Omneity® Pellets
All-In-One Vitamin & Mineral Pellet
Topic:Pathophysiology
Pathophysiology in horses involves the study of functional changes that occur in the body as a result of disease or injury. This field examines the mechanisms through which diseases develop and progress, as well as how they affect the body's normal physiological processes. In equine research, pathophysiology encompasses a wide range of conditions, including respiratory disorders, musculoskeletal injuries, gastrointestinal diseases, and metabolic syndromes. Understanding these processes helps in identifying potential therapeutic targets and developing effective treatment strategies. This page collects peer-reviewed research studies and scholarly articles that explore the underlying mechanisms, clinical manifestations, and implications of various pathophysiological conditions in equine health.
Plasma concentration of insulin-like growth factor I (IGF-I) in growing Ardenner horses suffering from juvenile digital degenerative osteoarthropathy. Degenerative osteoarthropathy resulting in a reduced active lifespan was observed in Ardenner horses. In the context of joint biology, insulin-like growth factor I (IGF-I) is a potential candidate to affect the anabolism of cartilage matrix molecules. A group of 30 Ardenner horses reared under standardized conditions from weaning were evaluated periodically from 15 to 28 months of age to detect the early manifestations of the disease. At the end of this period, horses were classified in two pathological groups related to the degree of interphalangeal degenerative osteoarthropathy based on clin...
Serial alterations in digital hemodynamics and endothelin-1 immunoreactivity, platelet-neutrophil aggregation, and concentrations of nitric oxide, insulin, and glucose in blood obtained from horses following carbohydrate overload. To quantify changes in endothelium-derived factors and relate those changes to various aspects of digital hemodynamics during the prodromal stages of carbohydrate overload (CHO)-induced laminitis in horses. Methods: 20 adult horses without abnormalities of the digit. Methods: Digital and jugular venous blood samples were collected at 1-hour intervals (for assessment of endothelin-1 [ET-1] immunoreactivity and measurement of glucose, insulin, and nitric oxide [NO] concentrations) or 4-hour intervals (CBC and platelet-neutrophil aggregate assessment) for 8 hours or 16 hours after induction of CH...
The blood vessel system in the periodontal ligament of the equine cheek teeth–part II: The micro-architecture and its functional implications in a constantly remodelling system. The micro-vasculature of the equine periodontal ligament (PDL) was investigated using corrosion casts for scanning electron microscopy. Specimens from eight healthy warm-blooded horses were examined. Specific vascular features such as large ampullae with a diameter of up to 300 microm and blind vascular casts were found in the specimens of the equine PDL. The ampullae-shaped venules occurred only in the peripheral layer, where they were formed at the confluence of several vessels. Two types of blind stumps were identified. The first was developed in all three layers, while the second was found...
Breeding-induced endometritis in mares. Endometritis is a common cause of infertility in broodmares. In the past, the condition was believed to be exclusively the result of bacterial contamination of the uterus. Treatment strategies were focused on preventing bacteria from entering the uterus and on treating mares with signs of endometritis with antibiotics. More recent research on uterine defense mechanisms has increased our understanding of the pathophysiology of equine endometritis. Additional causative agents have been identified, and we have learned to separate uterine infections and a physiologic breeding-induced endometritis ...
Equine sweating and anhidrosis Part 1–equine sweating. Sweating has a variety of functions in mammals including pheromone action, excretion of waste products and maintenance of the skin surface ecosystem. In a small number of mammalian species, which includes humans and the Equidae, it also has an important role in thermoregulation. This review is focused specifically on the thermoregulatory role of sweat in Equidae and the causes of sweating failure (anhidrosis). The first part describes the glandular appearance, sweat composition, and output rates; and considers the latest theories on the glandular control and secretory mechanisms. It is conclud...
A comparison of laryngoplasty and modified partial arytenoidectomy as treatments for laryngeal hemiplegia in exercising horses. To compare upper airway mechanics, arterial blood gases, and tracheal contamination in horses with induced left laryngeal hemiplegia (recurrent laryngeal neuropathy [RLN]) treated by laryngoplasty/vocal cordectomy (LPVC) or modified partial arytenoidectomy (MPA). Methods: Repeated measures under the following conditions: Control, RLN, LPVC, and MPA. Methods: Six horses. Methods: Two trials were conducted under all conditions at 80% and 100% of maximal heart rate (HR(max)). In Trial 1, arterial blood gases, tracheal and pharyngeal pressures, and laryngeal videoendoscopy were recorded. In Trial ...
