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.
Rebordão MR, Galvão A, Pinto-Bravo P, Pinheiro J, Gamboa S, Silva E, Mateus L, Ferreira-Dias G.Oxytocin (OXT) has been used to prolong the luteal phase in mares, but its mechanism of action is unknown. The aim of this study was to evaluate the effect of chronic exogenous OXT administration to mid-luteal phase mares on luteal maintenance. Also, endometrial expression of prostaglandin endoperoxide synthase 2 (PTGS2), prostaglandin Fα, E and I synthases (AKR1C3, PTGES, and PTGIS), oxytocin receptor (OXTR), progesterone receptor (PGR), and estrogen receptors 1 (ESR1) and 2 (ESR2) were assessed in mares experiencing luteal maintenance 2 weeks after chronic exogenous OXT administration. Con...
Pirie RS, McGorum BC, Owen C, Carr O, Oakley H, McLachlan G.Despite frequent use of metered dose inhalers (MDIs) and spacers in equine practice, limited information exists on the efficiency of aerosol delivery using such devices. We determined the particle size distribution within an MDI-generated salbutamol aerosol delivered via an equine spacer using 'best practice' delivery technique and assessed the effect of variations in MDI use technique (shaking prior to each actuation, rapid repetitive actuations, and MDI angulation) on aerosol delivery efficiency. Under optimal conditions, only 53(±18) μg salbutamol per 100 μg actuation was delivered bey...
Cox KS, Nelson BB, Wittenburg L, Gold JR.Regional limb perfusion (RLP) is an effective treatment option for injuries and infections of the distal limb in horses. Using ceftiofur sodium in RLP has been studied due to its superior spectrum of Gram-positive organisms compared to aminoglycosides, but it is not known if this antimicrobial drug adequately penetrates subcutaneous tissue and bone. Objective: To determine the concentration of ceftiofur in plasma, subcutaneous tissue and bone in horses after RLP. Methods: Experimental prospective study. Methods: Six healthy horses were used in this study. Under standing sedation, an Esmarch to...
Loughran CM, Raisis AL, Hosgood G, Secombe CJ, Lester GD.Cardiac output does not always increase with dobutamine administration in anaesthetised horses and information on peripheral perfusion is lacking. Objective: To determine the effect of intravenous (i.v.) dobutamine infusion with and without a concurrent 20 mL/kg bodyweight (bwt) bolus of crystalloid fluids on the cardiovascular function of acepromazine premedicated, hypotensive, isoflurane-anaesthetised horses. Methods: Randomised, cross-over experiment. Methods: A total of 6 horses aged 5-13 years, weighing 464-578 kg were premedicated with acepromazine 0.02 mg/kg bwt and then sedated with xy...
Guedes A, Galuppo L, Hood D, Hwang SH, Morisseau C, Hammock BD.The roles of soluble epoxide hydrolase and lipid mediators in inflammatory and neuropathic pain could be relevant in laminitis pain management. Objective: To determine soluble epoxide hydrolase (sEH) activity in the digital laminae, sEH inhibitor potency in vitro, and efficacy of a sEH inhibitor as an adjunct analgesic therapy in chronic laminitic horses. Methods: In vitro experiments and clinical case series. Methods: sEH activity was measured in digital laminae from euthanised healthy and laminitic horses (n = 5-6/group). Potency of 7 synthetic sEH inhibitors was determined in vitro using eq...
Bachmann V, von Salis B, Fürst A.The goal of this study was to describe the development of equine drug testing in horses in Switzerland. This was achieved through evaluation of a film made by the Institute of Forensic Medicine at the University of Basel entitled 'Doping von Rennpferden' [Doping of Race Horses], toxicological detection, 1962', the analysis of doping test results of the Swiss Equestrian Federation and by interviewing individuals of various professions who were involved in equine drug testing at the time. The study compares early and modern methods of drug testing and highlights the changes in the attitude of eq...
Knych HK, Harrison LM, Steinmetz SJ, Chouicha N, Kass PH.Clenbuterol, a beta2-adrenergic receptor agonist, is used therapeutically to treat respiratory conditions in the horse. However, by virtue of its mechanism of action it has been suggested that clenbuterol may also have repartitioning affects in horses and as such the potential to affect performance. Clenbuterol decreases the percent fat and increases fat-free mass following high dose administration in combination with intense exercise in horses. In the current study, microarray analysis and real-time PCR were used to study the temporal effects of low and high dose chronic clenbuterol administr...
