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Topic:Veterinary Research
Veterinary research in horses encompasses the study of diseases, health management, and medical treatments specific to equine species. This field investigates various aspects of horse health, including infectious diseases, metabolic disorders, and musculoskeletal conditions. Researchers focus on understanding the pathophysiology of equine ailments, developing diagnostic tools, and evaluating therapeutic interventions. The study of horse health also involves examining preventive measures such as vaccination protocols and nutritional management to promote overall well-being. This page collects peer-reviewed research studies and scholarly articles that explore the diverse areas of veterinary science related to horses, providing insights into disease mechanisms, treatment strategies, and advancements in equine healthcare.
Transmission of Ehrlichia risticii, the agent of Potomac horse fever, using naturally infected aquatic insects and helminth vectors: preliminary report. Ehrlichia risticii, the agent of Potomac horse fever (PHF), has been recently detected in trematode stages found in snail secretions and in aquatic insects. Based on these findings, horses could conceivably be exposed to E. risticii by skin penetration with infected cercariae, by ingestion of infected cercariae in water or via metacercariae in a second intermediate host, such as an aquatic insect. In order to test this hypothesis, horses were challenged with infectious snail secretions and aquatic insects collected from a PHF endemic region in northern California. Two horses stood with their f...
Pharmacokinetics of acetazolimide after intravenous and oral administration in horses. To determine the pharmacokinetics of acetazolamide administered IV and orally to horses. Methods: 6 clinically normal adult horses. Methods: Horses received 2 doses of acetazolamide (4 mg/kg of body weight, IV; 8 mg/kg, PO), and blood samples were collected at regular intervals before and after administration. Samples were assayed for acetazolamide concentration by high-performance liquid chromatography, and concentration-time data were analyzed. Results: After IV administration of acetazolamide, data analysis revealed a median mean residence time of 1.71 +/- 0.90 hours and median total body c...
A comparison of the haemodynamic effects of isoflurane and halothane anaesthesia in horses. The purpose of this study was to compare the haemodynamic effects of equipotent isoflurane and halothane anaesthesia. Six adult horses were investigated on two separate occasions at least 4 weeks apart. On both occasions anaesthesia was induced by ketamine 2.2 mg/kg bwt given 5 min after i.v. administration 100 microg/kg bwt romifidine. Anaesthesia was maintained either by halothane or isoflurane (end-tidal concentrations 0.9-1.0% and 1.3-1.4%, respectively). Horses were ventilated by intermittent positive pressure to maintain PaCO2 between 40-50 mmHg. Haemodynamic variables were measured usin...
Pharmacokinetics of erythromycin estolate and erythromycin phosphate after intragastric administration to healthy foals. To determine pharmacokinetics and plasma concentrations of erythromycin and related compounds after intragastric administration of erythromycin phosphate and erythromycin estolate to healthy foals. Methods: 11 healthy 2- to 6-month-old foals. Methods: Food was withheld from foals overnight before intragastric administration of erythromycin estolate (25 mg/kg of body weight; n = 8) and erythromycin phosphate (25 mg/kg; 7). Four foals received both drugs with 2 weeks between treatments. Plasma erythromycin concentrations were determined at various times after drug administration by use of high-p...
Cytotoxicity of stimulated equine neutrophils on equine endothelial cells in culture. We studied the interactions of isolated equine neutrophils with endothelial cells in culture, mimicking a situation of acute inflammation. Our main purpose was to demonstrate that the supernatant of activated neutrophils was sufficient to damage endothelial cells. Equine endothelial cells (from carotid arteries) were covered either with increased numbers of equine neutrophils stimulated by phorbol myristate acetate, or with the supernatant collected after an in vitro stimulation of the neutrophils. Cytotoxicity was estimated by the release of preincorporated 51Cr, and by light microscopy obser...
Equine herpesvirus 1 (EHV-1) glycoprotein D DNA inoculation in horses with pre-existing EHV-1/EHV-4 antibody. We have shown previously that equine herpesvirus 1 (EHV-1) glycoprotein D (gD) DNA elicited protective immune responses against EHV-1 challenge in murine respiratory and abortion models of EHV-1 disease. In this study, 20 horses, all with pre-existing antibody to EHV-4 and two with pre-existing antibody to EHV-1, were inoculated intramuscularly with three doses each of 50, 200 or 500microg EHV-1 gD DNA or with 500microg vector DNA. In 8 of 15 horses, inoculation with EHV-1 gD DNA led to elevated gD-specific antibody and nine horses exhibited increased virus neutralising (VN) antibody titres co...
