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.
Felippelli G, Cruz BC, Gomes LV, Lopes WD, Teixeira WF, Maciel WG, Buzzulini C, Bichuette MA, Campos GP, Soares VE, Bergamasco PL, de Oliveira GP....By means of parasitological necropsies, the present study aimed to evaluate, in six experiments, the degree of susceptibility or resistance of different helminth species which naturally infect horses to ivermectin 0.2 mg/kg, abamectin 0.2 mg/kg, moxidectin 0.4 mg/kg, trichlorfon 35 mg/kg, ivermectin 0.2 mg/kg+praziquantel 2.5 mg/kg, abamectin 0.2 mg/kg+praziquantel 2.5 mg/kg and ivermectin 0.2 mg/kg+6.6 mg/kg pyrantel. At experimental day zero, the horses were allocated to treatment groups based on average counts of strongylid eggs per gram of feces (EPG) obtained on days -3, -2 and -1. Oxyuri...
Derochette S, Serteyn D, Mouithys-Mickalad A, Ceusters J, Deby-Dupont G, Neven P, Franck T.Excessive neutrophil stimulation and reactive oxygen species (ROS) production are involved in numerous human or horse pathologies. The modulation of the neutrophil NADPH oxidase (NOX) has a great therapeutic potential since this enzyme produces superoxide anion whose most of the other ROS derive. The measurement of NOX activity by cell-free systems is often used to test potential inhibitors of the enzyme. A major drawback of this technique is the possible interferences between inhibitors and the probe, ferricytochrome c, used to measure the activity. We designed the "EquiNox2", a new pharmacol...
López-Sanromán FJ, Gómez Cisneros D, Varela del Arco M, Santiago Llorente I, Santos González M.The aim of the present study was to quantify by accelerometry the trotting pattern of adult horses sedated with two different doses of acepromazine, in order to assess the use of this drug in equine lameness evaluations. Methods: Seven mature horses were used and three treatments were administered to each horse: saline solution, acepromazine (0.01 mg/kg), and acepromazine (0.02 mg/kg). The portable gait analyzer used consisted of three orthogonal accelerometers that measure accelerations along the dorsoventral, longitudinal, and lateral axes. Baseline values were obtained and after treatment, ...
Brünisholz HP, Schwarzwald CC, Bettschart-Wolfensberger R, Ringer SK.The aim of the present study was to investigate the effect of pentastarch on colloid osmotic pressure (COP) and cardiopulmonary function during and up to 24 h after anaesthesia in horses. Twenty-five systemically healthy horses were anaesthetised using isoflurane-medetomidine balanced anaesthesia. Twelve were assigned to treatment with hydroxyethyl starch (HES) (H group) and 13 to no HES (NH group). In the H group, 6 mL/kg of pentastarch 10% HES (200/0.5) was infused over 1 h starting 30 min after induction of anaesthesia. Horses of the NH group received an equal amount of lactated Ringer's so...
Underwood C, Pollitt CC, Metselaar JM, Laverman P, van Bloois L, van den Hoven JM, Storm G, van Eps AW.Liposomes are phospholipid nanoparticles used for targeted drug delivery. This study aimed to determine whether intravenous liposomes accumulate in lamellar tissue during laminitis development in horses so as to assess their potential for targeted lamellar drug delivery. Polyethylene-glycol (PEG) coated liposomes were prepared according to the film hydration method and labelled using (99m)Tc-hexamethyl-propylene-amine-oxime. Six horses received 10 g/kg oligofructose via nasogastric tube to induce laminitis, and four control horses received water via nasogastric tube. All horses received 300â...
Dória RG, Carvalho MB, Freitas SH, Laskoski LM, Colodel EM, Mendonça FS, Silva MA, Grigoletto R, Fantinato Neto P.Treatment for horses with pythiosis of a limb is challenging. This study aims to evaluate the effects of administering amphotericin B in a 10 % solution of dimethylsulfoxide by intravenous regional limb perfusion (IRLP) to treat horses for cutaneous pythiosis of a limb. Results: All 15 of the horses treated had complete resolutions of their lesion between 6 to 9 weeks after a single IRLP treatment. No complications were observed at the site of venipuncture for IRLP. Before initiation of treatment, there was anemia and marked leucocytosis which resolved following treatment. Serum biochemistry ...