Hasan M, Siegmund W, Oswald S.Cytochrome P450 3A (CYP) enzymes are involved in the elimination of many drugs and are known to be regulated by several environmental factors. Thus, it was the aim of this study to develop and validate an analytical method allowing estimation of the hepatic CYP3A enzyme activity using the 4-hydroxycholesterol to cholesterol ratio as an endogenous biomarker in serum. Both compounds were isolated from the biological matrix by liquid-liquid extraction using n-hexane after saponification with ethanolic sodium methoxide solution (2M) to cleave the steroids from their esterified forms without any ki...
Daniels SP, Proudman CJ.The ovicidal activity of benzimidazole (BZ) anthelmintics is unique and not seen in other drug classes. Such ovicidal efficacy is not widely reported for equine cyathostomins, nor has this activity been tested in the face of BZ resistance. Although the product label states that fenbendazole is for use against BZ-susceptible cyathostomins, susceptibility testing is rarely performed. In this field-based study, the ovicidal efficacy of fenbendazole in horses (n=39) harbouring BZ-resistant cyathostomins was compared when dosed at 7.5mg/kg body weight (BW) orally, as a single dose per os (n=21) or ...
Sykes BW, Underwood C, McGowan CM, Mills PC.This study aimed to investigate the effect of diet and dose on the pharmacokinetics of omeprazole in the horse. Six horses received two doses (1 and 4 mg/kg) of omeprazole orally once daily for 5 days. Each dose was evaluated during feeding either a high-grain/low-fibre (HG/LF) diet or an ad libitum hay (HAY) diet in a four-way crossover design. Plasma samples were collected for pharmacokinetic analysis on days 1 and 5. Plasma omeprazole concentrations were determined by ultra-high pressure liquid chromatography-mass spectrometry. In horses being fed the HG/LF diet, on day 1, the area under...
Kendall A, Mayhew IG, Petrovski K.Treatment of subclinical carriers of Streptococcus equi subsp. equi with a gelatine-penicillin formulation deposited in the guttural pouch has been empirically proposed, but data on local tissue penicillin concentrations after treatment are lacking. Methods: We analysed tissue levels of penicillin after administration into the guttural pouches of four healthy horses. Two horses received local treatment with gelatine-penicillin and two horses received local treatment with an intramammary formulation of penicillin. Tissues were harvested for analysis either 12 or 24 h later. Conclusions: Resul...
Wetmore LA, Pascoe PJ, Shilo-Benjamini Y, Lindsey JC.OBJECTIVE To determine the locomotor response to the administration of fentanyl in horses with and without the G57C polymorphism of the μ-opioid receptor. ANIMALS 20 horses of various breeds and ages (10 horses heterozygous for the G57C polymorphism and 10 age-, breed-, and sex-matched horses that did not have the G57C polymorphism). PROCEDURES The number of steps each horse took was counted over consecutive 2-minute periods for 20 minutes to determine a baseline value. The horse then received a bolus of fentanyl (20 μg/kg, IV), and the number of steps was again counted during consecutive 2-...
Kooyman FN, van Doorn DC, Geurden T, Mughini-Gras L, Ploeger HW, Wagenaar JA.For the control of cyathostomins in horses, the macrocyclic lactones (MLs), moxidectin (MOX) and ivermectin (IVM) are the most commonly used anthelmintics. However, reduced activity, observed as shortening of the egg reappearance period (ERP) has been described. Shortening of the ERP may be caused by a decreased susceptibility of immature worms for MLs. Alternatively, immature worms may develop faster into egg producing adults as a result of repeated ML treatments. The species composition of the larval cultures obtained shortly after ML and pyrantel (PYR) treatment can confirm the hypothesis o...
Davolli GM, Ball BA, Esteller-Vico A, Claes AN, Canisso IF, Fedorka CE, Woodward EM, Troedsson MH, Squires EL.The GnRH antagonist, acyline, has not yet been investigated in the stallion. Our study aimed to: (1) evaluate the downregulation of the stallion hypothalamic-pituitary-gonadal axis by acyline through assessment of seminal parameters, testicular volume, and sexual behavior; (2) assess hormonal response of acyline-treated stallions to GnRH stimulation; and (3) verify reversibility after treatment. Stallions were assessed pretreatment and subsequently treated (every five days) for 50 days: acyline (n = 4; 330 μg/kg acyline) or control (n = 4, vehicle). The stallions were then monitored for 62Â...