Determination of the activity of ponazuril against Sarcocystis neurona in cell cultures. The present study examined the efficacy of ponazuril in inhibiting merozoite production of Sarcocystis neurona in cell cultures. Ponazuril inhibited merozoite production by more that 90% in cultures of S. neurona treated with 1.0 microg/ml ponazuril and greater than 95% inhibition of merozoite production was observed when infected cultures were treated with 5.0 microg/ml ponazuril. Ponazuril may have promise as a therapeutic agent in the treatment of S. neurona induced equine protozoal myeloencephalitis (EPM) in horses.
Inoculation of Sarcocystis neurona merozoites into the central nervous system of horses. Equine protozoal myeloencephalitis (EPM) is a neurologic syndrome in horses from the Americas and is usually caused by infection with the apicomplexan parasite, Sarcocystis neurona. A horse model of EPM is needed to test the efficacy of chemotherapeutic agents and potential vaccines. Five horses that were negative for antibodies to S. neurona in their serum and cerebrospinal fluid (CSF) were injected in the subarachnoid space with living merozoites of the SN2 isolate of S. neurona. None of the horses developed clinical disease or died over a 132-day observation period. All five horses develope...
Purification, characterization, and cDNA sequencing of cytosolic phospholipase A(2) from equine neutrophils. It has been demonstrated that equine neutrophils, but not eosinophils, require exogenous arachidonic acid for calcium ionophore A23187-induced leukotriene synthesis. Because cytosolic phospholipase A(2) (cPLA(2)) plays an essential role in leukotriene formation in leukocytes, we investigated the presence of a functional cPLA(2) in equine neutrophils. To determine whether cPLA(2) from neutrophils was catalytically active, we purified the enzyme >6,500 fold with 3% recovery from equine neutrophils. The full-length cDNA sequence encoded a 749-amino acid protein. The deduced amino acid sequence...
Neospora hughesi: experimental infections in mice, gerbils, and dogs. Neospora hughesi is a recently described cause of equine protozoal myeloencephalitis (EPM). A rodent model for pathogenicity would facilitate development of therapies to be used in horses. In the present study, we examined the susceptibility of BALB/c gamma-interferon gene knockout (gamma-INFKO), BALB/c, CD-1, and C57BL/6 strains of mice and gerbils to infection with tachyzoites of the Nh-A1 strain of N. hughesi isolated from a horse from AL, USA. Only the gamma-IFNKO mice developed severe clinical disease following infection with N. hughesi and died 19-25 days after infection and exhibited se...
Detection of biological threat agents by immunomagnetic microsphere-based solid phase fluorogenic- and electro-chemiluminescence. This article reviews the recent development of two solid-phase chemiluminescence-based techniques, fluorogenic-chemiluminescence (FCL) and electro-chemiluminescence (ECL) for detection of biological threat agents. Both techniques entail a labeled sandwich immunoassay. The objectives of this work are to develop advanced techniques for sensitive and effective detection of a target analyte, particularly in cases where the analysis includes complex samples containing multiple contaminating factors. Other important considerations in developing such detection techniques include the ease of use, the ...
Safe and efficacious dosage of flecainide acetate for treating equine atrial fibrillation. To determine a safe and efficacious dose of flecainide acetate for treating equine atrial fibrillation (Af), the safe dosage level was determined by injecting 1, 2, or 3 mg/kg i.v. of 1% flecainide acetate solution at a rate of 0.2 mg/kg/min to five clinically healthy horses. Clinical signs and the ECG were monitored (HR, PR, QRS, and QT intervals) and blood was taken to measure the plasma flecainide concentration pre- and post-administration. No abnormal signs were observed in the 1- or 2-mg/kg groups, while agitation was observed in three of five horses in the 3-mg/kg group. The QRS, and QT ...
Application of a type-specific enzyme-linked immunosorbent assay for equine herpesvirus types 1 and 4 (EHV-1 and -4) to horse populations inoculated with inactivated EHV-1 vaccine. A type-specific enzyme-linked immunosorbent assay (ELISA) using equine herpesvirus types 1 (EHV-1) and 4 (EHV-4) glycoprotein G was applied for sero-epizootiology of EHV infections in Japan. Recently, an inactivated EHV-1 vaccine has been administered to racehorses for prevention of upper respiratory disease. To examine the effect of the vaccination on the result of the ELISA, 6 horses were experimentally inoculated three times intramuscularly or intranasally with inactivated EHV-1 vaccine. Sera collected from these horses were used to the type-specific ELISA and complement-fixation (CF) test....