McArthur CL, Handel IG, Robinson A, Hodgkinson JE, Bronsvoort BM, Burden F, Kaplan RM, Matthews JB.Cyathostomins are the most prevalent parasitic pathogens of equids worldwide. These nematodes have been controlled using broad-spectrum anthelmintics; however, cyathostomin resistance to each anthelmintic class has been reported and populations insensitive to more than one class are relatively commonplace. The faecal egg count reduction test (FECRT) is considered the most suitable method for screening anthelmintic sensitivity in horses, but is subject to variation and is relatively time-consuming to perform. Here, we describe a larval migration inhibition test (LMIT) to assess ivermectin (IVM)...
Decloedt AI, Bailly-Chouriberry L, Vanden Bussche J, Garcia P, Popot MA, Bonnaire Y, Vanhaecke L.Traditionally, steroids other than testosterone are considered to be synthetic, anabolic steroids. Nevertheless, in stallions, it has been shown that β-Bol can originate from naturally present testosterone. Other precursors, including phytosterols from feed, have been put forward to explain the prevalence of low levels of steroids (including β-Bol and ADD) in urine of mares and geldings. However, the possible biotransformation and identification of the precursors has thus far not been investigated in horses. To study the possible endogenous digestive transformation, in vitro simulations of t...
Kutter AP, Bettschart-Wolfensberger R, Schwarzwald CC, Portier KG, Ringer SK.To evaluate the non-calibrated, minimally invasive cardiac output (CO) monitor FloTrac/Vigileo (FloTrac) against thermodilution (TD) CO in standing horses. Methods: Prospective, experimental trial. Methods: Nine adult horses weighing a median (range) of 535 (470-602) kg. Methods: Catheters were placed in the right atrium, pulmonary artery and carotid artery under local anaesthesia. CO was measured 147 times by TD and FloTrac and indexed to body weight. Changes in CO were achieved with romifidine or xylazine and dobutamine constant rate infusions. Bland-Altman analysis, concordance and polar pl...
McClure SR, Koenig R, Hawkins PA.To evaluate the effectiveness of a novel trimethoprim-sulfadiazine oral suspension for the treatment of naturally acquired Streptococcus equi subsp zooepidemicus infection in horses. Methods: Randomized, controlled field trial. Methods: 180 horses with S equi subsp zooepidemicus infection. Methods: Horses with lower respiratory tract infections caused by S equi subsp zooepidemicus were treated with a new formulation of combined trimethoprim-sulfadiazine oral suspension at a dosage of 24 mg/kg (10.9 mg/lb) twice daily for 10 days (treatment group) or with an equivalent volume of saline (0.9% Na...
Douglas HF, Southwood LL, Meyer-Ficca ML, Hart SK, Meyer RG.To evaluate the poly (ADP-ribose) polymerase-1 (PARP1) enzyme and its inhibition in horses and explore its potential as a novel therapeutic target for equine intestinal ischemia-reperfusion injury by (1) identifying poly (ADP-ribose) (PAR) as an indication of PARP1 activation in equine cells using available immunoblot analytical techniques, (2) inducing PARP1 activation in an in vitro oxidative DNA damage model, (3) and demonstrating the inhibition of PARP1 in equine cells using commercially available PARP1 inhibitors. Methods: Experimental study. Methods: Blood samples were collected from sys...
Giguère S, Berghaus LJ, Lee EA.Studies with facultative intracellular bacterial pathogens have shown that evaluation of the bactericidal activity of antimicrobial agents against intracellular bacteria is more closely associated with in vivo efficacy than traditional in vitro susceptibility testing. The objective of this study was to determine the relative activity of 10 antimicrobial agents against intracellular Rhodococcus equi. Equine monocyte-derived macrophages were infected with virulent R. equi and exposed to erythromycin, clarithromycin, azithromycin, rifampin, ceftiofur, gentamicin, enrofloxacin, vancomycin, imipene...
de Laat MA, Robinson MA, Gruntmeir KJ, Liu Y, Soma LR, Lacombe VA.Equine metabolic syndrome is characterized by obesity and insulin resistance (IR). Currently, there is no effective pharmacological treatment for this insidious disease. Glucose uptake is mediated by a family of glucose transporters (GLUT), and is regulated by insulin-dependent and -independent pathways, including 5-AMP-activated protein kinase (AMPK). Importantly, the activation of AMPK, by 5-aminoimidazole-4-carboxamide-1-D-ribofuranoside (AICAR) stimulates glucose uptake in both healthy and diabetic humans. However, whether AICAR promotes glucose uptake in horses has not been established. I...