Singh S, Chopra M, Dilbaghi N, Manuja BK, Kumar S, Kumar R, Rathore NS, Yadav SC, Manuja A.Isometamidium hydrochloride (ISMM) is an effective drug for the treatment of trypanosomosis, but it causes local and systemic toxicity. Isometamidium hydrochloride has limited therapeutic index and exhibit considerable variation in their prophylactic activities. We developed a trypanocidal nanoformulation using ISMM and polymers sodium alginate/gum acacia to enhance the efficacy of the drug at lower doses, while minimizing undesirable side effects. It was characterized by transmission electron microscopy and infrared spectroscopy for evaluation of size, morphology, functional groups, etc. In v...
Nout-Lomas YS, Page KM, Kang HG, Aanstoos ME, Greene HM.There is poor agreement between observers of equine neurological gait abnormalities using the modified Mayhew grading scale. Objective: To stimulate a dose-dependent ataxia in horses through xylazine administration and identify quantifiable relevant gait parameters. Methods: Balanced, randomised, 2-way crossover design. Methods: Eight horses were assessed before and after administration of xylazine (low dose and high dose). Gait analyses performed before and after xylazine administration included: 1) kinematic data collected on an equine high-speed treadmill (flat and 10% decline) and from acc...
Pollio D, Michau TM, Weaver E, Kuebelbeck KL.This case report describes ivermectin-induced blindness in a dog and a foal with normal ophthalmic fundic examinations and attenuated electroretinography (ERG). Subsequent recovery in ERG was noted following intravenous lipid emulsion (ILE) therapy. A dog and a foal were evaluated for ivermectin-induced blindness. Clinical signs included dull mentation, absent pupillary light reflexes (PLRs), and absent menace on presentation. The animals had normal fundoscopic examinations; however, in both cases ERG was consistent with neurosensory retinal dysfunction. Following ILE therapy for ivermectin to...
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...
Afonso T, Giguère S, Rapoport G, Brown SA, Coleman AE.Benazepril has been shown to inhibit circulating angiotensin-converting enzyme (ACE) activity in horses but the optimal dosage is unknown. Objective: To determine the lowest tested dose of benazepril that results in ≥75% attenuation in the response of arterial blood pressure (BP) to exogenous angiotensin I (ANG-I) administration. Methods: Prospective experimental study. Methods: A total of 5 healthy horses were instrumented for the direct measurement of BP. Each horse received 4 intragastric doses of benazepril (0.5, 1, 2 and 4 mg/kg bwt) with a washout period of 7 days between doses. Prior ...
Rinnovati R, Romagnoli N, Gentilini F, Lambertini C, Spadari A.Platelet-rich plasma (PRP) commonly refers to blood products which contain a higher platelet (PLT) concentration as compared to normal plasma. Autologous PRP has been shown to be safe and effective in promoting the natural processes of soft tissue healing or reconstruction in humans and horses. Variability in PLT concentration has been observed in practice between PRP preparations from different patients or from the same individual under different conditions. A change in PLT concentration could modify PRP efficacy in routine applications. The aim of this study was to test the influence of envi...
Rotkina AS, Pronina IV, Lazarev VN, Akhaev DN, Baskova IP.The purpose. Identifying the capacity of the medicinal leech novel original recombinant thrombolytic preparation Destabilase-Lysozyme-2 to inhibit the blood platelet aggregation. Gene of destabilase-lysozyme. ds2 (mlDL-Ds2 ), was cloned in E.coli cells. Recombinant protein was isolated in denaturing conditions using metal-chelate chromatography followed by denaturation of the polypeptide by rapid dilution in exact accordance with the procedure described by Kurdyumov A.S. et al. ( 2016, Russian Journal of Bioorganic Chemistry, v.42, s. 42-52). Blood was collected from the jugular vein of 18 hor...
Suzuki T, Kobayashi H, Kawasaki Y, Okazuka K, Hatano K, Fujiwara S, Oh I, Ohmine K, Kanda Y.Anti-thymocyte globulin (ATG) is a key drug in immunosuppressive therapy for patients with aplastic anemia. The mainstay of ATG therapy had been a horse ATG (hATG) formulation, Lymphoglobulin or ATGAM, but Lymphoglobulin was recently discontinued, and Thymoglobulin, a rabbit ATG (rATG) formulation, is currently used as the first-line drug in many countries, including Japan. However, a recent randomized clinical trial reported significantly unfavorable outcomes associated with the use of rATG regimens. We retrospectively analyzed clinical outcomes of adult patients with moderate to severe aplas...
