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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.
Pinealitis coincident with recurrent uveitis: immunohistochemical studies. Although experimental models of autoimmune uveitis predict pinealitis coincident with uveitis, there is no direct evidence of pineal pathology accompanying a human uveitis. Horses with naturally occurring uveitis are a potential source of eye and pineal tissues that are not available from human patients with active uveitis. We have observed pinealitis in a mare with equine recurrent uveitis. By immunohistochemistry we demonstrated immunoglobulin and MHC Class II antigen on infiltrating and resident cells of eye and pineal gland. These results support the relevance of the animal models and sugg...
Elbow extensor muscles of the horse: postural and dynamic implications. Based on histochemical and immunohistochemical evidence, horse elbow extensor muscles are composed of two morphologically distinct muscle groups. The long and lateral heads of the triceps brachii are large, predominantly type II (presumed fast) muscles. The long and lateral heads of the triceps together account for 96% of the weight of the elbow extensors (long head of triceps is 81%). The long and lateral heads contain three histochemical fiber types: types I, IIa and IIb. Type I muscle fibers account for approximately 18 and 27% of the fibers in the long and lateral heads of the triceps, res...
An inhibitor of tumor cell growth from normal horse serum. During our studies of cytostatic cytokines in the mixed leukocyte culture, we found that horse serum in the medium control contained a tumor cell growth-inhibitory factor. The fraction isolated by molecular sieving and ion exchange chromatography inhibited the growth and DNA synthesis of the primary culture and passaged cell line of the canine transmissible venereal sarcoma, murine T (L5178Y) and B (P3-X63-Ag8.653) lymphoid tumor cells, murine mammary tumor cells (RIII), bovine lymphoid tumor cells (BL3), and the nontransformed cell line of baby hamster kidney cells. Nontransformed cell lines ...
Domestic animal models of severe combined immunodeficiency: canine X-linked severe combined immunodeficiency and severe combined immunodeficiency in horses. This review describes the clinical, immunologic and pathologic features of two naturally-occurring models of severe combined immunodeficiency (SCID) in domestic animals that represent different forms of human SCID. Canine X-linked SCID (XSCID) has an X-linked recessive mode of inheritance and, as such, represents a model for the most common form of human SCID in the United States. Affected dogs have normal percentages of circulating B cells and low to normal percentages of phenotypically mature, but nonfunctional T cells. Severe combined immunodeficiency in the horse is an autosomal recessive ...
Rotavirus serotype G3 predominates in horses. Foal fecal group A rotavirus strains were characterized by electropherotype, serotype, and subgroup and shown to be distinctly different from rotaviruses of other mammals. Of 86 strains that were electropherotyped, 98% had similar profiles, with gene segments 3 and 4 close together and segments 7, 8, and 9 widely spaced. Of 70 strains that had sufficient detectable VP7 antigen to be serotyped by enzyme-linked immunosorbent assays (ELISAs), 63% were serotype G3 (39% were subtype G3A and 24% were subtype G3B), 4% were serotype G13, and 33% were untypeable. Serotypes G1, G2, G4, G5, G6, G9, G10, ...
Preliminary studies on the vascular anatomy of the equine superficial digital flexor tendon. The vascular and microvascular anatomy of normal equine superficial digital flexor tendons was studied by dissection of vinyl-perfused specimens and by microangiography on high detail film. The presence of an extensive intratendinous vascular latticework was confirmed, and a 'nutrient artery' described closely associated with the accessory ligament of the superficial digital flexor tendon (proximal check ligament). Circumferential stripping of the paratenon from the tendon to eliminate afferent vessels was performed bilaterally in three horses and unilaterally in a fourth, followed by a treadm...
Early foetal death in the mare. Histological, bacteriological and cytological findings in the endometrium. Fifteen mares which had each lost their pregnancies 2 to 8 times during the preceding 6 years were used in a study comprising 1 or 2 breeding seasons for each mare. During the research period all 15 mares conceived and 10 of the mares had normal pregnancies in the 1st experimental year. Five mares resorbed/aborted once or twice during the 1st year. This was followed by a pregnancy that terminated in a live foal. Histopathological examinations of uterine biopsies showed a wide range of histopathological conditions, from absence of changes excessive for the mare's age and parity to the most seve...