Underwood C, Collins SN, van Eps AW, Mills PC, Allavena RE, Bailey SR, Medina Torres CE, Meizler A, Pollitt CC.No validated laminitis drug therapy exists, yet pharmaceutical agents with potential for laminitis prevention have been identified. Many of these are impractical for systemic administration but may be effective if administered locally. This study compared intraosseous infusion of the distal phalanx (IOIDP) with systemic intravenous constant rate infusion (CRI) to determine which was more effective for lamellar marimastat delivery. Ultrafiltration probes were placed in both forefeet of five horses to collect lamellar interstitial fluid as lamellar ultrafiltrate (LUF). Marimastat solution (3.5â€...
Afonso T, Giguère S, Rapoport G, Barton MH, Coleman AE.Pimobendan is an inodilator used in dogs for the management of heart failure due to myxomatous valve disease or dilated cardiomyopathy. The lack of data regarding the effects of pimobendan in horses prevents the rational use of this drug. Objective: To determine the cardiovascular effects of pimobendan in healthy mature horses. Methods: Randomised experimental study. Methods: Five horses were fasted overnight prior to receiving i.v. pimobendan (0.25 mg/kg bwt), intragastric (i.g.) pimobendan (0.25 mg/kg bwt) or i.g. placebo with a washout period of one week between each administration. Horses ...
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...
Nicpoń J, Siudzińska A, Marędziak M, Śmieszek A, Basińska K, Koszykowska M.The influences of NSAIDs (Nonsteroidal Anti-inflammatory Drugs)--non-selective metamizole and selectively-acting tolfenamic acid were estimated on morphology, ultrastructure, and cytophysiological activity of canine (Ca) and equine (Eq) adipose-derived mesenchymal stem cells (ASCs). The lowest concentration of metamizole (0.01 mg/mL) stimulated the viability and cytophysiological activity of Ca ASCs and did not affect cell morphology. Stimulated cells possessed a proper, fibroblastic shape, with large, eccentrically located nuclei. Similar effects to those observed in Ca ASCs were found in Eq ...
Arlas TR, Wolf CA, Petrucci BP, Estanislau JF, Gregory RM, Jobim MI, Mattos RC.Corticotherapy is a common treatment in mares susceptible to endometritis. Isoflupredone improves pregnancy rates and affects the protein profile of endometrial fluid in comparison to untreated mares. Dexamethasone decreases postbreeding fluid accumulation and uterine edema; however, its effects on the protein profile of the endometrial fluid have not yet been studied. The aim of the present study was to verify the effect of dexamethasone on the protein profile of endometrial fluid, in the presence or absence of infection, from mares susceptible to persistent postbreeding endometritis. Nine su...
Hunter BG, Duesterdieck-Zellmer KF, Larson MK.Anecdotal accounts of tiludronate administration via intravenous regional limb perfusion (IVRLP) exist despite a lack of information regarding safety for synovial structures in the perfused area. The objective of this study was to determine whether tiludronate concentrations in synovial structures after IVRLP with low dose (0.5 mg, LDT) or high dose (50 mg, HDT) tiludronate remain below a value demonstrated in vitro to be safe for articular cartilage (<19,000 ng/ml), and to determine effects of tiludronate on synovial fluid cytology variables compared to saline perfused control limbs. Using...
Rizk MA, El-Sayed SA, Terkawi MA, Youssef MA, El Said el Sel S, Elsayed G, El-Khodery S, El-Ashker M, Elsify A, Omar M, Salama A, Yokoyama N....A rapid and accurate assay for evaluating antibabesial drugs on a large scale is required for the discovery of novel chemotherapeutic agents against Babesia parasites. In the current study, we evaluated the usefulness of a fluorescence-based assay for determining the efficacies of antibabesial compounds against bovine and equine hemoparasites in in vitro cultures. Three different hematocrits (HCTs; 2.5%, 5%, and 10%) were used without daily replacement of the medium. The results of a high-throughput screening assay revealed that the best HCT was 2.5% for bovine Babesia parasites and 5% for equ...
Goodale L, Frank N, Hermida P, D'Oench S.To determine whether plasma ACTH concentrations vary following administration of a thyrotropin-releasing hormone (TRH) solution prepared for research purposes and stored at -20°C (rTRH) or prepared by a compounding pharmacy and stored at room temperature (approx 22°C; cTRH). Methods: 34 adult horses. Methods: The study consisted of 2 experiments. In experiment 1, each horse underwent 2 TRH stimulation tests separated by 24 hours; 10 horses were administered cTRH for the first test and rTRH for the second test (group 1), 10 horses were administered rTRH for the first test and cTRH for the sec...
