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.
Frankeny RL.Five horses with unilateral epidermal inclusion cysts located in the nasal diverticula were sedated and treated with intralesional injection of neutral-buffered 10% formalin (volume range, 2 to 4.5 mL). After aspiration of the cyst, formalin was injected intralesionally until leakage of fluid around the needle was observed. After several weeks, desiccation of the cyst was evident; it was excised 2 weeks after treatment in 3 horses, digitally removed by the owner of 1 horse, and never removed in 1 horse, because the owner declined further treatment after resolution of the original swelling of t...
Schumacher J, Schumacher J, Gillette R, DeGraves F, Schramme M, Smith R, Perkins J, Coker M.Analgesia of the palmar digital (PD) nerves has been demonstrated to cause analgesia of the distal interphalangeal (DIP) joint as well as the sole. Because the PD nerves lie in close proximity to the navicular bursa, we suspected that that analgesia of the navicular bursa would anaesthetise the PD nerves, which would result in analgesia of the DIP joint. Objective: To determine the response of horses with pain in the DIP joint to instillation of local anaesthetic solution into the navicular bursa. Methods: Lameness was induced in 6 horses by creating painful synovitis in the DIP joint of one f...
Dechant JE, Baxter GM, Frisbie DD, Trotter GW, McIlwraith CW.Osteoarthritis is a frequent sequela of joint disease, especially with severe injuries or if attempts at therapy are unsuccessful. Negative and positive effects of corticosteroid treatment of articular cartilage have been demonstrated by in vitro and in vivo studies. Objective: To assess the metabolic effects of varying dosages of methylprednisolone acetate (MPA) and triamcinolone acetonide (TA) on interleukin-1alpha (IL-1) conditioned equine cartilage explants. Our hypothesis was that lower dosages of corticosteroids would be less detrimental to cartilage metabolism than higher dosages. TA wo...
Gerber V, Robinson NE, Luethi S, Marti E, Wampfler B, Straub R.Horses housed in conventional stable environments are exposed to high dust loads. Long-term exposure to inhaled dust may lead to subclinical airway disease. Objective: Airway inflammation and mucus accumulation are 1) common in asymptomatic well-performing sport horses, 2) increased in older compared to younger individuals and 3) correlated. Methods: Mucus quantity and quality (endoscopic scoring) and BALF differential cytology were assessed in 13 younger horses (mean age 5 years) and 13 older horses (mean age 15 years), which had no historical or clinical evidence of lower airway disease, wer...
Mäkelä O, Sukura A, Penttilä P, Hiltunen J, Tulamo RM.To evaluate the effects of radiation synovectomy (RSYN) with holmium-166 ferric hydroxide macroaggregate (Ho-166 FHMA) on synovium and synovial fluid in normal metacarpo- and metatarsophalangeal joints of horses and to determine intraarticular distribution of radioactivity after Ho-166 FHMA treatment. Methods: Either Ho-166 FHMA or nonradioactive Ho-165 FHMA was injected into metacarpo- or metatarsophalangeal joints. Methods: Six adult mixed-breed horses without any clinical evidence of metacarpo- or metatarsophalangeal joint disease. Methods: Joints were injected with a single high dose of Ho...
Peters M, Brandt K, Wohlsein P.An intracranial epidermoid cyst was diagnosed in a Haflinger gelding aged 12 years suffering from episodes of neurological disturbance, apathy and fever. The extracerebral cyst was located in the region of the tentorium cerebelli and measured 9 x 8 x 5 cm. It displaced the cerebral hemispheres anteriorly and compressed the cerebellum and brainstem underneath. Histologically, the cyst was lined by keratinizing, stratified squamous epithelium and contained keratin scales, debris, focal haemorrhages, and degenerating inflammatory cells. The epithelium was supported by a vascularized fibrous capsu...
