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.
Furr M, Kennedy T.Ponazuril is used for the treatment of equine protozoal myeloencephalitis (EPM). Coadministration of ponazuril with oil could result in higher serum and cerebrospinal fluid (CSF) concentrations of ponazuril. Objective: Coadministration of corn oil will result in higher serum and CSF concentrations of ponazuril than when ponazuril is administered alone. Methods: Ten resident university-owned adult horses of either sex and >2 years of age. Methods: Cohort study. Ponazuril oral paste (5 mg/kg BW; ponazuril treatment group (PON); n = 5), or ponazuril oral paste (5 mg/kg BW; ponazuril and oil tre...
Mora-Pereira M, Abarca EM, Duran S, Ravis W, McMullen RJ, Fischer BM, Lee YP, Wooldridge AA.Keratomycosis is a relatively common, sight threatening condition in horses, where treatment is often prolonged and costly. Subconjunctival (SCo) injections offer less resistance to drug diffusion than the topical route, resulting in better penetration to the ocular anterior segment. Voriconazole, a second generation triazole antifungal, is effective against common fungal organisms causing keratomycosis. If combined with a thermogel biomaterial, voriconazole can be easily injected in the SCo space to provide sustained drug release. The purpose of this study was to evaluate the drug concentrati...
Zhao J, Marghitu DB, Schumacher J.Tranquilization of horses with acepromazine has been used to suppress erratic head movements and increase the accuracy of a lameness examination. Some equine clinicians believe that tranquilization with acepromazine will make lameness more evident by causing the horse to focus on adjusting its gait to avoid limb pain rather than its surroundings. The aim of this study was to investigate the effect of acepromazine on the Lyapunov exponents of lame horses. Ten lame horses were trotted in a straight line for a minimum of 25 strides. Kinematic data created by head movement were analyzed. Nonlinear...
Alonso JM, Rosa GDS, Santos B, Guerra S, Ribeiro M, Watanabe MJ, Alves A, Rodrigues C, Takahira RK, Hussni CA.Intraperitoneal administration of ceftriaxone maintains therapeutic abdominal concentrations for 24 hours in healthy horses. Therefore, it is a possible treatment for septic peritonitis. The aim of this study was to evaluate the efficacy of ceftriaxone as an adjuvant treatment in horses with septic peritonitis. Methods: Twenty-six horses with clinical signs, sonography and/or laboratory findings of septic peritonitis were included. Peritoneal fluid was collected for microbiological culture and in vitro microbial sensitivity profile assessment. Daily intraperitoneal administration of ceftriax...
Küls N, Trujanovic R, Otero PE, Larenza-Menzies MP.Colic surgery is one of the most painful procedures carried out in horses. Common strategies to alleviate immediate postsurgical abdominal pain include the administration of potent systemic analgesics; however, these may cause unwanted adverse effects such as cardiovascular depression, ileus, and ataxia. The administration of local anesthetics at the incision site in form of an ultrasound-guided subcostal transversus abdominis plane (TAP) block may therefore be preferred to provide adequate analgesia without significant side effects. To date, no technique for a TAP block in horses undergoing m...
Verhaar N, Pfarrer C, Neudeck S, König K, Rohn K, Twele L, Kästner S.Pharmacological preconditioning of dexmedetomidine on small intestinal ischaemia/reperfusion injury has been reported in different animal models including horses. Objective: The objective was to assess if xylazine and lidocaine have a preconditioning effect in an experimental model of equine jejunal ischaemia. Methods: Terminal in vivo experiment. Methods: Ten horses under general anaesthesia were either preconditioned with xylazine (group X; n = 5) or lidocaine (group L; n = 5). A historical untreated control group (group C; n = 5) was used for comparison. An established experimental mo...
Crandall A, Hopster K, Grove A, Levine D.In horses undergoing castration, direct comparison of intratesticular lidocaine vs mepivacaine as analgesic adjuncts has not yet been analysed. Objective: To compare the effects of intratesticular lidocaine and mepivacaine during equine castration using the Henderson drill under total intravenous anesthesia. Methods: Randomised, double-blinded clinical study. Methods: Thirty-four stallions were anaesthetised using xylazine-ketamine and randomly selected to receive 10 mL either lidocaine or mepivacaine injected into each testicle. Both surgeon and anaesthetist were blinded to the selected trea...