Scott I, Bishop RM, Pomroy WE.There is growing concern that given the high frequency with which anthelmintics are being administered to many horses, anthelmintic resistance amongst equine helminth populations will be an increasing problem, rendering many of the currently available products unusable with little prospect of new products becoming available, at least in the near future. Worldwide, much reliance has been placed on the macrocyclic lactone (ML) group of anthelmintics, but resistance has been reported to these products as well as to the two other major anthelmintic classes used in this species, the benzimidazoles ...
Sandersen C, Bienzle D, Cerri S, Franck T, Derochette S, Neven P, Mouytis-Mickalad A, Serteyn D.Horses commonly suffer from chronic respiratory disease and are also used in large animal models of spontaneous or induced airway inflammation. The anti-inflammatory properties of curcumin are largely described but its low bioavailability precludes its clinical use. NDS27, a lysin salt of curcumin incorporated in beta-cyclodextrine, has high bioavailability and can be administered by inhalation. The aim of this study was to investigate the effects of inhaled NDS27 on inflammatory cytokines and proteins in the broncho-alveolar lavage fluid using a model of neutrophilic airway inflammation. Meth...
Briganti A, Portela DA, Grasso S, Sgorbini M, Tayari H, Bassini JR, Vitale V, Romano MS, Crovace A, Breghi G, Staffieri F.The aim of this study was to evaluate the correlation of commonly used oxygenation indices with venous admixture (Qs/Qt) in anaesthetised horses under different infusion rates of dobutamine. Six female horses were anaesthetised with acepromazine, xylazine, diazepam, ketamine, and isoflurane, and then intubated and mechanically ventilated with 100% O2. A Swan-Ganz catheter was introduced into the left jugular vein and its tip advanced into the pulmonary artery. Horses received different standardised rates of dobutamine. For each horse, eight samples of arterial and mixed venous blood were simul...
Janssen IJ, Krücken J, Demeler J, von Samson-Himmelstjerna G.P-glycoproteins (Pgps) are suspected to mediate drug extrusion in nematodes contributing to macrocyclic lactone resistance. This association was recently shown for Parascaris Pgp-11. Ivermectin resistance was correlated with the presence of three pgp-11 single nucleotide polymorphisms and/or increased pgp-11 mRNA levels. In the present study, the ability of Pgp-11 to modulate ivermectin susceptibility was investigated by its expression in a pgp-11-deficient Caenorhabditis elegans strain. Expression of Parascaris pgp-11 in two transgenic lines significantly decreased ivermectin susceptibility i...
McKenzie EC, Di Concetto S, Payton ME, Mandsager RE, Arko M.To determine the effect of dantrolene premedication on various cardiovascular and biochemical variables and recovery in isoflurane-anesthetized horses. Methods: 6 healthy horses. Methods: Each horse was anesthetized twice with a 21- to 28-day washout period between anesthetic sessions. Food was not withheld from horses before either session. During each session, dantrolene (6 mg/kg in 2 L of water) or water (2 L) was administered via a nasogastric tube 1 hour before anesthesia was induced. Anesthesia was maintained with isoflurane for 90 minutes, during which blood gas analyses and lithium-dil...
Bienert-Zeit A, Gietz C, Staszyk C, Kietzmann M, Stahl J, Ohnesorge B.To monitor concentrations of sulfadimidine in the paranasal sinus mucosa (PSM) of unsedated horses following IV administration of trimethoprim-sulfadimidine via in vivo microdialysis. Methods: 10 healthy adult horses. Methods: Concentric microdialysis probes were implanted into the subepithelial layers of the frontal sinus mucosa of standing sedated horses. Four hours after implantation, trimethoprim-sulfadimidine (30 mg/kg) was administered IV every 24 hours for 2 days; dialysate and plasma samples were collected at intervals during that 48-hour period and analyzed for concentrations of sulfa...
Peachey LE, Pinchbeck GL, Matthews JB, Burden FA, Mulugeta G, Scantlebury CE, Hodgkinson JE.Cyathostomins are the most important gastrointestinal nematode infecting equids. Their effective control is currently under threat due to widespread resistance to the broad spectrum anthelmintics licenced for use in equids. In response to similar resistance issues in other helminths, there has been increasing interest in alternative control strategies, such as bioactive plant compounds derived from traditional ethnoveterinary treatments. This study used an evidence-based approach to evaluate the potential use of plant extracts from the UK and Ethiopia to treat cyathostomins. Plants were shortl...