Ultrasonography of the equine larynx. Nasopharyngeal and laryngeal evaluation is important when examining horses with upper airway signs for poor performance. Currently endoscopy is the most common method to evaluate the equine upper airway. Ultrasonography of the equine larynx has not previously been described. Using six cadaveric specimens and four standing horses, the ultrasonographic appearance of the equine larynx was established. A scanning technique, including useful acoustic windows and the normal ultrasonographic appearance at each site, is described. Ultrasound allowed visualization of portions of the hyoid apparatus, la...
Dynamic obstructions of the equine upper respiratory tract. Part 1: observations during high-speed treadmill endoscopy of 600 Thoroughbred racehorses. To review the prevalence of single and complex forms of dynamic airway obstructions within a large group of Thoroughbred horses in training referred for investigation of poor performance. Methods: Video-endoscopic recordings of the upper respiratory tract made during a standardised treadmill exercise test of 600 Thoroughbred racehorses were reviewed and analysed in real time and slow motion to identify dynamic collapse by the tissues bordering onto the pharyngeal and laryngeal airways. Results: Dynamic collapse within the nasopharynx or larynx was confirmed in 471 of the 600 horses. Dorsal dis...
Age-related and non-age-related changes in 100 surveyed horse brains. Brains from 100 horses, aged 2-25 years, were systematically examined by histopathology at 46 different neuroanatomical sites. The horses were sourced from a slaughterhouse (group A, n = 57), from a kennel that collected dead animals, and from 2 diagnostic laboratories (group B, n = 43). All horses from group A and 26 horses from group B were examined by a veterinarian in the period before death. None of the horses were known to exhibit clinical signs suggestive of neurologic disease. Among the main changes identified were vacuolation in the neuropil (n = 73), neurons (n = 32), white matter (n...
Assessment of endothelium-dependent vasodilation in equine digital resistance vessels. Haemodynamic disturbances leading to ischaemia and reperfusion injury of the digit are thought to be involved in the pathophysiology of acute equine laminitis. Identification of physiological regulators of blood flow through the equine digit is important in identifying factors, which may predispose animals to laminitis. A method was developed to assess endothelium-dependent responses of the isolated Krebs-perfused equine digit by co-administration of 5-hydroxytryptamine (5-HT) with vasodilator agents, carbachol (CCh), bradykinin (BK) and substance P (SP). Bolus co-administration of CCh (0.02-2...
Cricothyroid muscle function and vocal fold stability in exercising horses. To determine (1) if the cricothyroid muscle had respiratory-related electromyographic (EMG) activity that increased with respiratory effort and (2) if bilateral cricothyroid myotomy resulted in vocal fold instability and collapse in exercising horses. Methods: Experimental. Methods: Seven (3 EMG; 4 cricothyroid myotomy) Standardbred horses. Methods: Three horses exercised on a treadmill at speeds corresponding to the speed that produced maximum heart rate (HR(max)), 75% of maximum heart rate (HR(75%max)), and 50% of maximum heart rate (HR(50%max)) for 60 seconds at each speed while EMG activit...
Septicemia and cardiovascular infections in horses. This article first reviews cardiovascular infections, including endocarditis, myocarditis, vasculitis, and pericarditis. It then addresses what is known at this stage about the effects of sepsis on the cardiovascular system. Some information is provided from current human literature to familiarize the reader with the diagnostics and therapeutics that may eventually be used in equine practice as well.
Pathophysiology, diagnosis, and management of urinary tract infection in horses. Equine urinary tract infection (UTI) most commonly occurs as a sequela to structural or functional inhibition of normal urine flow. Although it is an infrequent diagnosis in equids, the incidence of UTI in human beings is high and has inspired great investigative effort. The resultant findings with potentially broad application as well as current equine studies are reviewed here. Recent developments in the understanding of host-agent interactions and renal defense mechanisms, emerging antimicrobial resistance, and novel therapeutic alternatives to prophylactic antibiotic use are emphasized.