Scanning electron microscopy of the microcotyledonary placenta of the horse (Equus caballus) in the latter half of gestation. Scanning electron microscopy was used to examine the microstructure of the maternal and fetal placenta from 25 pregnant ponies (Equus caballus) throughout the second half of gestation. Samples of placenta, 2-6 cm(2)in area, were collected from the antimesometrial region of the pregnant horn at 105 days (n=1), 165-219 days (n=5), 260 days (n=3), 270-277 days (n=3), 313-337 days (n=11) and immediately after spontaneous delivery at term (n=2). The maternal microcaruncle appears to be created from a clustering of about 16 uterine crypts encapsulated in a connective tissue sheath. There is a gestat...
Alterations in cartilage type-II procollagen and aggrecan contents in synovial fluid in equine osteochondrosis. The etiology and pathophysiology of osteochondrosis remain poorly understood because it is difficult to obtain material from lesions in the early stage of this disease and because there is no satisfactory experimental animal model. We wished to determine whether there are changes in articular cartilage turnover in equine osteochondrosis, which closely resembles the human disease, by assaying cartilage matrix molecules in synovial fluids. We used immunoassays that measure a keratan sulfate epitope and the epitope 846 on the cartilage proteoglycan aggrecan and the C-propeptide of cartilage type-...
Prevalence of selected species of internal parasites in equids at necropsy in central Kentucky (1995-1999). A survey to determine current prevalence of several species of endoparasites in equids (n=350) at necropsy was conducted at the Livestock Disease Diagnostic Center in central Kentucky (1995-1999). Thelazia lacrymalis were found in 42% of the 1- to 4-year olds (n=132), which was the only age group examined for these parasites. Five- to 30-year olds (n=157), examined for Onchocerca spp. worms/lesions, had a prevalence of 24%. In > or =1-year olds (n=324), the infection rate for Gasterophilus intestinalis was 12% for second instars and 14% for third instars and for Gasterophilus nasalis was 2%...
Identification of hydroxyropivacaine glucuronide in equine urine by ESI+/MS/MS. Ropivacaine is a local anesthetic that has a high potential for abuse in racing horses. It can be recovered from urine collected after administration as a hydroxylated metabolite following beta-glucuronidase treatment of the urine. Based on these findings, it has been inferred that ropivacaine is present in equine urine as a glucuronide metabolite; however, these metabolites have never been directly identified. Using ESI+/MS/MS, the presence of a [M+H]+ molecular ion of m/z 467 was demonstrated in urine corresponding to the calculated mass of a hydroxyropivacaine glucuronide +1. The abundance ...
The effectiveness of the haemodialysate Solcoseryl for second-intention wound healing in horses and ponies. Second-intention healing of limb wounds in horses is often problematic. Solcoseryl is a protein-free, standardized dialysate/ultrafiltrate (HD) derived from calf blood, which has been shown to improve healing in both animals and humans. The efficacy of HD in the healing of deep wounds in horses and ponies was investigated. Deep wounds of 20 by 35 mm were created on both metatarsi (skin, subcutis, periosteum) and on both femoral biceps muscles (skin, subcutis, muscle) of five horses and five ponies. The wounds on one side were treated with HD, four times a week during the period that the wounds...
Mutations occurring during serial passage of Japanese equine infectious anemia virus in primary horse macrophages. An attenuated equine infectious anemia virus (EIAV), named V26, was previously obtained after 50 passages of the Japanese virulent strain V70 in primary macrophage culture. To clarify the differences between both viruses, their full-length sequences were determined. There were higher mutations in S2 (6.15% amino acid difference) and LTR (10.7% nucleotide difference). The presumed initiation codon of the S2 gene was absent from the sequence of V26. There was a large insertion within the long-terminal repeat (LTR) U3 hypervariable region of V26. In addition, there were minor mutations in gag (1....
An outbreak of type C botulism in 12 horses and a mule. A USDA Early Response Team investigated deaths of several horses and a mule in northern Arizona at the request of local animal health officials. Thirteen animals (12 horses and 1 mule) housed at 5 facilities in a 7.4 square mile area died between August 1998 and January 1999. Clinical signs consisted of muscular weakness that rapidly progressed to lateral recumbency. Ten animals had paresis of the tongue, throat, or lips. Affected animals appeared alert and were interested in eating and drinking, even while recumbent. All 13 animals were euthanatized. Clostridium botulinum type C was isolated ...
Light and scanning electron microscopic studies of the nasal turbinates of the horse. The nasal turbinates of 5 young horses were studied by light and scanning electron-microscopy. Stratified cuboidal epithelium lined the rostral part of the dorsal and ventral nasal turbinates of the vestibular region. The polyangular microvillus cells of this region were separated by linear depressions. The mid and caudal parts of the dorsal and ventral nasal turbinates and the rostral part of the ethmoturbinates were lined by pseudostratified columnar ciliated respiratory epithelium. Numerous cilia with dilated blebs on the ciliated cells concealed adjacent non-ciliated supporting cells and g...