Redding LE, Elzer EJ, Ortved KF.Intravenous regional limb perfusions (RLP) are widely used in equine medicine to treat distal limb infections, including synovial sepsis. RLPs are generally deemed successful if the peak antibiotic concentration (Cmax) in the sampled synovial structure is at least 8-10 times the minimum inhibitory concentration (MIC) for the bacteria of interest. Despite extensive experimentation and widespread clinical use, the optimal technique for performing a successful perfusion remains unclear. The objective of this meta-analysis was to examine the effect of technique on synovial concentrations of antibi...
Jacobson GA, Raidal S, Robson K, Narkowicz CK, Nichols DS, Haydn Walters E.Salbutamol is usually administered as a racemic mixture but little is known about the enantioselectivity of salbutamol pharmacokinetics in the lung. This study was designed to investigate enantiomer concentrations in lung tissue after inhaled dosing. Horses (n = 12) received racemic salbutamol 1000 μg via inhalation. Enantioselective ultra performance liquid chromatography-tandem mass spectrometry was used to determine salbutamol concentrations in pulmonary epithelial lining fluid (PELF) sampled 2, 5, 10 and 15 min after administration, in central lung (endoscopic bronchial biopsy) and per...
Umar MA, Yamashita K, Kushiro T, Muir WW.To evaluate the cardiovascular effects of total IV anesthesia with propofol (P-TIVA) or ketamine-medetomidine-propofol (KMP-TIVA) in horses. Methods: 5 Thoroughbreds. Methods: Horses were anesthetized twice for 4 hours, once with P-TIVA and once with KMP-TIVA. Horses were medicated with medetomidine (0.005 mg/kg, IV) and anesthetized with ketamine (2.5 mg/kg, IV) and midazolam (0.04 mg/kg, IV). After receiving a loading dose of propofol (0.5 mg/kg, IV), anesthesia was maintained with a constant rate infusion of propofol (0.22 mg/kg/min) for P-TIVA or with a constant rate infusion of propofol (...
Colbath AC, Wittenburg LA, Gold JR, McIlwraith CW, Moorman VJ.To determine the effect of intravenous regional limb perfusion (IVRLP) with a combination of mepivacaine hydrochloride and amikacin sulfate on synovial fluid amikacin sulfate concentration, antimicrobial activity, and mechanical nociceptive threshold (MNT). Methods: Experimental study. Methods: Healthy adult horses (n=9). Methods: One IVRLP treatment was randomly administered by cephalic vein of each limb: amikacin alone (1 g amikacin in 60 mL saline) or amikacin with mepivacaine (1 g amikacin and 500 mg mepivacaine in 60 mL saline). Opposite treatments were repeated after a 24 hour wash-out p...
Spadavecchia C, Arendt-Nielsen L, Andersen OK, Spadavecchia L, Schatzmann U.To investigate the action of a single IV administration of romifidine on the thresholds of the nociceptive withdrawal reflex (NWR) and temporal summation in conscious horses. Methods: 10 adult horses. Methods: Single electrical stimulations were applied on the digital nerves to evoke NWR from the left forelimb and hind limb. Repeated electrical stimulations (10 stimuli, 5 Hz) were given to obtain temporal summation. Surface electromyographic reflex activity was recorded from the common digital extensor and cranial tibial muscles. After baseline assessment of NWR and temporal summation threshol...
Sun WC, Moore JN, Hurley DJ, Vandenplas ML, Linden JM, Murray TF.To evaluate anti-inflammatory effects of several novel adenosine receptor agonists and to determine their specificity for various adenosine receptor subtypes on neutrophils, cells heterologously expressing equine adenosine receptors, or equine brain membranes. Methods: Neutrophils isolated from 8 healthy horses. Methods: Radioligand binding experiments were performed to compare binding affinities of adenosine receptor agonists to equine adenosine A(1), A(2A), and A(3) receptor subtypes. Effects of these agonists on endotoxin-induced production of reactive oxygen species (ROS) by equine neutrop...
