Inflammation is a biological response of the horse's body to harmful stimuli, such as pathogens, damaged cells, or irritants. It is a complex process that involves the activation of immune cells, the release of inflammatory mediators, and changes in blood flow. In horses, inflammation can manifest in various forms, affecting different tissues and organs, including the joints, respiratory system, and skin. The inflammatory response is an essential component of the horse's immune system, aiming to eliminate the initial cause of cell injury, clear out damaged cells and tissues, and establish tissue repair. This topic page gathers peer-reviewed research studies and scholarly articles that explore the mechanisms, effects, and management of inflammation in equine health.
Moore RM, Couto CG, Muir WW, Moore BR, Kociba GJ.Twenty-four horses were randomly allocated to 3 groups. All horses underwent a ventral midline celiotomy, and the large colon was exteriorized and instrumented. Group-1 horses served as sham-operated controls, group-2 horses underwent 6 hours of colonic ischemia, and group-3 horses were subjected to 3 hours of ischemia and 3 hours of reperfusion. Baseline blood samples were collected, then low-flow colonic ischemia was induced in horses of groups 2 and 3 by reducing colonic arterial blood flow to 20% of baseline. All horses were monitored for 6 hours. Citrated systemic venous (SV) blood sample...
Moore RM, Muir WW, Bertone AL, Beard WL, Stromberg PC.Thirty horses were randomly assigned to 1 of 5 groups. All horses were anesthetized and subjected to ventral midline celiotomy, then the large colon was exteriorized and instrumented. Colonic arterial blood flow was reduced to 20% of baseline (BL) and was maintained for 3 hours. Colonic blood flow was then restored, and the colon was reperfused for an additional 3 hours. One of 5 drug solutions was administered via the jugular vein 30 minutes prior to colonic reperfusion: group 1, 0.9% NaCl; group 2, dimethyl sulfoxide: 1 g/kg of body weight; group 3, allopurinol: 25 mg/kg; group 4, 21-aminost...
Moore RM, Muir WW, Granger DN.Restoration of blood flow after a period of intestinal ischemia is necessary to maintain cell function and viability; however, the reintroduction of oxygen can initiate a cascade of events that exacerbates tissue injury. Intestinal I-R injury is manifested as increased microvascular and mucosal permeability, and mucosal necrosis. Reperfusion injury begins with the accumulation of hypoxanthine from ATP metabolism and the conversion of XDH to XO during ischemia. Upon reperfusion, the XO catalyzes the conversion of hypoxanthine to superoxide radicals in the presence of oxygen. Superoxide radicals...
Darien BJ, Stone WC, Dubielzig RR, Clayton MK.The morphologic changes following ascending colon volvulus result from the interaction of inflammatory and coagulation mediators. The objective of this study was to establish a quantifiable histopathologic scoring system to evaluate the serial pathomorphologic changes during ischemia and reperfusion. Such a scoring system could then be applied to subsequent studies designed to attenuate bowel lesions by regulating activity of individual mediators. Ten normal, healthy adult ponies were randomly divided into two equal groups. Following anesthesia and a 30-minute stabilization period, the colon o...
Rosenkrantz WS.Hopefully, the practitioner has obtained a basic broader knowledge of the options available for topical and systemic equine dermatologic therapy. There are many topical and systemic agents that can aid in the treatment of specific skin disease and there are safer alternatives to glucocorticoid therapy. Because equine dermatology is still in its infancy, there is still much to be learned. The practitioner is encouraged to pay close attention to this specialty because it will continue to evolve rapidly.
Fadok VA.Scaling and/or crusting are common clinical findings associated with equine skin diseases. Scaling and crusting may be associated with pruritic or nonpruritic dermatoses. This article focuses on those conditions that are usually nonpruritic in horses. They include the infectious dermatoses, the keratinization/seborrheic disorders, photosensitization, and the immunologic/inflammatory disorders, including pemphigus foliaceus, equine exfoliative eosinophilic dermatitis and stomatitis, and equine histiocytic dermatitis (sarcoidosis). Clinical signs that help differentiate the various disorders are...
Woods PR.Skin lesions can be associated with many internal diseases. Most organ systems seem to have conditions in which skin lesions can develop. Treatment of the skin lesions in such a situation is palliative. The underlying internal disease must be addressed for resolution of the skin lesions to occur. It is important to view the skin as an integral communicating part of the body and not just as the skin.