Totorikaguena L, Olabarrieta E, Lolicato F, Romero-Aguirregomezcorta J, Smitz J, Agirregoitia N, Agirregoitia E.The cannabinoid (CB) system has been involved in many aspects of reproduction and it is known that the systemic chronic use of exogenous CBs are deleterious to reproductive processes. Even so, it is not known what happens in relation to the physiology of the ovary when CB receptors are absent. The present study investigated the effect of the lack of CB1 and CB2 receptors in mice ovarian morphology, folliculogenesis, oocyte retrieval, and oocyte maturation and evaluated the use of Δ9-tetrahydrocannabinol (THC) on oocyte in vitro maturation (IVM) by comparing classical IVM and two-step IVM by a...
Pritchard A, Nielsen BD, Robison C, Spooner H.Previous research documented that furosemide negatively impacted calcium balance for 3 days but did not determine when calcium balance returned to baseline. This study hypothesized that furosemide's impact on calcium would return to control values before 7 days post-administration. Ten mature geldings were assigned to either control (CON, n = 5) or treatment (FUR, n = 5) for the first of two 8-day total collections in crossover design. Treatment horses received one administration of furosemide (1 mg/kg, IV). A 10% sample of pooled faeces and urine from each day was kept. Calcium concent...
Wang J, Qiu J, Xiao H, Gong X, Sun P, Li J, Zhang S, Cao X.The pharmacokinetic properties of three formulations of vitacoxib were investigated in horses. To describe plasma concentrations and characterize the pharmacokinetics, 6 healthy adult Chinese Mongolian horses were administered a single dose of 0.1 mg/kg bodyweight intravenous (i.v.), oral paste, or oral tablet vitacoxib in a 3-way, randomized, parallel design. Blood samples were collected prior to and at various times up to 72 hr postadministration. Plasma vitacoxib concentrations were quantified using UPLC-MS/MS, and pharmacokinetic parameters were calculated using noncompartmental analysis...
Fatemikia H, Kamyab M, Movahed A, Sadeghi M, Kim E, Behdani M, Mohammadpour Dounighi N, Shahrivar M, Seyedian R.In this study, the neutralizing abilities of the equine and the recently introduced camelid antivenoms on the hemodynamic parameters (inotropism, chronotropism, and arrhythmogenicity) were assessed following envenomation by venom in rats. Methods: At first, the electrophoretic profiles of both products were obtained by using the SDS-PAGE method (12.5%) and stained with Coomassie blue and silver nitrate. Secondly, different doses of the camelid antivenom (10, 50, and 100 µl) were given intravenously in 10 min before venom injection (400 µg/rat). The neutralizing potencies of camelid and equi...
Schoster A, van Spijk JN, Damborg P, Moodley A, Kirchgaessner C, Hartnack S, Schmitt S.Fourth-generation cephalosporins can select for extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae in horses, but it is unknown to what extent this occurs compared to penicillin/gentamicin combination treatment. The objective was to evaluate the effect of different antimicrobial treatments on faecal shedding and diversity of ESBL-producing Escherichia coli (ESBL-EC) in horses. Upon hospital admission, 86 horses in need of antimicrobial treatment or prophylaxis were randomly allocated to receive penicillin and gentamicin (PG) or cefquinome (CEF). Untreated horses were included a...
Kritchevsky JE, Muir GS, Leschke DHZ, Hodgson JK, Hess EK, Bertin FR.In metabolically stable horses, alpha-2-agonists suppress insulin secretion with transient hyperglycemia and rebound hyperinsulinemia. In horses with insulin dysregulation (ID), the effect of alpha-2-agonists has not been investigated; however, both the alpha-2-agonist-induced suppression of insulin secretion and rebound hyperinsulinemia could have clinical relevance. Objective: In horses with ID, alpha-2-agonists will alter insulin and glucose dynamics. Methods: Seven horses with ID and 7 control horses. Methods: In this randomized crossover study, xylazine hydrochloride (1.1 mg/kg) or detomi...
McIver VC, Tsang AS, Symonds NE, Perkins NR, Uquillas E, Dart CM, Jeffcott LB, Dart AJ.Evaluate the effect of topical 1% cannabidiol on second intention wound healing in distal limb wounds of horses. Methods: Experimental. Methods: Six Standardbred horses. Methods: A total of five 2.5 cm × 2.5 cm full thickness skin wounds were created on the dorsomedial aspect of the metacarpi of 6 horses. Wounds were contaminated with faeces on the day of wound creation. Each wound was then assigned to a treatment group; compounded 1% cannabidiol in unique manuka factor (UMF) 5 manuka honey, UMF 5 manuka honey, UMF 20 manuka honey or saline. Each treatment was applied topically daily ...
