such signs for the smaller mammals and for the non-mammalian species.
Verschooten F, Picavet TM.Desmitis of the fetlock annular ligament was diagnosed in 30 horses during a period of eight years. Most of the horses had been lame for a prolonged period and had chronically distended digital flexor tendon sheaths. Air tendograms demonstrated thickened palmar or plantar annular ligaments. In 25 horses the ligament was cut longitudinally; of these, 16 horses returned to full work without any difficulty and one became sound after a second operation. Follow up time varied from three months to seven-and-a-half years. None of the five untreated horses returned to work.
Reinemeyer CR, Smith SA, Gabel AA, Herd RP.Monthly variations in the magnitude of adult and larval cyathostome burdens were observed in 55 horses necropsied over a 15-month period in the northern USA. Peak numbers of adult cyathostomes occurred in late winter (March) and late summer (September). Larval cyathostomes demonstrated peak numbers from February to April and again in October, beginning one month earlier than the spring adult peak and one month after the autumn adult peak, respectively. The reproductive status of individual female Cyathostomum catinatum, Cyath coronatum, Cylicocyclus nassatus, Cylicostephanus goldi and Cylicost...
Hodges AA, Harrison AG, Wathes CM.The heights of 89 horses were measured at the withers before and after half a furlong of trotting exercise. The mean (+/- sd) height increase after exercise was 1.75 +/- 0.86 cm and the horses returned to their resting height within seven minutes. There was no linear relationship between gain in height and pre-exercise height.
Webb AI, Daniel RT, Miller HS, Kosch PC.The capability of a transconjunctival oxygen monitoring system to provide an accurate and reliable means of observing arterial oxygenation trends was evaluated in 12 horse and pony foals between 5 and 20 days of age. Ten of the foals were anesthetized with isoflurane in oxygen and nitrous oxide, and 2 foals were conscious. Inspired oxygen concentration was manipulated by differing proportions of oxygen and nitrous oxide in the fresh gas supplied to the breathing circuit. With arterial oxygen tension values ranging from less than 20 to greater than 400 mm of Hg, all foals had significant positi...
Yovich JV, Powers BE, Stashak TS.The intervertebral disks and adjacent vertebral bodies of the 2nd to 7th cervical vertebrae from 17 horses (3 months to 19 years of age) were examined grossly and by light microscopy. In each specimen, the disk tissue was fibrocartilagenous centrally and became more fibrous peripherally, but without a distinct demarcation between the nucleus pulposus and anulus fibrosus. Demarcation between the anulus fibrosus and the dorsal longitudinal ligament was not apparent. With increasing age of the horses, cellularity of the central fibrocartilagenous portion of the disk decreased. The caudal end plat...
Pérez W, Martin E.Thirteen fresh equine heads were dissected in an attempt to determine the cause of a groove frequently found on the dorsal border and medial side of the nasal process of the incisive bone. This groove appeared on both sides in 40 out of 44 equine skulls. The sulcus seems to be caused by the combined action of the lateralis nasi muscle and the medial accessory cartilage of the nose (cartilago nasalis accessoria medialis). Other sulci found on the nasal process of the bone may be explained as impressions caused by nerves.
Beroza GA, Perry RW, Cotter DM.Permanent implantation of nonabsorbable materials is appropriate in many surgical circumstances but is not commonly used to close equine celiotomies. This paper describes a simple method of continuous nonabsorbable implantation of polyamide suture used successfully to close 48 equine celiotomies. Forty-eight clean or clean-contaminated celiotomies were successfully performed over 5 years using this technique. The postsurgical survival observation period ranged from 1-6 years (median 3.5 years). There were 45 long-term survivors (93.75%). Only 2 minor implant complications (4.4%) were observed ...
Littlewort MC.This paper outlines the major problems in evaluating and assessing prognosis in horses with minor cardiac abnormalities. It emphasises that progress will only be made if adequate data on the "natural history" of equine cardiac disease can be collected. This will necessitate a long-term study of suitable cases and will require the collaboration of specialist institutions and general practitioners if it is to be successful.
