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Topic:Horses
"Horses" is a broad topic that encompasses various aspects of equine biology, behavior, and management. This category includes studies on the anatomy, physiology, and genetics of horses, as well as their behavior, nutrition, and care. Research in this area may also cover the historical and cultural significance of horses, their roles in agriculture, sport, and therapy, and the challenges associated with their conservation and welfare. The page aggregates peer-reviewed research articles and scholarly studies that explore the multifaceted relationships between humans and horses, examining both scientific and socio-economic perspectives.
Effects of gestation, lactation, and maternal calcium intake on mechanical strength of equine bone. Skeletal homeostasis during late gestation, lactation, and the post-lactational recovery period is poorly understood. In an experiment using an animal model (the horse), metacarpal breaking strengths (MBS) estimated via transmission ultrasonics were examined during the last 12 weeks of gestation and for 40 weeks after parturition. MBS increased during the last 6-10 weeks of gestation in mares fed amounts of calcium (Ca) recommended by the National Research Council; maximum MBS coincided with the week of parturition. In contrast, MBS in mares fed 20% less Ca remained relatively constant during ...
Equine influenza. Influenza continues to be one of the most important diseases of horses despite the availability and widespread use of equine influenza vaccines for almost 30 years. In recent years, infection with the influenza A/equine/2 subtype has become endemic in the equine populations of North America, Europe, and Scandinavia. Continued antigenic drift of field virus has compromised the efficacy of vaccines, most of which contain antigens prepared from influenza viruses isolated more than 10 years ago. This article reviews the history, virology, epidemiology, pathogenesis, immunology, clinical presentati...
African horse sickness. AHS is a noncontagious vector-borne disease of Equidae caused by Orbiviruses. Species susceptibility in decreasing order is horses, mules, donkeys, and zebras. The main vectors of AHS are culicoides. The disease is endemic in sub-Saharan Africa, but epizootics have occurred outside of this area on several occasions. The most recent outbreaks outside of the endemic area were in Spain, Morocco, and Portugal between 1987 and 1990. AHS causes mortality up to 95% and is classically divided into four clinical forms: the pulmonary, cardiac, mixed, and horse fever forms. Pathologic changes are subcuta...
Serum osteocalcin concentration in horses treated with triamcinolone acetonide. The effect of triamcinolone acetonide (0.09 mg/kg of body weight, IM) on serum osteocalcin concentration was studied. Two groups of horses were investigated and included clinically normal horses (group 1, n = 5) and horses with chronic obstructive pulmonary disease (group 2, n = 5). Before treatment, results of a t-test did not reveal any significant difference in serum osteocalcin concentration between the 2 groups. After treatment, a significant (P < 0.05) decrease in serum osteocalcin concentration was observed for both groups. Osteocalcin concentration in individual horses reached a min...
Possible normokalemic variant of hyperkalemic periodic paralysis in two horses. Hyperkalemic periodic paralysis (HPP), characterized by intermittent episodes of muscle fasciculations, profound muscle weakness, and hyperkalemia, has been described in Quarter Horses, Appaloosas, and Paints. In previous reports, the hallmark of this syndrome has been the development of hyperkalemia during each episode. Two affected horses had episodes of paralysis without associated hyperkalemia, demonstrating that normokalemia during an episode otherwise consistent with HPP does not eliminate HPP as a diagnosis. This clinical presentation appeared to be a variant of HPP.
Equine plasma and blood volumes decrease with dehydration but subsequently increase with exercise. The effects of dehydration and 40 min of exercise at approximately 40% of maximal O2 consumption on plasma volume (PV) and blood volume (BV) were studied in six horses. Horses were exercised while euhydrated (C); 4 h after administration of furosemide (1.0 mg/kg i.v.; FDH), which induced isotonic dehydration; and after 30 h without water (DDH), which caused hypertonic dehydration. Dehydration resulted in decreases of 6.3 and 9.9% for PV and BV, respectively, with FDH and 10.7 and 8.5%, respectively, with DDH. During exercise in C, PV and BV increased by 12.7 and 20.0%, respectively; during exe...
Lyme disease (Lyme borreliosis) in horses. This article reviews epizootiology, public health considerations, antibody testing, and molecular biology of Lyme borreliosis. Correlation of clinical signs with titer response is discussed.
[Salmonellosis in the horse]. Salmonellosis is a worldwide problem of both men and animals. Equine salmonellosis is an increasing problem and a review of the recent knowledge is given. Etiology, symptomatology, diagnostic procedures, therapy and prevention are discussed.
Transoral axial division, under endoscopic guidance, for correction of epiglottic entrapment in horses. Transoral axial division was performed, using endoscopic guidance, in 20 horses with epiglottic entrapment. Mean age of affected horses was 3 years (range, 2 to 5 years), and there were 18 Standardbreds and 2 Thoroughbreds. Standardbreds and female horses were significantly overrepresented when compared with a reference population. Upper respiratory noise prompted endoscopic examination before surgery in 16 horses, but noise was not heard in 4 horses. Ten horses had entrapment by thin tissue without ulceration, 6 horses had entrapment by thin tissue with small, partial-thickness ulceration, 3 ...