Infections in the equine abdomen and pelvis: perirectal abscesses, umbilical infections, and peritonitis. This article addresses the pathophysiology, diagnosis, management, and prognosis of several different infections within the equine abdomen and pelvic region. The latest advances in the diagnosis and treatment of perirectal abscesses, umbilical infections, and local and diffuse peritonitis are discussed. Emphasis is placed on recent advances in diagnostics and therapeutics with reference to human literature that may be useful in equine practice.
Temporomandibular joint cytokine profiles in the horse. It has been suggested that dental abnormalities lead to temporomandibular joint inflammation and pain that may be mitigated by regular dental care. There is considerable literature on the pathophysiology of equine joint disease including studies on cytokine profiles in diseased appendicular joints. This study examined the effects of age and dental malocclusions summarized as a dental pathology score on equine temporomandibular joint cytokine (IL-1, IL-6, IL-8, TNF alpha and TGF-beta1, -beta2, -beta3) concentrations. TGF-beta3 was not detected in any joint sample. IL-1, IL-6 and TNF alpha were ...
Effects of an endothelin receptor antagonist and nitroglycerin on digital vascular function in horses during the prodromal stages of carbohydrate overload-induced laminitis. To evaluate changes in digital vascular function in horses with carbohydrate overload (CHO)-induced laminitis and determine the effects of an endothelin (ET) receptor antagonist and nitroglycerin on laminitis-associated vascular dysfunction. Methods: 20 adult horses without abnormalities of the digit. Methods: Hemodynamic variables were recorded before (baseline) and hourly after all horses were administered a CHO ration via nasogastric tube. In 4 groups of 5 horses each, saline (0.9% NaCl) solution or ET receptor antagonist (10(5)M in digital blood) was administered into the digital arterial ...
Measurement of skin desmosine as an indicator of altered cutaneous elastin in draft horses with chronic progressive lymphedema. Chronic progressive lymphedema in Clydesdale and Shire draft horses causes severe disability of the limbs which leads to premature death of these horses. Since appropriate function of lymph vessels is dependent on the presence of viable elastin fibers, the goal of this study was to document differences in skin elastin fibers in affected horse breeds, compared to a nonaffected draft horse breed. Results: Biochemical analysis of cutaneous desmosine, a cross-linking amino acid found only in elastin, was used to measure elastin in the skin from 110 draft horses. This included 7 normal, 38 mildly a...
Equine laminitis: bites by Bothrops spp cause hoof lamellar pathology in the contralateral as well as in the bitten limb. The envenoming caused by Bothrops snakebite includes local symptoms, such as pronounced edema, hemorrhage, intense pain, vesicles, blisters and myonecrosis. The principal systemic symptom consists in the alteration of blood clotting, due to fibrinogen consumption and platelet abnormalities. The horses involved in this study had this symptomatology and one of them exhibited symptoms consistent with laminitis in the bitten and in the contralateral limbs. Laminitis lesions were characterized by separation of the hoof lamellar basement membrane (BM) from basal cells of the epidermis. These results...
Gastrointestinal derived factors are potential triggers for the development of acute equine laminitis. Equine laminitis is the painful and debilitating condition resulting from cellular damage and inflammation of the tissues comprising the bonds supporting the pedal bone within the hoof capsule. One of the reasons why this condition is so complicated and enigmatic is its association with gastrointestinal disturbances, particularly a diet of lush grass at certain times of the year. Determining the link between disturbances to the hindgut flora and pathophysiology in the foot is one of the keys to preventing this condition. Therefore, one of the biggest challenges in equine laminitis research is ...
The adrenocorticotropin stimulation test: contribution of a physiologically based model developed in horse for its interpretation in different pathophysiological situations encountered in man. The present study aimed to characterize the adrenal response to ACTH. A model was developed that coupled the nonlinear disposition of cortisol with a physiologically based model for cortisol secretion by the adrenals. It was assumed that the response to ACTH resulted from two mechanisms: a stimulation of the cortisol secretion rate and control of the duration of the secretion. Seven dose levels of ACTH were tested in horses, a species similar to man as regards adrenal function. The main result was that the secretion rate of the adrenal gland can be modelized by a zero order process that is max...
