Oral administration in horses refers to the delivery of medications, supplements, or nutrients via the mouth. This method is commonly used in equine veterinary medicine for its practicality and ease of use. Oral formulations can include powders, pastes, or liquids, which are designed to be palatable and easily ingested by horses. The effectiveness of oral administration depends on factors such as the horse's digestive physiology, the formulation of the product, and the consistency with which it is administered. This page compiles peer-reviewed research studies and scholarly articles that explore the techniques, efficacy, and considerations of oral administration in equine care.
Macias A, Delvescovo B, Donaldson SF, Divers TJ, Donnelly CG.Ursodeoxycholic acid (UDCA), a secondary bile acid (BA) with therapeutic applications, is standard therapy for cholestatic hepatopathies in humans. In recent years, its use has been increasingly explored in equine medicine for similar indications. Pharmacokinetic data for UDCA in horses are currently lacking. This study aimed to describe the pharmacokinetic parameters following a single intragastric administration of 15 mg/kg in nine healthy, fasted horses and to characterize the changes in their BA profiles. Plasma concentrations of UDCA were measured at specific time points using liquid ch...
Morales CJ, Sykes BW, McKemie DS, Kass PH, Knych HK.Current treatment options for equine gastric ulcer syndrome (EGUS), such as omeprazole-a proton pump inhibitor (PPI)-have notable limitations, including the need for administration on an empty stomach. Potassium-competitive acid blockers (P-CABs), such as vonoprazan, are a newer class of acid suppressants that offer several advantages over PPIs in humans and may provide similar benefits in horses. Objective: To describe the pharmacokinetics and effect of a single oral dose of vonoprazan on intragastric pH in horses. We hypothesised that vonoprazan would follow linear kinetics across the doses ...
Calero IM, McKenzie EC, Johns JL.This report describes the diagnosis and successful management of a yearling filly with Coombs-positive anemia, thrombocytopenia, and fungal pneumonia. Diagnostic procedures, including thoracic ultrasonography and radiography, respiratory pathogen PCR testing, and evaluation of tracheal wash and bronchoalveolar lavage samples established multi-pathogen lower respiratory tract infection including a fungal agent. Orally administered voriconazole was a key component of treatment in this case to successfully eliminate fungal infection, alongside therapies for managing hematologic disease. This case...
Kuroda T, Minamijima Y, Niwa H, Mita H, Nomura M, Ohta M.A pharmacokinetics/pharmacodynamics (PK/PD) approach was used to determine the dosage regimens of trimethoprim/sulfamethoxazole for methicillin-resistant Staphylococcus aureus (MRSA) infections after intravenous (IV) and per os (PO) administration in horses. Methods: Trimethoprim/sulfamethoxazole plasma concentrations were measured in six horses after a single IV administration of 15 mg/kg (2.5 mg/kg trimethoprim and 12.5 mg/kg sulfamethoxazole) and PO administration of 30 mg/kg (5.0 mg/kg trimethoprim and 25.0 mg/kg sulfamethoxazole). The data were modeled using a nonlinear mixed-effects mode...
Wermer K, Korbacska-Kutasi O, Berkecz R, Csupor D, Ágh N, Sztojkov-Ivanov A, Cserhalmi D.Cannabidiol (CBD) has shown potential therapeutic benefits in veterinary medicine, but further investigations are needed to establish its pharmacokinetics and therapeutic dosing in horses and ponies. The present study aimed to investigate the pharmacokinetic properties of CBD in Connemara ponies following oral administration of CBD oil. Unassigned: Ten healthy ponies received a single oral dose of CBD oil at 2 mg/kg. Blood samples were collected before dosing and up to 16 days post-administration, with physical examinations conducted at baseline and at 8, 12, and 24 h post-dose. Addition...
Bazzano M, Laus F, Cerquetella M, Spaterna A, Marchegiani A.Phytocannabinoids have the potential to lower intraocular pressure in both normal and glaucomatous eyes and they have been tested in different animal species, but not in the horse. The present paper describes the tonometric curve of healthy adult Italian Saddle horses after oral administration of cannabidiol oil (CBD). Methods: CBD 20% was administered orally (oily solution) at the dose of 1 mg/kg to 8 adult horses and intraocular pressure (IOP) was evaluated by tonometric curve. Data were then compared to those of the same horses obtained the day before (blank) CBD administration. Results: ...