Bollwein H, Sowade C, Stolla R.Transrectal color Doppler sonography was used to evaluate the effect of intrauterine infusion of skim milk semen extender, seminal plasma and raw semen on the endometrium and blood flow in the uterine and ovarian arteries in mares. Six Trotter mares (mean age: 12 years) were examined during estrus in three cycles. Each mare received an intrauterine infusion of 20 ml of skim milk semen extender, seminal plasma or raw semen during estrus in one of three cycles. Blood flow measurements in both uterine and ovarian arteries and the determination of intrauterine fluid via sonography were performed b...
Mallem MY, Gogny M, Gautier F, Bucas V, Desfontis JC.To investigate the functional expression of beta3-adrenoceptors (beta3-ARs) in equine digital veins (EDVs) and to examine whether beta3-AR relaxation was altered in EDVs incubated with endotoxin. Methods: Forelimbs obtained from 30 horses. Methods: Forelimbs were obtained from horses in an abattoir. Equine digital veins were carefully removed from distal portions of the forelimbs. Rings of dissected EDVs were mounted in 5-mL organ baths to record isometric tension in the presence of various beta3-AR agonists (SR 58611A, ZD 2079, and ZM 215001). Results: In intact EDVs, isoprenaline, SR 58611A,...
Byron CR, Orth MW, Venta PJ, Lloyd JW, Caron JP.To characterize potential mechanisms of action of glucosamine inhibition of matrix metalloproteinase (MMP) expression and activity in lipopolysaccharide (LPS)-stimulated equine chondrocytes. Methods: Chondrocytes cultured from samples of metacarpophalangeal articular cartilage collected from cadaveric limbs of horses. Methods: The effect of glucosamine on MMP activity in conditioned medium from LPS-stimulated cartilage explants was determined by a colorimetric assay with azocoll substrate. Treatments consisted of negative and positive controls, glucose (50 mM), and glucosamine (50, 25, 6.25, 3...
Miller MA, Kottler SJ, Ramos-Vara JA, Johnson PJ, Ganjam VK, Evans TJ.Response to 3-methylindole (3MI) varies among species. Mice recover from 3MI-induced bronchiolar epithelial injury but sustain persistent olfactory mucosal injury with scarring and epithelial metaplasia. In contrast, 3MI induces obliterative bronchiolitis in horses and ponies, but olfactory mucosal injury has not been reported. To evaluate the effect of 3MI on equine olfactory mucosa, ponies were dosed orally with 100 mg 3MI/kg (n = 9) or corn oil vehicle (n = 6). All ponies treated with 3MI developed obliterative bronchiolitis with mild olfactory injury. By 3 days after 3MI dosing, olfactory ...
Kim DY, Taylor HW, Moore RM, Paulsen DB, Cho DY.Osteoarthritis (OA) is the most common joint disease in horses. Chondrocyte apoptosis has been implicated as a major pathological OA change in humans and experimental animals but no studies have been performed on equine OA. Articular cartilage was collected from three normal and five OA horses. Histopathological changes were scored by a modified Mankin grading system. A terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay was performed to identify chondrocyte apoptosis. Nitric oxide (NO) production from chondrocytes was indirectly evaluated by immunohistochemistr...
Carter CA, Jolly DG, Worden CE, Hendren DG, Kane CJ.Nonhealing wounds of the lower equine limb represent a challenging model. The platelet is a natural source of a myriad of growth factors and cytokines that promote wound healing. This study evaluates the potential of platelet derived factors to enhance wound healing in the lower equine limb. Platelets were isolated from horse blood and activated with thrombin, a process known to induce growth factor release. This produced a platelet gel composed of platelet-rich plasma (PRP). To test this all-natural wound healant, 2.5-cm(2) full thickness cutaneous wounds were created below the knee and hock ...
Holmes LC, Gaughan EM, Gorondy DA, Hogge S, Spire MF.Infrared thermography is an imaging modality gaining popularity as a diagnostic aid in the evaluation of equine lameness. Anecdotal reports of skin hyperthermia induced by local anesthesia, detected by thermography, have been made; however, no controlled studies have been reported. The purpose of this study was to examine the effects of perineural anesthesia on infrared thermographic images of the forelimb digits in normal horses. After environmental acclimation, infrared thermographs were made at intervals of 0, 5, 10, 15, 30, and 45 min from administration of mepivacaine hydrochloride or pho...