Gonadotropin secretion and pituitary responsiveness to GnRH in mares with granulosa-theca cell tumor. Granulosa-theca cell tumors (GTCTs) are able to secrete variable amounts of sex steroids and immunoreactive inhibin (ir-INH). Although the pituitary appears to be affected by the presence of a GTCT, pituitary responsiveness to exogenous GnRH has not been examined. The aims of the present study were to: (i) assess the plasma hormone concentrations of ir-INH, gonadotropins and sex steroids in eight mares with GTCT and (ii) assess the responsiveness of pituitary gonadotroph cells to exogenous GnRH stimulus both before and after tumor removal. In seven mares, the contralateral ovary was firm, smal...
Splenectomy impairs diffusive oxygen transport in the lung of dogs. The spleen acts as an erythrocyte reservoir in highly aerobic species such as the dog and horse. Sympathetic-mediated splenic contraction during exercise reversibly enhances convective O2 transport by increasing hematocrit, blood volume, and O2-carrying capacity. Based on theoretical interactions between erythrocytes and capillary membrane (Hsia CCW, Johnson RL Jr, and Shah D. J Appl Physiol 86: 1460-1467, 1999) and experimental findings in horses of a postsplenectomy reduction in peripheral O2-diffusing capacity (Wagner PD, Erickson BK, Kubo K, Hiraga A, Kai M, Yamaya Y, Richardson R, and Sea...
Doppler sonographic evaluation of the digital blood flow in horses with laminitis or septic pododermatitis. The aim of this study was to evaluate the use of Doppler ultrasonography to monitor vascular blood flow dynamics in defined diseases of the equine digit in a noninvasive way. Doppler sonography was used to evaluate medial digital artery blood flow in eight horses with septic pododermatitis and four horses with laminitis in comparison with 10 horses of a control group. Doppler sonographic measurement and lameness examinations were performed in lame horses before treatment (day 0) and at 3, 6, and 9 days following treatment. Before treatment, blood flow velocities, arterial diameter, and flow vo...
Immune response to Sarcocystis neurona infection in naturally infected horses with equine protozoal myeloencephalitis. Equine protozoal myeloencephalitis (EPM) is one of the most common neurologic diseases of horses in the United States. The primary etiologic agent is Sarcocystis neurona. Currently, there is limited knowledge regarding the protective or pathophysiologic immune response to S. neurona infection or the subsequent development of EPM. The objectives of this study were to determine whether S. neurona infected horses with clinical signs of EPM had altered or suppressed immune responses compared to neurologically normal horses and if blood sample storage would influence these findings. Twenty clinical...
Endothelin receptor alterations in equine airway hyperreactivity. The purpose of this study was to evaluate the role of endothelin-1 (ET-1) and its receptors in the airway hyperreactivity of horses with obstructive pulmonary disease associated with summer pasture (SPAOPD). The right diaphragmatic lobe of the lung of 8 clinically healthy (unaffected) and 8 SPAOPD-affected horses was collected immediately after euthanasia. Bronchial rings (4 mm wide) were prepared and mounted in organ baths and attached to force transducers interfaced with a polygraph. Four rings were used to study each ET-1 receptor; 1 ring served as the control, and the other 3 were incubate...
Penetration of equine leukocytes by merozoites of Sarcocystis neurona. Horses are considered accidental hosts for Sarcocystis neurona and they often develop severe neurological disease when infected with this parasite. Schizont stages develop in the central nervous system (CNS) and cause the neurological lesions associated with equine protozoal myeloencephalitis. The present study was done to examine the ability of S. neurona merozoites to penetrate and develop in equine peripheral blood leukocytes. These infected host cells might serve as a possible transport mechanism into the CNS. S. neurona merozoites penetrated equine leukocytes within 5 min of co-culture. I...
Medical treatment of osteoarthritis in the horse – a review. The medical treatment of osteoarthritis (OA) in the horse is one of the most utilized therapeutic regimens in the equine practice. It is important to understand the anatomy of synovial joints and the pathophysiology of the disease process to treat OA adequately. Once a thorough understanding of the disease process is comprehended the proper combination of systemic nonsteroidal anti-inflammatory drugs (NSAIDs), intraarticular steroids, viscosupplementation and chondroprotectants can be used to treat the disease and inhibit further progression of degenerative changes to the cartilage surface. Th...
