Pharmacology in horses involves the study and application of drugs and medications to diagnose, treat, and prevent diseases and conditions in equine species. This field encompasses the understanding of pharmacokinetics and pharmacodynamics specific to horses, including how drugs are absorbed, distributed, metabolized, and excreted by the equine body. Commonly studied pharmacological agents in horses include non-steroidal anti-inflammatory drugs (NSAIDs), antibiotics, sedatives, and anthelmintics. Research in equine pharmacology focuses on determining appropriate dosages, understanding drug interactions, and minimizing adverse effects. This page compiles peer-reviewed research studies and scholarly articles that investigate the efficacy, safety, and regulatory aspects of pharmacological interventions in equine veterinary practice.
McIlwraith CW, Lattermann C.The use of intra-articular corticosteroids for traumatic arthritis and osteoarthritis (OA) is common in the horse. The beneficial and deleterious effects of the principal corticosteroids used betamethasone esters (Celestone [Soluspan], methylprednisolone acetate [Depo Medrol], and triamcinolone acetonide [TA] [Vetalog or Kenalog]) have been defined for the horse. While TA has both disease-modifying as well as symptom-modifying effects, methyl prednisolone acetate has deleterious effects on the articular cartilage. Studies in traumatically injured joints show the same rationale (suppression of ...
Gozalo-Marcilla M, de Oliveira AR, Fonseca MW, Possebon FS, Pelligand L, Taylor PM, Luna SPL.Standing surgery avoids the risks of general anaesthesia in horses. Objective: To assess sedation, antinociception and gastrointestinal motility in standing horses after a detomidine loading dose and 2-h constant rate intravenous (i.v.) infusion, with or without methadone. Methods: Blinded, randomised, crossover with seven healthy adult cross-bred horses, three geldings and four females (404 ± 22 kg). Methods: Five i.v. treatments were administered to all horses with 1-week washout period: saline (SAL), detomidine low (2.5 μg/kg bwt + 6.25 μg/kg bwt/h) (DL) and high doses (5 μg/kg ...
Pratt S, Cunneen A, Perkins N, Farry T, Kidd L, McEwen M, Rainger J, Truchetti G, Goodwin W.There is no information directly comparing midazolam with guaifenesin when used in combination with an alpha-2 agonist and ketamine to maintain anaesthesia via i.v. infusion in horses. Objective: To compare ketamine-medetomidine-guaifenesin with ketamine-medetomidine-midazolam for total intravenous anaesthesia (TIVA) in young horses anaesthetised for computerised tomography. Methods: Prospective, randomised, blinded, crossover trial. Methods: Fourteen weanlings received medetomidine 7 μg/kg bwt i.v. and anaesthesia was induced with ketamine 2.2 mg/kg bwt i.v. On two separate occasions hors...
Schoonover MJ, Whitfield CT, Young JM, Sippel KM, Payton ME.OBJECTIVE To determine effects for 2 IV regional limb perfusion (IVRLP) protocols involving tiludronate on lameness of horses with navicular syndrome. ANIMALS 15 horses with bilateral forelimb navicular syndrome. PROCEDURES Shoeing and anti-inflammatory injection into the distal interphalangeal joint (DIPJ) of both forelimbs (day 0) were performed on all horses. On day 14, horses received 1 of 3 IVRLPs consisting of 0.1 mg of tiludronate/kg (low-dose tiludronate [LDT]; n = 5), 0.2 mg of tiludronate/kg (high-dose tiludronate [HDT]; 5), or saline (0.9% NaCl) solution (placebo; 5); treatments wer...
Charvet CL, Guégnard F, Courtot E, Cortet J, Neveu C.The control of parasitic nematodes impacting animal health relies on the use of broad spectrum anthelmintics. However, intensive use of these drugs has led to the selection of resistant parasites in livestock industry. In that respect, there is currently an urgent need for novel compounds able to control resistant parasites. Nicotine has also historically been used as a de-wormer but was removed from the market when modern anthelmintics became available. The pharmacological target of nicotine has been identified in nematodes as acetylcholine-gated ion channels. Nicotinic-sensitive acetylcholin...
Hwang HJ, Han JW, Jeon H, Han JW.Lectin is an important protein in medical and pharmacological applications. Impurities in lectin derived from natural sources and the generation of inactive proteins by recombinant technology are major obstacles for the use of lectins. Expressing recombinant lectin with a tandem repeat structure can potentially overcome these problems, but few studies have systematically examined this possibility. This was investigated in the present study using three distinct forms of recombinant mannose-binding lectin from (BPL2)-i.e., the monomer (rD1BPL2), as well as the dimer (rD2BPL2), and tetramer (rD4...