Fadok VA.Papules and nodules are common lesions on horses and have a variety of underlying causes. This article addresses inflammatory and congenital nodules primarily, including urticaria, erythema multiforme, those nodules caused by infectious agents, epidermoid and dermoid cysts, and the uniquely equine skin tumor, the sarcoid. The eosinophilic nodules and other tumors are covered elsewhere in this issue. Diagnostic and therapeutic approaches to each of the diseases are emphasized.
Miyamoto A, Kanda J, Nishio A.Transmural nerve stimulation (TNS) induced relaxations in porcine and bovine basilar arteries which were abolished by tetrodotoxin (TTX) and by L-nitro-arginine (LNAG). However, TNS induced contractions in equine basilar artery which were abolished by TTX and by guanethidine, but not by LNAG. These results suggest that the TNS-induced contractions of equine basilar arteries may be mediated by norepinephrine release.
Troedsson MH, Scott MA, Liu IK.Four intrauterine treatment strategies were evaluated for effectiveness in mares that were confirmed to be susceptible to chronic uterine infection. Pretreatment samples were obtained at detection of estrus, and a genital strain of Streptococcus zooepidemicus was infused into the uterus when a preovulatory (> 35 mm) follicle was detected. At 12 hours after inoculation, mares were assigned to 1 of 4 selected treatment groups: autologous plasma, 100 ml (n = 5); potassium penicillin, 5 million U in 100 ml of phosphate-buffered saline solution (PBSS; n = 5); 10 mg of prostaglandin F2 alpha in 1...
Honnas CM, Schumacher J, McClure SR, Crabill MR, Carter GK, Schmitz DG, Hoffman AG.Medical records of 10 horses with olecranon bursitis were reviewed to examine treatments, evaluate a technique for en bloc resection of the bursa in standing horses, and determine outcome of the horses after treatment. Before admission, 6 horses had been treated by needle aspiration of fluid from the mass, followed by injection of corticosteroids. Subsequent treatment for 2 of these 6 horses included open drainage and packing of the cavity with gauze soaked in 7% iodine solution. None resolved after these treatments. After admission to the hospital, 5 horses were treated medically and 5 were t...
Greet TR.Thirty eight horses with epiglottal entrapment were examined. In 29 the dorsally displaced mucosa was split axially with a curved hook knife, per nasum. The condition was also treated by subepiglottal mucosal resection (4 horses) and solely by the administration of an anti-inflammatory throat spray (4 horses). All surgical cases were treated with an anti-inflammatory throat spray and parenteral phenylbutazone. Those horses treated via a laryngotomy incision were box rested until the laryngotomy incision healed. The other horses were restricted to walking and trotting exercise for 10 days befor...
Osborne AC, Carter SD, May SA, Bennett D.An investigation was made into the possible contribution of autoimmune mechanisms to equine arthropathies. Serum and synovial fluid (SF) immune complexes and anti-collagen Type II antibodies were measured, by ELISA, in groups of horses with naturally occurring osteoarthritis (OA), osteochondritis dissecans (OCD), bone fracture, traumatised joints, synovitis, infected joints and non-diseased (control) joints. Significantly raised anti-collagen Type II antibodies were found in osteoarthritic (P < 0.02) and traumatised joint synovial fluids (P < 0.01) compared with the control, where ten of...
Hawkins JF, Ross MW.Medical records of 40 racing Standardbreds with superficial digital flexor tendinitis that underwent transection of the accessory ligament of the superficial digital flexor (SDF) muscle (superior check desmotomy) were reviewed. Surgery was performed bilaterally in 32 horses and unilaterally in 8. Concurrent palmar annular desmotomy was performed in 8 horses in which tendinitis involved the distal metacarpal region and confinement of the deep and SDF tendons by the annular ligament was suspected. Follow-up information was obtained for 32 horses, by telephone, and racing results were available f...
Wang ZW, Yu MF, Robinson NE, Derksen FJ.The present study was conducted to determine if acetylcholine (ACh) release from airway cholinergic nerves is increased and if modulation of ACh release by prejunctional receptors is altered in horses with heaves, an obstructive airway disease characterized by airway inflammation and bronchospasm. Trachealis strips and bronchial segments of normal horses and horses affected with heaves were suspended in 2-ml tissue baths. ACh release was induced by electrical field stimulation and the bath ACh content was measured by high performance liquid chromatography (HPLC) with electrochemical detection....