Gilday R, Richard H, Beauchamp G, Fogarty U, Laverty S.The administration of bisphosphonate medications, which target osteoclastic-bone remodelling, to juvenile and adult racehorses is a matter of debate owing to concerns that these molecules remain bound to the bone-mineralised matrix and may interfere with subsequent bone growth, adaptation to exercise and healing of bone microdamage in equine athletes. Osteoclasts participate in endochondral ossification, subchondral bone remodelling and bone repair. There is a knowledge gap on the role of equine osteoclast biology in the growth and maturation of joint surfaces and this information is important...
Navarrete-Calvo R, Morgaz J, Gómez-Villamandos RJ, Quirós-Carmona S, Domínguez JM, Ruiz-López P, Granados MM.The bispectral index (BIS) has been evaluated as an indicator of central nervous system (CNS) depression in horses during general anaesthesia. The spectral entropy is another electroencephalographic device and it has not been evaluated yet in horses. Objective: To determine if spectral entropy can assess anaesthetic depth during the different phases of anaesthesia, define the value of state and response entropy during surgical plane of anaesthesia and compare them with BIS. Methods: Clinical, prospective, non-blinded observational study. Methods: Thirty-five horses ASA I or II undergoing sched...
Hector RC, Rezende ML, Mama KR, Hess AM.Post-anaesthetic sedation is administered to horses to improve recovery quality from inhalant anaesthesia and reduce the risk of catastrophic injury. A single dose of dexmedetomidine for this purpose has not been evaluated clinically. Objective: To determine whether dexmedetomidine improves recovery quality from sevoflurane anaesthesia compared to a previously studied dose of romifidine. Methods: Prospective, randomised, masked clinical trial. Methods: Ninety-nine, adult, client-owned horses anaesthetised for elective procedures completed the trial. Anaesthetic protocol was standardised. Horse...
Smith MC, Bass L, Damone J, Mama K, Rao S.The ideal field anaesthetic protocol for castration will offer an adequate duration and depth of anaesthesia using a single injection without compromising safety or recovery quality. Objective: The objective of this study was to compare intravenous (IV) xylazine and detomidine as sedatives in combination with midazolam and ketamine for induction of anaesthesia in horses undergoing field castration. Methods: Randomised, blinded, clinical study. Methods: Fifty-seven male Quarter Horses were randomly assigned to receive xylazine (group X) (1.1 mg/kg bwt) or detomidine (group D) (0.03 mg/kg bwt)...
Wetzig M, Venner M, Giguère S.Given the importance of rifampin in treatment protocols for tuberculosis in people, its use in veterinary medicine is under increasing scrutiny in some countries and alternatives might be needed in the near future. Objective: This study was set up to evaluate whether azithromycin combined with doxycycline is effective for the treatment of bronchopneumonia in foals and noninferior to the combination of azithromycin and rifampin. Methods: This is a controlled, randomised and double-blinded clinical trial. Two hundred and forty foals on a farm endemic for infections caused by Rhodococcus equi wer...
Bampidis V, Azimonti G, Bastos ML, Christensen H, Dusemund B, Kouba M, Kos Durjava M, López-Alonso M, López Puente S, Marcon F, Mayo B, Pechová A....Following a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on hexamethylene tetramine (HMTA) for pigs, poultry, bovines, sheep, goats, rabbits and horses. In 2015, the FEEDAP Panel delivered an opinion on the safety and efficacy of HMTA. In that opinion, the Panel noted that the residues of HMTA in the silage amounted to about 5% of the inclusion level of 600 mg HMTA/kg fresh ensiling material. Since the HMTA residues in silage were analysed as formaldehyde, it was not possible to...
MacNicol JL, Murrant C, Pearson W.G's Formula is a novel equine feed additive formulated to promote optimal GI function. The objective of this study was to determine whether the addition of a simulated digest of the composite feed additive G's Formula (FA) would alter the contractile response of gastric smooth muscle to acetylcholine (Ach). Smooth muscle strips from porcine stomachs were excised and attached to an isometric force transducer. An experiment was run to compare tissue contraction between tissue exposed to FA (FA; n = 8, simulated digest of FA was added to the bath) and control tissue (CO; n = 8, no additions m...
