Dexamethasone is a synthetic glucocorticoid commonly used in equine medicine for its anti-inflammatory and immunosuppressive properties. It is employed in the management of various inflammatory and allergic conditions in horses, such as arthritis, respiratory diseases, and skin disorders. Dexamethasone works by inhibiting the release of inflammatory mediators and suppressing immune responses. Its administration can be through oral, intravenous, or intramuscular routes, depending on the specific clinical situation. This page compiles peer-reviewed research studies and scholarly articles that investigate the pharmacokinetics, therapeutic applications, and potential side effects of dexamethasone in equine health.
Gentry LR, Thompson DL, Gentry GT, Davis KA, Godke RA.Mares that had previously been fed to attain body condition scores (BCS) of 7.5 to 8.5 (high) or 3.0 to 3.5 (low) were used to determine the interaction of BCS with the responses to 1) administration of equine somatotropin (eST) daily for 14 d beginning January 20 followed by administration of GnRH analog (GnRHa) daily for 21 d and 2) 4-d treatment with dexamethasone later in the spring when mares in low BCS had begun to ovulate. The majority of mares with high BCS continued to cycle throughout the winter, as evidenced by larger ovaries (P < 0.002), more corpora lutea (P < 0.05), greater proge...
Cartmill JA, Thompson DL, Gentry LR, Pruett HE, Johnson CA.In experiment 1, nine light horse geldings (three 3 x 3 Latin squares) received dexamethasone (DEX; 125 microg/kg BW, i.m.), glucose (0.2 g/kg BW, i.v.), or nothing (control) once per day for 4 days. DEX increased (P < 0.001) glucose, insulin, and leptin concentrations and resulted in a delayed increase (P < 0.001) in IGF-I concentrations. In experiment 2, mares were similarly treated with DEX (n = 6) or vehicle (n = 6). DEX again increased (P < 0.01) glucose, insulin, and leptin concentrations; the delayed elevation in IGF-I concentrations occurred on day 10, 12, and 19, relative to ...
Abraham G, Brodde OE, Ungemach FR.In 12 healthy horses, the effects of the beta2-agonist clenbuterol and the glucocorticoid dexamethasone on the lymphocyte beta2-adrenoceptor density and affinity (determined by (-)-[125I]-iodocyanopindolol binding) as well as its responsiveness (assessed by lymphocyte cyclic AMP [cAMP] responses to 10 micromol/l (-)-isoprenaline) were studied. Clenbuterol treatment, 2 x 0.8 microg/kg/day i.v. for 12 days, decreased significantly ICYP binding sites by approximately 30-40%; concomitantly, lymphocyte cAMP response to (-)-isoprenaline was reduced. After withdrawal of clenbuterol, beta2-adrenocepto...
Tung JT, Venta PJ, Eberhart SW, Yuzbasiyan-Gurkan V, Alexander L, Caron JP.To determine the effects of recombinant equine interleukin -1beta (reIL-1beta) and 4 anti-inflammatory compounds on the expression and activity of cyclooxygenase (COX)-2 in cultured equine chondrocytes. Methods: Articular cartilage from 9 young adult horses. Methods: Reverse transcriptase-polymerase chain reaction methods were used to amplify a portion of equine COX-2 to prepare a cDNA probe. Northern blot analysis was used to quantify the expression of COX-2 in first-passage cultures of equine articular chondrocytes propagated in media containing dexamethasone (DEX), phenylbutazone (PBZ), pol...
Manohar M, Goetz TE, Hassan AS, Depuy T, Humphrey S.In view of the suggestion that pulmonary injury-induced release of histamine and/or other chemical mediators from airway inflammatory and mast cells contribute to the exercise-induced arterial hypoxemia (EIAH) in human athletes, we examined the effects of pretreatment with a potent anti-inflammatory agent, dexamethasone, on EIAH and desaturation of hemoglobin in horses. Seven healthy, sound, exercise-trained Thoroughbreds were studied in the control (no medications) experiments, followed in 7 days by intravenous dexamethasone (0.11 mg.kg(-1).day(-1) for 3 consecutive days) studies. Blood-gas m...