Baxter GM.Low doses of endotoxin cause vasoconstriction and hypoperfusion of the digit, small intestine, and cecum in horses. To determine the potential cause of these vascular alterations, in vitro vascular responses of palmar digital arteries and veins were determined in 8 horses after intravenous (IV) infusion of 1 L 0.9% NaCl (control) and 0.1 microgram/kg Escherichia coli 055:B5 endotoxin in 1 L of 0.9% NaCl (endotoxin-treated). Vessels were surgically removed under general anesthesia, cut into 4-mm vascular rings, suspended in tissue baths, and attached to force displacement transducers for measur...
Gomez-Cuetara C, Flores JM, Sanchez J, Rodriguez A, Sanchez MA.An histological study of the postpartum period in 29 mares was carried out. Uterine biopsies were taken daily during the first 10 days postpartum in a total of 87 samples. At day 0, equine endometrium was characterized in the surface by the presence of regularly ordered microcaruncles; the stratum spongiosum was oedematous and contained distended and scarce glands. Degenerative changes in microcaruncles and endometrial glands were present on day 1 postpartum. The epithelium of the microcaruncles from 2 to 5 days postpartum showed cytoplasmic vacuolization, karyorrhexis and an inflammatory reac...
Santschi EM, Adams SB, Robertson JT, DeBowes RM, Mitten LA, Sojka JE.Six mares had ovariohysterectomy performed for chronic pyometra associated with cervical abnormalities, uterine neoplasia, or removal of a macerated fetus. Ovariohysterectomy was performed through a ventral midline incision with access to the ovarian and uterine vessels aided by traction on the uterus and retraction of abdominal viscera. Abdominal pain, the most common complication after surgery, occurred in four mares but resolved within 36 hours. Peritonitis occurred in two mares; one mare was subsequently euthanatized. Other complications that resolved with treatment included infection of t...
Raidal SL, Love DN, Bailey GD.Confinement of horses with their heads elevated for periods up to 24 hours was used to evaluate the extent and the effects of bacterial contamination of the equine lower respiratory tract. Significant (P < 0.05) increases in bacterial numbers (up to 10(9) colony forming units/mL in transtracheal aspirate derived samples) occurred within 6 or 12 hours in most horses. Pasteurella/Actinobacillus spp and Streptococcus spp were most commonly isolated. Lowering of the head for 30 minutes every 6 hours to facilitate postural drainage did not prevent multiplication of organisms to levels equivalent...
Sutton RH, Coleman GT.Abstract Extract A 15-year-old pony mare developed firm irregular bony swellings on all four legs. These were most severe around the carpal and fetlock joints of the forelegs, restricting both flexion and extension. Over about 6 months the horse had periodic bouts of coughing. She showed moderate weight loss and a depressed demeanour.
Gosztonyi G, Ludwig H.Natural BD is a nonpurulent acute/subacute encephalitis of horses and sheep with a propensity to involve the olfactory and limbic systems, and the brain stem. The inflammation is concentrated primarily in the gray matter, but subcortical white matter may also be affected. Experimental BD can be produced in a series of animals from birds to primates. The neuropathology after experimental infection is similar to that in natural disease but the inflammatory changes are more diffuse. In the rat and mouse, a persistent/tolerant infection can also be induced, in which inflammatory changes are conspi...
Foster AP, Lees P, Cunningham FM.Hypersensitivity responses to biting flies such as Culicoides are believed to be the cause of sweet itch, a seasonal intensely pruritic skin condition of horses. Little is known about the mediators released by antigen in the skin of affected horses. In the present study the cutaneous vascular and cellular responses to intradermally injected platelet activating factor (PAF) have been characterised in sweet itch cases during the active phase of the disease and compared with those of Culicoides antigen extract. Histamine was used as a positive control in vascular permeability studies. Responses w...
Widders PR, Warner S, Huntington PJ.Normal mares were immunised by the intramuscular and intrauterine administration of an antigen with adjuvant and they and unimmunised control mares were later challenged by the intrauterine instillation of pathogenic Streptococcus zooepidemicus; the response of all the mares was monitored clinically and bacteriologically for seven days. Significantly fewer S zooepidemicus were present in cervical swabs taken from the immunised mares than from the control mares (P < 0.01) and the degree of inflammation in the genital tract of the immunised mares was also significantly less (P < 0.001). Th...
