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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.
Stress echocardiography and its role in performance assessment. Stress echocardiography in the horse is in its infancy, and investigations need to continue to determine the significance and mechanism of postexercise echocardiographic abnormalities detected in horses. This work should be coupled with investigations on the exercise-induced changes in cardiac isoenzymes, cTnI, arterial oxygen content, and cardiac rhythm that may occur concurrently. With continued investigations into the cardiovascular problems that occur in the exercising horse, the sport horse veterinarian should be better able to accurately diagnose and treat problems causing poor performan...
The variability and repeatability of indices derived from the single-breath diagram for CO2 in horses with chronic obstructive pulmonary disease and the effect of lobelin hydrochloride on these indices. Several indices of ventilatory heterogeneity can be identified from the volumetric capnogram and its graphic presentation, the single-breath diagram for CO2 (SBD-CO2). Physiologically based indices of pulmonary function (VTE, VCO2, FACO2, VDBohr% VDBohr%, VD/VTE, A1/A2) were calculated for healthy horses (group I, n = 5) and for horses with subclinical (group II, n = 7) or clinically manifest chronic obstructive pulmonary disease (COPD) (group III, n = 8) during tidal breathing and after medication with lobelin hydrochloride (Lobelin). We investigated the variability and repeatability of the l...
Endothelin in the equine hypoxic pulmonary vasoconstrictive response to acute hypoxia. Elevated concentrations of endothelin (ET), a potent endothelium-derived vasoactive peptide, have been reported in a number of pathophysiological conditions associated with pulmonary hypertension, both in the horse and other species. We have previously shown, both in vitro and in vivo, that the pulmonary and systemic vascular response to exogenous ET is mediated predominantly via ET(A) receptors. Our hypothesis in the present study was that ET is involved in the equine hypoxic pulmonary vasoconstrictive response to acute hypoxia. In this study, we investigated the effects of a selective ET(A) ...
Specific heterologous F(ab’)2 antibodies revert blood incoagulability resulting from envenoming by Lonomia obliqua caterpillars. Contact with Lonomia obliqua caterpillars results in a bleeding syndrome characterized by hemorrhage and blood coagulation disturbances. Conventional therapy using antifibrinolytics or cryoprecipitates has been unable to treat pathophysiologic alterations. As antivenoms are effective therapy for treatment of victims of venomous animals, a process of manufacturing a specific antilonomic serum by immunizing horses with Lonomia caterpillar bristle extracts (LBE) was developed. Lonomia caterpillar bristle extracts exhibited several protein bands on SDS-PAGE, induced blood coagulation abnormalities...
Evaluation of hoof wall surface temperature as an index of digital vascular perfusion during the prodromal and acute phases of carbohydrate-induced laminitis in horses. To evaluate the use of hoof wall surface temperature (HWST) as an indirect indicator of digital perfusion and to describe HWST patterns during the prodromal and acute phases of carbohydrate-induced laminitis in horses. Methods: 30 adult horses without foot abnormalities. Methods: Three experiments were performed. In the first, HWST was measured in 2 groups of horses acclimatized to hot (n = 6), or cold (6) environments and exposed to cold (15 C) ambient temperature. In the second experiment, HWST were measured in both forefeet of 6 horses before and after application of a tourniquet to 1 foref...
Effects of 8-epi-PGF2alpha on isolated bronchial smooth muscle of healthy and heaves-affected horses. 8-Epi-PGF2alpha, a prostaglandin-like compound generated by oxidative stress, has been shown to be an in vitro bronchoconstrictor in airways from healthy laboratory animals and healthy humans, but it has never been studied in diseased airways. Here, the bronchoconstrictive capacity of 8-epi-PGF2alpha on isolated bronchial rings (BR) of healthy and heaves-affected horses was evaluated by comparing the maximal effect and the potency of 8-epi-PGF2alpha to those of (1) acetylcholine (ACh), (2) its stereoisomer PGF2alpha and (3) its synthetic receptor agonist, U46619. Furthermore, the potential cap...
Cerebrospinal fluid and serum concentrations of ponazuril in horses. Ponazuril was administered orally to 10 adult horses at 5 mg/kg body weight, once a day for 28 days. Blood was collected once a week from each horse from Days 0 through 35, daily from Days 35 through 42, and on Day 49. Cerebrospinal fluid (CSF) was also collected once a week from Day 0 through Day 49. Concentrations of ponazuril in the serum and CSF were determined, and pharmacokinetic calculations were performed. Ponazuril was readily absorbed following oral administration; and after 7 days of dosing, the serum concentration was 4.33 +/- 1.10 mg/L, and the mean CSF concentration was 0.162 +/-...