Morphogenesis of compound melanosomes in melanoma cells of a gray horse. A thoroughbred horse, gelding, gray color, aged 19 years old had cutaneous melanomas from the root to the middle of the tail, and throughout the connective tissues of the whole body. Histologically, the tumors were diagnosed as mature melanotic melanomas characteristically deposited with abundant melanin pigment. Examined with an electron microscope, melanosomes were electron opaque without internal structure (stage IV), or as mature granular and lamellar types. Most of them were fused with each other, and formed compound melanosomes, which was similar to internal melanin aggregates in shape. ...
Equine ehrlichiosis. Equine ehrlichiosis is a seasonal disease of horses first reported in 1969. Clinical signs in horses include high fever, depression, partial hypophagia, anorexia, limb edema, petechiation, icterus, ataxia, and reluctance to move. Hematologic changes include leukopenia, thrombocytopenia, icterus, anemia, and inclusion bodies, principally in neutrophils and occasionally in eosinophils. Diagnosis is made by clinical signs and observing characteristic morulae in a blood smear with standard Wright's stain. Mortality is low unless secondary infection develops or injury occurs as a result of incoordi...
[Pilot study of the occurrence of Prototheca in fecal samples of horses]. Fecal samples of 146 horses were culturally investigated for occurrence of Prototheca spp. using a selective medium, developed by PORE (1973). Prototheca zopfii could be isolated in monoculture from 9 fecal samples (6.2%). The results of this pilot study show that horses too can harbour and shed Prototheca spp. in variable frequency.
Characterization of virulence variants of African horsesickness virus. There are three clinicopathologic syndromes associated with African horsesickness (AHS) virus infection in horses. These different forms of AHS (pulmonary, cardiac, and fever forms) vary in the organs affected, the severity of lesions, time of onset of clinical signs and mortality rates. We have studied the effects of infection with three cell culture passaged variants of AHS virus in naive North American horses. One of these viruses, AHS/4SP, consistently caused the pulmonary form of AHS with rapid onset of severe pulmonary edema and 100% mortality. A second variant, AHS/9PI, resulted in sign...
African horse sickness. AHS is a noncontagious vector-borne disease of Equidae caused by Orbiviruses. Species susceptibility in decreasing order is horses, mules, donkeys, and zebras. The main vectors of AHS are culicoides. The disease is endemic in sub-Saharan Africa, but epizootics have occurred outside of this area on several occasions. The most recent outbreaks outside of the endemic area were in Spain, Morocco, and Portugal between 1987 and 1990. AHS causes mortality up to 95% and is classically divided into four clinical forms: the pulmonary, cardiac, mixed, and horse fever forms. Pathologic changes are subcuta...
Clostridia-associated enterocolitis in adult horses and foals. A review of the literature describing clostridia-associated enterocolitis is presented. The bacteria, their toxins, and possible factors that interact to contribute to the pathogenesis of enterocolitis are described. Clinical signs associated with clostridia-associated enterocolitis, methods of diagnosis, treatments, and preventive strategies are discussed.
Role of decreased plasma volume in hematocrit alterations during incremental treadmill exercise in horses. Six intact (IN) and six splenectomized (SP) mares were subjected to an incremental exercise test to examine the role of decreases in plasma volume (PV) in the changes in hematocrit (Hct) normally seen with exercise. Each horse underwent an incremental exercise test in which it ran on a treadmill up a fixed incline of 6 degrees. The test started at a speed of 4 m/s, and speed was increased 1 m/s each min until heart rate reached a plateau. Blood samples were obtained at rest and at the end of the 4, 5, 6, and 7 m/s steps of the exercise test. Resting PV was greater (P < 0.05) in the IN group...
Synteny mapping in the horse using horse-mouse heterohybridomas. In a study of 35 horse-mouse heterohybridoma cell lines, synteny in the horse was found between LDHB, PEPB and IGF1 and between NP, MPI and IDH2. A synteny between ADA and PEPC was also indicated. The loci for horse immunoglobulin light chain (IgL) genes and for LDHA were independent.
Biomechanical considerations in the treatment of navicular disease. In recent years much attention has been paid to vascular studies of the navicular bone in health and disease; however, the relative importance of these studies has overshadowed biomechanical factors which may yet prove to be of importance. This paper outlines the pertinent anatomy, and discusses current concepts in the aetiology and pathogenesis of the disease. It describes the treatment regimens which are based on biomechanical considerations and compares the results of some currently employed techniques. All aspects of navicular disease remain controversial. This paper is not intended to rev...
Hematuria and leptospiruria in a foal. A Thoroughbred foal that was born after 305 days of gestation was referred 6 hours after birth. On initial examination, the foal was alert, but weak and unable to stand. Heart rate was 150 beats/min, respiratory rate was 48 breaths/min, and rectal temperature was 33 C. Leukocytosis was detected (26,000 WBC/microliters). Dysuria and passage of red urine was observed approximately 30 hours after admission. Urine collected by free catch had a 3+ reaction for blood on dipstick analysis. Examination of Warthin Starry-stained sections of allantochorion revealed organisms morphologically characterist...