Pathogenesis of equine herpesvirus-1 in specific pathogen-free foals: primary and secondary infections and reactivation. Six specific pathogen-free foals shown to be free of equine herpesvirus-1 and 4 (EHV-1 and -4) and lacking in maternally-derived antibodies were used to investigate the pathogenesis of EHV-1 in horses. Following primary intranasal inoculation with EHV-1 all foals showed signs of a mild, self-limiting upper respiratory tract infection. A leucopenia was observed, comprising both a lymphopenia and neutropenia. Virus was isolated from nasal mucus and buffy coat cells over several days during the clinical episode and after the animals became clinically normal. Notwithstanding the mildness of the cl...
A comparison of end-tidal halothane concentrations measured at proximal and distal ends of the endotracheal tube in the horse. Measurements (n = 126) of end-tidal halothane concentrations were taken from 21 horses anesthetized for routine and emergency surgery. One hundred five paired values allowed comparison of gas samples taken near the oral end of the endotracheal tube (Y1) to samples obtained at the cuffed end of the endotracheal tube (Y2). Twenty-one paired readings were assessed to compare samples taken 25 cm beyond the cuffed end of the tube (Y3) to samples from Y1. Measurements were made at all locations at 15-minute intervals starting 30 minutes after beginning halothane. All measurements were made in tripli...
Bile acid fractionations by high-performance liquid chromatography in equine liver disease. Serum bile acids were fractionated by high-performance liquid chromatography (HPLC) in 13 control and 8 cases of liver disease in horses. The severity and type of liver injury was determined by histopathological examination of biopsy and/or necropsy specimens. The total serum bile acids (tSBA) were determined in these horses by an enzymatic method (SBA-EA) and by summation of the bile acids (SBA-LC) as fractionated by the HPLC. The SBA-LC were generally higher than the SBA-EA in both the controls and liver disease and they did not parallel each other. The primary bile acids, total cholates and...
Pathological findings in horses dying during an outbreak of the paralytic form of Equid herpesvirus type 1 (EHV-1) infection. In 1988 an outbreak of the paralytic form of Equid herpesvirus type 1 (EHV-1) infection occurred on a stud farm and several animals died. This provided an opportunity to perform detailed pathological investigations to gain insights into the pathogenesis of this spontaneous disease. Two paretic mares, three foals, an aborted foetus and its non-paretic dam were examined. The endotheliotropism of the virus was clearly demonstrated by the use of an indirect immunoperoxidase (IP) stain. At autopsy, evidence of viral infection was widespread in the foetus and foals, but limited or absent in the mare...
[Useful life, departure rates and causes in sport horses]. A review of the operational life, attrition and lethality rates, major causes of attrition and death for thoroughbred and standardbred race horses and competition horses is given. Because of the lack of data, it was not possible to supply answers for all the sport disciplines. The operational life in sports for thoroughbred race horses was 3.3 years, for standardbred horses 4.1 and for competition horses 5.5 years. Attrition and lethality rates could be determined only for the thoroughbred race horses. The yearly rates of attrition and lethality were 30% and 2% respectively. The major causes o...
In vivo measurement of bone quality in the horse: estimates of precision for ultrasound velocity measurement and single photon absorptiometry. The in vivo precision of ultrasound velocity measurement and single photon absorptiometry for the assessment of equine bone quality is discussed. In vivo precisions for ultrasound velocity measurements were less than 0.5 per cent, whereas cortical cross-sectional area, compact bone density and modulus of elasticity were around 1 per cent, and bone mineral content and density were just over 2 per cent. Except for ultrasound velocity, substantial improvements could be achieved by taking the mean of five readings for each measurement. The long-term precision of the techniques was also high, with ...
The pharmacokinetics of a slow-release theophylline preparation in horses after intravenous and oral administration. The pharmacokinetics of a slow-release theophylline formulation was investigated following intravenous and oral administration at 10 mg/kg in horses. A tricompartmental model was selected to describe the intravenous plasma profile. The elimination half-life (t1/2 beta) was 16.91 +/- 0.93 h, the apparent volume of distribution (Vd) was 1.35 +/- 0.18 L/kg and the body clearance (ClB) was 0.061 +/- 0.009 L kg-1 h. After oral administration the half-life of absorption was 1.24 +/- 0.30 h, and the calculated bioavailability was above 100%. The t1/2 beta after oral administration was 18.51 +/- 1.75 ...