Craigo JK, Leroux C, Howe L, Steckbeck JD, Cook SJ, Issel CJ, Montelaro RC.The genetic variation of equine infectious anaemia virus (EIAV) clearly affects the antigenic properties of the viral envelope; however, effects on immunogenicity remain undefined, although widely assumed. Here, the immunogenicity is reported of a novel, neutralization-resistant, pony-isolate envelope EIAV(PV564DeltaPND) that contains a 14-residue deletion in the designated principal neutralizing domain (PND) of the gp90 protein. Two ponies inoculated with a chimeric virus, EIAV(DeltaPND), containing the EIAV(PV564DeltaPND) envelope in a reference provirus strain, remained asymptomatic through...
Lavoie JP, Léguillette R, Pasloske K, Charette L, Sawyer N, Guay D, Murphy T, Hickey GJ.To evaluate whether the leukotriene (LT) D4 receptor antagonist L-708,738 is therapeutically beneficial in treating horses with recurrent airway obstruction (heaves). Methods: 12 adult horses with heaves and healthy lung lobes from 20 slaughtered horses. Methods: Lung lobes were used for smooth muscle tension and radioligand binding studies. Horses with heaves were given a placebo for 14 days and administered L-708,738 (n = 6; 2.5 mg/kg PO, q 12 h) or dexamethasone (6; 0.04 mg/kg, IV, q 24 h) from days 14 to 28. Pulmonary function was measured weekly for 36 days, and bronchoalveolar cells were...
Tung JT, Venta PJ, Caron JP.To determine the effects of recombinant equine IL-1beta and a number of antiinflammatory compounds on the expression and activity of inducible nitric oxide synthase (iNOS) in cultured equine chondrocytes. Methods: RT-PCR methods were used to amplify a portion of the equine iNOS message to prepare an RNA probe. Northern blot analysis was used to quantify the expression of iNOS in first passage cultures of equine articular chondrocytes propagated in the presence or absence of recombinant equine interleukin-1beta (reIL-1beta), dexamethasone (DEX), polysulfated glycosaminoglycan (PSGAG), hyalurona...
Robinson NE, Jackson C, Jefcoat A, Berney C, Peroni D, Derksen FJ.This study used a cross-over design to compare the efficacy of 3 corticosteroids for the relief of airway obstruction and inflammation in 9 heaves-affected horses. The severity of airway obstruction and inflammation was quantified by measurement of lung function and by bronchoalveolar lavage fluid (BALF) cytology, respectively. Airway obstruction was induced by stabling the horses and they remained stabled during the 10 day treatment period. Lung function was measured before treatment (baseline), at Days 3, 7, and 10 of treatment, and after 30 days at pasture. BALF cytology was investigated at...
Reeves HJ, Lees R, McGowan CM.A high basal plasma or serum insulin concentration is commonly accepted as an indicator of Cushing's disease in horses. The results of the combined dexamethasone suppression test and thyrotropin-releasing hormone stimulation test were compared with the basal insulin concentrations and insulin response tests of eight hyperinsulinaemic and insulin-resistant ponies with clinical histories of chronic or recurrent laminitis that were suspected of having Cushing's disease. Seven of the eight ponies had normal responses to the combined test indicating that basal insulin concentrations are not a speci...
Cutler TJ, MacKay RJ, Ginn PE, Gillis K, Tanhauser SM, LeRay EV, Dame JB, Greiner EC.Equine protozoal myeloencephalitis is a common neurologic disease of horses in the Americas usually caused by Sarcocystis neurona. To date, the disease has not been induced in horses using characterized sporocysts from Didelphis virginiana, the definitive host. S. neurona sporocysts from 15 naturally infected opossums were fed to horses seronegative for antibodies against S. neurona. Eight horses were given 5x10(5) sporocysts daily for 7 days. Horses were examined for abnormal clinical signs, and blood and cerebrospinal fluid were harvested at intervals for 90 days after the first day of chall...
Slack J, Risdahl JM, Valberg SJ, Murphy MJ, Schram BR, Lunn DP.To determine the effects of dexamethasone on development of IgG subclass responses following vaccination of healthy horses. Methods: 11 mature Thoroughbreds. Methods: Horses received 2 IM injections at 2-week intervals of a vaccine containing inactivated infectious bovine rhinotracheitis, bovine viral diarrhea, and parainfluenza-3 viral antigens and were then randomly assigned to 2 groups. Six horses received dexamethasone (0.2 mg/kg of body weight, IM) twice weekly for 8 weeks starting the day of the first vaccination. Five control horses received an equivalent volume of saline (0.9% NaCl) so...
