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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.
Correct occlusive bladder width for indirect blood pressure measurement in horses. The influence of occlusive bladder width on blood pressure, measured indirectly using a doppler ultrasound technique at the middle coccygeal artery, was studied in 6 anesthetized horses. The relationship was investigated on tails with and without hair, and the optimum bladder width (BW)/tail girth (TG) ratio was determined for systolic pressure (SP) and diastolic pressure (DP), with the data grouped as unclipped tails (TT-1), clipped tails (TT-2), and both unclipped and clipped tails collectively (TTB). The optimum BW/TG ratios for SP and DP were 0.296 and 0.866 for TT-1, 0.376 and 1.156 for T...
An investigation of sperm migration into the oviducts of the mare. A total of 23 mares were inseminated once within 0-6 h after clinical detection of ovulation, 14 with fresh and 9 with deep-frozen semen containing 0.1 x 10(9) to 4.7 x 10(9) motile spermatozoa. Within these two groups, the mares were slaughtered 2, 4 or 6 h after insemination and their genital tracts removed. The utero-tubal junction, isthmus and ampulla ipsilateral to the ovary in which ovulation occurred were flushed separately for sperm recovery. In 1 or 2 mares of each group, the uterine horn and corpus uteri, the cervix and vagina were also flushed. Tissue samples were collected from the...
Studies on the composition and antibacterial activity of uterine fluid from mares. Forty uterine fluid samples were obtained during oestrus and dioestrus of successive cycles from 4 mares classified as resistant to bacterial infection of the uterus. The flushings were assayed for peroxidase activity and ability to influence phagocytosis by polymorphonuclear neutrophils. Uterine fluid volumes and protein concentrations and serum oestrogen values were similar during oestrus and dioestrus. Serum progesterone concentrations were depressed during oestrus. Equine neutrophils adherent to glass slides were exposed to a genital strain of Streptococcus zooepidemicus suspended in salin...
Effect of PGF-2 alpha on LH receptors in the equine corpus luteum. As quantified by Scatchard analysis, a 27 000 g crude luteal membrane fraction contained a single population of unoccupied LH receptors characterized by high affinity, ka = 0.647 +/- 0.158 X 10(11) M-1 and low binding capacity, Rt = 4.91 +/- 0.78 X 10(-11) M/mg membrane fraction. Acceptable hormonal specificity, reversibility, saturability, high affinity and tissue specificity indicated that the binding protein was a physiological receptor. To ensure that the methods used for Scatchard analysis were valid, hCG was characterized for specific activity and maximum bindability, non-specific bindin...
Immunity to and immunotherapy for Rhodococcus equi. Immune responses to Rhodococcus equi were assayed in mares and foals on 7 studs in south-eastern Australia using skin test reactivity to the intradermal injection of culture filtrate and an indirect fluorescent antibody test. The prevalence of positive skin-test reactions did not differ between studs with a history of R. equi disease and those without but there were more mares with high antibody titres on studs with a disease history. A leucocyte extract prepared from mares that were skin-test positive was evaluated for its ability to protect foals exposed to experimental or natural challenge:...
Effect of adrenergic neurotransmitters upon the ejaculatory process in the stallion. Successful empirical treatment of 17 out of 24 stallions, which had failed to ejaculate after normal penile erection, intromission and friction, by chemical blockage of beta-receptors and additional stimulation of alpha-receptors led us to investigate stallions with normal ejaculatory patterns. In an initial experiment one adult half-bred stallion was injected with 4.88 mg noradrenaline hydrochloride (treatment A), 10 mg bunitrolol (treatment B = beta-receptor blockage) and a combination of treatment A and B. Investigations of the same stallion on dated occasions without treatment served as co...
Equine onchocerciasis: lesions in the nuchal ligament of midwestern U.S. horses. Nuchal ligaments from midwestern U.S. horses infected with adult Onchocerca sp. were studied. The prevalence of Onchocerca sp. infection in horses increased with age. Ten percent of horses less than one year old were infected, 28% of horses one to five years old, 48% of horses six to 15 years old, and 90% of horses over 16 years old. Lesions in Onchocerca sp.-infected nuchal ligaments varied with age of the horse. Horses less than five years old had few or no lesions, whereas most horses six to 15 years old had focal mineralization and granuloma formation around adult worms. In infected nuchal...
Indirect hemagglutination test in equine infectious anemia. An indirect hemagglutination was developed for the diagnosis of equine infectious anemia using sheep red blood cells coated with group specific virus antigen which had been highly purified by affinity chromatography. The presence of indirect hemagglutination antibodies was demonstrated in horses with equine infectious anemia since the cells were specifically agglutinated by all the serum samples obtained from experimentally infected horses. Antibodies appeared within 35 days after inoculation, and development of which coincided well with that of precipitating and complement fixing antibodies. ...