Baudler A, Lütkefels E, Drommer W, Deegen E, Ohnesorge B.Epiglottic augmentation by transendoscopic injection of an implant material was performed on ten clinically healthy horses. In six cases bovine collagen (Zyplast) was used, in the remaining four horses the injection was done with polytetrafluorethylene (PTFE-Paste). The results of the surgery were observed endoscopically and by contrast radiography. Using the radiographs, epiglottic length and thickness were measured. For necropsy and histologic assessment the horses, three and two animals of the two groups, were euthanized at three and 12 weeks after surgery. The data obtained from the measur...
Davis EG, Rush BR, Blecha F.Immunomodulation with Propionibacterium acnes is used for prophylaxis of respiratory disease or in horses suffering from chronic pulmonary inflammation; however, the mechanism for this response is poorly understood. Semiquantitative reverse transcriptase-polymerase chain reaction assays were used to evaluate gene expression of interleukin (IL)-2, IL-10, interferon (IFN)-gamma, and NK-lysin in healthy horses treated with P. acnes. Findings in the study indicated that horses treated with a P. acnes-based immunomodulator exhibited increased IFN-gamma and NK-lysin gene expression in peripheral blo...
Wilderjans H, Boussauw B, Madder K, Simon O.Inflammation of the digital flexor tendon sheaths is a chronic and nebulous condition often unresponsive to medical and surgical treatment. Objective: To evaluate the incidence of longitudinal tears (LT) as the underlying cause of chronic tenosynovitis and annular ligament constriction syndrome (ALCS) in warmblood horses. Methods: The records of 25 horses with chronic tenosynovitis and ALCS in which tenoscopical inspection of the digital flexor tendon sheath (DFTS) was performed between 1999-2000 were reviewed. Of 25 horses, 17 were diagnosed with an LT in the deep digital flexor tendon (DDFT)...
Robinson NE, Berney C, Eberhart S, deFeijter-Rupp HL, Jefcoat AM, Cornelisse CJ, Gerber VM, Derksen FJ.To investigate relationships between cough frequency and mucus accumulation, airway obstruction, and airway inflammation and to determine effects of dexamethasone on coughing and mucus score. Methods: 13 horses with recurrent airway obstruction (RAO) and 6 control horses. Methods: 6 RAO-affected and 6 control horses were stabled for 3 days. Coughing was counted for 4 hours before and on each day horses were stabled. Before and on day 3 of stabling, tracheal mucus accumulation was scored, airway obstruction was assessed via maximal change in pleural pressure (deltaPpl(max)), and airway inflamma...
Latimer FG, Eades SC, Pettifer G, Tetens J, Hosgood G, Moore RM.Abdominal insufflation is performed routinely during laparoscopy in horses to improve visualisation and facilitate instrument and visceral manipulations during surgery. It has been shown that high-pressure pneumoperitoneum with carbon dioxide (CO2) has deleterious cardiopulmonary effects in dorsally recumbent, mechanically ventilated, halothane-anaesthetised horses. There is no information on the effects of CO2 pneumoperitoneum on cardiopulmonary function and haematology, plasma chemistry and peritoneal fluid (PF) variables in standing sedated horses during laparoscopic surgery. Objective: To ...
Gerber V, Robinson NE, Venta RJ, Rawson J, Jefcoat AM, Hotchkiss JA.Increased mucin gene expression may be an important cause of mucus accumulation observed in recurrent airway obstruction (RAO)-affected horses. To date, however, no mucin gene sequences are available for the horse. Objective: To identify equine homologues of gel-forming mucins and investigate their expression at different airway generations of healthy and RAO-affected horses. Methods: Two equine homologues were identified by cloning and sequencing fragments of equine (eq)MUC5AC and eqMUC2. Results: Semiquantitative RT-PCR on RNA from airways (generations 1, 5, 10, 15; small airways and parench...