Blackford J, Doherty TJ, Ferslew KE, Panus PC.In human rehabilitation medicine, dexamethasone-phosphate is theoretically iontophoresed to localized subcutaneous tissue where conversion to dexamethasone occurs. This delivery system has recently been introduced into veterinary medicine for the same purpose. However, the pharmacokinetic justification for parenteral delivery of this prodrug remains undocumented. Utilizing iontophoretic methods that are relevant to both human and veterinary clinical practice, the present investigation compared injection and iontophoresis of dexamethasone-phosphate into the equine tibiotarsal joint, also known ...
Grippa E, Santini L, Castellano G, Gatto MT, Leone MG, Saso L.Ethyl acetate extracts of equine serum, containing 0-5 microg/ml of hydrocortisone (HYD), dexamethasone (DEX), oxyphenbutazone (OPB), indomethacin (IND), phenylbutazone (PB) and probenecid as internal standard, were evaporated with nitrogen, resuspended in methanol and analyzed by HPLC, using a C-18 column equilibrated with 51:49 acetonitrile-water, 0.1% trifluoroacetic acid, at 1 ml/min. The eluate was monitored at 254 nm. The selectivity (inter-assay C.V.<4%), sensitivity (limits of quantitation of 0.25 microg/ml for HYD, DEX and IND, 0.5 microg/ml for PB and 1 microg/ml for OPB, despite ...
Feige K, Eser MW, Geissbühler U, Balestra E, Metzler K.Hirsutism was the most often observed symptom in horses with a pituitary gland tumor and was present in all 13 examined horses. Other symptoms were atrophy of muscles (n = 10), hyperhidrosis (n = 8), polyuria/polydipsia (n = 5), bulging or supraorbital fat (n = 3), polyphagia (n = 2), apathy (n = 2) and seizures (n = 2). Laminitis was the most frequently observed concurrent disease (n = 8). Hyperglycaemia (mean, 9.9 +/- 3.71 mmol/l) in 13 horses and glucosuria (median, 55 [range, 2-55] mmol/l) in 7 horses were the most important laboratory results. The dexamethasone suppression test was positi...
Chang YF, Novosol V, McDonough SP, Chang CF, Jacobson RH, Divers T, Quimby FW, Shin S, Lein DH.Seven specific-pathogen-free (SPF) ponies, 1-5 years old, were exposed to Borrelia burgdorferi-infected adult ticks while being treated with dexamethasone over 5 consecutive days. One SPF pony (pony No. 178) was first exposed to laboratory-reared nymphs without B. burgdorferi infection and 3 weeks later was exposed to B. burgdorferi-infected adult ticks with concurrent dexamethasone treatment for 5 consecutive days. Four uninfected ponies treated with dexamethasone, exposed to laboratory-reared ticks without B. burgdorferi infection served as uninfected controls. Clinical signs, bacteriologic ...
Möstl E, Messmann S, Bagu E, Robia C, Palme R.After 14C-labelled cortisol infusion in ponies and pigs, faecal samples were collected. Extraction of 0.5 g faeces with 5 ml 80-90% methanol yielded the highest radioactivity in the supernatant. Most of the metabolites were ether soluble. After high performance liquid chromatography (HPLC), the presence of immunoreactive metabolites was demonstrated by measuring each HPLC fraction using enzyme immunoassays for cortisol, corticosterone and 11-oxoaetiocholanolone. Only the assay for 11-oxoaetiocholanolone revealed peaks with co-eluting radioactivity. For biological validation of the test system,...
Spiess BM, Nyikos S, Stummer E, Sahin A, Naegeli H.To determine concentrations of dexamethasone in serum and urine of horses treated repeatedly with a topically administered ophthalmic dexamethasone preparation. Methods: 4 clinically normal horses (2 mares, 2 geldings). Methods: 0.1% dexamethasone ophthalmic ointment was administered to the left eye of each horse every 5 to 9 hours for 8 consecutive days, yielding an estimated cumulative dexamethasone dose of 6.4 microg/kg of body weight. Serum and urine samples were obtained before the first dexamethasone treatment, on days 4 and 8 of treatment, and 24, 48, and 96 hours after cessation of tre...