Edmunds JL, Worgan HJ, Dougal K, Girdwood SE, Douglas JL, McEwan NR.The present study uses in vitro analytical techniques to investigate the effect of activated charcoal on the microbial community of the equine hindgut and the metabolites they produce. Incubations were performed in Wheaton bottles using a 50 ml incubation of a high-energy feed or a low-energy feed, plus bottles with no added food source, together with five levels of activated charcoal (0, 10, 25, 50 or 100 mg per bottle) and fecal samples as a bacterial inoculum. Using this method the rate of gas production, volatile fatty acid and ammonia concentrations, and pH values were analyzed and found ...
Arroyo MG, Couëtil LL, Nogradi N, Kamarudin MM, Ivester KM.The (R)-enantiomer of racemic albuterol (levalbuterol) has bronchodilatory properties whereas the (S)-enantiomer causes adverse effects in human airways, animal models, and isolated equine bronchi. Levalbuterol is commercially available and improves pulmonary function of asthmatic patients with a longer duration of effect than albuterol. Objective: To determine the dose at which inhaled levalbuterol produces maximal bronchodilatory effect (EDmax) and determine its duration of action in recurrent airway obstruction (RAO)-affected horses in comparison to racemic albuterol. Methods: Nine horses w...
Schumann B, Winkler J, Mickenautsch N, Warnken T, Dänicke S.Both deoxynivalenol (DON), zearalenone (ZEN), and their metabolites are known to modulate immune cells in various species whereby viability and proliferation are influenced. Such effects were rarely examined in horses. Therefore, one aim of the present study was to titrate the inhibitory concentrations of DON, 3-acetyl-DON (3AcDON), de-epoxy-DON (DOM-1), ZEN, and α- and β-zearalenol (ZEL) at which viability and proliferation of equine PBMC were reduced by 50 % (IC50) and 10 % (IC10) in vitro. For evaluation of practical relevance of the in vitro findings, a further aim was to screen horses...
Lyons ET, Dorton AR, Tolliver SC.Activity of fenbendazole (FBZ), oxibendazole (OBZ), piperazine (PIP) and pyrantel pamoate (PRT) alone and combinations of OBZ and PIP and of OBZ and PRT was evaluated against parascarids, strongyles and strongyloides in horse foals (n=281).This was on two farms - Farm A - mixed light-horses (n=26) and Farm B-Thoroughbreds (n=255) - in Central Kentucky in field tests in 2014 and 2015. Foals on both farms were treated one to three times each; an exception was that seven foals on Farm A were nontreated controls. Before treatment, the foals on Farm A were all weighed on scales but weights for Farm...
Zholobenko A, Mouithys-Mickalad A, Modriansky M, Serteyn D, Franck T.A recent study showed that silymarin, a standardized extract of S. marianum might be used in the prevention of equine laminitis. We investigated the effects of quercetin and some compounds found in silymarin (silybin, taxifolin and dehydrosilybin) on reactive oxygen species (ROS) production and myeloperoxidase (MPO) release by stimulated equine neutrophils (PMNs) and on MPO activity. All compounds (tested between 100 nm and 100 μm) inhibited superoxide anion production by stimulated PMNs in a dose-dependent manner. Dehydrosilybin and quercetin inhibited superoxide production and MPO release...
Knych HK, Arthur RM, Steinmetz S, McKemie DS.Ketoprofen (KTP) is currently only available as an injectable formulation for intravenous administration to horses. The primary goal of the study reported here was to characterize the pharmacokinetics of KTP, including determination of bioavailability following oral administration of the currently available injectable formulation as well as a paste formulation. KTP was administered intravenously and orally, and blood and urine samples were collected at various time points up to 96 h. KTP enantiomer concentrations were determined using LC–MS/MS, and pharmacokinetic analyses were performed. Me...