Kamutzki CJ, Emmerich IU.In 2024, there was no release of a novel pharmaceutical agent for horses and food-producing animals or an extension of existing active ingredients to other animal species on the German veterinary medicinal products market. Formic acid is now available for a new form of treatment, the short-term treatment of honeybees, and clenbuterol is available in a new dosage form, as an oral solution for horses. In the field of immunological veterinary medicinal products, three new vaccines were launched on the German veterinary medicinal products market. For the first time, a vaccine against in cattle, a...
Quattrini C, Knych HK, Magdesian KG.Alprazolam is used to facilitate mare-foal bonding in aggressive or anxious postpartum mares. In humans, alprazolam crosses the blood-milk barrier, but the amount transferred into milk is minor and compatible with breastfeeding as the relative infant dose is < 10%. Similar data are not available for horses. The aim of this study was to measure alprazolam in serum and milk of mares (milk: serum ratio) administered alprazolam, and to determine alprazolam serum concentrations in nursing foals to estimate the extent of absorption. This was a prospective observational study involving 7 healthy...
Kazama T, Hector RC, Hess AM, Rezende ML.To determine the cardiopulmonary effects of oral trazodone before isoflurane anesthesia in systemically healthy horses. Unassigned: 12 horses donated for euthanasia (from August 2022 through June 2023) due to conditions unrelated to the cardiovascular system were included in this prospective, randomized, controlled trial. Horses were assigned to receive oral trazodone (6 mg/kg; n = 7) or corn syrup (n = 5) 1 hour before xylazine (1 mg/kg, IV) sedation, ketamine (2.2 mg/kg, IV) and propofol (0.7 mg/kg, IV) induction, and anesthetic maintenance with inhaled isoflurane (target 1.6% expired) for 7...
Palmer AT, Watts MR, Timko KJ, Pinnell EF, Keefer KA, Gorman O, Hostnik LD, Burns TA.Corticosteroids are used routinely in horses and induce insulin dysregulation (ID). Nutrition is important for ID management and includes low nonstructural carbohydrate (NSC) diets and, often, high-protein ration balancers (RB). Insulin and incretin secretion increase after high-protein meals; corticosteroids may influence these effects. Objective: A high-protein mixed meal will induce hyperinsulinemia and increased concentrations of glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) in horses with ID; dexamethasone (DEX) will amplify this effect. Methods: F...
Pain management in horses plays a pivotal role in the therapeutic approach to several diseases. Horses have cannabinoid receptors at the level of dorsal root ganglia, blood vessels, and synoviocytes that can be up or down- regulated by inflammatory conditions, justifying the possible efficacy of exogenous cannabinoids (i.e., phytocannabinoids) in managing several painful pathologies in this animal species. However, the current use of supplements containing cannabidiol (CBD) in equines is based on anecdotal evidence, without the support of sufficient pharmacokinetic studies. In humans, the conc...
Dedecker L, Ceriotti S, Mora-Pereira M, Knych HK, Zuber E, Lascola KM.To describe and compare the pulmonary and plasma pharmacokinetics of different oral formulations of chloramphenicol administered as a single dose to healthy adult horses. Unassigned: A single dose of chloramphenicol was administered to 6 healthy, university-owned fasted adult horses IV (25 mg/kg), orally as commercial tablets (50 mg/kg), or orally or intragastrically as compounded suspension (50 mg/kg), according to a randomized crossover protocol. Plasma was collected 5, 10, 15, 20, and 30 minutes and 1, 1.5, 2, 3, 4, 6, 8, 12, and 24 hours after drug administration. Bronchoalveolar lavage (B...
Wang TC, Wakshlag JJ, Jager MC, Schwark WS, Trottier NL, Chevalier JM, Pearson G, Cercone M.To compare the pharmacokinetics of cannabidiol (CBD) and cannabidiolic acid (CBDA) in horses and to evaluate the safety of their chronic administration. Methods: CBD- and CBDA-rich oil (1 mg/kg) were administered orally twice daily to 7 adult horses over 6 weeks in a randomized, crossover design with a 2-week washout period. A 12-hour pharmacokinetic analysis was conducted on day 1 of each 6-week trial, followed by the measurement of peak and trough concentrations at weeks 1, 2, 4, and 6. The cannabinoids safety was assessed via daily physical examination, periodic bloodwork, and liver biopsy ...
Shroff K, Stefanovski D, Reef VB, Kraus MS, Solis CN.Information about congestive heart failure (CHF) treatment in the horse is limited. Torsemide, an oral loop diuretic, is increasingly used in humans, dogs, and cats with CHF. Torsemide is well absorbed and induces diuresis in healthy horses, and its use in a horse with CHF has been reported. This retrospective descriptive study aimed to describe the use of torsemide in equids with CHF. Methods: 12 equids (10 horses, 1 miniature donkey, and 1 mule). Methods: Horses presented to a referral practice with clinical signs of congestive heart failure. Diagnosis was confirmed with echocardiography. Tr...