Goodale L, Frank N, Hermida P, D'Oench S.To determine whether plasma ACTH concentrations vary following administration of a thyrotropin-releasing hormone (TRH) solution prepared for research purposes and stored at -20°C (rTRH) or prepared by a compounding pharmacy and stored at room temperature (approx 22°C; cTRH). Methods: 34 adult horses. Methods: The study consisted of 2 experiments. In experiment 1, each horse underwent 2 TRH stimulation tests separated by 24 hours; 10 horses were administered cTRH for the first test and rTRH for the second test (group 1), 10 horses were administered rTRH for the first test and cTRH for the sec...
Gunkel CI, Valverde A, Robertson SA, Thompson MS, Keoughan CG, Ferrell EA.A mature horse developed acute signs of bronchoconstriction causing hypoxemia and hypercapnia during anesthesia for computerized tomography of the maxillary sinus after i.v. administration of diatrizoate contrast medium. The horse was treated with aerosolized albuterol, atropine, and oxygen insufflation and recovered uneventfully despite severe hypoxemia and low hemoglobin saturation. The horse's condition continued to improve after treatment, and the horse was discharged with no further complications. Caution is advised with the use of contrast media in anesthetized horses.
Jean D, Vrins A, Lavoie JP.To determine temporal variations of pulmonary function in horses without respiratory tract disease (controls) and horses with chronic obstructive pulmonary disease (COPD) and determine whether reversibility of airway obstruction after environmental control can be predicted by response to atropine administration. Methods: 7 COPD-affected and 5 control horses. Methods: Pulmonary function testing was performed monthly during 3 consecutive months, daily for 5 consecutive days, and at 6-hour intervals for 24 hours before and after administration of atropine (0.02 mg/kg of body weight, i.v.) and aft...
Erol E, Shaffer CL, Lubbers BV.The alarming increase in rifampin and macrolide resistance among Rhodococcus equi isolates highlights the need to identify alternative therapeutic options that can effectively control rhodococcosis in foals while limiting the further development of drug resistance. Objective: To evaluate bacterial killing, antibiotic synergism and mutant prevention concentrations (MPCs) of clarithromycin alone and in combination with doxycycline, minocycline or rifampin against clinical isolates of R equi. Methods: In vitro experiments. Methods: Bacterial time-kill, fractional inhibitory concentration (checker...
Cook VL, Holcombe SJ, Gandy JC, Corl CM, Sordillo LM.Monocytes are among the initial cells that interact with circulating LPS. Binding of LPS to monocyte surface receptors triggers an intracellular signaling cascade and results in the production of proinflammatory cytokines. Ethyl pyruvate, a stable derivative of pyruvate, has been effective in mitigating LPS induced alterations in isolated human monocytes. We hypothesized that ethyl pyruvate would suppress proinflammatory gene expression in LPS-stimulated equine monocytes without affecting cell viability. Equine monocytes were isolated from whole blood using a sediment-gradient centrifugation p...
Allison A, Robinson R, Jolliffe C, Taylor PM.There are limited investigations comparing ketamine to a ketamine-midazolam co-induction. Objective: To compare quality and safety of general anaesthesia induced using ketamine alone with anaesthesia co-induced using ketamine and midazolam. Methods: Randomised, double blinded, placebo controlled trial. Methods: After i.v. detomidine (20 μg/kg) thirty-eight ponies undergoing field castration received either 0.06 mg/kg (0.6 mL/50 kg) midazolam (group M) or 0.6 mL/50 kg placebo (group P) with 2.2 mg/kg ketamine i.v. for anaesthetic induction. Quality of anaesthetic induction, endotracheal intuba...
Church ML, Norman JC.The main objective was to record electroretinogram (ERG) parameters of normal thoroughbred mares using the HMsERG, a mini-Ganzfeld electroretinographic unit, and a contact lens electrode. The second objective was to determine whether IV detomidine hydrochloride at 0.015 mg/kg is consistently an effective choice for sedation of horses undergoing this ERG protocol. Methods: The study population consisted of 30 normal thoroughbred mares. ERG data were harvested using a protocol that included three different light intensities (10, 3000, and 10,000 mcd s/m(2)) and a 30-Hz flicker at 3000 mcd s/m(2)...
Bijman J, Quinton PM.Single equine sweat glands were found to secrete for more than 1 h in vitro in response to pharmacologic secretagogues. The adrenergic agonists epinephrine and norepinephrine evoked maximal sweat rates of 2.0 nl X gland-1 X min-1. However, the concentration of norepinephrine (10(-5) M) required to evoke the maximal response was 10 times higher than that for epinephrine. Maximal sweat rates also were stimulated with the beta 2-adrenergic agonist terbutaline. This stimulation was blocked by the beta-adrenergic antagonist propranolol. Moderate sweating responses were also obtained with the alpha-...