Evolutionary pattern of the H 3 haemagglutinin of equine influenza viruses: multiple evolutionary lineages and frozen replication. The nucleotide and deduced amino acid sequences of the haemagglutinin genes coding for the HA 1 domain of H3N8 equine influenza viruses isolated over wide regions of the world were analyzed in detail to determine their evolutionary relationships. We have constructed a phylogenetic model tree by the neighbour-joining method using nucleotide sequences of 15 haemagglutinin genes, including those of five viruses determined in the present study. This gene tree revealed the existence of two major evolutionary pathways during a twenty five-year period between 1963 to 1988, and each pathway appeared t...
Equine thyroid function tests: a preliminary investigation. A similar and significant (P less than 0.001) increase in plasma thyroxine (T4) concentration was seen in seven clinically normal thoroughbred horses 2 h after the intravenous administration of either 2.5 iu or 5 iu of thyroid stimulating hormone (TSH) with a peak response around 4 h after administration. The intravenous administration of 0.2, 0.5 or 1 mg thyrotrophin releasing hormone (TRH) resulted in a significant (P less than 0.01) increase in T4 concentration in three groups of animals; six thoroughbreds in full work, five thoroughbreds at rest and four ponies at rest. The peak response w...
Long term ECG recording with Holter monitoring in clinically healthy horses. The electrocardiogram of 9 horses was continuously recorded for 24 h with Holter monitoring to examine the variations in heart rate and rhythm during daily routine procedures and at night. Three horses had transient sinus bradycardia, and 3 had periods of sinus tachycardia. Heart blocks were detected in 3 horses, and all horses had periods of sinus arrhythmia. These changes in the heart rate and rhythm were apparently caused by variations in autonomic nervous system tone and they are probably "normal" findings in resting, undisturbed horses. Ventricular premature depolarisations were not obser...
Muscarinic receptor subtypes in equine tracheal smooth muscle. Selective muscarinic receptor antagonists were used to identify muscarinic receptor subtypes in equine trachealis strips. The M1 receptor antagonist pirenzepine (10(-7) mol/L to 3 x 10(-5) mol/L) and the M3 receptor antagonist 4-diphenylacetoxy-N-methylpiperidine (4-DAMP, 10(-9) mol/L to 3 x 10(-7) mol/L3) dose dependently inhibited the contractile responses to electrical field stimulation (EFS) and exogenous acetylcholine (ACh). Schild plots yielded a pA2 value for pirenzepine vs ACh of 6.75 +/- 0.09, which is consistent with the affinity for M2 or M3 receptors, and a pA2 value for 4-DAMP vs ...
Artificial respiration in the anesthetized horse using bilateral, percutaneous, cervical phrenic-nerve stimulation with needle electrodes: a preliminary report. In this preliminary study, artificial respiration was produced in four anesthetized horses using trains of stimuli applied to long needle electrodes inserted bilaterally at the base of the neck. The needles were insulated to within 1 cm of the tips. The frequency of the stimuli (0.1 msec) was 35/sec and the train duration (duration of inspiration) was 1 sec. Inspired volume increased with increasing stimulus intensity. In two animals, inspired volumes of 6 liters were achieved. In another animal 4.5 liters was achieved and in another, 2.5 liters. This lower value probably represented less-than...
Pedicle skin flaps in ponies: viable length is related to flap width. The relationship between pedicle flap width and viable length was characterised for skin flaps of the flank in ponies. Four dorsally based, pedicle type skin flaps of 20 cm in length and 3, 6, 9 or 12 cm in width were created in a random sequence on one flank in each of 10 ponies. Flap survival length was assessed by skin texture and appearance, depilation of hair and wound healing at 14 days after surgery. There was considerable variation between animals in the viable length of flaps of the same width; however, a significant difference in the viable length of flaps of different widths was det...
Linkage of hyperkalaemic periodic paralysis in quarter horses to the horse adult skeletal muscle sodium channel gene. A genetic disease observed in certain Quarter horses is hyperkalaemic periodic paralysis (HYPP). This disease causes attacks of paralysis which can be induced by ingestion of potassium. Recent studies have shown that HYPP in humans is due to single base changes within the adult skeletal muscle sodium channel gene. A large Quarter horse pedigree segregating dominant HYPP was studied to determine if mutations of the sodium channel gene are similarly responsible for HYPP in horses. We used cross-species, PCR-mediated, cDNA cloning and sequencing of the horse adult skeletal muscle sodium channel a...