Gold JR, Grubb TL, Green S, Cox S, Villarino NF.In humans, gabapentin an analgesic, undergoes non-proportional pharmacokinetics which can alter efficacy. No information exists on the pharmacokinetics of dosages >20 mg/kg, escalating dosages or dose proportionality of gabapentin in horses. Objective: Gabapentin exposure in plasma would not increase proportionally relative to the dose in horses receiving dosages ≥20 mg/kg. To assess the plasma pharmacokinetics of gabapentin after nasogastric administration of gabapentin at dosages of 10 to 160 mg/kg in adult horses. Methods: Nine clinically healthy adult Arabian and Quarter Horses....
Souto MTM, Fantoni DT, Hamaji A, Hamaji M, Vendruscolo CP, Otsuki DA, Pinto ACB, Ambrósio AM.To develop a technique for ultrasound-guided continuous median and ulnar peripheral nerve block in horses. Methods: Anatomical and prospective experimental study. Methods: A total of 16 thoracic limbs from horse cadavers and 18 adult horses. Methods: This study was conducted in three phases. Phase 1: Dissection of median and ulnar nerves in the antebrachial region of two cadaver limbs to identify localizing landmarks. Description of sonoanatomy in 14 cadaver limbs using ultrasound-guided perineural infiltration of a combination of cellulose gel (5 mL), contrast medium (4 mL) and methylene blue...
Karakka Kal AK, Perwad Z, K Karatt T, Nalakath J, Subhahar M.Recently, an increased tendency to use various metals has been observed in the sports competition fields. Many of these metals and their organic complexes reportedly have good pharmacologic, therapeutic and performance-enhancement uses; they are banned or recommended as controlled medications in competitive sports. The objective of this research was to determine the concentration of pharmacologically relevant metals in urine samples collected from racehorses at various sport events, develop a method and assess the concentrations of above metals using inductively coupled plasma mass spectrometr...
Weber LA, Meißner J, Delarocque J, Kalbitz J, Feige K, Kietzmann M, Michaelis A, Paschke R, Michael J, Pratscher B, Cavalleri JV.Equine malignant melanoma (EMM) is a frequently occurring dermoepidermal tumor in grey horses. Currently available therapies are either challenging or inefficient. Betulinic acid (BA), a naturally occurring triterpenoid, is a promising compound for cancer treatment. To evaluate the potential of BA as a topical therapy for EMM, its anticancer effects on primary equine melanoma cells and dermal fibroblasts and its percutaneous permeation through isolated equine skin were assessed in vitro. Results: BA showed antiproliferative and cytotoxic effects on both primary equine melanoma cells and fibrob...
Scholtzek AD, Hanke D, Eichhorn I, Walther B, Lübke-Becker A, van Duijkeren E, Köck R, Schwarz S, Feßler AT.Based on antimicrobial susceptibility testing (AST), correct classifications as susceptible, intermediate or resistant are challenging for some antimicrobial agent-bacterial species combinations. In this study, we investigated 19 equine Staphylococcus aureus isolates for their susceptibility to the combination sulfamethoxazole/trimethoprim (SXT) by using broth microdilution (BMD), agar disk diffusion (DD) and automated test systems. To elucidate the presence of the corresponding genetic resistance properties among the isolates, whole genome sequence analysis was performed and the genomes were ...
Dordas-Perpinyà M, Normandin L, Dhier T, Terris H, Cochard A, Frilley C, Huiban F, Bruyas JF.The aim of this study was to assess the efficacy of different doses of buserelin acetate and another GnRH agonist, triptorelin acetate, in saline solution in a single subcutaneous injection, to induce ovulation of growing pre-ovulatory follicle in mare and compare it with the classical treatment of a single injection of hCG. The study is split into 3 experiments over different breeding seasons in the same stud with a random distribution of treatment. The first one was to compare the injection of 6 mg of buserelin with 1,500 IU of hCG; the second one consisted of comparing different doses of ...