Noble GK, Li X, Zhang D, Sillence MN.Tryptophan (TRP) is marketed as a calmative for horses despite reservations about its efficacy. The aim of this study was to measure the effect of oral TRP administration on the reaction speed of horses. Sixty mature horses were used in a two stage randomised, blind, cross-over study, receiving a placebo and an oral dose of TRP (30, 60 or 120 mg/kg body weight), before undergoing a reaction speed test. Blood samples were taken up to 96 h after TRP administration, to identify signs of acute haemolytic anaemia. Plasma TRP concentrations were increased (P <0.001) by the administration of...
Murcia RY, Vargas A, Lavoie JP.Glucocorticoids (GCs) are the most effective drugs for the treatment of human asthma. However, a subgroup of asthmatic patients with neutrophilic airway inflammation is insensitive to GCs. Interleukin-17 (IL-17), a cytokine upregulated in the airways of a subset of human asthmatic patients, contributes to the recruitment of neutrophils and induces a glucocorticoid resistance in human airway epithelial cells. We hypothesized that IL-17 similarly activates neutrophils and contributes to their persistence in the asthmatic airways in spite of glucocorticoid therapy. To determine whether IL-17 dire...
Gingerich DA, Auer JA, Fackelman GE.A single intra-articular injection of 20 or 40 mg of purified hyaluronic acid of rooster comb origin resulted in restoration of normal joint function in horses with experimentally induced osteoarthritis. The functional improvement, measured by pressure sensitive force plate techniques, was detectable within one week after treatment and persisted throughout a four week experimental period despite continued use of the joints. The response was dose dependent in that injection of 0 (saline), 5 or 10 mg hyaluronic acid per joint space resulted in no significant change in joint function while dosage...
Morsy TA, Salem HS, Haridy FM, Rifaat MM, Abo-Zenadah NY, Adel el-Kadi M.To continue the study on fascioliasis in Tamyia Center, some farm animals were investigated for natural infection with Fasciola species by stool examination. The results showed 40% infection in sheep, 20% in buffalos, 6.7% in donkeys and zero% in horses. The overall percentage of infection was 25.5. The sheep (total dose 1800mg) and the donkey (total dose (4500 mg.) were successfully treated with Mirazid. On the other hand, one buffalo was successfully treated by a total dose 7500mg, the seconds one did not cured, but the eggs deposited per gm markedly decreased.
de Niederhäusern S, Sabia C, Messi P, Guerrieri E, Manicardi G, Bondi M.Vancomycin-resistant enterococci (VRE) in healthy people and in food-producing animals seems to be quite common in Europe. The existence of this community reservoir of VRE has been associated with the massive use of avoparcin in animal husbandry. Eight years after the avoparcin ban in Europe, we investigated the incidence of VanA enterococci, their resistance patterns, and the mobility of their glycopeptide-resistance determinants in a sampling of animal rectal swabs and clinical specimens. A total of 259 enterococci isolated from equine, swine, and clinical samples were subcultured on KF-stre...
Hardy J, Bednarski RM, Biller DS.Pharmacologically induced splenic contraction might be useful during certain medical or surgical procedures in horses. The effects of phenylephrine, an alpha 1-adrenergic receptor agonist, on hemodynamic function and splenic dimensions were examined in 6 healthy adult horses. Phenylephrine infusion (1, 3, or 6 micrograms/kg of body weight/min for 15 minutes) resulted in a dose-related increase in mean pulmonary artery pressure; right atrial pressure; systolic, mean, and diastolic arterial pressures; and packed cell volume (P = 0.0001). Concurrent decreases in heart rate and specific cardiac ou...
Arnoczky SP, Lavagnino M, Gardner KL, Tian T, Vaupel ZM, Stick JA.To determine the effects of oxytetracycline on matrix metalloproteinase-1 (MMP-1) mRNA expression and collagen gel contraction by equine myofibroblasts in an effort to explain the mechanistic basis for the pharmacologic treatment of flexural deformities in foals. Methods: Cultured myofibroblasts from the accessory ligament (distal check ligament) of 6 foals. Methods: Collagen gel scaffolds seeded with equine myofibroblasts were cultured in individual culture dishes containing complete media (Dulbecco's modified Eagle medium with 10% fetal bovine serum) and oxytetracycline (0, 12.5, 25, or 75 m...
Parry BW, Anderson GA, Gay CC.The hypotensive effect of acepromazine maleate was related to both the dose and route of administration. The degree and duration of hypotension varied between individual horses. In general, intravenous administration produced a more rapid maximum effect than intramuscular injection and the larger the dose the longer blood pressure remained at low levels. Average systolic pressure (of 6 horses) remained significantly below control values for more than 6 h after an intramuscular injection of 0.05 mg acepromazine maleate/kg body weight. Respiratory rate was markedly decreased, with the duration, ...