Hanel RM, Crawford PC, Hernandez J, Benson NA, Levy JK.To determine whether passive transfer of IgG in neonatal kittens affects plasma opsonic capacity and neutrophil phagocytic and oxidative burst responses to bacteria in vitro. Methods: 22 kittens from 6 specific pathogen-free queens. Methods: Kittens were randomized at birth into the following treatment groups: colostrum-fed, colostrum-deprived, or colostrum-deprived supplemented with feline or equine IgG. Blood samples were collected at intervals from birth to 56 days of age. Plasma IgG concentrations were determined by radial immunodiffusion assay. Neutrophil function was assessed by a flow c...
Pirie RS, Collie DD, Dixon PM, McGorum BC.Equine heaves is a naturally occurring organic dust-induced asthma characterized by airway neutrophilia, mucus hypersecretion and obstructive lung dysfunction. However, the relative role of different dust components in disease severity remains unclear. Objective: This study investigated the relative contribution of inhaled endotoxin and organic dust particulates (mainly mould spores) in inducing heaves in heaves-susceptible horses. Methods: Control and heaves-susceptible horses received inhalation challenges with hay dust suspension (HDS) before and after lipopolysaccharide (LPS) depletion. He...
Léguillette R.Heaves, or recurrent airway obstruction (RAO), is a chronic respiratory disease featuring lower airway inflammation, bronchoconstriction, and mucus accumulation. Inhaled organic dusts and T helper 2 type immunologic reactions are involved in the complex pathophysiology of RAO. Clinical signs vary and alternate with remission periods. The diagnosis is often based on history and clinical examination in severe cases, but bronchoalveolar lavage may be useful for the detection of early cases. The most important aspect of treatment is to avoid exposure to allergens. Corticosteroids may be administer...
Deaton CM, Marlin DJ, Smith NC, Roberts CA, Harris PA, Kelly FJ, Schroter RC.Vitamin C (ascorbic acid) is a non-enzymatic antioxidant important in protecting the lung against oxidative damage and is decreased in lung lining fluid of horses with airway inflammation. To examine possible therapeutic regimens in a species with ascorbate-synthesising capacity, we studied the effects of oral supplementation of two forms of ascorbic acid, (each equivalent to 20 mg ascorbic acid per kg body weight) on the pulmonary and systemic antioxidant status of six healthy ponies in a 3 x 3 Latin square design. Two weeks supplementation with ascorbyl palmitate significantly increased mean...
Martoriati A, Gérard N.A growing body of evidences suggests that the ovary is a site of inflammatory reactions, and thus, ovarian cells could represent sources and targets of the interleukin-1 (IL-1) system. The purpose of this study was to examine the IL-1 system gene expressions in equine granulosa cells, and to study the IL-1beta content in follicular fluid during the follicle maturation. For this purpose, granulosa cells and follicular fluids were collected from the largest follicle at the early dominance stage (diameter 24 +/- 3 mm) or during the preovulatory maturation phase, at T0 h, T6 h, T12 h, T24 h and T3...
Cohen ND, Carey VJ, Donahue JG, Seahorn JL, Harrison LR.Epidemiological and pathological findings of 433 late-term abortions associated with the mare reproductive loss syndrome (MRLS) in central Kentucky were identified by reviewing the records of the University of Kentucky Livestock Diseases Diagnostic Center. The distribution of dates of abortion was clustered during a brief period of time, presumably from a simultaneous environmental exposure. The most common pathological findings were microscopic pulmonary lesions consisting of squamous epithelial cells present in alveoli with or without concurrent infiltration of inflammatory cells (neutrophil...
Jones SL, Davis J, Rowlingson K.To determine whether ultrasonography would be useful in the diagnosis of right dorsal colitis in horses. Methods: Retrospective study. Methods: 5 horses with right dorsal colitis and 15 healthy adult horses. Methods: Mural thickness and appearance of the right dorsal colon were determined from ultrasonographic images obtained at right intercostal spaces 10, 11, 12, 13, and 14. Results: The right dorsal colon could be imaged most consistently at the right 11th, 12th, and 13th intercostal spaces, below the margin of the lung and axial to the liver. Mural thickness measured from ultrasonographic ...