[The diagnostic value of venous blood gas parameters and pH value in newborn foals with pulmonary diseases]. Analysis of blood gases in equine neonatology is regarded as a diagnostic tool to study the neonatal adaptation period. Aim of this study therefore was to compare the diagnostic value of venous blood gas parameters to arterial parameters in newborn foals with pulmonary disorders. Venous as well as arterial blood samples were taken from 24 foals (1 to 6 days old) and the partial pressure of oxygen (pO2), partial pressure of carbon dioxide (pCO2), pH, and oxygen parturition (S-O2) of these samples were investigated. In addition, the alveolar (A) to arterial (a) gradients (A-aDO2) were calculated...
Mucosal microvasculature of the gastric pars nonglandularis and margo plicatus in the horse: a scanning electron microscopic study on corrosion casts. The microvascularisation of the equine non-glandular gastric mucosa was investigated using corrosion casts for scanning electron microscopy. Specimens from 11 healthy horses were examined. Corresponding to the high incidence of gastric lesions in the margo plicatus, special attention was paid to the differentiation between the pars nonglandularis and the margo plicatus as a distinct area of the aglandular mucosa. In both areas, the blood vessels of the lamina propria mucosae were arranged in three vascular layers; i. e. I) a basal, II) an intermediate, and III) a subepithelial horizontal level...
Pharmacokinetics of amoxycillin in normal horses and horses with experimental arthritis. The serum and synovial pharmacokinetics of amoxycillin (AMX) were studied after i.v. administration at a dosage of 40 mg/kg to normal horses and horses with induced aseptic carpal arthritis. The best estimates of serum and synovial pharmacokinetic parameters were calculated by mono or bivariable non-linear regression analysis. A biexponential equation was used to describe the concentration vs. time profiles in both normal and arthritic horses. There were no serum kinetic differences between normal and arthritic horses. There were, however, major synovial kinetic changes between these groups. T...
Expression of interleukin-1beta in the digital laminae of horses in the prodromal stage of experimentally induced laminitis. To study expression of interleukin-1beta (IL-1beta) in the digital laminae of horses in the prodromal stage of experimentally induced laminitis. Methods: 8 healthy adult horses with no signs of laminitis. Methods: Black walnut extract was administered via nasogastric tube to 4 horses, and water was administered to the remaining 4 (controls). Complete blood counts and physical examinations were performed every 30 minutes after administration of black walnut extract or water. General anesthesia was induced when total WBC count decreased by 30% in horses given the black walnut extract and 3 hours...
Effect of venous strangulation obstruction on length of equine jejunum and relevance to small-intestinal resection. To determine if venous strangulation obstruction (VSO) of the distal half of the equine small intestine would increase length of that segment. Methods: Halothane-anesthetized horses were assigned randomly to 3 groups of 5 horses: Group 1 (controls)--the entire small intestine was measured and rubber-shod clamps were applied to mark each end of the most distal 50% of the small intestine; Group 2--same procedure, except that VSO was induced in the distal 50% of the small intestine for 180 minutes; and Group 3--same initial procedure, except that VSO was induced for 90 minutes and followed by rep...
Effects of sodium citrate, low molecular weight heparin, and prostaglandin E1 on aggregation, fibrinogen binding, and enumeration of equine platelets. To investigate the effects of sodium citrate, low molecular weight heparin (LMWH), and prostaglandin E1 (PGE1) on aggregation, fibrinogen binding, and enumeration of equine platelets. Methods: Blood samples obtained from 4 Thoroughbreds. Methods: Blood was collected into syringes in the ratio of 9 parts blood:1 part anticoagulant. Anticoagulants used were sodium citrate, LMWH, sodium citrate and LMWH, or 300 nM PGE1/ml of anticoagulant. Platelet aggregation in response to ADP, collagen, and PGE1 was assessed, using optical aggregometry. Platelet activation was evaluated, using flow cytometry, ...
Statistical shape analysis of volumetric capnograms: evaluation of a new approach for the assessment of pulmonary function in horses with chronic obstructive pulmonary disease. The shape of the volumetric capnogram is modified by airway obstruction, and the evaluation of this deformation could allow an indirect measurement of bronchial patency. The study included 35 horses; five horses without evidence of pulmonary disease (group I) and 30 horses suffering from different degrees of chronic obstructive pulmonary disease (COPD) (groups II-IV). Data of recorded CO2 and volume curves were off-line plotted and statistically analysed using regression analysis. Analyses were performed separately for fractions 25-95% (VTE25-95), 25-50% (VTE25-50) and 50-95% (VTE50-95) of exp...
