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Topic:Clinical Study
Clinical studies in equine research involve the systematic investigation of health and disease in horses through structured scientific methods. These studies aim to evaluate the safety and efficacy of treatments, understand disease mechanisms, and improve veterinary care practices. Clinical studies can include randomized controlled trials, observational studies, and case-control studies. They may focus on various aspects such as pharmacokinetics, therapeutic interventions, and diagnostic techniques. This page compiles peer-reviewed research studies and scholarly articles that explore the design, implementation, and findings of clinical studies in equine medicine, providing insights into their impact on horse health and veterinary practices.
The effect of drugs used in the treatment of osteoarthrosis on stromelysin (proteoglycanase) of equine synovial cell origin. There is increasing evidence that the proteoglycan-degrading neutral metalloproteinase, stromelysin, is a key enzyme in the pathogenesis of osteoarthrosis. Equine synovial lining cells were stimulated in vitro to produce stromelysin, and phenylbutazone, flunixin, betamethasone, sodium hyaluronate and polysulphated glycosaminoglycan (PSGAG) were tested for their ability to inhibit the action of this enzyme on 14C-labelled casein substrate. Only PSGAG possessed inhibitory activity at concentrations likely to be achieved therapeutically in the equine fetlock joint.
Atypical myoglobinuria: an acute myopathy in grazing horses. Four out of 12 horses grazing a field in Berkshire, England, suffered a prostrating illness and died within 12 to 72 h. Serum biochemical abnormalities, including markedly elevated muscle enzymes, were demonstrated and at post mortem widespread myodegeneration was found in both skeletal muscle and myocardium. Urine analysis revealed myoglobinuria, and renal changes were seen histologically. Although similar pathologically, the clinical syndrome and circumstances of the outbreak were not typical of equine exertional rhabdomyolysis (EER). The outbreak bore a striking resemblance to other reporte...
Enumeration of anaerobic bacterial microflora of the equine gastrointestinal tract. Samples from the duodenum, jejunum, and ileum, as well as from the cecum and colon, were obtained from 11 mature grass-fed horses. Viable counts of total culturable and proteolytic bacteria were made on habitat-simulating media containing 40% clarified ruminal fluid. The mean pHs in the duodenum, jejunum, and ileum were 6.32, 7.10, and 7.47, respectively; the mean pH decreased to 6.7 in the hindgut. The acetate concentration increased along the length of the small intestine and was the only volatile fatty acid present in this gut segment. Molar proportions of acetate, propionate, and butyrate ...
Some observations on lameness associated with pain in the proximal metacarpal region. The carpus and metacarpus of 40 horses which were free from lameness and 40 horses with lameness associated with the metacarpophalangeal joint or more distal limb were examined radiographically (Group A). The opacity of the proximal third of the third metacarpal bone was regular, with a uniform trabecular pattern. Osseous cyst-like lesions (OCLLs) were identified in the radial carpal bone (1), the ulnar carpal bone (2), the second carpal bone (15) and the fourth carpal bone (1). Thirty-one of 638 horses (4.8 percent) with forelimb lameness had pain localised to the proximal metacarpal region u...
Concentration of serum testosterone in XY sex reversed horses. The XY Sex Reversal Syndrome of the horse is a condition associated with female or intersexual development in genetic males. In our previous study, 38 sex reversed XY mares were classified according to behavior, gross clinical phenotype, gonadal status, and H-Y phenotype. Four classes were described, ranging from potentially fertile female (Class I) to virilized intersex (Class IV). In the present study, serum testosterone concentrations were measured in 29 sex-reversed XY mares, 3 normal mares and 3 normal stallions. Serums were obtained during the breeding season (March-August), and were sto...
Characterisation of IgE-mediated histamine release from equine basophils in vitro. In vitro IgE-mediated histamine release by equine blood basophils was characterised as the basis for a screening test for immediate hypersensitivity responses in horses. The responses are initiated by inducing agents that are capable of crosslinking or bridging the membrane-bound IgE molecules. The release process is complete within 40 mins. In vitro histamine release is dose-dependent, with a submaximal response at less or greater than the optimal dose of inducing agent. Exogenous calcium is required but not magnesium; the optimal release calcium concentration is 1.0 to 1.5 mM. If an IgE-medi...