Clegg PD, Jones MD, Carter SD.Loss of articular cartilage, which is the most important pathological lesion occurring in osteoarthritis, has been shown to be enzymatically mediated. The matrix metalloproteinases (MMPs) are a group of enzymes which have been implicated in this degradation of articular cartilage matrix. The use of pharmacological agents to inhibit this catabolic process in the joint is a potential route for therapeutic intervention. The gelatinase MMPs, MMPs-2 and 9, were purified by affinity chromatography from equine cell cultures. The ability of phenylbutazone, flunixin, betamethasone, dexamethasone, methy...
Rush BR, Flaminio MJ, Matson CJ, Hakala JE, Shuman W.To determine cytologic changes in horses with recurrent airway obstruction (heaves) after administration of aerosolized beclomethasone dipropionate and dexamethasone parenterally. Methods: 6 horses with inducible and reversible heaves. Methods: Episodes of heaves were induced by exposure to moldy hay and straw for 7 days. Horses were assigned to treatment groups (aerosolized beclomethasone, parenterally administered dexamethasone, aerosolized propellant), and pulmonary inflammation was evaluated by serial cytologic examination of bronchoalveolar lavage (BAL) fluid samples obtained on days 0, 7...
Rush BR, Raub ES, Rhoads WS, Flaminio MJ, Matson CJ, Hakala JE, Gillespie JR.To determine changes in clinical signs of disease and response to pulmonary function testing in horses with recurrent airway obstruction (heaves) after aerosol and parenteral administration of beclomethasone dipropionate and dexamethasone, respectively. Methods: 6 horses with inducible and reversible heaves. Methods: Episodes of heaves were induced by exposure (challenge) to moldy hay and straw for 7 days. Horses were assigned to treatment groups (aerosolized beclomethasone dipropionate, parenterally administered dexamethasone, aerosolized propellant [control]), and respiratory frequency and s...
Rush BR, Worster AA, Flaminio MJ, Matson CJ, Hakala JE.To determine alteration in adrenocortical function in horses with recurrent airway obstruction (heaves) after aerosol and parenteral administration of beclomethasone dipropionate and dexamethasone, respectively. Methods: 6 horses with inducible and reversible heaves. Methods: Episodes of heaves were induced by exposure to moldy hay and straw for 7 days (natural challenge). Horses then underwent treatment (aerosolized beclomethasone, parenterally administered dexamethasone, and aerosolized propellant) for 7 days. Horses remained in the mold-contaminated environment for 7 days after discontinuat...
Piercy RJ, Swardson CJ, Hinchcliff KW.A Standardbred gelding and a colt were examined because of poor performance and anemia. Each horse had been given recombinant human erythropoietin (rhEPO; 4,000 IU) at least twice within the preceding 2 to 4 months. The horses had an Het of 16 and 24%, serum iron concentrations of 210 and 304 micrograms/dl (reference range, 73 to 140 micrograms/dl), total iron binding capacities of 239 and 321 micrograms/dl (reference range, 266 to 364 micrograms/dl), values for the percentage saturation of transferrin by iron of 87.9 and 94% (reference range, 20 to 52%), and serum ferritin concentrations of 2...
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.
Ribeiro Neto LM, Spinosa HS, Salvadori MC.Dexamethasone is a corticosteroid drug widely used in racehorses because of its anti-inflammatory effect. It is, therefore, frequently detected in antidoping tests. A method for the antidoping control of dexamethasone in equine urine using screening by ELISA and confirmation by immunoaffinity chromatography combined with reversed-phase high-performance liquid chromatography-diode array detection (HPLC-DAD) is described. The ELISA test is frequently used in antidoping tests for its sensitivity, relative speed, and low cost. The test showed linearity in the range of 4-500 ng/mL of urine, and the...
Eiler H, Oliver JW, Andrews FM, Fecteau KA, Green EM, McCracken M.To evaluate results of a combined dexamethasone suppression/thyrotropin-releasing hormone (TRH) stimulation test in horses suspected clinically to have a pars intermedia pituitary adenoma (PIPA). Methods: Case-control study. Methods: 7 healthy adult horses and 5 horses suspected to have a PIPA. Methods: A baseline blood sample was collected, and dexamethasone (40 micrograms/kg [18 micrograms/lb] of body weight, IV) was administered; a second blood sample was collected 3 hours later, and TRH (1.1 mg, IV) was administered; serial blood samples were collected 15, 30, 45, 60, and 90 minutes and 21...