Buergelt CD, Greiner EC.Fibrosing granulomas were found in the liver and occasionally on the intestinal and diaphragmatic serosae and in the lung of 11 horses submitted for necropsy. Although these granulomas were considered incidental findings in most of the horses, they had caused liver failure in 1 horse. The granulomas typically were characterized by a dense collagenous core that frequently was mineralized. The periphery contained a rim of inflammatory cells. Only in 1 of the 11 horses was there evidence of an egg shell suggestive of schistosomes. Schistosomal eggs were not detected in the feces of the horses. Th...
Edwards RB, Fubini SL.Five Holstein calves and two foals with omphalophlebitis were treated by surgical marsupialization of the umbilical vein remnant because complete resection of the infected tract was not possible. The infected umbilical stalk was resected, and the umbilical vein remnant was marsupialized in a one-stage procedure by suturing it into the abdominal wall lateral to the abdominal incision. Antimicrobial drugs were administered, and the marsupialized tract was irrigated until closure by second intention healing. Cellulitis associated with the marsupialization site occurred in two calves but resolved ...
Collatos C, Barton MH, Moore JN.Plasma fibrinolytic activity was evaluated over 5 consecutive days in 59 horses admitted to the Large Animal Teaching Hospital with acute gastrointestinal diseases. Only horses hospitalized for at least 5 days were included in the study. Tissue plasminogen activator (tPA) and plasminogen activator inhibitor type-1 (PAI-1) were quantitated using standard chromogenic activity assays. Statistical analyses were performed using analysis of variance; differences were considered significant when P < or = .05. Activity of PAI-1, the primary endogenous inhibitor of fibrinolysis, was significantly incre...
Gomez-Villamandos RJ, Santisteban Valenzuela JM, Ruiz Calatrava I, Gomez-Villamandos JC, Avila Jurado I.A study was made of the effects of low-level laser irradiation on the cicatrization of superficial wounds in the pharyngeal mucosa of the horse. Methods: Duplicate pharyngeal mucosal ulcers were induced in 12 Spanish horses with submucosal injection of sulfuric acid. A fibroendoscope and an He-Ne laser were used to treat one of the ulcers and the second ulcer in each animal was left untreated, serving as a control. Biopsy samples for the histological study were taken after the seventh laser therapy session from the two animals. Results: Irradiated lesions cicatrized at 10.5 days and nonirradia...
Johannisson A, Gröndahl G, Demmers S, Jensen-Waern M.Methodological aspects of flow-cytometric evaluation of the phagocytic properties of equine neutrophils were elucidated. The kinetics of attachment and ingestion were studied, and the phagocytic process was more rapidly completed when serum-opsonized yeast cells were used than with use of IgG-opsonized yeast cells. Trypan blue was successfully used to quench fluorescence of non-ingested yeast cells. There were only minor differences in the kinetics of phagocytosis between quenched and unquenched samples, indicating that attachment is rapidly followed by ingestion. Trypan blue quenching caused ...
Baxter GM.Laminitis is an inflammation of the sensitive laminae along the dorsal aspect of the digit and is considered to be a secondary complication of several predisposing or primary factors. Affected horses are usually very lame, have increased digital pulses, are painful to hoof testers along the toe of the foot, and have evidence of downward rotation or distal displacement of the distal phalanx present on radiographs. Treatments for acute laminitis include anti-inflammatory drugs, anti-endotoxin therapy, vasodilators, antithrombotic therapy, corrective trimming and shoeing, and surgical procedures....
Rebhun WC.Most ocular and orbital injuries or acute ocular inflammation in horses result in similar signs of adnexal swelling, photophobia, blepharospasm, and lacrimation. It is hoped that detailed examination and the suggestions in this article will enable veterinarians attending horses having ocular emergencies to arrive at a correct diagnosis and appropriate therapy.
Ribeiro Neto LM, Salvadori MC, Spinosa HS.Due to the widespread use of dexamethasone in racing horses, mostly in low doses by intra-articular administration for the treatment of inflammatory processes, a method is developed to detect this drug in horse urine samples using liquid-liquid extraction followed by immunoaffinity chromatography. Liquid chromatography with diode-array detection is used for the identification of the drug. The use of immunoaffinity columns enhances the selectivity of the analysis, and the results show that dexamethasone can be detected up to 28 h after intra-articular administration.