Curettage of subchondral bone cysts in medial femoral condyles of the horse. Fifty-one horses and unilateral or bilateral femorotibial arthrotomy with medial condyle bone cyst curettage. A total of 60 cyst were treated. Treated horses responded to the surgery three to 12 months postoperatively. In 42 horses lameness was reduced or eliminated, enabling them to return to an remain in their intended function. Of these 42 horses 35 are sound, four of which have not started training, and seven showed partial improvement, two of which had no long term follow up. Of the remaining nine horses, two showed no reduction in lameness and seven were not followed up. Arthrotomy was s...
Evaluation of equine locomotion during different degrees of experimentally induced lameness. I: Lameness model and quantification of ground reaction force patterns of the limbs. Force plate data from walking horses were used to evaluate the locomotion of a group of six horses during experimentally induced lameness in a forelimb or a hindlimb. By tightening or loosening screws in modified horseshoes the resulting pressure pain on the sole enabled induction and release of three different degrees of supporting lameness within a period of 2 h. The ground reaction force (GRF) patterns of the different recording sessions were compared with control data of the same horse as well as with the 'standard' horse data using a quantitative evaluation procedure involving 93 GRF para...
Partial arytenoidectomy in the horse with and without mucosal closure. Left-sided partial arytenoidectomy was performed in eight horses to evaluate healing. Four horses underwent conventional partial arytenoidectomy with suture apposition of the mucosa. In four horses, most of the arytenoid cartilage, including overlying mucosa, vocal fold, and laryngeal saccule, were excised en bloc without mucosal closure. The horses were monitored clinically by endoscopic examination. One horse from each group was euthanatized at weeks 2, 4, 8, and 16. Complete necropsies with gross and histologic examination of the arytenoidectomy sites were performed. Postoperative complicat...
In vitro evaluation of a sustained-release veterinary peroral pellet preparation. In a preceding in vivo study in horses, wide interindividual variation was found in the extent of bioavailability and time to reach peak concentration after peroral administration of one specific theophylline sustained-release dosage form. The purpose of the present study was to investigate the factors of potency, the pH of dissolution medium, the enzymes in the dissolution medium, and the crushing of the pellets on in vitro performance. The results show a wide variation in potency for the individual units, an increase in release rate with increasing pH, and an increase in release rate if the ...
Biochemical and toxigenic characteristics of Aeromonas spp. isolated from diseased mammals, moribund and healthy fish. In this study we describe biochemical, toxigenic and surface characteristics of 33 motile Aeromonas isolated from diseased mammals, 3 from moribund marine mammals, 24 from healthy fish and 4 from moribund fish. Aeromonas hydrophila, A. caviae and A. sobria were isolated from both mammals and fish but at a different incidence. Aeromonas hydrophila was the predominant species isolated from clinical specimens; it was isolated from pneumonia, wound infections, septicemia and abortion in horses, cattle and pigs. Aeromonas sobria was isolated from one mammal and 11 healthy fish. Aeromonas caviae was...
Experimental chemotherapy in horses infected with benzimidazole-resistant small strongyles. The presence of benzimidazole-resistant strains of equine small strongyles was confirmed in horses at two properties in north west England by a series of faecal egg counts and larval cultures after treatment with mebendazole. A trail formulation of mebendazole in combination with piperazine citrate gave greater reductions in faecal egg counts than mebendazole alone but was much less effective than pyrantel embonate or dichlorvos.
Small intestinal obstruction associated with wood chewing in two horses. Although wood chewing by horses is recognised as a common vice, there are few reports of specific disease associated with the habit. Two cases of acute obstruction of the small intestine by solid aggregations of wood splinters are described in horses which were both habitual wood chewers. Details are presented of the clinical findings in these cases, including the surgical treatment of acute colic. Both horses returned to full working fitness. The authors review the syndrome of enterolithiasis in horses, and discuss the causes and significance of wood chewing as a stable vice.
Esophageal duplication cyst as a cause of choke in the horse. A mare was examined for episodic choking and an abscess in the perilaryngeal region. One month before referral, the mass progressively enlarged, causing esophageal choking. An extraluminal compression of the esophagus 90 cm from the external nares was found on endoscopy and contrast radiography. Serosanguinous fluid aspirated from the mass contained keratinized squamous cells and neutrophils, compatible with an esophageal cyst. Surgical exploration was performed, with incomplete surgical excision. The remaining portion of the cyst was marsupialized and treated locally with a 2% inorganic iodin...