Hébert L, Guitton E, Madeline A, Géraud T, Zientara S, Laugier C, Hans A, Büscher P, Cauchard J, Petry S.The aim of this study was to evaluate the ability of melarsomine hydrochloride (Cymelarsan) to cure horses suffering from a nervous form of dourine, a sexually-transmitted disease caused by Trypanosoma equiperdum. The recently described experimental model for assessing drug efficacy against horse trypanosomosis allowed us to obtain eight horses (Welsh pony mares) infected by T. equiperdum with parasites in their cerebrospinal fluid. The Cymelarsan treatment evaluated consisted of the daily administration of 0.5 mg/kg of Cymelarsan over 7 days. Two control horses remained untreated, three hor...
Tokushige H, Okano A, Arima D, Ito H, Kambayashi Y, Minamijima Y, Ohta M.The aim of the present study was to evaluate clinical efficacy of constant rate infusions (CRIs) of medetomidine-propofol combined with sevoflurane anesthesia in Thoroughbred racehorses undergoing arthroscopic surgery. Thirty horses were sedated intravenously (IV) with medetomidine (6.0 μg/kg) and midazolam (0.02 mg/kg) and induced IV with ketamine (1.0 mg/kg) and propofol (1.0 mg/kg). These horses were randomly allocated to three groups and maintained with sevoflurane and CRI of either medetomidine (3.0 μg/kg/h) (Group M; n = 10); or medetomidine (3.0 μg/kg/h) and propofol (3.0 ...
Wellcome open researchNovember 5, 2018
Volume 3 58 doi: 10.12688/wellcomeopenres.14587.2
Loan HT, Yen LM, Kestelyn E, Hao NV, Thanh TT, Dung NTP, Turner HC, Geskus RB, Wolbers M, Tan LV, Van Doorn HR, Day NP, Wyncoll D, Hien TT....Despite long-standing availability of an effective vaccine, tetanus remains a significant problem in many countries. Outcome depends on access to mechanical ventilation and intensive care facilities and in settings where these are limited, mortality remains high. Administration of tetanus antitoxin by the intramuscular route is recommended treatment for tetanus, but as the tetanus toxin acts within the central nervous system, it has been suggested that intrathecal administration of antitoxin may be beneficial. Previous studies have indicated benefit, but with the exception of one small trial n...
Elad D.This review focuses on aspects of antimycotic therapy specific to veterinary medicine. In the first part, drug availability, limited mostly by economic consideration but also by clinical applicability and specific adverse effects, is described for polyenes, 5 fluorocytosine, azoles, echinocandins and terbinafine. In the second part, current knowledge and experience in the treatment of selected fungal infections are overviewed. These mycoses include disseminated mold infections in small animals (dogs and cats) and avian species, upper respiratory tract infections of small animals (sino-nasal an...
Martin EM, Schirmer JM, Jones SL, Davis JL.Misoprostol is an E prostanoid (EP) 2, 3 and 4 receptor agonist that is anecdotally used to treat and prevent NSAID-induced GI injury in horses. Misoprostol elicits anti-inflammatory effects in vivo in men and rodents, and inhibits TNFα production in equine leucocytes in vitro. Objective: Define the pharmacokinetic parameters of oral misoprostol in horses, and determine the inhibitory effect of oral misoprostol administration on equine leucocyte TNFα production in an ex vivo inflammation model. Methods: Pharmacokinetic study, ex vivo experimental study. Methods: Six healthy adult horses ...
Morales N, Henriquez C, Sarmiento J, Uberti B, Moran G.Neutrophils are terminally differentiated innate effector cells at the first line of host defense. Neutrophil migration within tissues is complex and involves several steps, during which these cells must be able to interpret a variety of chemical and physical signals. Exacerbated neutrophil activity can be harmful to surrounding tissues; this is important in a range of diseases, including equine asthma. Tamoxifen (TX) is a non-steroidal estrogen receptor modulator with effects on cell growth and survival. Previous studies showed that TX treatment in horses with induced acute pulmonary inflamma...
Olave C, Alvarez P, Uberti B, Morales N, Henriquez C, Folch H, Sarmiento J, Moran G.Neutrophils play an important role in the exacerbation and maintenance of severe equine asthma; persistent neutrophil activity and delayed apoptosis can be harmful to surrounding tissues. Tamoxifen (TX) is a nonsteroidal estrogen receptor modulator with immunomodulatory effects and induces early apoptosis of blood and bronchoalveolar lavage neutrophils from horses with acute lung inflammation. This study investigated if the in vitro effects of tamoxifen are produced by its action on nuclear (α and β) and membrane (GPR30) estrogen receptors in healthy equine neutrophils. Results showed that T...
Hanson RR.Suitable use of prophylactic antimicrobial drugs for wounds depends on the accurate selection of appropriate antibiotics, dosing regimen, and duration of use. Regional intravenous delivery and intraosseous infusion of antibiotics are pivotal to a successful outcome for deep-rooted infections, inadequately perfused tissue, and infected wounds containing biofilm. Antibiotic-impregnated polymethylmethacrylate beads are predominantly helpful for wounds that have a poor blood supply and for those containing surgical implants that must remain in place.