Fine structure of the retinal pigment epithelium, Bruch’s membrane and choriocapillaris in the horse. The fine structure of the retinal pigment epithelium (RPE), Bruch's membrane and choriocapillaris was investigated by light and transmission electron microscopy in both the tapetal and non-tapetal fundus of the horse eye. In all locations, the RPE consisted of a single layer of low cuboidal cells. The epithelial cells were joined laterally by apically located tight junctions. These cells displayed numerous basal infoldings and abundant thin apical processes which enclosed the rod outer segments. The epithelial cell nuclei were large and located basally. Within the epithelial cells, smooth endo...
Remifentanil in the horse: identification and detection of its major urinary metabolite. Remifentanil (4-methoxycarbonyl-4-[(1-oxopropyl)phenylamino]-1-piperidinepropionic acid methyl ester) is a mu-opioid receptor agonist with considerable abuse potential in racing horses. The identification of its major equine urinary metabolite, 4-methoxycarbonyl-4-[(1-oxopropyl)phenylamino]-1-piperidinepropionic+ ++ acid, an ester hydrolysis product of remifentanil is reported. Administration of remifentanil HCl (5 mg, intravenous) produced clear-cut locomotor responses, establishing the clinical efficacy of this dose. ELISA analysis of postadministration urine samples readily detected fentany...
In vitro evaluation of the effect of dimethyl sulfoxide on equine articular cartilage matrix metabolism. To evaluate the effects of dimethyl sulfoxide (DMSO) on equine articular cartilage matrix metabolism. Methods: Using a cartilage explant culture system, proteoglycan (PG) synthesis, PG release, lactate metabolism, chondrocyte viability, and metabolism recovery were determined after cartilage exposure to DMSO. Methods: Cartilage harvested from metacarpophalangeal and metatarsophalangeal joints of 12 horses (age range, 1 to 10 years). Methods: Explants were exposed to concentrations of DMSO (1% to 20%) for variable times (3 to 72 hours). PG synthesis and release were determined by a radiolabel i...
The acute phase protein serum amyloid A (SAA) as an inflammatory marker in equine influenza virus infection. The acute phase protein serum amyloid A (SAA) has proven potentially useful as an inflammatory marker in the horse, but the knowledge of SAA responses in viral diseases is limited. The aim of this study was to evaluate SAA as a marker for acute equine influenza A2 (H3N8) virus infection. This is a highly contagious, serious condition that inflicts suffering on affected horses and predisposes them to secondary bacterial infections and impaired performance. Seventy horses, suffering from equine influenza, as verified by clinical signs and seroconversion, were sampled in the acute (the first 48 h...
[Sensitivity of bovine and equine streptococci to beta-lactam antibiotics (benzylpenicillin, ampicillin, oxacillin, cefotaxime) in the agar diffusion and E-test]. 368 streptococcal strains from udder secretions of cattle (Sc. agalactiae, Sc. dysgalactiae, Sc. uberis) and 191 streptococcal isolates from horse specimens (Sc. equi ssp. zooepidemicus, Sc. equi ssp. equi) originating from different agricultural regions in Germany (Lower Saxony, in particular the region of Weser-Ems, Bavaria, Altmark) were investigated for their sensitivity to 4 beta-lactam antibiotics (benzylpenicillin, ampicillin, oxacillin, cefotaxime). Two different test methods were applied: the agar diffusion test for determination of the diameter of the zone of inhibition and the E-tes...
Pathogenicity of Rhodococcus equi expressing a virulence-associated 20 kDa protein (VapB) in foals. Rhodococcus equi strains of intermediate virulence (IMV) for mice possess a 20kDa protein designated Virulence Associated Protein B (VapB) and a virulence plasmid of 79-100kb, and can be recovered from the submaxillary lymph nodes of pigs. The pathogenicity of such R. equi strains for foals is unknown. In this study, two foals, 42 and 43 days of age, were infected intratracheally with 10(6) and 10(9) cells of R. equi IMV strain A5, respectively. The foal infected with 10(9) cells of strain A5 became clinically ill, with the onset of illness (pyrexia and depression) occurring 21 days after inoc...
[The “problem” mare part 3: veterinary supervision at the stud and during early pregnancy]. In this last article the veterinary supervision of problem mares at the stud is reviewed. Treatment possibilities are evaluated. The usefulness of treatment with progestagens in order to sustain pregnancy or to prevent embryonic death is discussed.