Glucocorticoid-induced inhibition of osteolysis and the development of osteopetrosis, osteonecrosis and osteoporosis. Changes in the developing femoral epiphysis, especially those concerning the osteocytes, were examined in pony foals systemically treated with daily intramuscular injections of either 0.5 or 5.0 mg of dexamethasone per 100 kg bodyweight for either 3, 8 or 11 months. Midsagittal sections of proximal femur from animals treated for 3 months contained significantly more bone tissue subchondrally and epiphyseally than did sections from untreated ponies. Large portions of the bone tissue appeared necrotic, although osteoblasts and patent capillaries were abundant. After 8 months the bone sections re...
Endometrial change in the annual reproductive cycle of the mare. Cervical and endometrial swabs were taken from 7 mares at various stages of the oestrous cycle. There was no consistent pattern of cell change throughout the cycle. The dominant cell in smears from normal mares was the columnar epithelial cell, especially in smears obtained during oestrus. A ciliated columnar epithelial cell was found much less frequently but appeared more often in smears before oestrus. Endometrial biopsies were also collected from 7 mares at intervals 2-3 weeks over an 8-month period from the beginning of spring to the end of autumn. There was no obvious change in the endome...
Control of the oestrous cycle in mares with altrenogest. The clinical effectiveness of the synthetic progestagen, altrenogest, was evaluated in field trials with 449 mares during the 1980 breeding season. An oral dose of 27 mg altrenogest was administered daily for 15 days. In the first trial treated mares were compared with controls, and in the second trial the effectiveness of treatment for prolonged or erratic spring oestrus was evaluated. Oestrus was suppressed in 94% of the treated mares in the first trial. The post-treatment response was related to the stage during the transition from winter anoestrus to the spring breeding season and degree o...
Termination of twin gestation by blastocyst crush in the broodmare. Manual crushing of one blastocyst performed on 181 bicornuate twin pregnancies between Days 24 and 45 has shown that the uncrushed blastocyst can either survive and develop normally to full term or may be rejected and resorbed like its crushed twin, depending mainly on the stage of pregnancy. Crushing, which causes rupture of fetal membranes, results in a rapid fall in the survival rate of the uncrushed blastocyst when performed after Day 31. In some mares rupture is not possible after Day 35 even if extreme pressure is used. Crushed, but unruptured, blastocysts mainly between Days 35 and 45 m...
Uterine prostaglandin F metabolite production in relation to glucose availability in late pregnancy and a possible influence of diet on time of delivery in the mare. The production of uterine PGFM during different dietary states has been investigated in pregnant mares in late gestation. Arterial and uterine venous plasma concentrations of PGFM rose when food was withdrawn for 12-30 h and the V-A difference widened significantly. There was an inverse correlation between the rise in PGFM and the fall in plasma glucose during a fast, and a significant decrease in the A-V plasma glucose differences across the uterus. Plasma PGFM and free fatty acid concentrations before and during food withdrawal were also correlated but no uterine A-V difference in free fatty...
Influence of bacterial products on the motility of stallion spermatozoa. Sterile filtrates were prepared from equine isolates of Klebsiella pneumoniae (genitalium), Proteus mirabilis, Pseudomonas aeruginosa, Escherichia coli, Streptococcus zooepidemicus, Streptococcus equisimilis, Actinobacillus equuli, and Corynebacterium equi and mixed individually with extended stallion semen. When diluted in the extended semen the filtrates represented bacterial populations of 0.5 x 10(6), 1 x 10(6), 2 x 10(6) and 4 x 10(6) cells/ml. pH values were recorded for each filtrate. Specimens were monitored for percentage motile spermatozoa at 30-min intervals until they reached 10% o...
Ovarian response, pregnancy rate, and incidence of multiple fetuses in mares treated with an equine pituitary extract. The ability of a pituitary extract to induce ovulation and the effect of multiple ovulations on pregnancy rate and incidence of multiple fetuses were studied in seasonally anovulatory mares. The extract induced ovulation in 95% of mares having a greater than or equal to 25 mm follicle at the onset of treatment and in 64% the ovulations were multiple. The extract was less effective when the largest initial follicle was less than 25 mm. Approximately 50% of the treated mares that ovulated did not become pregnant or enter prolonged dioestrus before returning to an anovulatory condition. In treate...
Ovarian disorders: clinical and morphological observations in 30 mares. A five year prospective study of equine ovarian problems requiring surgical correction was undertaken at the Ontario Veterinary College. Thirty mares were studied, of which 14 had granulosa cell tumors, six were with anovulatory persistent follicular "structures", five had ovarian hemotoma, two presented ovarian hypoplasia and one each of ovarian dysgerminoma, teratoma and abscessation. The clinical signs manifested by the affected animals were varied. The affected ovaries were removed via flank or midline laparotomy or through colpotomy. Their morphology was studied and representative portion...
Effect of the stage of the oestrous cycle on the follicular population in pony mares. In the middle of the breeding season, 16 pony mares (n = 4 per day) were slaughtered on four different days (days 6, 14, 17 and the preovulatory day) of the oestrous cycle, day 0 being the day of the last ovulation. All the ovaries were examined histologically; the number, size and atresia (defined by granulosa cell pyknosis) of all follicles larger than 1 mm in diameter were studied, using a Kryotome-video recorder-TV system. Follicular distribution of all the sizes studied (1-5 mm, 5-10 mm, greater than 10 mm in diameter) was very similar in the right and left ovaries. However, compared to t...