Hébert L, Guitton E, Madeline A, Géraud T, Carnicer D, Lakhdar L, Pitel PH, Coste M, Laloy E, Giraudet A, Zientara S, Büscher P, Laugier C, Hans A....Trypanosoma equiperdum, the causative agent of dourine, may affect the central nervous system, leading to neurological signs in infected horses. This location protects the parasite from most (if not all) existing chemotherapies. In this context, the OIE terrestrial code considers dourine as a non-treatable disease and imposes a stamping-out policy for affected animals before a country may achieve its dourine-free status. The use of practices as drastic as euthanasia remains controversial, but the lack of a suitable tool for studying a treatment's efficacy against dourine hampers the developmen...
Alvarez AV, Schumacher J, DeGraves FJ.OBJECTIVE To determine whether addition of epinephrine to a lidocaine solution would prolong and potentiate the efficacy of a palmar digital nerve block (PDNB) in horses. ANIMALS 6 adult horses with naturally occurring forefoot lameness. PROCEDURES Initially, a PDNB with a 2% lidocaine solution was performed on the affected foot of each horse. Three days later, the PDNB was repeated with a 1% lidocaine solution or a 1% lidocaine solution containing epinephrine (dilution, 1:200,000). After another 3-day washout period, the PDNB was repeated with the treatment opposite that administered for the ...
Lavoie JP, Leclere M, Rodrigues N, Lemos KR, Bourzac C, Lefebvre-Lavoie J, Beauchamp G, Albrecht B.Corticosteroids are the most potent drugs for the control of severe equine asthma, but adverse effects limit their chronic systemic administration. Inhaled medications allow for drug delivery directly into the airways, reducing the harmful effects of these drugs. Objective: To evaluate the efficacy of inhaled budesonide specifically formulated for the equine use and administered by a novel inhalation device in horses with severe asthma. Methods: Experimental studies in horses with naturally occurring asthma with cross-over, randomised, blinded experimental designs. Methods: In Study 1, budeson...
Okada CTC, Andrade VP, Freitas-Dell'Aqua CP, Nichi M, Fernandes CB, Papa FO, Alvarenga MA.Embryo mobility occurs as a result of prostaglandin production by the embryo and endometrium, promoting uterine smooth muscle contractions, which propels the embryonic vesicle through the lumen. Non-steroidal anti-inflammatory drugs (NSAIDs), as flunixin meglumine, are routinely used in equine medicine and can alter the conceptus mobility if applied in early pregnancy, which may impair maternal recognition of pregnancy. The objective of this study was to evaluate and compare the effect of flunixin meglumine (FM; 1.1 mg/kg IV), firocoxib (FIRO; 0.2 mg/kg PO), and meloxicam (ML; 0.6 mg/kg,...
Axmann S, Hummel K, Nöbauer K, Razzazi-Fazeli E, Zitterl-Eglseer K.Devil's claw is used for the treatment of inflammatory symptoms and degenerative disorders in horses since many years, but without the substantive pharmacokinetic data. The pharmacokinetic parameters of harpagoside, the main active constituent of Harpagophytum procumbens DC ex Meisn., were evaluated in equine plasma after administration of Harpagophytum extract FB 8858 in an open, single-dose, two-treatment, two-period, randomized cross-over design. Six horses received a single dose of Harpagophytum extract, corresponding to 5 mg/kg BM harpagoside, and after 7 days washout period, 10 mg/kg ...
Mitchell A, Wright G, Sampson SN, Martin M, Cummings K, Gaddy D, Watts AE.Clodronate is prescribed to performance horses with lameness. Despite its clinical popularity, little research has been done to understand the effects of clodronate in the horse. Objective: Our objective was to determine if a single treatment with clodronate at the clinically approved dose altered bone remodelling, bone cell recruitment or lameness in the horse. Methods: Twelve university-owned equestrian team competition horses with a history of forelimb lameness due to navicular syndrome were randomised to receive either 1.4 mg/kg clodronate (CLOD n = 6) or an equivalent volume of LRS (CONT;...
Easton-Jones CA, Madigan JE, Barnum S, Maxwell LK, Taylor SD, Arnesen T, Pusterla N.Equine herpesvirus-5 is commonly isolated from the lungs of horses with EMPF, suggesting an etiological link. Valacyclovir is used empirically to treat EMPF; however, no data is available concerning its impact on EHV-5 viral kinetics. Objective: To determine the effect of oral administration of valacyclovir on EHV-5 viral load measured by qPCR in blood, nasal secretions (NS) and BALF in horses with EMPF. Methods: Six horses diagnosed with EMPF. Methods: A prospective clinical trial was performed. Horses received 10 days of PO administered valacyclovir (loading dose 30 mg/kg, maintenance dose 2...