Simões J, Sales Luís JP, Tilley P.Severe equine asthma (SEA) syndrome is a chronic recurrent respiratory disease, common among adult horses. The disease occurs in genetically susceptible individuals after their exposure to organic dust. Thus, environmental management has proved essential in controlling airway challenge and disease exacerbation. This is a demanding process that can only be achieved through the horse owners' cooperation. One year after initial diagnosis of SEA in a group of 39 horses, owner compliance to an environmental management protocol was evaluated. The overall compliance to the protocol was poor and the h...
do Nascimento AD, Marques JCC, Cezar ARR, Batista AM, Kastelic JP, Câmara DR.Although equine blastocysts ≤ 300 µm in diameter can be successfully vitrified, larger equine blastocysts are not good candidates for cryopreservation. As Na, K-ATPase is involved in maintaining blastocyst expansion, perhaps inhibition of this enzyme would be a viable method of reducing blastocyst diameter prior to cryopreservation. Objectives were to evaluate effects of ouabain-induced inhibition of Na, K-ATPase in equine blastocysts. Sixteen mares were ultrasonographically monitored, given deslorelin acetate to induce ovulation, and inseminated. Embryos (D7 and D9) were harvested and Na, ...
Franck T, Kohnen S, Deby-Dupont G, Grulke S, Deby C, Serteyn D.An original method called SIEFED (specific immunological extraction followed by enzymatic detection) was developed for the specific detection of the activity of equine myeloperoxidase (MPO). The method consists of the extraction of MPO from aqueous solutions by immobilized anti-MPO antibodies followed by washing (to eliminate proteins and interfering molecules) and measurement of MPO activity using a detection system containing a fluorogenic substrate, hydrogen peroxide, and nitrite as reaction enhancer. The SIEFED technique was applied to study active MPO in horse biological fluids and the ef...
Kuttler KL, Zaugg JL, Gipson CA.The therapeutic efficacies of imidocarb and parvaquone were tested against Babesia equi of European origin in carrier horses and for induced acute infections in splenectomized ponies. Imidocarb, at a dosage of 4 mg/kg of body weight, given IM at 72-hour intervals 4 times, was ineffective in eliminating B equi-carrier infection in 9 mature geldings. A single IM administration of 4 mg/kg was not therapeutic in acutely infected splenectomized ponies. When given at 3 different dosages and treatment schedules, parvaquone was ineffective in clearing carrier infection. Parvaquone given IM once at a d...
Königová A, Várady M, Corba J.The objective of the study was to compare the in vitro egg hatch test (EHT), larval development test (LDT) and in vivo faecal egg count reduction test (FECR test) for the detection of benzimidazole resistance in equine strongyles. The presence of resistant or susceptible strongyle populations was determined in 25 stud farms using the in vivo FECR test and in vitro EHT. On the basis of the FECR values, resistance to fenbendazole was detected on 15 of the 25 farms (60%). The ED50 value (anthelmintic concentration producing 50% inhibition of hatching) for suspected resistant populations varied fr...
Luthersson N, Bolger C, Fores P, Barfoot C, Nelson S, Parkin T, Harris P.Diet is an accepted risk factor for equine squamous gastric disease (ESGD), but there is little published evidence for the benefit of dietary change (DC). This study evaluated the effect of DC with or without initial omeprazole medication. Twelve pairs of exercising horses with ESGD Grade 2/4 (EM) and 17 pairs with ESGD Grade ≥3/4 (ES), were monitored. Paired horses had similar management, feeding times, workloads, and initially feed or forage. One of each pair was randomly assigned, postgastroscopy (Scope1), to a specified restricted starch ration; the other remained on their original diet....
Bueno AC, Cornick-Seahorn J, Seahorn TL, Hosgood G, Moore RM.To determine the cardiopulmonary and sedative effects of medetomidine hydrochloride in adult horses and to compare those effects with effects of an equipotent dose of xylazine hydrochloride. Methods: 10 healthy adult female horses. Methods: 5 horses were given medetomidine (4 microg/kg of body weight, i.v.), and the other 5 were given xylazine (0.4 mg/kg, i.v.). Heart rate, respiratory rate, arterial blood pressures, pulmonary arterial blood pressures, and cardiac output were recorded, and sedation and ataxia scores were assigned before and every 5 minutes after drug administration for 60 minu...
Donnellan CM, Page PC, Nurton JP, van den Berg JS, Guthrie AJ.Imidocarb, an effective treatment for piroplasmosis, may cause colic and diarrhoea in horses. Atropine and glycopyrrolate are anticholinergics that could reduce the adverse effects of imidocarb. However, atropine and glycopyrrolate inhibit gastrointestinal motility, potentially causing ileus and colic. Objective: To compare glycopyrrolate and atropine in ameliorating the adverse effects of imidocarb dipropionate in horses and to determine the effect of combinations of these drugs on the gastrointestinal tract. Methods: A blinded, randomised, crossover study was performed in 8 healthy horses. E...