Morais JF, de Freitas MC, Yamaguchi IK, dos Santos MC, da Silva WD.IgG and F(ab')2 fragments were prepared from horse plasma rich in specific antibodies against Brazilian Bothrops or Crotalus venoms. Both preparations, free of gross contamination with non-immunoglobulin proteins, were able to combine in vitro with their respective antigens, forming immune complexes at antigen excess, equivalence or antibody excess, and activating the C system, through either the classical or the alternative pathways. The IgG preparation was more effective in neutralizing the lethal factors in Bothrops or Crotalus venoms, compared with the F(ab')2 fragments. In contrast, IgG a...
Moore RM, Eades SC, Stokes AM.To date, there is a substantial amount of data to support the hypotheses that vascular and enzymatic changes are ongoing in experimental laminitis. Furthermore, there is substantial in vitro evidence that the enzymatic changes weaken the dermo-epidermal attachments leading to mechanical failure of the hoof-bone interface of the equine digit. However, investigators of both the vascular and enzymatic theories have, to date, been unable to substantiate the effects of these pathophysiological changes in vivo on laminar tissues of horses afflicted with experimentally induced or naturally acquired l...
Payne SE, Kotze AC, Durmic Z, Vercoe PE.Anthelmintic resistance in gastrointestinal parasites of horses is an increasing problem, particularly in cyathostomins, and there is a need to find alternative means for the control of these parasites. We screened crude extracts from 37 species of Australian native plants for their anthelmintic activity in vitro against cyathostomin larvae (development from egg to third larval stage), with the aim of identifying those species that may be suitable for incorporation into sustainable parasite management programs. Water extracts from seven species, namely Acacia baileyana, Acacia melanoxylon, Aca...
Schlupp A, Anielski P, Thieme D, Müller RK, Meyer H, Ellendorff F.The beta2-agonist clenbuterol is commonly administered for therapeutic purposes in the horse, but its use an an anabolic agent is illegal. Clenbuterol can be detected in blood and urine for a relatively short period after administration and detection in hair could enhance the analytical range and be used to determine the history of clenbuterol application. Objective: That detection in mane or tail hair is possible over an extended period. Methods: Four horses received 0.8 microg clenbuterol hydrochloride/kg bwt b.i.d. for 10 days. Four other horses were used as untreated controls. Blood, urine...
Stout TA.Situations in which suppression or stimulation of reproductive activity in stallions has been attempted, or is desired, include resolution of the equine arteritis virus 'shedding' state, induction of testicular descent in inguinal cryptorchids, and the improvement of sperm production capacity and/or semen quality in sub-fertile stallions. However, the most common reason for wanting to modulate reproductive activity in a stallion is to alter the expression of sexual behaviour. In the case of intact stallions used for competitive or recreational purposes, the overt expression of sexual or aggres...
Alape-Giron A, Stiles BG, Gutierrez JM.An ELISA based, non-radioactive acetylcholine receptor (AchR) binding assay was used to detect the alpha-neurotoxins present in Micrurus nigrocinctus nigrocinctus venom. Sera from horses hyperimmunized against M. nigrocinctus venom contain antibodies which inhibit the binding of M. n. nigrocinctus alpha-neurotoxins to AchR and reverse the binding of toxins already complexed with the receptor. This result supports the importance of using antivenom therapeutically in M. n. nigrocinctus envenomations even after the onset of neurological symptoms. M. nigrocinctus antivenoms cross-reacted in an ELI...
Saengtienchai A, Ikenaka Y, Nakayama SM, Mizukawa H, Kakehi M, Bortey-Sam N, Darwish WS, Tsubota T, Terasaki M, Poapolathep A, Ishizuka M.Interspecific differences in xenobiotic metabolism are a key to determining relative sensitivities of animals to xenobiotics. However, information on domesticated livestock, companion animals, and captive and free-ranging wildlife is incomplete. The present study evaluated interspecific differences in phase II conjugation using pyrene as a nondestructive biomarker of polycyclic aromatic hydrocarbon (PAH) exposure. Polycyclic aromatic hydrocarbons and their metabolites have carcinogenic and endocrine-disrupting effects in humans and wildlife and can have serious consequences. The authors collec...