Meier A, Reiche D, de Laat M, Pollitt C, Walsh D, Sillence M.There are no registered veterinary drugs for treating insulin dysregulation and preventing insulin-associated laminitis in horses. Velagliflozin is a sodium-glucose co-transport 2 inhibitor that reduces renal glucose reabsorption, promotes glucosuria, and consequently, decreases blood glucose and insulin concentrations. This study aimed to determine if velagliflozin reduced hyperinsulinemia and prevented laminitis in insulin-dysregulated ponies fed a challenge diet high in non-structural carbohydrates (NSC). An oral glucose test (1 g dextrose/kg BW) was used to screen 75 ponies for insulin dys...
Ross KA, Kolb DS, Macedo A, Anderson M, Klein C.This study tested the hypothesis that the presence of prostaglandin E2 in seminal plasma would aid in the transport of phenolsulfonphthalein (PSP) across the uterotubal junction. Five mares in estrus were inseminated during estrus with PSP dissolved in phosphate-buffered saline and during the subsequent estrus with PSP added to a standard insemination dose. Serum and urine samples were obtained at hours 0, 1, 2, and 3 following treatment and examined for the presence of PSP. Phenolsulfonphthalein could not be detected in any of the urine samples collected from mares following either treatment....
Levionnois OL, Graubner C, Spadavecchia C.To investigate the pharmacological profile and side effects of buprenorphine administered as a sustained-release formulation in horses. Methods: Pilot trial. Methods: A total of four experimental horses, aged 18-27 years and weighing 508-578 kg. Methods: Buprenorphine (0.1 mg kg) was mixed as a freshly prepared sterile solution with a sustained-release drug carrier. It was administered by the subcutaneous (n = 2) or intramuscular (n = 2) route. During the experiment, the horses were closely monitored, equipped with a step counter and blood samples were collected for quantification of bup...
Donahue SW.August Krogh was a comparative physiologist who used frogs, guinea pigs, cats, dogs, and horses in his research that led to his Nobel Prize on muscle physiology. His idea to choose the most relevant organism to study problems in physiology has become known as Krogh's principle. Indeed, many important discoveries in physiology have been made using naturally occurring animal models. However, the majority of research today utilizes laboratory mouse and rat models to study problems in physiology. This paper discusses how Krogh's principle can be invoked in musculoskeletal research as a complementa...
Tokushige H, Kushiro A, Okano A, Maeda T, Ito H, Wakuno A, Nagata SI, Ohta M.Alfaxalone has a number of pharmacological properties which are desirable for constant rate infusion (CRI). Previously, the co-administration of alfaxalone and medetomidine is shown to be suitable for short-term anesthesia in horses. However, the use of alfaxalone-medetomidine CRI with inhalational anesthesia under surgical procedures have not been investigated in clinical cases. The aim of the present study was to evaluate the clinical efficacy of alfaxalone-medetomidine CRI in sevoflurane-anesthetized Thoroughbred racehorses undergoing arthroscopic surgery. Sevoflurane requirement, cardiovas...
Trahan RA, Byron CR, Dahlgren LA, Pleasant RS, Werre SR.OBJECTIVE To compare the effects of 3 equimolar concentrations of methylprednisolone acetate (MPA), triamcinolone acetonide (TA), and isoflupredone acetate (IPA) on equine articular tissue cocultures in an inflammatory environment. SAMPLE Synovial and osteochondral explants from the femoropatellar joints of 6 equine cadavers (age, 2 to 11 years) without evidence of musculoskeletal disease. PROCEDURES From each cadaver, synovial and osteochondral explants were harvested from 1 femoropatellar joint to create cocultures. Cocultures were incubated for 96 hours with (positive control) or without (n...
Hernández-Avilés C, Serafini R, Love CC, Teague SR, LaCaze KA, Lawhon SD, Wu J, Blanchard TL, Varner DD.Two experiments were conducted to evaluate the effects of antibiotic-containing extender of on sperm quality and control of bacterial growth. In Experiment 1, ejaculates were diluted in extender containing no antibiotics, potassium penicillin G-amikacin disulfate (PEN-AMIK), ticarcillin disodium-potassium clavulanate (TICAR-CLAV), piperacillin sodium/tazobactam sodium (PIP-TAZ), or meropenem (MERO). In freshly extended semen, only slight differences were detected among some antibiotic treatments for total sperm motility, curvilinear velocity, and viable acrosome-intact sperm (P < 0.05)....
Whitfield-Cargile CM, Chamoun-Emanuelli AM, Cohen ND, Richardson LM, Ajami NJ, Dockery HJ.Non-steroidal anti-inflammatory drugs (NSAIDs) are routinely used in both veterinary and human medicine. Gastrointestinal injury is a frequent adverse event associated with NSAID use and evidence suggests that NSAIDs induce gastrointestinal microbial imbalance (i.e., dysbiosis) in both animals and people. It is unknown, however, whether cyclooxygenase (COX)-2-selective NSAIDs induce dysbiosis, or if this phenomenon occurs in horses administered any class of NSAIDs. Therefore, our objectives were to determine whether the composition and diversity of the fecal microbiota of adult horses were alt...