Smith MZ, York M, Townsend KS, Martin LM, Gull T, Coghill LM, Ericsson AC, Johnson PJ.Whereas restoration of fecal consistency after treatment with clioquinol for chronic diarrhea and free fecal water syndrome has been attributed to its antiprotozoal properties, actions of clioquinol on the colonic bacterial microbiota have not been investigated. Objective: Characterize the dynamics of fecal microbial diversity before, during, and after PO administration of clioquinol to healthy horses. Methods: Experimental prospective cohort study using a single horse group. Methods: Eight healthy adult horses received PO clioquinol (10 g, daily) for 7 days. Feces were obtained daily for ...
Kaufman KL, Suagee-Bedore JK, Johnson SE, Ely KM, Ghajar SJ, McIntosh BM.Forage is essential for equine health and performance, but intake of elevated pasture nonstructural carbohydrates (NSC) may exacerbate metabolic disorders. This study aimed to investigate the influence of laminitis history on metabolic and morphometric responses in grazing horses. Twelve non-pregnant mares (15 ± 3.4 yrs) were selected based on previous diagnosis of laminitis (PRELAM; n=6) or not (NOLAM; n=6). Horses were maintained on 8.5-ha pasture. Weekly pasture samples were clipped at random for nutrient analysis. Monthly blood samples were collected and analyzed for glucose and insulin c...
Loos CMM, Zhao S, Li L, Li J, Han W, Vanzant ES, McLeod KR.The objective of this study was to investigate the effect of essential oil (EO) supplementation on insulin sensitivity (IS) and the plasma metabolome in insulin dysregulated (ID) horses. Horses were blocked by degree of IS and assigned randomly to treatment: oral daily bolus (50 mL) of either a plant derived EO supplement or carrier (CON). Mares were housed in dry lots with access to grass hay and supplemented individually twice daily with a concentrate to meet nutrient requirements for mature horses. Before and after 6 wks of treatment, mares underwent a combined glucose-insulin tolerance ...
Jargielo MM, Kritchevsky JE, Bertin FR.Pergolide, labeled for the treatment of pituitary pars intermedia dysfunction, is 90% protein bound and might cause a decrease in blood thyroid hormone concentrations by displacing them from binding proteins. This study investigated the effect of pergolide on the equine thyroid function. Methods: This was an analytic, observational, cohort study. Six horses (17 to 24 years old and 530 to 599 kg) received 1 mg of pergolide mesylate orally once a day from days 1 to 6. Total T4 (tT4) was measured daily from day 0 to 11 (before, during, and after pergolide treatment). Thyrotropin-releasing hormone...
de Moura Alonso J, Watanabe MJ, de Moraes Gimenes Bosco S, Apolonio EVP, de Vasconcelos AB, do Prado AC, Alves ALG, Rodrigues CA, Hussni CA.Fungal rhinitis in horses is rare, although severe, due to the progressive nasal obstruction. Aspergillus is one of the fungi most often involved in these cases. A 7-year-old Quarter Horse mare weighing 325 kg was admitted with a history of recurrent nasal discharge and bleeding, foul smell, reluctance to exercise, and abortion. Laboratory and imaging examinations revealed eosinophilia, scarring and erosion areas in the nasal mucosa, purulent and bloody secretions, and remarkable yellowish plaques. Histopathological examination revealed fungal rhinitis and bacterial culture revealed the prese...
Sundra T, Knowles E, Rendle D, Kelty E, Lester G, Rossi G.The metabolic and lipid profiles of horses treated with sodium-glucose cotransporter 2 inhibitors are not well understood. This retrospective study evaluated blood parameters in hyperinsulinemic horses treated with either ertugliflozin (0.05 mg/kg) or dapagliflozin (0.02 mg/kg) orally once daily. Blood samples were collected at baseline (day 0) and after 7 and/or 30 days of treatment. Statistical analyses were conducted using Wilcoxon signed-rank, Mann-Whitney and Spearman's rank correlation tests. Thirty-four horses received dapagliflozin and 24 received ertugliflozin. Significant (p<0.05)...