Burling K, Seguin MA, Marsh P, Brinkman K, Madigan J, Thurmond M, Moon-Massat P, Mannis M, Murphy CJ.OBJECTIVE-To characterize healing of corneal epithelial defects in horses and to evaluate the ability of epidermal growth factor (EGF) to modulate rate of corneal epithelial healing in horses. Methods: 20 eyes in 12 adult horses. Methods: Corneal epithelial wounds were created by mechanically debriding the limbus. Corneal healing was recorded for 3 treatment groups: 50 microg of EGF/ml (n = 5 eyes), 5 microg of EGF/ml (7), and PBS solution (8). Corneal healing was recorded once daily after instillation of fluorescein stain by use of photography and calculating the area of the wound, using imag...
Frank M, Weckman TJ, Wood T, Woods WE, Tai CL, Chang SL, Ewing A, Blake JW, Tobin T.Hordenine is an alkaloid occurring naturally in grains, sprouting barley, and certain grasses. It is occasionally found in post race urine samples, and therefore we investigated its pharmacological actions in the horse. Hordenine (2.0 mg/kg bodyweight [bwt]) was administered by rapid intravenous (iv) injection to 10 horses. Typically, dosed horses showed a flehmen response and defecated within 60 secs. All horses showed substantial respiratory distress. Respiratory rates increased about 250 per cent and heart rates were approximately double that of resting values. All animals broke out in a sw...
Richardson LM, Whitfield-Cargile CM, Cohen ND, Chamoun-Emanuelli AM, Dockery HJ.To determine whether a cyclooxygenase (COX)-2 selective nonsteroidal anti-inflammatory drug (NSAID) would reduce gastric ulceration and gastrointestinal (GI) inflammation compared with a non-COX selective NSAID. Methods: Randomized block design. Methods: Twenty-five healthy adult horses. Methods: Horses were randomly assigned to receive placebo (n = 5), phenylbutazone (n = 10), or firocoxib (n = 10) administered daily for 10 days. Gastroscopy was performed on days 0 and 10, and both squamous and glandular ulcers were scored according to established scoring criteria. Fecal samples w...
Landa L, Trojan V, Demlova R, Jurica J, Hrib R.In connection with the use of cannabinoids for therapeutic purposes in human medicine, there is increased attention for their use in veterinary medicine, particularly by the owners of companion animals and horses. Therefore, veterinarians are expected to face this interest and have the corresponding knowledge on these substances. Presently, it is not possible to use medical marijuana (in terms of the dried cannabis flowers) for veterinary purposes in many countries, but there is increasing evidence that isolated cannabinoids also have beneficial effects (namely cannabidiol - CBD)...
Secombe CJ, Lester GD, Krockenberger MB.Cryptococcus is the most common fungal respiratory pathogen in Australian horses, manifesting primarily as pulmonary granulomas. Disease severity at presentation is dependent on the athletic use of the horse. The diagnosis and estimation of disease severity are centred around clinical findings, cytological evaluation of respiratory tract secretions, diagnostic imaging, and antigen titre testing. Both the lateral flow assay and the latex cryptococcal antigen titre are used, and important similarities and differences between species are discussed. Cryptococcus gattii occurs with greater frequenc...
Kaukinen H, Aspegrén J, Hyyppä S, Tamm L, Salonen JS.The objective of the study was to determine the absorption, bioavailability and sedative effect of detomidine administered to horses as an oromucosal gel compared to intravenous and intramuscular administration of detomidine injectable solution. The study was open and randomized, with three sequences crossover design. Nine healthy horses were given 40 μg/kg detomidine intravenously, intramuscularly or administered under the tongue with a 7-day wash-out period between treatments. Blood samples were collected before and after drug administration for the measurement of detomidine concentration...
McDonnell SM.Self-mutilation in horses includes biting, stomping and kicking, rubbing, and lunging into objects. Based on the author's clinical experience, three distinct types of self-mutilation are proposed and described. Type I represents normal behavioral response to continuous or intermittent physical discomfort. Type II, seen in stallions and geldings, can be recognized as self-directed intermale aggression. The behavior includes the elements and order of the natural interactive sequence typical of encounters between two stallions, except that the stallion himself is the target of his intermale behav...