Parker WG, Sullivan JJ, First NL.Fifty mares were inseminated on Days 2, 4, 7, 11 or 17 of the oestrous cycle with spermatozoa from one of three stallions to observe the distribution of the spermatozoa in various parts of the reproductive tract 12 hr later (Days 3, 5, 8, 12 and 18). Only 0-06 to 2-21% of inseminated spermatozoa were recovered from the tract. More (P less than 0-05) spermatozoa were recovered from the cervix and uterus on Day 12 than on Days 3, 5, 8 and 18. The mean number of spermatozoa recovered from either or both oviducts was significantly greater (P less than 0-10) on Days 5 and 8 than on Days 3, 12 and 1...
Lund RJ, Guthrie AJ, Killeen VM.Stables housing more than 20 horses in training were surveyed in the Pretoria, Witwatersrand, Vereeniging area of South Africa. Most racehorses were kept in loose boxes, bedded on straw or sawdust and remained indoors while the stables were cleaned. The average floor area was 13 m2 and airspace was 55 m3 per animal. The average predicted minimum air change rate by natural convection in calm winds was 7.0 air changes per hour, which was reduced to 2.2 when the doors and shutters were closed. The survey showed that many of the stables had been built without due consideration to factors that migh...
Schröter C, Bielefeld M, Bielefeld D, Macke C, Winkelmann C, Mommsen P, Krettek C, Zeckey C.The upper limb is one of the most frequently injured body regions in equestrian sports, but it is unclear which injuries are involved, and there are no data on the associated accident mechanism. The present study is aimed at evaluating the accident mechanisms, injuries of the upper limbs, and the circumstances of the accident in equestrian sports. We included 218 patients who were all treated between 2006 and 2014 at the level I trauma center at the Medical University in Hannover because of equestrian-related accidents. The most frequent injuries were fractures and bruising in the shoulder ...
Cogley TP, Cogley MC.A synthetic alpha-2 adrenergic agonist, detomidine hydrochloride, was used in the study of in vivo activity of Gasterophilus intestinalis (Diptera: Gasterophilidae) during migration in the tongue of the horse. Use of the drug allowed the investigator to manipulate the tongue and closely observe the movement patterns and tissue disturbance caused by burrowing first-stage larvae. Detomidine hydrochloride should be utilized in studies of drug efficacy and larval biology, whenever possible, to avoid the need to sacrifice the horse.
Smith HJ.From 1967--1978 observations were made on the presence of the small equine pinworm, Probstmayria vivipara, in seven experimental ponies. The life cycle of this nematode is unusual in that it is endogenous with development of all stages occurring within the host's digestive tract. Initially, worms were found in the feces of four of seven ponies following treatment with thiabendazole but the infection was later transmitted to all ponies possibly via coprophagy. Still later, based on fecal and postmortem examinations, four of the seven ponies lost their pinworm burdens. At necropsy, the principal...
Gehring R, Beard L, Wright A, Coetzee J, Havel J, Apley M.Pituitary pars intermedia dysfunction (PPID) is probably the most common disease of geriatric horses. Affected horses show a variety of clinical signs, including hirsutism, polyuria/polydipsia, immunosuppression, muscle wasting, and laminitis. The most common treatment for PPID is pergolide, a dopamine agonist; however, there are no pharmacokinetic data about the use of this drug in horses. This article describes a study designed to address this complete lack of pharmacokinetic information. The pharmacokinetics of pergolide are described in a small group of relatively young, healthy mares (n =...
Attenburrow DP, Flack FC, Portergill MJ.The technique of impedance plethysmography is described and its application to observation of lung volume changes in the horse at exercise is discussed. The results from horse at rest show that there is a close relationship between rate of lung volume change (flow rate) and the associated impedance changes during both inspiration and expiration. Impedance changes during exercise were related to inspiration and expiration by observation of associated respiratory sounds. Artefacts related to technical difficulties are also indicated.
Tischner M, Bielański A.Observations were made on 14 mares which were non-surgically flushed on one or more occasions for recovery of embryos on Days 7-9 after ovulation. Flushing alone shortened the oestrous cycle by about 2.7 days but increased the number of mares failing to ovulate. Flushing followed by an injection of a prostaglandin analogue shortened the cycle by about 4.5 days and hence increased the frequency of ovulations. From a total of 70 flushings performed, 27 embryos were recovered and of 12 mares inseminated during the first oestrus after embryo collection, 6 conceived and foaled. The other 7 mares we...