Herd RP, Miller TB, Gabel AA.The effectiveness of 1 pro-benzimidazole (pro-BZD) drug, 3 benzimidazole (BZD) drugs, and 3 non-benzimidazole (non-BZD) drugs in keeping fecal egg counts below 50 eggs per gram 2 and 4 weeks after treatment at 6-week intervals was compared in groups of brood mares and yearlings at 2 Standardbred farms. In a preliminary study (December 1978 to April 1979) as well as major study (April to November 1979), horses were kept in the same groups in the same areas. In the major study, treatments were arranged in a Latin square design. On farm 1, which had a history of repeated use of BZD drug since 196...
Flammini L, Mantelli L, Volpe A, Domenichini G, Di Lecce R, Dondi M, Cantoni AM, Barocelli E, Quintavalla F.Rifaximin is an unabsorbed oral antibiotic showing anti-inflammatory properties in human pathologies like irritable bowel syndrome and inflammatory bowel disease. In veterinary medicine, rifaximin is primarily used in the treatment of dermatological diseases in all animal species, in therapy and prophylaxis of mastitis in cows and in the treatment of endometritis in cattle and horses. The aim of this preliminary study was to evaluate the anti-inflammatory properties of rifaximin on primary cell cultures from bovine endometrium in which inflammatory response was induced by Lipopolysaccaride (LP...
Henderson SE, Santangelo KS, Bertone AL.To determine effects of various concentrations of retinoic acid (RA) or a synthetic RA receptor antagonist (LE135) on equine chondrocytes or bone marrow-derived equine mesenchymal stem cells (BMDMSCs) in monolayer cultures. Methods: Articular cartilage and BMDMSCs from 5 clinically normal horses. Methods: Monolayers of chondrocytes cultured in standard media and of BMDMSCs cultured in chondrogenic media were treated with RA at concentrations of 0, 0.1, 1, or 10 μM or LE135 at concentrations of 0, 0.1, 1, or 10 μM on day 0. On days 7 and 14, samples were analyzed for DNA concentration, chondr...
Wilkie DA, Colitz CM.The purpose of this review is not to specifically discuss the techniques of veterinary cataract surgery, but rather to emphasize some of the differences between the veterinary and human cataract patients, procedures and outcomes. Results: In general, veterinary cataract surgery has more similarities than differences when compared to its human counterpart. This is especially true when comparing pediatric cataract patients. Veterinary cataract surgery has changed dramatically in recent years with regards to surgical technique, ocular pharmacology, viscoelastic devices, phacoemulsification, and t...
Goehring L, Dorman DC, Osterrieder K, Burgess BA, Dougherty K, Gross P, Neinast C, Pusterla N, Soboll-Hussey G, Lunn DP.Equine herpes virus type 1 (EHV-1) infection in horses is associated with upper respiratory disease, neurological disease, abortions, and neonatal death. Objective: Does pharmacological therapy decrease either the incidence or severity of disease or infection caused by EHV-1 in domesticated horses? Methods: A systematic review was preformed searching AGRICOLA, CAB Abstracts, Cochrane, PubMed, Web of Science, and WHO Global Health Index Medicus Regional Databases to identify articles published before February 15, 2021. Selection criteria were original research reports published in peer reviewed...
Koj A, Chudzik J, Dubin A.Two proteinases (2A and 2B) purified from the granular fraction of horse blood leucocytes degrade casein (Km values 12.8 and 6mg/ml respectively) with maximum activity at pH 7.4 and in the presence of 2m-urea. Urea-denatured haemoglobin, fibrinogen, albumin and resorcin/fuchsin-stained elastin are digested at a slower rate. The enzymes hydrolyse synthetic substrates of elastase, N-benzyloxycarbonyl-L-alanine 4-nitrophenyl ester (Km 0.114 and 0.178 mM) and N-acetyl-tri-L-alanine methyl ester (Km 5.55 and 0.98 mM), but they do not hydrolyse synthetic substrates of trypsin, chymotrypsin and throm...
Marntell S, Nyman G.The clinical and cardiorespiratory effects of premedication with acepromazine, butorphanol or diazepam in addition to romifidine before induction of anaesthesia with ketamine were studied in 6 horses on 4 random occasions. Administration of romifidine alone or in combination with butorphanol resulted in an increase in arterial blood pressure, accompanied by a significant decrease in heart rate with second-degree atrio-ventricular heart block. Induction of anaesthesia with ketamine returned the heart rate to baseline value, but the arterial blood pressure was significantly increased compared to...