Carstensen H, Hesselkilde EZ, Fenner M, Loft-Andersen AV, Flethøj M, Kanters JK, Sattler SM, Tfelt-Hansen J, Pehrson S, Jespersen T, Buhl R.Pharmacological treatment of atrial fibrillation (AF) in horses can be challenging because of low efficacy and adverse effects. Flecainide has been tested with variable efficacy. Objective: To test whether the efficacy of flecainide is dependent on AF duration. Methods: Nine Standardbred mares. Methods: Factorial study design. All horses were instrumented with a pacemaker and assigned to a control or an AF group. On day 0, all horses were in sinus rhythm and received 2 mg/kg flecainide IV. Atrial fibrillation subsequently was induced in the AF group by pacemaker stimulation. On days 3, 9, 27, ...
Wearn JG, Suagee JK, Crisman MV, Corl BA, Hulver MW, Hodgson DR, Geor RJ, McCutcheon LJ.Equine metabolic syndrome (EMS) is a condition of obese horses characterized by insulin resistance, systemic inflammation, and an increased risk of laminitis. The pathogenesis of EMS is thought, in part, to be due to inflammatory proteins produced by adipose tissue. Reducing inflammation may decrease the incidence of laminitis in horses with EMS. Pioglitazone hydrochloride, a thiazolidinedione, has efficacy to reduce obesity associated inflammation in humans. Eight normal, adult, horses were administered 1mg/kg pioglitazone for 14 days, and eight horses served as controls. Physical examination...
Hinrichs K, Spensley MS, McDonough PL.To investigate a model for equine endometritis, 12 mares with normal reproductive tracts were divided into 2 groups. All mares received progesterone in oil, 250 mg im, daily. At 5 days after initiation of progesterone administration, the uteri were inoculated with 10(6) colony forming units of Pseudomonas aeruginosa. The day of inoculation was designated Day 0. On Day 6, endometrial swab samples yielded P. aeruginosa in 5 mares; samples from the other 7 mares yielded heavy growth of Escherichia coli, Streptococcus zooepidemicus, Klebsiella pneumoniae, Enterobacter spp., Citrobacter diversus, S...
Macpherson ML, Giguère S, Pozor MA, Burden CA, Berghaus LJ, Berghaus RD, Varner JC, Hayna JT, Benson SM, Randell SA, Lyle SK, Kelleman AA, Hart KA....Minimal evidence exists supporting therapeutic selections for equine placentitis. The goal of this study was to characterize the anti-inflammatory effects of firocoxib when administered to mares with placentitis. Mares (gestation D270-300) were assigned to: INFECT (n = 6; placentitis, no treatment), FIRO (n = 6; placentitis, firocoxib, 0.1 mg/kg, PO, daily), and NORM (n = 6; no infection/treatment). Allantoic fluid (8 hours, 24 hours, birth) and amniotic fluid (birth) were collected from mares after infection. Concentrations of IL-1β, IL-6, TNF-α, IL-10, PGF , and PGE in fluids were...
Kwan C, Bell R, Koenig T, Bischofberger A, Horadagoda N, Perkins NR, Jeffcott LB, Dart AJ.Evaluate synovial fluid cytology, total protein concentration and viscosity after intra-articular administration of combined pentosan polysulfate and glucosamine in horses. Methods: Ten adult Standardbred horses had each carpal joint (n = 20) randomly assigned to one of two treatments: control (5 mL saline) or treated (pentosan polysulfate and glucosamine). All horses received an intra-articular injection every 7 days for 3 weeks and synovial fluid samples were collected on days 1 (baseline), 2, 3, 7, 8, 9, 14, 15, 16 and 21. Synovial fluid variables measured included total protein concentrati...
Decloedt A, Verheyen T, Sys S, De Clercq D, van Loon G.Tissue Doppler imaging (TDI) and 2-dimensional speckle tracking (2DST) can quantify left ventricular (LV) function in horses. Objective: To evaluate LV function by TDI and 2DST in horses with myocardial dysfunction after accidental ionophore intoxication. Methods: Sixty-seven horses exposed to lasalocid in feed. Methods: Prospective study. Horses were included in the study if a full cardiac examination was performed, consisting of determination of cardiac troponin I (cTnI), electrocardiography, and echocardiography. By TDI, radial systolic velocity and strain were measured. By 2DST, circumfere...
Eggleston RB, Mueller PO.As with many aspects of clinical medicine, there is yet to be a single or definitive cure for postoperative adhesion formation. Current methods of prevention target risk factors predisposing horses to adhesion formation. Systemic pharmacologic therapies, such as antimicrobials, nonsteroidal anti-inflammatory drugs, Salmonella antiserum, and hyperimmune plasma, help to reduce abdominal inflammation and minimize the effects of endotoxemia. Intra-abdominal or systemic heparin aids in enhancing peritoneal fibrinolysis. Prokinetic therapy promotes early postoperative return of intestinal motility, ...