Frean SP, Bryant CE, Fröling IL, Elliott J, Lees P.Recent research in several species has suggested nitric oxide (NO) as a mediator of articular cartilage damage and an inhibitor of cartilage matrix neosynthesis. This study investigated NO production by cultured equine articular chondrocytes in response to 2 arthritogenic molecules, namely lipopolysaccharide (LPS) and interleukin-1 beta (IL-1 beta), and compared NO production by cultured equine synoviocytes stimulated with LPS. Synoviocytes exhibited a low basal level of NO synthesis (measured as nitrite, a NO metabolite) that was neither significantly increased nor decreased by exposure to LP...
Klaus AM, Hapke HJ.This review compromises data about endogenous cortisol and its physiological variations in horses. The influence of synthetic glucocorticoids on the endogenous cortisol concentrations is discussed as well. The second part of the review summarizes detection times of therapeutically used glucocorticoids (dexamethasone, betamethasone, triamcinolone, prednisone, prednisolone, methylprednisolone and hydrocortisone) in the horse and their implication for doping control.
Stanley SM, Wilhelmi BS, Rodgers JP.A comparison of the sensitive analytical methods of radioimmunoassay (RIA) and immunoaffinity chromatography (IAC) combined with gas chromatography-negative ion chemical ionisation mass spectrometry for the specific and reliable screening of dexamethasone in equine post-race urine is presented. Results from analyses of samples collected from a mare during 144 hours post administration of 26 mg of dexamethasone sodium phosphate are described.
McNeill-Wiest DR, Thompson DL, Wiest JJ.Twelve long-term ovariectomized (OVX) pony mares were used to determine the effects of dexamethasone (DEX) or progesterone (PR) on concentrations of follicle stimulating hormone (FSH) and luteinizing hormone (LH) in daily blood samples and after administration of gonadotropin releasing hormone (GnRH). All mares were subsequently administered dihydrotestosterone (DHT) to determine if DEX or PR treatment altered the FSH or LH response to this androgen. Daily blood sampling was started on day 1. After a pretreatment injection of GnRH on day 5, four mares were administered DEX at 125 micrograms/kg...
Jeffcott LB, Rossdale PD.The efficacy and safety of oxytocin, dexamethasone and prostaglandin, used alone or in combination as inducing agents, are discussed. It is contended that insufficient evidence exists to support the routine application of any of these methods in practice. Oxytocin has been the most widely used and it is claimed by some to be free from side effects. However, the synthetic prostaglandin analogue, fluprostenol, seems to pose the least risk to the foetus and dexamethasone appears to be either ineffective, or too dangerous to use at all. The main indications for induced foaling are managerial conve...
Asa CS, Ginther OJ.Dexamethasone, a synthetic glucocorticoid, was administered (30 mg/day) from Day 10 after ovulation to assess the involvement of the adrenal glands in the ovulatory cycle. Only 1 of 8 mares treated in this way exhibited behavioural oestrus, compared to 7 of 8 control mares. Mean maximum LH concentration and follicle size were significantly reduced. Ovulation occurred in 1 and possibly in 2 other treated mares, compared to all 8 control mares. The results demonstrated that dexamethasone can interfere with ovulation and associated events in the mare, but the mechanism of action is uncertain.
Slone DE, Purohit RC, Ganjam VK, Lowe JL.Three ponies and 1 horse were bilaterally adrenalectomized (BADX). The initial hypoadrenal episode after BADX was reversed with 20 mg of dexamethasone (DXM) IM (n = 2) or 20 mg of triamcinolone (TMC) IM (n = 2). Nine hypoadrenal crises were reversed with 20 mg of DXM given IM (n = 4) or 20 mg of TMC given IM (n = 5). Sodium and chloride retention and potassium excretion were documented based on changes in serum electrolytes and urinary excretion. Eight intact adult horses were randomly assigned to 2 groups to study the effects of a single IM injection of DXM (0.044 mg/kg of body weight) or TMC...
Rautschka R, Stanek C, Knezevic PF.In seven sound horses histamine plasma levels were evaluated by means of a radioenzymatic method using the enzyme histamine-N-methyltransferase (mean = 4.46 nmol/l, SD = 1.55 nmol/l). Histamine levels of laminitic horses were significantly higher (n = 11; mean = 12.46 nmol/l, SD = 3.24 nmol/l). In three sound horses plasma histamine levels were determined over a two week period following a double administration of 10 mg dexamethasone-21-isonicotinate/100 kg body weight. Histamine levels remained within the range of sound control horses.