Morphology of the laminar junction in relation to the shape of the hoof capsule and distal phalanx in adult horses (Equus caballus). The purpose was to investigate whether differences in equine hoof shape, which are inferred to alter foot function, are accompanied by differences in morphology of the laminar junction. Ten fore feet from adult horses were segregated into normal and low-angle groups, depending on the dorsal angle of the hoof wall. Twenty measurements of external hoof shape and four of the enclosed distal phalanx were tested for differences between groups, and for intragroup correlations. Three measurements of laminar morphology (spacing, orientation and degree of bend) were recorded for samples of up to 50 pri...
Intermittent hypoglycemia in a horse with anaplastic carcinoma of the kidney. Clinically apparent hypoglycemia is rare in adult horses. Hypoglycemia is a well-recognized paraneoplastic syndrome in humans and dogs with non-insulin-secreting tumors and may occur in horses as well. Hypoglycemia associated with non-insulin-secreting tumors is believed to result from production of an abnormal form of insulin-like growth factor II. Neoplasia should be considered in the differential diagnosis for adult horses with hypoglycemia.
Effects of anti-inflammatory drugs on lipopolysaccharide-challenged and -unchallenged equine synovial explants. To evaluate the effects of anti-inflammatory drugs on lipopolysaccharide (LPS)-challenged and -unchallenged equine synovial membrane in terms of production of prostaglandin E2 (PGE2) and hyaluronan, viability, and histomorphologic characteristics. Methods: Synovial membranes were collected from the carpal, tarsocrural, and femoropatellar joints of 6 adult horses. Methods: Synovial membranes from each horse were minced and pooled and explants were treated with one of the following: no drug (control), drug, LPS alone, or LPS and drug. Treatment drugs were phenylbutazone (PBZ), flunixin meglumine...
Evaluation of polymyxin B in an ex vivo model of endotoxemia in horses. To evaluate effects of polymyxin B sulfate (PMB) on response of horses to endotoxin, using an ex vivo model. Methods: 8 healthy horses. Methods: In a crossover design, 3 doses of PMB (100, 1,000, and 10,000 U/kg of body weight) and physiologic saline solution (control) were evaluated. Prior to and for 24 hours after administration of PMB, blood samples were collected into heparinized tubes for use in 2 assays. For the endotoxin-induced tumor necrosis factor (TNF) assay, blood samples were incubated (37 C for 4 h) with 1 ng of Escherichia coli or Salmonella Typhimurium endotoxin/ml of blood. Pl...
Comparative responses of bronchial rings to mediators of airway hyperreactivity in healthy horses and those affected with summer pasture-associated obstructive pulmonary disease. To compare responses of bronchial rings obtained from healthy horses and horses affected with summer pasture-associated obstructive pulmonary disease (SPAOPD) to selected mediators of airway hyperreactivity in vitro. Methods: Bronchial rings from 6 healthy horses and 6 horses affected with SPAOPD. Methods: Bronchial rings obtained from each group of horses were mounted in organ baths and attached to force transducers interfaced with a polygraph. After applying 2g of tension, each ring was allowed to equilibrate for 45 minutes in Tyrode's solution at 37 C. Cumulative concentration-response rela...
Effects of intraluminal distention and decompression on microvascular permeability and hemodynamics of the equine jejunum. To determine whether intraluminal distention and subsequent decompression of the equine jejunum affects intestinal blood flow, hemodynamics, and microvascular permeability. Methods: 5 healthy adu t horses. Methods: Horses were anesthestized and underwent exploratory laparotomy. Two jejunal segments were identified as sham-operated or instrumented segments. After baseline values were obtained, intraluminal distention was created in the experimental segment to induce an ntraluminal pressure of 18 cm H2O. After 120 minutes of distention, the intestine was decompressed for 120 minutes. Mesenteric ...
Hypercoagulation and hypofibrinolysis in horses with colic and DIC. Changes in haemostasis in horses with colic were assessed by using specific and sensitive markers of coagulation and fibrinolysis activity. Blood samples from 41 horses with severe colic and from 30 healthy control horses were tested. Diagnosis of DIC was based on the findings of at least 3 of 6 abnormalities: thrombocytopenia, prolonged clotting times (PT and APTT), increased polyclonal FDPs, decreased fibrinogen and decreased AT-III activity. Plasma thrombin-antithrombin III complexes (TAT), monoclonal fibrin degradation products fragment D (D-dimer) and monoclonal fibrinogen degradation pro...