Polysaccharide storage myopathy associated with recurrent exertional rhabdomyolysis in horses. A polysaccharide storage myopathy is described in nine Quarterhorses, Quarterhorse crossbreds, American Paints and Appaloosa horses which had a history of recurrent exertional rhabdomyolysis. Muscle biopsies were characterized by high muscle glycogen concentrations with up to 5% of type 2 muscle fibers containing inclusions which stained positively with the periodic acid Schiff (PAS) stain. The inclusions were classified as an acid mucopolysaccharide, based on their histochemical staining characteristics. Ultrastructural studies revealed that the inclusions were composed of beta glycogen parti...
Evaluation of exclusive use of ivermectin vs alternation of antiparasitic compounds for control of internal parasites of horses. A study for about a 30-month period was done to compare strongyle control programs, using per os treatments of ivermectin (IVE) paste exclusively or alternation of 4 antiparasitic paste compounds: IVE, oxfendazole (OFZ), oxibendazole (OBZ), or pyrantel pamoate (PRT). Every 8 weeks, 1 group of horses (barn C; n = 14 to 16) was given IVE paste exclusively, and a second group (barn E; n = 16) was given the 4 antiparasitic pastes on an alternating schedule. Worm eggs and larvae per gram of feces (epg and lpg, respectively) values were determined every 2 weeks during the investigation. This study i...
Determination of the early age of onset of equine recurrent laryngeal neuropathy. 2. Nerve pathology. The left and right recurrent laryngeal nerves and peroneal nerves from two groups of foals, one less than 1 month of age and the other 6 months of age, were examined by light and electron microscopy. While there was no evidence of fiber loss on light microscopy, occasional onion bulbs, regenerating clusters and swollen axons were seen in the recurrent laryngeal nerves. To quantitate these changes, total counts of the main pathological structures were performed using the electron microscope. In all the foals the most common abnormality seen in the laryngeal nerves were Bungner bands, which were...
The electron microscopic and immunohistochemical demonstration of a papillomavirus in equine aural plaques. This research study investigates the cause of aural plaques in horses and provides strong evidence that papillomaviruses are to blame. The study used various tools including electron microscopic examination, immunohistochemical […]
Respiratory muscle recruitment in awake ponies during exercise and CO2 inhalation. We measured respiratory muscle electromyograms (EMG), inspiratory (I) and expiratory (E) airflow patterns and functional residual capacity (FRC) in six ponies at rest, during treadmill walking at 1.8 mph-5, 10, and 15% grades, and during 2, 4, and 6% CO2 inhalation. There were several similarities in the responses to exercise and CO2 inhalation. The shapes of the I and E flow patterns were not changed appreciably from the respective control patterns during either condition. Mean diaphragm EMG increased from control (P less than 0.05) at 1.8 mph-10 and 15% grades, and during 4 and 6% inhalation...
Standing surgery of the neck and thorax. Many surgical procedures of the head and neck can be safely performed in the standing horse, with easy access to all aspects of the surgical field. Some procedures, such as tracheotomy, are easier to perform with the horse standing with the head in a more natural position than with the horse under general anesthesia. Procedures of the neck and thorax that require evacuation of purulent and necrotic material from confined spaces, such as occur in horses with esophageal ruptures and extensive intrathoracic abscesses, can be done as standing procedures to avoid the risks of general anesthesia on ...
Mucosal histamine inhibits Na absorption and stimulates Cl secretion across equine tracheal epithelium. When the equine tracheal epithelium is mounted in Ussing chambers and bathed in plasma-like Ringer solution, the tissue generates a lumen-negative transepithelial potential (PD) of 22 mV and a short-circuit current (Isc) of 70-200 microA/cm2. Mucosal addition of 10 microM histamine produces a transient increase in the Isc followed by a return to baseline or below. Mucosal addition of 2 microM diphenhydramine inhibits the Isc response to mucosal histamine, whereas 100 microM mucosal cimetidine produces no effect. The average initial increases in Isc over time for mucosal vs. serosal histamine a...