Trim CM.Complications following the use of the cuffless large animal endotracheal tube during general anesthesia in 2 horses are reported. One horse developed laryngeal edema during recovery. The edema was treated successfully with dexamethasone, but severe laryngeal trauma was confirmed 24 hours later at necropsy. The second horse had a swollen tongue and had difficulty eating for 3 days after anesthesia. The condition resolved without treatment. this report is a reminder of the potential damage which can occur from endotracheal intubation.
Luo Y, Uboh CE, Soma LR, Guan FY, Rudy JA, Tsang DS.A method for the simultaneous separation, identification, quantification and confirmation of the presence of 21 glucocorticoids (GCC) in equine plasma by liquid chromatography coupled with triple stage quadrupole tandem mass spectrometry (LC/TSQ-MS/MS) is described. Plasma sample augmented with the 21 GCC was extracted with methyl tert-butyl ether (MTBE) and analyzed by positive electrospray ionization. Desoxymetasone or dichlorisone acetate was used as the internal standard (IS). Quantification was performed by IS calibration. For each drug, one major product ion was chosen and used for scree...
Stucki M, Voegel CD, Binz TM, Kraemer T, Lavaud A, Voelter K.Equine sport agencies list steroids as prohibited substances for competing horses. Objective: The objective of this study was to investigate if the controlled substances dexamethasone and prednisolone are detectable in equine serum and urine samples during and after treatment with eye drops and if this can generate a positive doping test. Methods: Prospective cohort study. Methods: The study cohort included 11 horses. One eye of the horses was treated with either dexamethasone (Maxitrol 0.1%, n = 5 eyes) or prednisolone (Pred forte 1%, n = 6 eyes) eye drops 3 times daily for 14 days. Dexa...
Valenzuela OA, Jellyman JK, Allen VL, Holdstock NB, Fowden AL.Synthetic glucocorticoids are used to treat inflammatory conditions in horses. In other pregnant animals, glucocorticoids are given to stimulate fetal maturation with long-term metabolic consequences for the offspring if given preterm. However, their metabolic effects during equine pregnancy remain unknown. Objective: Thus, this study investigated the metabolic effects of dexamethasone administration on pregnant pony mares and their foals after birth. Methods: Experimental study. Methods: A total of 3 doses of dexamethasone (200 μg/kg bwt i.m.) were given to 6 pony mares at 48 h intervals beg...
Feige K, Eser MW, Geissbühler U, Balestra E, Metzler K.Hirsutism was the most often observed symptom in horses with a pituitary gland tumor and was present in all 13 examined horses. Other symptoms were atrophy of muscles (n = 10), hyperhidrosis (n = 8), polyuria/polydipsia (n = 5), bulging or supraorbital fat (n = 3), polyphagia (n = 2), apathy (n = 2) and seizures (n = 2). Laminitis was the most frequently observed concurrent disease (n = 8). Hyperglycaemia (mean, 9.9 +/- 3.71 mmol/l) in 13 horses and glucosuria (median, 55 [range, 2-55] mmol/l) in 7 horses were the most important laboratory results. The dexamethasone suppression test was positi...
Symonds NE, Dart AJ, Keledjian J, Lau ML, Ennis LC, McIver VC, Tsang AS, Biasutti SA, Jeffcott LB.To quantify the time to clear dexamethasone from plasma and urine of horses following a single nebulisation. Methods: Experimental using six Standardbred mares. Methods: Dexamethasone sodium phosphate (0.04 mg/kg) diluted in 0.9% sodium chloride was administered as an aerosol using a Flexineb E2® nebuliser. Blood samples (0, 2, 4, 6, 8, 10, 12, 24, 32, 48, 72 and 96 h) and urine samples (0, 1, 4, 8, 24, 32, 48, 72 and 96 h) were collected for analysis using liquid chromatography mass spectrometry. Results: Maximum plasma concentrations (t ) were reached by the earliest detection point (...
Hatazoe T, Kawaguchi H, Hobo S, Misumi K.Equine pituitary pars intermedia dysfunction (PPID) generally occurs in older horses showing hirsutism, delayed molting, weight loss, polydipsia, polyuria, laminitis, and reproductive disorders (in broodmares), but there have been no reports on stallions. This report presents a case of a 21-year-old Thoroughbred stallion that developed hirsutism and experienced delayed molting. There were no abnormal findings for semen quality or the stallion's sexual desire. The horse was diagnosed with PPID based on dexamethasone suppression test and plasma levels of adrenocorticotropic hormone. It was then ...