Witherington DH.The post-race heart rates have been recorded in 1,000 Thoroughbreds following Flat, Hurdle and Steeplechase races in varying climatic conditions and on 54 different British racecourses. The post-race deceleration of the heart rate, under racecourse conditions, was marked by an apparent three-phase recovery period. Reference is made to the normal heart sounds and to the relationship between the heart and respiratory rates.
McCarthy PH.The anatomy of each feature and structure of the laryngeal and adjacent regions, as perceived by palpation, is described for clinically normal standing horses. Visible skin contours produced by some of the superficial structures are also described. Concurrent dissection was performed on fresh cadavers to confirm initial findings. The procedure of systematic palpation in relation to clinical diagnosis and surgical procedure is discussed.
Dusek J, Munk Z.In a set of mares of English Thoroughbred horse of the Napajedla stock the gravidity length in the time period from 1880 to 1972 was evaluated. The variability of the gravidity length was evaluated in sets which were put together by combination of two age groups with a division of the studied time period into ten-year stages. Variance and sample means of the gravidity lengths in these sub-groups are significantly different in the period under study. In order to eliminate the action of non-genetic influences qualifying the variability of the gravidity length, and to increase the objectivity of ...
Les CM, Stover SM, Willits NH.Paired metacarpi obtained at necropsy from 100 horses ranging in age from term fetus to 35 years were examined to estimate the prevalence and sites of metacarpal fusion. Metacarpal fusion was seen in 192 of 200 metacarpi, and 78% of all horses 2 years or older had 2 or more fusions. Fusion of the second metacarpal bone to the third metacarpal bone was significantly (P < 0.001) more common than was fusion of the fourth to the third metacarpal bone. Fusions appeared for the most part in pairs and were bilaterally symmetric. Rooney-Prickett type-A carpometacarpal joint configurations (in which...
Shojaei B, Kheirandish R, Azizi S.The present study describes the anatomical and microscopic features of a horseshoe kidney that was found in a 7-year-old male horse. The specimen consisted of two kidneys joined at their caudal poles by an isthmus composed of renal parenchyma and situated caudal to the caudal mesenteric artery. Six main renal arteries arose from the aorta and the external iliac arteries and ramified into 21 branches before entering the kidney. A hypoplastic and ectopic left testis, located in the inguinal canal, was observed as an associated anomaly.
Jensen H, Mikkelsen R, Paulsen ET.Therapeutic riding for somatic disabled has been established as one of the treatment modalities at Beitostølen Health Sports Centre ever since it opened in 1970. The accumulated experience indicates positive effects of the treatment, on empirical grounds, but there is a need of further evaluation and controlled studies. The authors briefly review the principle of the treatment and present the results of a study on the level of pain in patients with Bechterew's disease before and after treatment.
Barker BB, Stannard AA, Maibach HI.Epidermal cell labeling index and cell renewal time were estimated in 8 adult horses, using autoradiography after [3H]thymidine was given intradermally. The mean labeling index was 1.45 +/- 0.47%, and the mean cell renewal time of the viable epidermis was approximately 17 days.
Hornof WJ, Stover SM, Koblik PD, Arthur RM.The research article discusses a study on the use of oblique dorsal views in detecting stress fractures in horses who participate in races. The aim of the researchers was to […]
Feighelstein M, Ricci-Bonot C, Hasan H, Weinberg H, Rettig T, Segal M, Distelfeld T, Shimshoni I, Mills DS, Zamansky A.[This corrects the article DOI: 10.1371/journal.pone.0302893.].
Butler CL, Houpt KA.The objectives of this study were to determine the prevalence of pawing behavior in a population of Standardbred racehorses and the relationship of pawing frequency to time of day. Standardbreds (n=41) were observed using instantaneous scan sampling twice daily, in the morning before training and in the afternoon after training. A majority of the horses, twenty-four (58.5%) of the 41 horses showed pawing behavior at least once (median=7, interquartile range=2-15). After training, there were a median of 4 (interquartile range 1-11) observations of pawing or 11.2% of total observations. In the m...