Vanderwall DK, Woods GL.To determine the effect on fertility of large-volume uterine lavage with lactated Ringer's solution (LRS) performed immediately prior to insemination in mares. Methods: Prospective randomized controlled study. Methods: 20 mares. Methods: Control mares (n = 10) were inseminated with 1 billion (estimated before cooling) progressively motile spermatozoa that had been cooled in a passive cooling unit for 24 hours. Mares (n = 10) in the treatment group were inseminated with 1 billion progressively motile spermatozoa (cooled as described for control mares) immediately after uterine lavage with 4 L o...
Lohmann KL, Vandenplas M, Barton MH, Moore JN.Endotoxemia is associated with the principal causes of death in adult horses and equine neonates and, therefore, veterinary researchers are expending efforts to identify new therapeutic interventions that might be beneficial in these animals. Endotoxin antagonists inhibit interaction of endotoxin with cellular receptors and may be beneficial in the treatment of endotoxemia and sepsis. Diphosphoryl lipid A from Rhodobacter sphaeroides (RsDPLA) is a potent antagonist of enteric LPS in human cells, but is an agonist in hamster cells. In this study, the effect of lipopolysaccharide from R. sphaero...
Mair TS, Sherlock CE, Fews D, Harley R, Pearson GR.Histological evidence of fibrosis affecting the outer layer of the large intestinal tunica muscularis was identified in five of 32 horses affected by colic. In three cases, foci of pale eosinophilia and vacuolation of myocytes were observed. These findings are suggestive of a degenerative and fibrotic abnormality in the outer layer of the tunica muscularis of the large intestinal smooth muscle of some horses with colic.
Chan CC, Munroe GA.Chronic septic tenosynovitis with concurrent, associated focal osteomyelitis of the lateral proximal sesamoid bone was diagnosed in a seven-year-old thoroughbred gelding. Surgical management of this case consisted of open annular ligament desmotomy and curettage of the affected sesamoid. Following lavage of the digital sheath the incisional wound was closed but a 2 cm gap was left distally to allow for postoperative open drainage. The distal limb was bandaged and the horse treated with antibiotics and non-steroidal anti-inflammatories. Sepsis resolved and the horse made a gradual return to ful...
Raizner NT, Gedon NKY, Zablotski Y, Kania SA, Kühnle HF, Kühnle C, Mueller RS.Equine pastern dermatitis (EPD) is a common multifactorial clinical syndrome in horses. Treatment can be difficult; pathogenesis and triggering factors cannot always be determined. Objective: To assess risk factors for developing EPD in a large group of horses kept under the same conditions and to analyse whether or not a spot-on containing essential fatty acids and antimicrobial agents is able to prevent the development of EPD or accelerate the healing process. Methods: Each year 50 young, privately owned, warmblood horses were prospectively included. Methods: All horses were examined weekly ...
Risberg AI, Webb CB, Cooley AJ, Peek SF, Darien BJ.A pregnant quarterhorse mare became acutely lame as a result of severe swelling of its right hind leg, thought to have been caused by a fracture or a muscle tear. Diagnostic procedures ruled out a traumatic musculoskeletal cause and a physical examination revealed chronic pastern dermatitis ('scratches'/'grease heel'). Histopathological evaluation of biopsy samples from the right hind leg was consistent with a leucocytoclastic vasculitis, and culture yielded Staphylococcus intermedius. The treatment and infectious causes of pastern dermatitis are discussed.
Youngquist RS, Blanchard TL, Lapin D, Klein W.Four groups of five pony mares each were used to determine if the intrauterine infusion of EDTA-Tris solution caused adverse effects on the endometrium. The uteri of mares were infused with either saline or EDTA-Tris solution or biopsied or sham-biopsied without infusion. Acute endometritis developed in one (20%) to three (60%) mares in each group during the seven days following treatment, but there were no differences (P > 0.05) in the incidence of endometritis among the groups. Endometrial fibrosis was not evident in biopsies taken on days 14, 30 and 60 following infusion of saline or EDT...