Dönselmann Im Sande P, Hopster K, Kästner S.Various opioids are available for use in equine medicine. Studies directly comparing their analgesic effects and side effects are rare. Therefore, the aim of this study was to compare the antinociceptive effect and the duration of analgesia of two different doses of morphine, butorphanol and levomethadone in horses. Methods: Eight adult, healthy horses were used for this randomized, placebo-controlled, blinded cross-over trail. Each horse received placebo (P = 0.9% saline) and morphine (M = 0.1 mg/kg; M = 0.2 mg/kg), butorphanol (B = 0.1 mg/kg; B = 0.2 mg/kg) and levomethadone (L...
Mironneau J, Martin C, Arnaudeau S, Jmari K, Rakotoarisoa L, Sayet I, Mironneau C.Saturable, high-affinity binding sites for [3H]saxitoxin were identified in equine portal vein smooth muscle membranes. These sites had a dissociation constant of 0.29 nM and a maximal binding capacity of 115 fmol.mg-1 of protein. A similar dissociation constant was obtained with cells prepared from rat portal vein. Specific binding of [3H]saxitoxin was completely displaced by unlabelled saxitoxin and tetrodotoxin, with inhibition constants of 0.42 and 2.10 nM, respectively. Tetrodotoxin blocked the fast Na+ current in single cells of rat portal vein in a concentration-dependent manner, with a...
Vivrette S, Cowgill LD, Pascoe J, Suter C, Becker T.Acute renal failure in a 4-day-old foal secondary to oxytetracycline toxicosis was treated by hemodialysis. Oxytetracycline had been administrered as treatment for forelimb flexor tendon contracture. Conservtive treatment with fluids, furosemide, and dopamine partially alleviated serum electrolyte concentration imbalances, but was ineffective in promoting diuresis or decreasing azotemia. Three hemodialysis treatments over 4 days were administered, after which the clinical appearance of the foal improved, and biochemical and electrolyte values returned to within reference ranges. The nephrotoxi...
Read WK.Thirty-five cases of renal medullary crest necrosis morphologically similar to the renal papillary necrosis of analgesic nephropathy as described in man and rats are reported in horses receiving maintenance dosages of phenylbutazone. The primary lesion is a well-demarcated focal medullary necrosis resulting in sequestration of fragments of the renal crest. Renal cortical lesions are considered secondary to the medullary necrosis and consist of segmental pallor as a result of tubular dilatation, filtrate retention, and interstitial edema. Ischemia in concert with phenylbutazone is suggested as ...
Zavoshti FR, Andrews FM.Equine gastric ulcer syndrome (EGUS) is an umbrella term used to describe ulcers in the nonglandular squamous and glandular mucosa, terminal esophagus, and proximal duodenum. Gastric ulcers in the squamous and glandular regions occur more often than esophageal or duodenal ulcers and likely have a different pathogenesis. At present, omeprazole is accepted globally as the best pharmacologic therapy for both regions of the stomach; however, the addition of coating agents and synthetic prostaglandins could add to its effectiveness in treatment of EGUS. Dietary and environmental management are nece...
Andrews FM, Frank N, Sommardahl CS, Buchanan BR, Elliott SB, Allen VA.The study was performed to evaluate the efficacy of omeprazole powder in sterile water, administered intravenously, on gastric juice pH in adult horses with naturally occurring gastric ulcers. Omeprazole (0.5 mg/kg, IV) was administered once daily for 5 days to 6 adult horses with gastric ulcers. Gastric juice was aspirated through the biopsy channel of an endoscope and pH was measured before and 1 hour after administration of omeprazole on day 1, and then before and after administration of omeprazole on day 5. Gastric ulcer scores were recorded on day 1 before administration of omeprazole and...
Cruz FS, Carregaro AB, Machado M, Antonow RR.This study investigated the sedative, cardiopulmonary, and gastrointestinal effects produced by buprenorphine and xylazine given in combination to horses. Six healthy adult horses underwent 4 randomized treatments, with an interval of 1 wk between treatments. A control group was given a saline solution intravenously (IV) and the experimental groups received buprenorphine [10 μg/kg bodyweight (BW)] in combination with 1 of 3 different doses of xylazine: 0.25 mg/kg BW (BX25), 0.50 mg/kg BW (BX50), or 0.75 mg/kg BW (BX75), all of them by IV. Cardiopulmonary parameters were evaluated for 120 min ...