Peritonitis in horses: 67 cases (1985-1990). Peritonitis was diagnosed in 67 horses between 1985 and 1990: 14 horses developed septic peritonitis after intestinal rupture, 25 horses developed peritonitis after abdominal surgery, and 28 horses had peritonitis not associated with intestinal rupture or abdominal surgery. Forty of 67 horses (59.7%) did not survive. Nonsurvivors had higher heart rates (P = 0.01), RBC count (P = 0.039), serum creatinine concentration (P = 0.036), PCV (P = 0.007), and anion gap (P = 0.005); lower venous blood pH (P = 0.002); and a greater number of bacterial species cultured from peritoneal fluid samples (P = 0...
Standing laparoscopic laser technique for ovariectomy in five mares. Laparoscopic laser instrumentation and endoscopic stapling techniques were used to perform 10 unilateral ovariectomy procedures on 5 standing Thoroughbred mares. In all instances, mares had a clinically normal reproductive tract and estrous cycle, and ovariectomy was performed to eliminate regular estrous behavior. All procedures were accompanied by minimal trauma and uncomplicated postoperative recovery. Mares were able to resume normal activity 2 weeks after surgery. Regular estrous behavior was eliminated in all 5 mares, although 1 mare continued to have signs of estrous behavior occasional...
Reconstitution of horse heart myoglobin with hemins methylated at 6- or 7-positions: a circular dichroism study. The reconstitution kinetics of horse heart myoglobin, as met-cyano derivative, with two synthetic hemins in which the 6- or the 7-propionate is replaced by a methyl group, has been investigated by circular dichroism, in order to gain information on the heme re-orientation process following the heme insertion into the globin pocket. The results obtained confirm that the preferred heme orientation places the sole propionate into the position occupied by the 6-propionate in the crystal structure, supporting the importance of the salt bridge occurring between this propionate and the basic CD3 resi...
Diagnosis of grass sickness by ileal biopsy. Ileal biopsies were obtained from 18 horses with grass sickness, 15 horses with other alimentary disease and three horses without gastrointestinal disease. Samples of small intestine were also obtained from nine cases of obstruction due to small intestinal strangulation. Histological examination revealed that severe enteric neuropathy in the absence of other significant morphological changes was confined to the horses with grass sickness.
Correlation between the individual heterozygosity of parents and their offspring. Specific formulations are derived for the correlation between the heterozygosity of a randomly mating parent and its offspring for a diallelic locus, and for the correlation when multiple loci are considered. The expected correlation is maximal, approaching r = 0.50, when allelic frequencies are highly asymmetric, and it is zero when the allelic frequencies are equal to 0.50. Parent-offspring correlations, up to a maximum of 0.50 for diallelic loci, indicate that levels of heterozygosity can respond to selection. Multilocus allozyme data from limber pine, Pinus flexilis, and from horses of sta...
Uterine transport of prostaglandin E(2)-releasing simulated embryonic vesicles in mares. Transrectal ultrasonography was used to test the hypothesis that prostaglandin E(2) (PGE(2)) would increase the uterine transport of simulated embryonic vesicles in mares. Uterine transport of PGE(2)-releasing (PGE) vesicles, vehicle-releasing (sham) vesicles, and equine embryos was contrasted on Day 12 or Day 13 post ovulation. In Experiment 1, there was no difference (P>0.10) in transport of PGE vesicles, sham vesicles, Day-12 embryos, and Day-12 embryos after cervical manipulation (n = 3 per group). In Experiments 2 and 3, respectively, transport of PGE and sham vesicles was contrasted with...
Hemodialysis for treatment of oxytetracycline-induced acute renal failure in a neonatal foal. Acute renal failure in a 4-day-old foal secondary to oxytetracycline toxicosis was treated by hemodialysis. Oxytetracycline had been administrered as treatment for forelimb flexor tendon contracture. Conservtive treatment with fluids, furosemide, and dopamine partially alleviated serum electrolyte concentration imbalances, but was ineffective in promoting diuresis or decreasing azotemia. Three hemodialysis treatments over 4 days were administered, after which the clinical appearance of the foal improved, and biochemical and electrolyte values returned to within reference ranges. The nephrotoxi...
Comparison of five tests for the serologic diagnosis of myiasis by Gasterophilus spp. larvae (Diptera: Gasterophilidae) in horses and donkeys: a preliminary study. Sera from 41 horses and 159 donkeys, from twelve States of México, were tested to ascertain anti-Gasterophilus circulating antibodies by double immunodiffusion (DD), counterimmunoelectrophoresis (CIE), indirect haemagglutination (IH), thin layer immunoassay (TIA) and diffusion-in-gel ELISA (DIG-ELISA) methods using crude somatic antigen from third instar larvae of G. intestinalis (DeGeer). At necropsy, 33/41 horses and 24/159 donkeys were found to be parasitized by G. intestinalis and/or G. nasalis (L.). Gasterophilus intestinalis was the species most commonly found in the equines. Analysis o...