Horse brain acylphosphatase: purification and characterization. Two structurally different acylphosphatases found in horse brain were purified; they were not immunologically related. The molecular masses were almost identical and the kinetic parameters were rather similar. The data reported indicate that one of the purified brain acylphosphatases and an enzyme, previously isolated from horse muscle, are the same protein. The presence of this acylphosphatase form in the brain has not been reported before. The other acylphosphatase seemed to be the same as the enzyme which had been purified from calf brain and partially characterized by Diederich and Grisoli...
XY sex reversal syndrome in the mare: clinical and behavioral studies, H-Y phenotype. An inherited genetic disorder causes XY embryos of the horse to develop as mares. On the basis of our study of 38 such mares, we have identified four grades or classes of XY sex reversal according to this scheme: class I, nearly normal female, of which some are fertile; class II, female with gonadal dysgenesis, normal mullerian development; class III, intersex mare with gonadal dysgenesis, abnormal mullerian development, enlarged clitoris; class IV, virilized intersex characterized by high levels of testosterone. In general, class I and class II mares were typed H-Y antigen-negative whereas cl...
Control of the estrous cycle in the mare. All current approaches to manipulating the reproductive biology of the nonpregnant mare are discussed.
Embryonic loss in mares. Incidence, possible causes, and diagnostic considerations. Fertilization rates were similar for normal and subfertile mares, and much of the difference in fertility between normal and subfertile mares was due to embryonic loss. Fertilization rate estimates for mares ranged from 71 to 96 per cent. The incidence of embryonic loss detected by ultrasonography between Days 11 and 50 was approximately 9 per cent for normal mares, and the estimated incidence of embryonic loss before Day 14 was also 9 per cent. Therefore, the estimated incidence of embryonic loss in normal mares between fertilization and Day 50 is approximately 18 per cent (Fig. 1). In subfer...
Nonsurgical treatment of uterine torsion in seven mares. Nonsurgical correction of uterine torsion was performed in 7 mares, and 6 foals were subsequently born alive. Uterine rupture necessitated euthanasia in 1 mare. Correction was achieved by rolling of the mares after general anesthesia had been induced. Previously, this technique was believed to be associated with a high prevalence of fetal and maternal mortality. Nonsurgical correction may be a satisfactory alternative to abdominal surgery in treating uterine torsion in mares.
Endometrial biopsy of the mare. A review and update. The endometrial biopsy is a safe and effective means of predicting a mare's prognosis for foaling. A thorough understanding of the normal cyclic and seasonal pattern displayed by the normal endometrium is necessary before interpreting pathologic changes. Several systems for prognostic classification have been proposed, including a recent one that combines many of the criteria used in the other systems.
Assessment of hepatic function and damage in animal species. Animal Clinical Chemistry Association. There are a wide variety of laboratory tests available to assess damage to and functional impairment of the liver, though the effectiveness of these tests varies greatly depending upon the type of damage and the animal species involved. Species differences in tissue localization, metabolism, specificity and sensitivity of parameters relating to the liver influence the choice of tests. Some tests can be applied usefully to most animal species while others may be highly specific in one species but show very low discriminatory potential in others. The tests available, and their use in veterinary ...
Ultrasonic imaging of equine ovarian follicles and corpora lutea. One of the most profound theriogenology applications of transrectal diagnostic ultrasonography in mares involves the imaging of ovarian follicles and corpora lutea. The resolving capabilities (frequency) and quality of the scanner directly affect the minimal size of a structure that can be imaged and the quality of the image. High-frequency scanners (5 or 7.5 MHz) of good quality can image a 2-mm follicle and the corpus luteum throughout its functional life. A low-frequency scanner (3 or 3.5 MHz) can image a 6-mm follicle and the corpus luteum for several days after ovulation. Equine follicles...
Kinetics and kinematics of the equine hind limb: in vivo tendon strain and joint kinematics. Strains of the suspensory ligament and deep digital flexor, superficial digital flexor, and long digital extensor tendons in the equine (pony) hind limb were recorded in vivo, using implanted strain gauges consisting of silicone rubber tubes filled with mercury. The relationship between strain gauge signals and tendon strains was obtained from tension-strain tests performed on isolated tendons after death of the ponies. During normal walking, maximal tendon strain (elongation over initial length, relative to the length of the structures at first ground contact) was 3.1% in the suspensory ligam...