Ninu AR, Saxena AC, Sivanarayanan TB, Remya V, Binsila BK, Maiti SK, Zama MM.A nulliparous non-descript mare was presented with a complaint of dystocia. The mare was recumbent and physical examination revealed that the animal was in shock. There was no straining and foetal forelimbs were visible outside the vulva. The foetus was dead as there was no pedal reflex. Vaginal examination revealed anterior presentation with dorso-sacral position and rigid lateral head deviation. Pre-operatively, the mare was given 5 ml Tetanus toxoid and 3 g Ceftriaxone as intramuscular injection, and 5 ml Dexamethasone in 15 L of 5% Dextrose Normal Saline (DNS) as intravenous (i/v) infusion...
Brown KA, Johnson AL, Bender SJ, Nolan TJ, Pfisterer B, Slack J, Willis E, Rule EK.A 5-year-old imported Zangersheide gelding was evaluated for SC swellings over both forelimbs and lameness localized to the distal metacarpus. Ultrasound examination of the SC masses was compatible with verminous granulomas. Linear hyperechoic foci were present within the suspensory ligament branches of both forelimbs, suggestive of ligamentous parasitic infiltrates. A diagnosis of onchocerciasis was confirmed on biopsy of a SC mass. The gelding was treated with ivermectin and a tapering course of PO dexamethasone but was eventually euthanized. Necropsy confirmed the presence of SC eosinophili...
Skrabalak DS, Covey TR, Henion JD.Several important corticosteroids were qualitatively determined in the plasma and urine of horses by micro-liquid chromatography-mass spectrometry (micro-LC-MS). The sensitivity and specificity of micro-LC-MS are demonstrated as is the ability of micro-LC-MS to deal with endogenous interferences. In turn, the relative amount of dexamethasone and its major unconjugated metabolite were determined in equine urine by micro-LC-MS; the conclusions drawn are reported.
Ehrmann C, Hartung S, Hirz M, Fey K.A 15-year-old Warmblood gelding was presented with multiple large, ulcerative, and crusty dermal lesions that had been existing for 4 years. Histopathology of a skin biopsy revealed cleft formation at the dermal-epidermal junction beneath the basal cells and above the basement membrane leading to the diagnosis of bullous pemphigoid. Immunosuppressive therapy with dexamethasone and azathioprine was initiated and after 14 weeks full remission of the ulcers was achieved. Scar tissue formation was evident in the areas of the formerly affected lesions. Following medication tapering over a perio...
Pusterla N, Pratt SM, Magdesian KG, Carlson GP.This paper describes the clinical, laboratory and histological findings in three horses with immune-mediated polysynovitis; they had lost weight, suffered intermittent fever, were lethargic and stiff, and had effusions in several joints. Laboratory abnormalities included anaemia, leucocytosis, hyperfibrinogenaemia and hyperglobulinaemia. The diagnosis was based on the presence of a suppurative, non-septic inflammation in at least two different joints in each of the horses and the presence of immunoglobulins in the synovial membrane of one of them. The horses were treated with a combination of ...
Gehlen H, Bradaric Z.The evaluation of plasma ACTH and the dexamethasone suppression test are considered the methods of choice to evaluate the course of therapy of pituitary pars intermedia dysfunction (PPID). Sampling protocols as well as vacutainers for analysis differ between the laboratories. To evaluate the reproducability of plasma ACTH measurement between four different laboratories (A, B, C, D) in Germany as well as within the laboratories themselves, ten horses with previously diagnosed PPID and four healthy horses were sampled and analyzed. Each laboratory received two differently labeled samples of each...
Bell SA, Drew CP, Wilson WD, Pusterla N.Idiopathic chronic eosinophilic pneumonia of horses is incompletely described. Objective: To describe the physical examination, clinicopathologic, histopathologic, and radiographic features and response to corticosteroid treatment of idiopathic chronic eosinophilic pneumonia of horses. Methods: Seven horses with eosinophilic pneumonia. Methods: Retrospective, descriptive study. Results: Anamnesis, clinical signs, and clinicopathologic and radiologic findings in 7 adult horses with histologically confirmed eosinophilic pneumonia were reviewed. The horses were examined for signs of chronic respi...