Klei TR, Chapman MR, French DD, Taylor HW.The efficacy of a high dose of ivermectin (1.0 mg per kg Eqvalan liquid drench) on encysted cyathostomes was tested in a controlled study using 12 adult ponies with naturally acquired cyathostome infections. Six treated ponies and six non-treated controls were held in separate stalls for a period of 5 weeks. Cyathostome burdens, which included lumenal larvae, adults and encysted larvae, were determined at necropsy. The viability of encysted larvae, based on morphologic integrity, was assessed by observation of mural transillumination and by the histologic appearance of 12 larvae per pony. Effi...
Magdesian KG.Neonatal foals are at high risk of developing sepsis, which can be life-threatening. Early antimicrobial use is a critical component of the treatment of sepsis. Because the neonatal foal has unique pharmacologic physiology, antimicrobial choice and dosing are often different than in adult horses. Broad-spectrum, bactericidal, and intravenous antimicrobials should be considered first-line therapy for septic foals. A combination of aminoglycoside and beta-lactam antimicrobial or third-generation cephalosporin is an excellent empirical first choice for treating septic foals, until culture and sus...
Pantaleon LG, Furr MO, McKenzie HC, Donaldson L.Small volume resuscitation has been advocated as a beneficial therapy for endotoxemia in horses but this therapy has not been investigated in a prospective manner. The objective of this study was to determine the cardiopulmonary effects of small-volume resuscitation using hypertonic saline solution (HSS) plus Hetastarch (HES) during experimental endotoxemia in anesthetized horses. Objective: Treatment of horses with induced endotoxemia using HES-HSS does not alter the response of various cardiopulmonary indices when compared to treatment with either small- or large-volume isotonic crystalloid ...
Ho EN, Wan TS, Wong AS, Lam KK, Stewart BD.Insulin administration can increase muscle glycogen by utilising hyperinsulinaemic clamps prior to sports events or during the recovery phases, and increase muscle size by its chalonic action to inhibit protein breakdown. In order to control insulin abuse in equine sports, a method to detect effectively the use of insulins in horses would be required. Besides the readily available human insulin and its synthetic analogues, structurally similar insulins from other species can also be used as doping agents. This study describes a method for the simultaneous detection of bovine, porcine and human...
Joubert KE, Briggs P, Gerber D, Gottschalk RG.Butorphanol and detomidine constitute an effective combination for sedation and analgesia in horses. This trial was undertaken to assess the effectiveness of this combination in donkeys. The detomidine and butorphanol were given intravenously one after the other. A dose of 10 microg/kg of detomidine and 25 microg/kg of butorphanol was used. Sedation is easily extended by additional doses of butorphanol. The average dose of detomidine was 11.24 microg/kg and that of butorphanol was 28.0 microg/kg. Four donkeys in the detomidine group required additional sedation and analgesia. Detomidine alone ...
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...
Weiss DJ, Evanson OA, McClenahan D, Fagliari JJ, Jenkins K.To determine whether platelets are hyperaggregable or form platelet-neutrophil aggregates during the prodromal stages of acute laminitis of ponies. Methods: Healthy adult ponies: 8 experimental and 6 control. Methods: Acute laminitis was induced by oral administration of corn starch and wood flour to 8 ponies, and indices of platelet activation were evaluated. Blood samples were collected before and at 4, 8, 12, 24, 28, and 32 hours after carbohydrate administration, and PCV, total plasma protein concentration, platelet count, activated clotting time, whole blood recalcification time, spontane...
Fortin JS, Benskey MJ, Lookingland KJ, Patterson JS, Howey EB, Goudreau JL, Schott HC.Pituitary pars intermedia dysfunction (PPID) develops slowly in aged horses as degeneration of hypothalamic dopaminergic neurons leads to proliferation of pars intermedia (PI) melanotropes through hyperplasia and adenoma formation. Dopamine (DA) concentrations and tyrosine hydroxylase (TH) immunoreactivity are markedly reduced in PI tissue of PPID-affected equids and treatment with the DA receptor agonist pergolide results in notable clinical improvement. Thus, we hypothesized that pergolide treatment of PPID-affected horses would result in greater DA and TH levels in PI tissue collected from ...