Evaluation of immune complexes and collagen type-specific antibodies in sera and synovial fluids of horses with secondary osteoarthritis. Thirty-one horses with secondary osteoarthritis as a sequel of trauma (chip fractures) or osteochondritis dissecans were screened for immune complexes (IC) and anticollagen antibodies. Eighty-two percent of horses with joint disease had circulating C1q-binding IC; 77% of those horses had IC in synovial fluids of affected joints. Although only a few horses had anticollagen type-II antibodies, anticollagen type-I antibodies were found in sera of 25% of the horses and in 41% of their synovial fluids. This correlated well with the clinical data and suggested that antibodies might have been elicite...
Cardiorespiratory responses to HCl vs. lactic acid infusion. Previous reports indicate that intravenous infusion of HCl can alter breathing and blood pressure even if reductions in systemic arterial pH are prevented. To extend these findings, as well as to determine whether other acids elicit comparable results, this report compares the cardiopulmonary response between right atrial infusion of lactic acid and HCl in awake ponies. Lactic acid, infused at a dose of 1.5 mmol/kg over 18 min, lowered systemic and pulmonary arterial pH 0.062 and 0.092 U, respectively, and increased pulmonary arterial pressure (delta Ppa, 4 mmHg), heart rate (HR, 4/min), and t...
Platelet function testing in the pony. Platelet isolation techniques and platelet function were evaluated in 35 adult ponies. Platelet recovery from whole blood was consistent and the preparation of platelet rich plasma was facilitated by an enhanced erythrocyte sedimentation rate. All platelet samples aggregated in response to 10 microM ADP. However, concentrations of ADP as high as 100 microM did not elicit significant 14C-serotonin release. Collagen induced irreversible platelet aggregation and 14C-serotonin release in all samples. The threshold dose for collagen in most ponies was 1.5 micrograms. Arachidonic acid (500 microM) f...
An inherited connective tissue disease in the horse. The hyperextensible, fragile skin of two related horses was compared with the skin of eight normal horses. Skin sections were examined by light microscopy and transmission electron microscopy. The deep dermal layer of the dorsal abdomen was much thinner in the affected horses, and contained bundles of collagen fibers which were more loosely packed. Within individual fibers, the fibrils were frequently curved and nonparallel rather than straight and parallel. Both of the affected animals had a greater range of fibril diameters than a normal horse. They had some unusually thick fibrils with very...
The effect of artificial photoperiod at the end of the breeding season on plasma testosterone concentrations in stallions. Testosterone concentrations in stallions showed a seasonal trend with peak concentrations in the spring (April and May in Britain) and lowest concentrations in the period from December to February. The effect on this pattern of changing the length of the photoperiod at the end of the normal breeding season (mid-summer's day) was studied in 2 experiments. In the first experiment artificial illumination was organised from 21 June to mimic the effect of transfer to a southern hemisphere spring and summer, that is short days becoming longer. The stallions had low concentrations of testosterone in ...
Slab fractures of the third carpal bone in standardbreds and thoroughbreds: 155 cases (1977-1984). Case records and radiographs of 155 horses with third carpal bone (C3) slab fractures were reviewed. Of these cases, race records were obtained for 72 Thoroughbreds and 61 Standardbreds. Three performance criteria were examined: ability to make 1 start, ability to make 10 starts or earn $2,000 (within 1 year of first start after the fracture), and earnings per start. Treatment distribution (lag screw fixation, fragment excision, or rest) was similar in both breeds. Significant differences between breeds were identified in age and sex distributions, fracture displacement, and postinjury perform...
Effects of frequency and airway pressure on gas exchange during interrupted high-frequency, positive-pressure ventilation in ponies. Cardiovascular effects and pulmonary gas exchange were compared during conventional mechanical ventilation (CMV) and interrupted high-frequency, positive-pressure ventilation (IHFPPV) in 6 anesthetized ponies in dorsal recumbency. When the peak airway pressure (Paw) was held constant at control values attained during CMV (18 to 20 cm of H2O), and the ventilator frequency of IHFPPV was varied over the range, 2.5 to 12.5 Hz, significant (P less than 0.05) changes from control values were observed only in the ratio of dead-space volume to tidal volume (VD/VT) and in the respiratory minute volume ...