Houghton E, Dumasia MC, Wellby JK.Negative ion chemical ionization mass spectra of some corticosteroids have been obtained by direct syringe introduction on to the Finnigan moving belt high-performance liquid chromatography-mass spectrometer interface. Proprietary preparations based upon dexamethasone, betamethasone and prednisolone were administered to horses at therapeutic dose level. Urine samples were extracted, the extracts purified by Sephadex LH-20 chromatography and the presence of the parent steroids in the eluates was confirmed by combined high-performance liquid chromatography negative ion chemical ionization mass s...
Winter JC, Thieme K, Eule JC, Saliu EM, Kershaw O, Gehlen H.Primary photosensitization rarely occurs in horses and can easily be misinterpreted. Descriptions of the disease in horses after ingestion of parsnip are lacking. The aim of this case series was to describe the dermatological and ocular changes due to photosensitization and to raise awareness of parsnip being a possible aetiologic agent. Methods: Nine horses from three different stables in Berlin and Brandenburg, Germany, presented variable degrees of erythema, scaling, crusting and necrosis of unpigmented skin at the head and prepuce. Horses were of different breeds with a median age of 15 ...
Eiler H, Oliver JW, Andrews FM, Fecteau KA, Green EM, McCracken M.To evaluate results of a combined dexamethasone suppression/thyrotropin-releasing hormone (TRH) stimulation test in horses suspected clinically to have a pars intermedia pituitary adenoma (PIPA). Methods: Case-control study. Methods: 7 healthy adult horses and 5 horses suspected to have a PIPA. Methods: A baseline blood sample was collected, and dexamethasone (40 micrograms/kg [18 micrograms/lb] of body weight, IV) was administered; a second blood sample was collected 3 hours later, and TRH (1.1 mg, IV) was administered; serial blood samples were collected 15, 30, 45, 60, and 90 minutes and 21...
Dumasia MC, Houghton E, Moss MS, Chakraborty J, Marks V.The pro-drugs of dexamethasone, a potent glucocorticoid, are frequently used as anti-inflammatory steroids in equine veterinary practice. In the present study the biotransformation and urinary excretion of tritium labelled dexamethasone were investigated in cross-bred castrated male horses after therapeutic doses. Between 40-50% of the administered radioactivity was excreted in the urine within 24 h; a further 10% being excreted over the next 3 days. The urinary radioactivity was largely excreted in the unconjugated steroid fraction. In the first 24 h urine sample, 26-36% of the total dose was...
Brennan KM, Graugnard DE, Spry ML, Brewster-Barnes T, Smith AC, Schaeffer RE, Urschel KL.To determine effects of a microalgae nutritional product on insulin sensitivity in horses. Methods: 8 healthy mature horses. PROCEDURES :Horses (n = 4/group) received a basal diet without (control diet) or with docosahexaenoic acid-rich microalgae meal (150 g/d) for 49 days (day 0 = first day of diet). On day 28, an isoglycemic hyperinsulinemic clamp procedure was performed. Horses then received dexamethasone (0.04 mg/kg/d) for 21 days. On day 49, the clamp procedure was repeated. After a 60-day washout, horses received the alternate diet, and procedures were repeated. Plasma fatty acid, gluco...
Kikuchi M, Nagata SI, Ishige T, Minamijima Y, Hirota KI, Tozaki T, Kakoi H, Kizaki K.Glucocorticoid preparations have anti-inflammatory effects, and are commonly used in the equine clinical setting; however, such treatments can cause a number of side effects. Adrenal insufficiency is an adverse effect induced by the suppression of adrenal function following drug administration. This study aimed to investigate the influence of two glucocorticoid preparations, dexamethasone and hydrocortisone, on adrenocortical function in horses. The usual doses of dexamethasone and hydrocortisone preparations in equine practice were administered intramuscularly to six horses, and peripheral bl...
Lane PJ, Lees P, Fink-Gremmels J.In a crossover study in seven New Forest ponies the actions of dexamethasone, at a dose rate of 0.06 mg kg-1 administered intravenously, were compared with those of a placebo treatment. Dexamethasone exerted expected effects on plasma and inflammatory exudate concentrations of cortisol and on blood glucose concentration and circulating leucocyte numbers, but it failed to affect exudate concentrations of the eicosanoids, prostaglandin E2, thromboxane B2, 6-keto-PGF1 alpha and leukotriene B4. These findings do not support the hypothesis that the anti-inflammatory actions of dexamethasone in the ...