Whitlock F, McGlennon A, Newton R, Riley K.As part of her undergraduate research project, Cambridge vet student Katie Riley surveyed the attitudes of UK veterinarians with regard to preventing and controlling strangles, including the use of vaccination. Here, she and Fleur Whitlock, Abigail McGlennon and Richard Newton of Equine Infectious Disease Surveillance discuss her findings.
Selecky ME, Louie EW, Donnelly C, Finno CJ, Morgan JM.Echocardiographic reference intervals for Quarter Horses are infrequently reported. Objective: To provide standard echocardiographic measurements for sedentary Quarter Horses and evaluate the relationship between physical characteristics (body weight, age, sex) and echocardiographic measurements. Methods: Forty-one sedentary Quarter Horses, free of cardiac disease, from a university research herd. Methods: A cross-sectional study evaluating standardized echocardiograms performed on sedentary Quarter Horses (41) between 2020 and 2022. Reference intervals were calculated for raw and weight-corre...
Ball BA.There are considerable differences between mammalian species in the distribution and activity of ciliated cells within the oviduct, and limited information is available concerning either the distribution or activity of cilia within the equine oviduct. Patterns of ciliary activity were characterized in the ampulla and isthmus of oviducts recovered at 2 d after ovulation from 10 mares, and scanning electron microscopy was used to examine regional differences in the distribution of cilia in oviducts from 3 of these mares. Based upon the motility of 15 microm latex microspheres, ciliary activity w...
Spaas J, Helsen WF, Adriaenssens M, Broeckx S, Duchateau L, Spaas JH.There is general agreement that horses have dichromatic colour vision with similar capabilities to human beings with red-green colour deficiencies. However, whether colour perception has an impact on equine jumping performance and how pronounced the colour stimulus might be for a horse is unknown. The present study investigated the relationship between the colour of the fences (blue or green) and the show jumping performance of 20 horses ridden by two riders using an indoor and outdoor set of green and blue fences. In the indoor arena, significantly more touches and faults were made on blue fe...
Hollenbach E, Robert MP, le Roux C, Smit Y.If the number of events alone is considered, endurance riding is the fastest growing and the second-most popular Fédération Equestre Internationale (FEI) discipline. Lameness is the most common cause of elimination from endurance races worldwide. To the authors' knowledge, no studies have been published investigating the prevalence of radiographic changes in the forelimb digits and metacarpophalangeal joints (MCP) of endurance racehorses in South Africa. Unassigned: Investigate the prevalence of radiographic changes in the forelimb digits and MCP joints of South African endurance racehorses....
Turner AS, White N, Ismay J.Thirty-five horses with a history of crib biting or wind sucking were treated with a modification of the Forssell procedure. The technique involved bilateral neurectomy of the ventral branch of the accessory nerve combined with excision of a portion of the omohyoideus, sternohyoideus, and sternothyroideus muscles. Twenty horses became free of the vice, while in 11 there was a noticeable reduction in frequency of the vice. Four horses returned to crib biting/wind sucking at the same intensity as before surgery. The observation time following each operation was at least 12 months. Complications ...
Crijns CP, Van Bree HJ, Broeckx BJG, Schauvliege S, Van Loon G, Martens A, Vanderperren K, Dingemanse WB, Gielen IM.The objective of this study was to examine the influence of the size, age and sex of the horse on the size of the pituitary gland and determine the possibility of using the pituitary gland height-to-brain area ratio (P:B ratio) to allow comparison of different sized and aged horses. Thirty-two horses without pituitary pars inter-media dysfunction that underwent a contrast-enhanced computed tomographic (CT) examination were included in a cross-sectional study. On the CT images, the pituitary gland height was measured and the P:B ratio was calculated. These measurements were correlated to the si...
Lusi CM, Davies HMS.Passive dynamics is an aspect of locomotion which is entirely dependent on the mechanical configuration and linkages of adjacent body segments. Tension distribution along mechanical linkages enables the execution of movement patterns with reduced need for complex neurological pathways and may play a role in reestablishing postural stability following external disturbances. Here we demonstrate a uni-directional mechanical relationship between the equine forelimb, head and neck, which may have implications for balance and forelimb loading in the horse. These observations suggest that forelimb, h...