Transuterine migration of the fetus in the mare between day 42 and parturition. A total of 2187 Thoroughbred and Standardbred mares was examined over a 4-year period to determine the location of the fetus at 42 days, the location of the previous fetus as determined by examination 5-15 days after foaling, and pregnancy location the next season. Maiden mares showed 44 and 56% of pregnancies in the left and right horns respectively. No transuterine migration was observed in 139 maiden mares examined after their first foal. Lactating mares showed 62% implantations and full-term pregnancies on one side of the uterus with the next season's pregnancy being in the opposite uterin...
Effects of pituitary stalk transection on endocrine function in Pony mares. The pituitary stalk was transected in 10 Pony mares by a surgical approach that involved dorsal reflection of the brain and micro-dissection from the ventro-lateral aspect of the pituitary. Diabetes insipidus was the most immediate and marked result, requiring extensive electrolyte and antidiuretic therapy for approximately 48 h after operation. Fluid stasis then developed and no further supportive measures were necessary. Endocrine challenge tests with GnRH and TRH before and after stalk transection indicated a loss of responsiveness (GnRH) or suppressed responsiveness (TRH) after the operati...
Control of ovulation in mares in the early breeding season with ovarian steroids and prostaglandin. Two trials were conducted to (1) determine the degree of control of ovulation achieved by treating mares in late winter with progesterone and oestradiol-17 beta combined after prior exposure to an artificially increased photoperiod, and (2) to examine the effectiveness of such a procedure incorporated into equine breeding farm management systems. Following a 15-day treatment of 150 mg progesterone and 10 mg oestradiol-17 beta daily with 10 mg PGF-2 alpha on the last day of steroid treatment, 27 of 31 mares ovulated on Days 8-14 after the last injection in one trial. Conception rate for mares m...
Chronic obstructive pulmonary disease anatomical cardiac studies. An abattoir survey on horses diagnosed as suffering from chronic obstructive pulmonary disease (COPD) on clinical grounds showed that the right ventricular wall thickness was not significantly different from that of normal horses. However, the weight ratio between the left and right ventricles was found to be significantly (P less than 0.001) different in COPD affected, compared with control, horses in a study of 17 physiologically and pathologically confirmed COPD cases, using ventricular weight measurements. No clinical evidence of right heart failure nor post mortem evidence of right heart ...
Cytogenetic and DNA analyses of equine abortion. Although no major structural or numerical abnormalities were found in the karyotypes of 12 aborted equine fetuses, two unrelated abortuses each carried a large polymorphism for the amount of heterochromatin in chromosome 1. In both karyotypes this chromosome was shown to be larger than its homolog. To determine the nature of the extra DNA in these chromosomes, equine DNA was isolated and characterized by buoyant density analysis. Equine mainband DNA had a buoyant density in neutral CsCl of 1.699 g/cm3, while the highly repetitive (dG+dC)-rich fraction had a buoyant density of 1.715 g/cm3. A ra...
Seasonal and individual effects on ovarian and endocrine responses of mares to a synchronization treatment with progestagen-impregnated vaginal sponges. The 8 saddle-type mares were treated with progestagen-impregnated vaginal sponges for 8 days and prostaglandin on the day of sponge removal. The treatment was given at random days of the cycle in April, May, July and September. Sponge insertion induced a sharp decrease in LH levels; at sponge removal, there was an immediate increase in LH and a large FSH rebound. Ovulation was synchronized 11 +/- 2 . 8 days (s.d.) after the end of treatment. In April the interval from sponge removal to ovulation was longer (14 days compared with 10 . 1, 10 . 7 and 10 . 2 days), the basal and peak LH levels low...
[Sensitivity and fidelity of the rabies laboratory diagnosis]. The author describes a method for evaluating the minimal number of diagnosis failures for each animal species (this diagnosis uses the Fluorescent Rabies Antibodies Test and mouse inoculation simultaneously). The percentage of well diagnosed rabid animals on total rabid ones is called sensibility of the diagnosis: it varies according to the species of animal examined: from 99.98% for the fox, to 98.61% for the horse. The percentage of errored negative diagnosis on total negative diagnosis is called infidelity of negative responses: it varies for each species according to the sensibility of the...
Postanesthetic myonecrosis in horses. Two horses died of massive myonecrosis following surgery. The hematological, biochemical and pathological changes are described and compared with those previously reported in the literature.
Bacteriologic examination of equine fecal flora as a diagnostic tool for equine intestinal clostridiosis. The fecal flora of 56 clinically healthy and 23 sick horses were examined bacteriologically for counts of Clostridium perfringens, molds, coliforms, alpha- and beta-hemolytic streptococci, and microbes belonging to genus Bacillus, as well as for the presence of Salmonella spp. Of the healthy horses, 85.7% had a C perfringens count less than 10(1) colony-forming units/g of feces. Of the healthy horses, lowest counts were found in race-horses. Of the sick horses, equine intestinal clostridiosis was diagnosed in 2 horses with large C perfringens counts (10(4) to 10(7) colony-forming units/g) and ...