McCoy AM, Secor EJ, Roady PJ, Gray SM, Klein J, Gutierrez-Nibeyro SD.Plantar osteochondral fragments (POF) are common but their effect on joint health of young Standardbreds in race training is largely unknown. Objective: Evaluate the inflammatory effects of POF in metatarsophalangeal joints of young Standardbreds as a step towards developing evidence-based recommendations for surgical removal. Methods: Cohort study. Methods: Forty-nine Standardbred horses (age 11-33 months) presented for surgical removal of POF from 56 metatarsophalangeal joints. Synovial tissue collected at arthroscopy was subjected to histopathology. IL-1β, TNF-α, and PGE-2 were measured ...
Pycock JF, Allen WE, Porter DJ, Boyd EH.Two independent assay systems were used to study the effect of three antibacterial preparations on in vitro morphology and chemotaxis of equine neutrophils. Incubation of neutrophils with high (200 micrograms/ml) and medium (20 micrograms/ml) concentrations of neomycin impaired their response to standard chemoattractants. Trimethoprim/sulfadoxine (0.4/2.0 micrograms/ml-40/200 micrograms/ml) and benzylpenicillin (0.25-25 micrograms/ml) had no effect. Neutrophils collected from geldings 2 and 24 h after neomycin (5 mg/kg) administration had impaired responses to standard chemoattractants. Benzyl...
Frankeny RL.Five horses with unilateral epidermal inclusion cysts located in the nasal diverticula were sedated and treated with intralesional injection of neutral-buffered 10% formalin (volume range, 2 to 4.5 mL). After aspiration of the cyst, formalin was injected intralesionally until leakage of fluid around the needle was observed. After several weeks, desiccation of the cyst was evident; it was excised 2 weeks after treatment in 3 horses, digitally removed by the owner of 1 horse, and never removed in 1 horse, because the owner declined further treatment after resolution of the original swelling of t...
Luethy D.Treatment of equine laminitis continues to be a challenge despite recent advancements in knowledge of the pathophysiology of laminitis. With more evidence supporting its use, distal limb hypothermia or cryotherapy has become a standard of care for both prevention of laminitis and treatment of the early stages of acute laminitis. Recent studies have demonstrated that cryotherapy reduces the severity of sepsis-related laminitis and hyperinsulinemic laminitis in experimental models and reduces the incidence of laminitis in clinical colitis cases. This article reviews the recent literature support...
Rebhun WC, Mirro EJ, Georgi ME, Kern TJ.Habronemic blepharoconjunctivitis was characterized clinically by raised yellow gritty plaques in the palpebral and bulbar conjunctivae. Lid granulomas and blepharitis were observed in some cases. On histologic examination, mast cells, eosinophils, and collagenolysis was found in most sections, but if only one section was examined an erroneous diagnosis of mastocytosis could have been made. Treatment consisted of larvicidal mixtures for lid lesions and organophosphate ophthalmic drops along with corticosteroids for the conjunctivitis. If the cornea was damaged by the gritty conjunctival plaque...
Cho DY, Hubbard RM, McCoy DJ, Stewart TB.A well-circumscribed proliferative mass was protruding from the body of the mandible of a 4-year-old Appaloosa gelding. The mass was uniformly firm and was ulcerated on the dorsal surface. The horse was euthanatized due to extensive involvement of the jaw and difficulty in eating. Microscopically, the mass consisted of numerous discrete microgranulomas separated by bands of abundant fibrous connective tissue containing lymphocytes, plasma cells, and histiocytic macrophages. Numerous rhabditiform nematodes were in the microgranulomas as well as in the surrounding connective tissue. The nematode...
Carelle MS, Galuppi R, Ragaini L, Tampieri MP.The authors report, for the first time in Italy, a case of dermatitis of "hypopodes" origin in a horse. The hypopodes are a particular nymphal stage of mites of the suborder Astigmata. The "hypopus" is non-feeding, lacks a mouth and has a ventral suctorial plate with suckers and conoids for attaching itself to insects as a mode of dispersal. Some of these larval stages can enter into the hair follicles and into the subcutaneous layers causing lesions similar to mange. There are few reports of dermatitis in horses specifically associated with the presence of hypopodes and these have been attrib...