Alberts MK, Clarke CR, MacAllister CG, Homer LM.To determine the pharmacokinetics of acetazolamide administered IV and orally to horses. Methods: 6 clinically normal adult horses. Methods: Horses received 2 doses of acetazolamide (4 mg/kg of body weight, IV; 8 mg/kg, PO), and blood samples were collected at regular intervals before and after administration. Samples were assayed for acetazolamide concentration by high-performance liquid chromatography, and concentration-time data were analyzed. Results: After IV administration of acetazolamide, data analysis revealed a median mean residence time of 1.71 +/- 0.90 hours and median total body c...
Sah RL, Tsushima RG, Backx PH.We examined the ability of local anesthetics to correct altered inactivation properties of rat skeletal muscle Na+ channels containing the equine hyperkalemic periodic paralysis (eqHPP) mutation when expressed in Xenopus oocytes. Increased time constants of current decay in eqHPP channels compared with wild-type channels were restored by 1 mM benzocaine but were not altered by lidocaine or mexiletine. Inactivation curves, which were determined by measuring the dependence of the relative peak current amplitude after depolarization to -10 mV on conditioning prepulse voltages, could be shifted in...
König KS, Verhaar N, Hopster K, Pfarrer C, Neudeck S, Rohn K, Kästner SBR.Small intestinal strangulation associated with ischaemia-reperfusion injury (IRI) is common in horses. In laboratory animals IRI can be ameliorated by ischaemic preconditioning (IPC) and pharmacological preconditioning (PPC) with dexmedetomidine. The aim of this study was to determine the effect of PPC with dexmedetomidine or IPC in an equine model of small intestinal ischaemia-reperfusion (IR). In a randomized controlled experimental trial, 15 horses were assigned to three groups: control (C), IPC, and PPC with dexmedetomidine (DEX). All horses were placed under general anaesthesia and 90% je...
Decloedt A, Van Steenkiste G, Vera L, Buhl R, van Loon G.Atrial fibrillation (AF) is suspected by an irregularly irregular rhythm during auscultation at rest and should be confirmed by electrocardiography. Heart rate monitoring is potentially interesting for AF detection by horse owners, based on the disproportionally high heart rate during exercise or increased heart rate variability. Echocardiography and laboratory analysis are useful to identify underlying cardiac disease. Horses with severe cardiac disease should not undergo cardioversion due to the risk of recurrence. Cardioversion is recommended especially in horses performing high intensity e...
Reese RE, Andrews FM.Equine gastric ulcer syndrome (EGUS) is common in horses. Diagnosis is based on history, clinical signs, gastroscopic examination, and response to treatment. Effective pharmacologic agents are available to treat EGUS, but more comprehensive measures of environmental and dietary management are needed to decrease ulcer severity and recurrence. This article provides an understanding of dietary components and how feeds interact with stomach mucosal barrier function to cause EGUS. In addition, a secondary goal is to provide information on how diet and environmental management can reduce ulcer sever...
Gelzer AR, Moïse NS, Vaidya D, Wagner KA, Jalife J.Atrial fibrillation (AF) is common in healthy horses. We studied the temporal organization of AF to test the hypothesis that the arrhythmia is governed by a high degree of periodicity and therefore is not random in the horse. Further, we surmised that concealed conduction of AF impulses in the AV node results in an inverse relationship between AF frequency and ventricular frequency. Results: Fast Fourier transform (FFT) analysis of atrial activity was done on signal-averaged ECGs (n = 11) and atrial electrograms (n = 3) of horses with AF at control (C), after quinidine sulfate (22 mg/kg by mou...
Weber LA, Puff C, Kalbitz J, Kietzmann M, Feige K, Bosse K, Rohn K, Cavalleri JV.The naturally occurring betulinic acid (BA) and its derivative NVX-207 show anticancer effects against equine malignant melanoma (EMM) cells and a potent permeation in isolated equine skin in vitro. The aim of the study was to determine the in vivo concentration profiles of BA and NVX-207 in equine skin and assess the compounds' local and systemic tolerability with the intent of developing a topical therapy against EMM. Eight horses were treated percutaneously in a crossover design with 1% BA, 1% NVX-207 or a placebo in a respective vehicle twice a day for seven consecutive days with a seven-d...