Messenger KM, Davis JL, LaFevers DH, Barlow BM, Posner LP.To describe the pharmacokinetics and adverse effects of intravenous (IV) and sublingual (SL) buprenorphine in horses, and to determine the effect of sampling site on plasma concentrations after SL administration. Methods: Randomized crossover experiment; prospective study. Methods: Eleven healthy adult horses between 6 and 20 years of age and weighing 487-592 kg. Methods: In the first phase; buprenorphine was administered as a single IV or SL dose (0.006 mg kg(-1)) and pharmacokinetic parameters were determined for each route of administration using a noncompartmental model. In the second phas...
Breuhaus BA.Regulatory control of the thyroid gland in horses is similar to other species. Clinical signs of hypothyroidism in adult horses are minimal. Several drugs and physiologic and pathophysiological states can cause circulating thyroid hormone concentrations to be low without actual pathology of the thyroid gland. Thus, nonthyroidal factors must be ruled out before a diagnosis of hypothyroidism can be made. Thyroid hormone supplementation seems to be well tolerated, even in euthyroid horses. Neonatal foals have very high circulating thyroid hormone concentrations, and deficiencies result in signif...
Hernández-Avilés C, Serafini R, Love CC, Teague SR, LaCaze KA, Lawhon SD, Wu J, Blanchard TL, Varner DD.Two experiments were conducted to evaluate the effects of antibiotic-containing extender of on sperm quality and control of bacterial growth. In Experiment 1, ejaculates were diluted in extender containing no antibiotics, potassium penicillin G-amikacin disulfate (PEN-AMIK), ticarcillin disodium-potassium clavulanate (TICAR-CLAV), piperacillin sodium/tazobactam sodium (PIP-TAZ), or meropenem (MERO). In freshly extended semen, only slight differences were detected among some antibiotic treatments for total sperm motility, curvilinear velocity, and viable acrosome-intact sperm (P < 0.05)....
Lowden S, Gray S, Dawson K.The horse biting louse (Werneckiella equi) is a common global equine ectoparasite. To our knowledge, benzoyl(phenyl)urea insecticides (triflumuron, diflubenzuron) commonly used as sheep lousicides, have not been evaluated for efficacy against W. equi. The aim of this study was to determine louse control efficacy, general wellness and dermal safety following triflumuron application as a backline pour-on to horses. Two efficacy trials using 25 adult naturally infested lousy horses, and a dermal safety trial using 10 adult louse-free horses were conducted over a 14-month period. Lousy animals wer...
Baker A, Plummer CE, Szabo NJ, Barrie KP, Brooks DE.To determine the concentration of doxycycline in preocular tear film following oral administration in horses as a possible therapeutic modality for infectious and keratomalacic equine keratitis. Methods: Eight broodmares without ocular disease from a Thoroughbred breeding facility were included in this study. Each mare received 20 mg/kg of doxycycline by mouth once daily in the morning for five consecutive days. Tears were collected 1 h after doxycycline administration starting on day one of administration and continuing for 10 consecutive days. Doxycycline levels in the tears were measured us...
Traub-Dargatz JL, Bertone JJ, Gould DH, Wrigley RH, Weiser MG, Forney SD.Effects of a therapeutic dose of flunixin meglumine on gastric mucosa of horse foals were determined by endoscopy, double-contrast radiography, and gross and histologic examinations. Foals were administered 1.1 mg of flunixin meglumine/kg of body weight, PO/day for 30 days in an encapsulated form that was divided into 2 doses/day (group 1; n = 3) or by IM injection once a day (group 2; n = 7). Three control foals (group 3; n = 3) were administered capsules (n = 1) containing dextrose powder or IM injections (n = 2) of vehicle solution without flunixin meglumine. All 3 groups-1 foals given flun...
Esteller-Vico A, Ball BA, Troedsson MHT, Squires EL.Equine pregnancy is characterized by very high circulating concentrations of estrogens. The physiological roles of estrogens during equine gestation are largely unknown, although some studies suggest a role in the regulation of uterine artery hemodynamics and a relationship between low circulating estrogen concentrations and late pregnancy loss. The objectives of this experiment were to evaluate the effects of estrogen suppression on uterine artery hemodynamics and on pregnancy outcome. Estrogen synthesis was suppressed using letrozole, a potent aromatase inhibitor. Twelve pregnant mares were ...
Morton AJ, Campbell NB, Gayle JM, Redding WR, Blikslager AT.Synovitis in horses is frequently treated by administration of non-steroidal anti-inflammatory drugs (NSAIDs), which inhibit cyclooxygenase isoforms (COX-1 and COX-2). Constitutively expressed COX-1 is involved in physiologic functions such as maintenance of gastric mucosal integrity, whereas COX-2 is up-regulated at sites of inflammation. Thus, COX-2 inhibitors reduce inflammation with reduced gastrointestinal side effects as compared to non-selective COX inhibitors. The objective of the present study was to compare the anti-inflammatory effects of the preferential COX-2 inhibitor etodolac wi...