Heinrich B.This research article corrects a common misconception about the energy metabolism in horses during short sprinting and long-distance running events, emphasizing that short sprints are primarily powered by anaerobic activity, […]
Trsan J, Nottle BF, Pusterla N.This study was designed to determine the effect of PPG and/or flunixin meglumine on SAA response when used at clinical dosing regimens in healthy adult horses. Six healthy adult horses were enrolled in a crossover study design including one control and three treatment groups: no treatment (control); PPG alone (intramuscularly q12h for 72h); flunixin meglumine alone (intravenously q24h for 72h); and PPG (intramuscularly q12h for 72h) and flunixin meglumine (intravenously q24h for 72h). Whole blood was collected at 0, 24, 48, 72, 96 and 120 hours post-initial drug administration to measure SAA u...
Tallon RE, Gough RL, McGovern KF.To describe the use of an equine compression suit to manage a deep axillary wound in a Thoroughbred filly with bilateral pneumothorax. Methods: A 2-year-old Thoroughbred filly was referred for management of a deep wound to the left axilla. Packing and bandaging of the area were initially attempted, but this became repeatedly dislodged, and bandaging was discontinued. The filly subsequently developed widespread subcutaneous emphysema, and the wound was slow to granulate. Acute onset respiratory distress occurred 11 days after admission, secondary to bilateral worsening pneumothorax, and requir...
Elder E, Wong D, Johnson K, Robertson H, Marner M, Dembek K.Bacterial sepsis is the leading cause of death in foals and is associated with hypothalamic-pituitary-adrenocortical axis (HPAA) dysfunction. HPAA function can be evaluated by an arginine-vasopressin (AVP) stimulation test. Objective: Administration of AVP will stimulate a dose-dependent rise in systemic adrenocorticotropin-releasing hormone (ACTH) and cortisol in neonatal foals. There will be no response seen in corticotropin-releasing hormone (CRH) and baseline AVP will be within reference interval. Methods: Twelve neonatal foals, <72 hours old. Methods: HPAA function was assessed in foals...
Carroll EJ, Lasmanis J, Schalm OW.A method is described for production of an equine anti-bovine leukocyte serum (EABLS). Leukocytes were harvested from the milk of cow's udders which had been irritated with endotoxin. The washed leukocytes as antigens were administered to 2 horses in a series of subcutaneous and intravenous injections. There was a variably progressive increase in total serum proteins and a decrease in albumin/blobulin ratios, but the most pronounced change was an increase in beta2-globulins. Accompanying these changes was an increase in the number of precipitin lines as shown by Ouchterlony analysis. Four old ...
Ettlinger JJ, Ford T, Palmer JE.Proximal enteritis was diagnosed on the basis of clinical signs of disease in 2 Standard-bred yearlings from the same farm. Large volumes of fluid were repeatedly obtained during gastric decompression. The horses did not respond to treatment with IV administered fluids, antimicrobial agents, cimetidine, and metoclopramide. Postmortem findings confirmed severe focal chronic active duodenitis with stricture formation. An etiologic agent was not identified.
Tallmadge RL, Antczak DF, Felippe MJB.Host defenses against infection by viruses, bacteria, fungi, and parasites are critical to survival. It has been estimated that upwards of 7% of the coding genes of mammals function in immunity and inflammation. This high level of genomic investment in defense has resulted in an immune system characterized by extraordinary complexity and many levels of redundancy. Because so many genes are involved with immunity, there are many opportunities for mutations to arise that have negative effects. However, redundancy in the mammalian defense system and the adaptive nature of key immune mechanisms bu...
Noschka E, Moore JN, Peroni JF, Lewis SJ, Morrow JD, Robertson TP.Inflammation and vascular dysfunction occur concurrently during the prodromal stages of equine laminitis. The aim of this study was to provide insights into the role that thromboxane and isoprostanes may play in the development of black walnut heartwood extract (BWHE)-induced laminitis. Horses were divided into two groups, either control or BWHE-administered horses. Plasma concentrations of thromboxane increased transiently after administration of BWHE and coincided with the nadir in white blood cell counts, whereas plasma concentrations of iso-prostaglandin PGF(2alpha) (iso-PGF(2alpha)) did n...