In vitro mucolytic activity of recombinant human deoxyribonuclease on equine tracheobronchial mucus. The viscosity of the mucus, its DNA concentration and the size range of the DNA were determined on tracheobronchial samples from 11 horses with lower airway diseases before and after incubation with recombinant human deoxyribonuclease (rhDNase). The horses were divided into two groups on the basis of the cytology of the samples: group A (five horses) with more than 60 per cent neutrophils and group B (six horses) with fewer than 50 per cent neutrophils. The mean mucus viscosity and DNA concentration in the preincubation samples were significantly higher in group A than in group B, and there wa...
The influence of strenuous exercise on collagen characteristics of articular cartilage in Thoroughbreds age 2 years. In order to assess the influence of strenuous exercise on collagen characteristics of articular cartilage, the response of the collagen network was studied in seven 2-year-old Thoroughbreds subjected to strenuous exercise compared to 7 nontrained individuals. After 13 weeks, the animals were subjected to euthanasia, fetlock joints of the forelimbs were scored macroscopically after Indian Ink staining, and articular cartilage from different locations of the articular surface of the proximal first phalanx was sampled and analysed for water content, collagen content, hydroxylysine content and amo...
Metalloproteinases and tumor necrosis factor-alpha activities in synovial fluids of horses: correlation with articular cartilage alterations. Early detection of osteoarthritis in horses represents a challenge for equine practitioners. Several biological markers have been implicated in the pathological processes involved in articular cartilage destruction. To further document cartilage matrix proteases production, synovial fluid was collected from 14 horses (90 joints) before they were subjected to euthanasia. Growth macroscopic examination of the joints gave information on cartilage alterations. Samples were analyzed for matrix metalloproteinase (MMPs) activities by gelatin zymography and tumor necrosis factor alpha (TNF-alpha) cyto...
Phosphodiesterase activity in neutrophils from horses with chronic obstructive pulmonary disease. Neutrophils are recruited to the lungs of horses with chronic obstructive pulmonary disease (COPD) and exhibit increased activity after antigen challenge. Phosphodiesterase type4 (PDE4) inhibitors have been shown to attenuate human neutrophil activation. The aim of this study was to establish the PDE isoenzyme profile of equine neutrophils using isoenzyme selective inhibitors to determine if these compounds should be evaluated in horses with COPD. Total cAMP and cGMP dependent PDE activity was no different in neutrophils from normal (156.2+/-7.1 and 6.8+/-0.6 pmol/min/mg for cAMP and cGMP, res...
Relationship of pulmonary arterial pressure to pulmonary haemorrhage in exercising horses. Exercise-induced pulmonary haemorrhage (EIPH) is characterised by blood in the airways after strenuous exercise and results from stress failure of the pulmonary capillaries. The purpose of this experiment was to establish a threshold value of transmural pulmonary arterial pressure at which haemorrhage occurs in the exercising horse. Five geldings, age 4-14 years, were run in random order once every 2 weeks at 1 of 4 speeds (9, 11, 13, 15 m/s); one day with no run was used as a control. Heart rate, pulmonary arterial pressure and oesophageal pressure were recorded for the duration of the run. T...
Nodular diseases. The development of a nodule is a fairly common reaction pattern in the skin and subcutaneous tissues of the horse. In many such nodules, the inciting aetiologic agent or antigen is unknown, but in some equine cases there is significant evidence for insect bite origin. The pathogenesis of some equine nodular diseases appears to involve marked collagen degeneration which varies from hyalinization to lysis and can become mineralized. The exact role the lytic collagen has in the pathogenesis of these lesions is still unknown. Vascular changes may be present in some entities. Other nodules may be c...
Functional morphology of the equine pelvic flexure and its role in disease. A review. The hindgut is the major site in the horse for nutrient digestion and absorption. Most of this activity occurs in the large intestinal compartments, i.e., cecum, right and left ventral colon and left and right dorsal colon. The colonic pelvic flexure is a short and narrow loop connecting the left ventral and left dorsal colon. It is not significant directly in digestive and absorptive processes but plays an important functional role in regulating colonic aboral and retropropulsive transit of digesta through its motility pacemaker activity. The pelvic flexure also contributes to the pathophysio...