Nikolakopoulos E, Watson ED.Bacteria were infused into the uteri of 5 estrous mares resistant to persistent mating-induced endometritis, first during a control cycle, and then during treatment with clenbuterol, a beta 2 agonist. Uterine cellular response was evaluated 48 h later by transrectal ultrasonography, followed by uterine lavage. During clenbuterol treatment all mares accumulated intrauterine fluid, whereas in the control cycle none of the mares retained fluid. There was no significant difference between the 2 cycles in the cloudiness of the lavage fluid, number of cells per milliliter, percentage of neutrophils ...
Pollitt CC, Pass MA, Pollitt S.A method for culturing explants of lamellar hoof was developed to investigate the process of lamellar separation that occurs in laminitis. Explants, consisting of hoof wall, dermal and epidermal lamellae and the adjacent sub-lamellar connective tissue remained intact when cultured in tissue culture medium for 2 days. However, when cultured in the presence of the matrix metalloproteinase (MMP) activator aminophenylmercuric acetate (APMA), the lamellae separated when tension was applied by pulling the hoof wall in an opposite direction to the connective tissue. The separation occurred between th...
Schaefer EC, Stewart AA, Durgam SS, Byron CR, Stewart MC.OBJECTIVE-To determine whether the effects of a high-molecular-weight sodium hyaluronate alone or in combination with triamcinolone acetonide can mitigate chondrocyte glyocosaminoglycan (GAG) catabolism caused by interleukin (IL)-1 administration. SAMPLE POPULATION-Chondrocytes collected from metacarpophalangeal joints of 10 horses euthanized for reasons unrelated to joint disease. PROCEDURES-Chondrocyte pellets were treated with medium (negative control), medium containing IL-1 only (positive control), or medium containing IL-1 with hyaluronic acid only (0.5 or 2.0 mg/mL), triamcinolone aceto...
Fenton JI, Chlebek-Brown KA, Peters TL, Caron JP, Orth MW.To determine whether glucosamine-3-sulfate, glucose-3-sulfate (control) and N-acetyl glucosamine inhibit experimentally induced degradation of equine articular cartilage explants similar to glucosamine HCl. Methods: Articular cartilage was obtained from the antebrachio-carpal and middle joints of horses (2-8 years old) killed for reasons unrelated to lameness. Cartilage discs were harvested from the weight-bearing region of the articular surface and cultured. Media were exchanged daily and the recovered media stored at 4 degrees C. On days 1 and 2 lipopolysaccharide (LPS, 10 microg/ml) was add...
Casoni D, Spadavecchia C, Wampfler B, Thormann W, Levionnois OL.Intravenous anaesthetic drugs are the primary means for producing general anaesthesia in equine practice. The ideal drug for intravenous anaesthesia has high reliability and pharmacokinetic properties indicating short elimination and lack of accumulation when administered for prolonged periods. Induction of general anaesthesia with racemic ketamine preceded by profound sedation has already an established place in the equine field anaesthesia. Due to potential advantages over racemic ketamine, S-ketamine has been employed in horses to induce general anaesthesia, but its optimal dose remains und...
Brightman AH, Manning JP, Benson GJ, Musselman EE.Schirmer I tear tests were conducted on 14 horses. The test was performed before and after IV administration of xylazine hydrochloride, during maintenance anesthesia with halothane in oxygen, and 3 hours after discontinuation of anesthesia. Xylazine hydrochloride did not decrease tear production from the mean base-line value of 23.94 +/- 5.23 mm/min after its IV administration. Tear production was decreased to mean values of 15.57 +/- 4.29 mm/min at 30 minutes and 13.84 +/- 4.25 mm/min at 60 minutes during the maintenance of halothane anesthesia. Three hours after anesthesia was discontinued, ...
Barton MH, Moore JN, Norton N.To evaluate the effect of pentoxifylline on response of horses to in vivo challenge exposure with endotoxin. Methods: 24 healthy horses in 3 treatment groups: pentoxifylline, endotoxin, or endotoxin and pentoxifylline. Methods: Horses of the pentoxifylline group were given a bolus of pentoxifylline (7.5 mg/kg of body weight, i.v.), followed by an infusion (3 mg/kg/h) over 3 hours, and those of the endotoxin group were given 20 ng of endotoxin/kg i.v. over 30 minutes. Those of the combination group were given both of the aforementioned compounds; pentoxifylline was administered immediately afte...
Davis JL, Salmon JH, Papich MG.To determine the pharmacokinetics of itraconazole after IV or oral administration of a solution or capsules to horses and to examine disposition of itraconazole in the interstitial fluid (ISF), aqueous humor, and polymorphonuclear leukocytes after oral administration of the solution. Methods: 6 healthy horses. Methods: Horses were administered itraconazole solution (5 mg/kg) by nasogastric tube, and samples of plasma, ISF, aqueous humor, and leukocytes were obtained. Horses were then administered itraconazole capsules (5 mg/kg), and plasma was obtained. Three horses were administered itraconaz...