Foreman JH, Constable PD, Waggoner AL, Levy M, Eppley RM, Smith GW, Tumbleson ME, Haschek WM.The objective of this experiment was to characterize a dose-dependent toxic effect of fumonisin B1 (FB1) and to document initial neurologic signs, clinical progression, and terminal cerebrospinal fluid (CSF) changes in horses administered FB1 IV. Seventeen healthy horses were administered 0.00 (n = 4), 0.01 (n = 3), 0.05 (n = 3), 0.10 (n = 3), or 0.20 mg (n = 4) of purified FB1 IV q24h. When neurologic abnormalities observed by a masked observer became severe, atlanto-occipital CSF taps were performed and CSF pressure, cell count, cytology, protein, albumin and glucose concentrations, and crea...
Hoffman A, Kuehn H, Riedelberger K, Kupcinskas R, Miskovic MB.Respiratory inductance plethysmographic (RIP) and pneumotachographic (Pn) flows were compared dynamically in horses with bronchoconstriction. On a breath-by-breath basis, RIP was normalized to inspiratory volume from Pn, and peak [peak of subtracted final exhalation waveform (SFE(max))] and selected area [integral of subtracted final waveform during first 25% of exhaled volume (SFE(int))] differences between RIP and Pn flows during early expiration were measured in three settings: 1) healthy horses (n = 8) undergoing histamine bronchoprovocation; 2) horses with naturally occurring lower airway...
Williams DC, Brosnan RJ, Fletcher DJ, Aleman M, Holliday TA, Tharp B, Kass PH, LeCouteur RA, Steffey EP.The effects of anesthesia on the equine electroencephalogram (EEG) after administration of various drugs for sedation, induction, and maintenance are known, but not that the effect of inhaled anesthetics alone for EEG recording. Objective: To determine the effects of isoflurane and halothane, administered as single agents at multiple levels, on the EEG and quantitative EEG (qEEG) of normal horses. Methods: Six healthy horses. Methods: Prospective study. Digital EEG with video and quantitative EEG (qEEG) were recorded after the administration of one of the 2 anesthetics, isoflurane or halothane...
Ohmura H, Hiraga A, Aida H, Kuwahara M, Tsubone H.To investigate the effects of repeated atropine injection on heart rate (HR) variability in resting Thoroughbred horses, two microg/ kg of atropine as parasympathetic nervous blockade was injected intravenously every 6 min to a total of 8 microg/kg after intravenous administration of 0.2 mg/kg of propranolol as sympathetic nervous blockade. We recorded electrocardiograms and obtained the HR, then evaluated variation in HR from the power spectrum in terms of low frequency (LF, 0.01-0.07 Hz) power and high frequency (HF, 0.07-0.6 Hz) power. Administration of atropine decreased parasympathetic ne...
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, ...
Marcinkowska M, Bucki A, Panek D, Siwek A, Fajkis N, Bednarski M, Zygmunt M, Godyń J, Del Rio Valdivieso A, Kotańska M, Kołaczkowski M....Serotonin 5-HT receptors, butyrylcholinesterase (BuChE) and oxidative stress are related to the pathophysiology of Alzheimer's disease. Inhibition of BuChE provides symptomatic treatment of the disease and the same effect was demonstrated for 5-HT antagonists in clinical trials. Oxidative stress is regarded as a major and primary factor contributing to the development of Alzheimer's disease; therefore, antioxidant agents may provide a disease-modifying effect. Combining BuChE inhibition, 5-HT antagonism, and antioxidant properties may result in multitarget-directed ligands providing cognitio...
Groppelli E, Tuthill TJ, Rowlands DJ.Equine rhinitis A virus (ERAV) is genetically closely related to foot-and-mouth disease virus (FMDV), and both are now classified within the genus Aphthovirus of the family Picornaviridae. For disease security reasons, FMDV can be handled only in high-containment facilities, but these constraints do not apply to ERAV, making it an attractive alternative for the study of aphthovirus biology. Here, we show, using immunofluorescence, pharmacological agents, and dominant negative inhibitors, that ERAV entry occurs (as for FMDV) via clathrin-mediated endocytosis and acidification of early endosomes...
Hoerdemann M, Smith RL, Hosgood G.To establish and compare the onset and duration of action of 2 local anesthetics based on objective lameness and skin sensitivity assessment. Methods: Interventional crossover experimental trial with balanced randomization. Methods: Eight horses. Methods: Reversible forelimb lameness was induced in 8 horses. A palmar digital nerve block (PDNB) was applied with mepivacaine or lidocaine (both 2%). Quantitative lameness and skin sensitivity data were collected with an inertial sensor system and a force gauge, respectively. The times to lameness resolution/skin desensitization (T1), consistent lam...