Kearns CF, McKeever KH.Clenbuterol is a beta(2)-agonist and potent selective bronchodilator that is used to treat bronchospasm in the horse. The drug is normally administered to horses orally as a syrup formulation. Once absorbed into the systemic circulation, clenbuterol has the potential to cause many side effects, including a repartitioning effect and major alterations in cardiac and skeletal muscle function. Recent studies have also reported that clenbuterol can affect bone and the immune, endocrine and reproductive systems. A great deal of information has been published on the beneficial effects of short term t...
Freitas GC, Carregaro AB, Gehrcke MI, De La Côrte FD, Lara VM, Pozzobon R, Brass KE.This study evaluated the analgesia effects of the epidural administration of 0.1 mg/kg bodyweight (BW) of morphine or 5 μg/kg BW of buprenorphine in ponies with radiocarpal joint synovitis. Six ponies were submitted to 3 epidural treatments: the control group (C) received 0.15 mL/kg BW of a 0.9% sodium chloride (NaCl) solution; group M was administered 0.1 mg/kg BW of morphine; and group B was administered 5 μg/kg BW of buprenorphine, both diluted in 0.9% NaCl to a total volume of 0.15 mL/kg BW administered epidurally at 10 s/mL. The synovitis model was induced by injecting 0.5 ng of lipopol...
Carroll GL, Matthews NS, Hartsfield SM, Slater MR, Champney TH, Erickson SW.Six ponies were used to investigate the effect of tolazoline antagonism of detomidine on physiological responses, behavior, epinephrine, norepinephrine, cortisol, glucose, and free fatty acids in awake ponies. Each pony had a catheter inserted into a jugular vein 1 hour before beginning the study. Awake ponies were administered detomidine (0.04 mg/kg intravenously [i.v.]) followed 20 minutes later by either tolazoline (4.0 mg/kg i.v.) or saline. Blood samples were drawn from the catheter 5 minutes before detomidine administration (baseline), 5 minutes after detomidine administration, 20 minute...
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...
Weber LA, Funtan A, Paschke R, Delarocque J, Kalbitz J, Meißner J, Feige K, Kietzmann M, Cavalleri JV.Equine sarcoid (ES) is the most prevalent skin tumor in equids worldwide. Additionally, aging grey horses frequently suffer from equine malignant melanoma (EMM). Current local therapies targeting these skin tumors remain challenging. Therefore, more feasible topical treatment options should be considered. In order to develop a topical therapy against ES and EMM, betulinyl-bis-sulfamate and NVX-207, derivatives of the naturally occurring betulin and betulinic acid, respectively, were evaluated for their antiproliferative (crystal violet staining assay), cytotoxic (MTS assay) and apoptotic (Anne...
Waguespack RW, Cochran A, Belknap JK.To compare the levels of mRNA expression of cycooxygenase (COX)-1 and COX-2 in the digital laminae of normal horses and horses in the developmental stages of laminitis experimentally induced by administration of black walnut extract (BWE). Methods: Samples of mRNA extracted from the digital laminae of 5 control horses and 5 horses at the onset of leukopenia after administration of BWE. Methods: Specimens of laminae were collected from anesthetized horses prior to euthanasia. Expression of COX-1 and COX-2 mRNA in laminae of control and affected horses was evaluated via real-time quantitative po...
Moore RM, Sedrish SA, Holmes EP, Koch CE, Venugopal CS.The objective of this study was to determine and compare the in vitro responses of equine large colon arterial and venous rings to vasodilatory neuropeptides; calcitonin gene-related peptide (CGRP); substance P (SP); vasoactive intestinal polypeptide (VIP); and acetylcholine (ACh), a standard nonpeptide endothelium-dependent vasodilator. Responses of vessel rings to graded concentrations (10(-11) M to 10(-5) M) of each drug were determined in endothelium-intact, denuded, and Nomega-nitro-L-arginine methyl ester (L-NAME, 10(-5) M)-treated rings that were pre-contracted with norepinephrine. Perc...
Prause AS, Stoffel MH, Portier CJ, Mevissen M.In horses, gastrointestinal (GI) disorders occur frequently and cause a considerable demand for efficient medication. 5-Hydroxytryptamine receptors (5-HT) have been reported to be involved in GI tract motility and thus, are potential targets for treating functional bowel disorders. Our studies extend current knowledge on the 5-HT(7) receptor in equine duodenum, ileum and pelvic flexure by studying its expression throughout the intestine and its role in modulating contractility in vitro by immunofluorescence and organ bath experiments, respectively. 5-HT(7) immunoreactivity was demonstrated in ...