Abbott JB, Mellor DJ, Barrett EJ, Proudman CJ, Love S.The serological changes in two groups of horses known to be harbouring Anoplocephala perfoliata were studied; 12 were treated with 1.5 mg/kg praziquantel and 200 microg/kg ivermectin, and 14 were treated with 200 microg/kg ivermectin. Serological and faecal analyses were carried out on each animal at intervals for 758 days. The titres of antibodies specific for A perfoliata decreased from the day of treatment to day 28 in both groups, and continued to decrease in the group treated with praziquantel and ivermectin, with the first significant decrease from the other group at day 121. From day 15...
Rols MP, Tamzali Y, Teissié J.Sarcoids are skin spontaneous tumours detected in horses. It can be cured by chemotherapy by using cisplatin. A multisequence treatment must be performed. Problems are present due to the poor diffusion of the hydrophilic product in the tumours. Electropulsation is known to drastically enhance the effect of antitumoral drugs in vivo. Taking into account the very successful results of the group in Ljubljana (Slovenia), we started a research clinical program where electropulsation was applied after local cisplatin injection. The size of sarcoids is large (several centimeters). A specially designe...
Burrows GE, Morton RJ, Fales WH.Gram-negative bacterial isolates (635) obtained from routine submissions to the Oklahoma Animal Disease Diagnostic Laboratory during 1983-1987 were tested for antimicrobial susceptibility. Minimal inhibitory concentrations (MICs) were determined for the following antimicrobials using commercially prepared microdilution assay materials: ampicillin, cephalothin, chloramphenicol, erythromycin, gentamicin, kanamycin, oxytetracycline, penicillin G, spectinomycin, sulfachlorpyridazine, sulfadimethoxine, and tylosin. Results for isolates from cattle, dogs, horses, and pigs are presented. In only a fe...
Skarda RT, Muir WW.To compare effects of electroacupuncture and butorphanol on hemodynamic and respiratory variables and rectal analgesia in mares after controlled rectal distention. Methods: 8 healthy mares. Methods: Each horse received saline (0.9% NaCl) solution (0.01 mL/kg, IV; control treatment), butorphanol tartrate (0.1 mg/kg, IV), or 2 hours of electroacupuncture (EA) at acupoints Bladder 21, 25, and 27 on both sides of the vertebral column, Bai hui, and Stomach 36 (right side only). Order of treatments in each mare was randomized. At least 7 days elapsed between treatments. A balloon was inserted in the...
Léguillette R, Désévaux C, Lavoie JP.To determine the effects of pentoxifylline (PTX) administration on lung function and results of cytologic examination of bronchoalveolar lavage fluid in horses affected by recurrent airway obstruction (RAO). Methods: 10 RAO-affected horses. Methods: 6 horses were orally administered PTX (16 g) mixed with corn syrup, and 4 horses were administered corn syrup alone, twice daily for 14 days. Pulmonary function was evaluated before administration (day 0) and on days 8 and 15. Bronchoalveolar lavage (BAL) was performed on days 0 and 15. Reversibility of airway obstruction was assessed by measuring ...
Westermann CM, Laan TT, van Nieuwstadt RA, Bull S, Fink-Gremmels J.To determine whether treatment of horses with antitussive agents before bronchoalveolar lavage (BAL) reduces the frequency and intensity of the cough reflex during BAL. Methods: 8 healthy horses. Methods: Standard BAL was performed on each horse weekly for 6 weeks. Detomidine was used as a general sedative, and various antitussive agents were evaluated for their suitability to suppress undesirable coughing. Treatments administered prior to BAL consisted of saline (0.9% NaCl) solution (control treatment), codeine, butorphanol tartrate, glycopyrrolate, lidocaine hydrochloride (final concentratio...
Steiss JE, Naylor JM.A three year old Quarter Horse stallion was presented with a one year history of episodes of generalized muscle tremors and stiffness, and spasm of the muscles of facial expression, lasting 10-15 minutes. Between attacks, the horse was either normal or had a localized muscle tremor in the flank region. Episodes appeared unrelated to exercise. The major abnormal findings included 1) a rise in plasma potassium from a resting level of 4.4 to 7.9 mmol/L during an attack and 2) electromyographic findings of generalized increased insertion activity and myotonic discharges. The horse was treated with...
Kramer CM, Tsang AS, Koenig T, Jeffcott LB, Dart CM, Dart AJ.To survey veterinary practitioners in Australia on how they administer pentosan polysulfate (PPS) to horses and their perceptions of the efficacy of PPS for: the prevention and treatment of osteoarthritis (OA), the treatment of OA when PPS is combined with other drugs, and the efficacy of PPS compared with other disease-modifying osteoarthritic drugs. Methods: Practitioners were contacted by email, which contained a link to an online survey. Results: A total of 76 responses (34.5%) to the survey were received. Respondents most commonly used PPS as prophylactic therapy prior to competition (80....