Philip M, Karakka Kal AK, Subhahar MB, Karatt TK, Graiban FM, Ajeebsanu MM, Joseph M, Jose SV.The phosphodiesterase 4 (PDE4) inhibitors constitute a relatively modern class of medications that are known for inducing bronchodilation and exhibiting anti-inflammatory properties within the body. Due to these properties, there is concern regarding their potential misuse as performance-enhancing substances in competitive sports. This study delves into the metabolic conversion of roflumilast in thoroughbred horses following oral administration and in vitro experimentation using equine liver microsomes and Cunninghamella elegans. High-performance liquid chromatography coupled with a Q Exactiv...
Elbourne M, Keledjian J, Cawley A, Fu S.Altrenogest, also known as allyltrenbolone, is a synthetic form of progesterone used therapeutically to suppress unwanted symptoms of estrus in female horses. Altrenogest affects the system by decreasing levels of endogenous gonadotrophin and luteinizing and follicle-stimulating hormones, which in turn decreases estrogen and mimics the increase of progesterone production. This results in more manageable mares for training and competition alongside male horses while improving the workplace safety of riders and handlers. However, when altrenogest is administered, prohibited steroid impurities su...
Muñoz-García CC, Luis-Calero M, Fernández-Hernández P, Pizarro-Hernández A, Fernández-González R, Gutiérrez-Adán A, Sánchez-Calabuig MJ....The present study aimed to evaluate whether primed anoestrus mares are suitable recipients for embryos produced by intracytoplasmic sperm injection (ICSI). Anoestrus was confirmed in four mares and daily doses of oestradiol benzoate (6 mg in total) over 5 days were administered; after 3 days of rest, oral altrenogest was administered at 0.088 mg/kg and embryos (1 to 5 embryos per mare; 15 in total) were transferred 3.5 days after progesterone onset. Uterine lavage was conducted 48 h after transfer. The results revealed an 80% embryo recovery rate, and among the retrieved embryos, 6...
Galinelli NC, Bamford NJ, Erdody ML, Warnken T, de Laat MA, Sillence MN, Harris PA, Bailey SR.Alpha-methyl-para-tyrosine (AMPT) is a reversible inhibitor of tyrosine hydroxylase, the rate-limiting enzyme in catecholamine synthesis. This study aimed to determine whether AMPT could reduce dopamine concentrations in horses. Six healthy adult Standardbred geldings were administered AMPT (40 mg/kg BW, orally) or placebo in a randomised crossover study design. Clinical examination findings were recorded, and blood samples were collected for up to 6 h after administration of AMPT or placebo, for measurement of blood glucose, plasma ACTH and cortisol concentrations, and plasma metabolomic anal...
Philip M, Kal AKK, Subhahar MB, Karatt TK, Graiban FM, Ajeebsanu MM, Joseph M, Jose SV.Phosphodiesterase 4 (PDE4) inhibitors are a newer class of drugs that induce bronchodilation and have anti-inflammatory effects, making them susceptible to misuse as performance enhancers in competitive sports. Methods: This study explores the metabolic conversion of PDE4 inhibitor ibudilast in thoroughbred horses after oral administration and in vitro using equine liver microsomes and Cunninghamella elegans. A liquid chromatography-high resolution mass spectrometry method was used to postulate the plausible structures of the detected metabolites. Results: A total of 20 in vivo metabolites wer...
Loy J, Cawley A, Sornalingam K, Scrivener CJ, Keledjian J, Noble GK.Altrenogest is a synthetic progestin that suppresses reproductive behaviours and assists pregnancy maintenance in female horses. Two formulations are available, a 'weekly' intramuscular injection and a daily oral formulation. Altrenogest administration has returned positive swabs for steroids; consequently, using injectable altrenogest in racing mares is prohibited. Oral administration may be permitted in race mares if there is one clear day between dosing and racing. The only pharmacokinetic data available were generated from geldings. Therefore, to assist veterinarians and analysts in determ...
Knych HK, Steinmetz SJ, Traynham ML, McKemie DS, Kass PH.Morphine is an effective analgesic in horses, however, IV administration at therapeutic doses has been shown to produce dose-dependent neuroexcitation and unwanted gastrointestinal effects. The analgesic effects of morphine have, at least in part, been attributed to the morphine-6-glucuronide (M6G) metabolite. Oral administration to horses results in comparable M6G concentrations to that achieved following IV administration of a therapeutic dose without the adverse effects. The anti-nociceptive effects have not yet been reported. In the current study the thermal anti-nociceptive effects of sin...
Knych HK, Blea J, Scollay M, Kass PH, McKemie DS.Ethanol, a central nervous system depressant and banned substance in horseracing, has reportedly been administered to horses prior to competition to "calm a horse's nerves." In this study, the pharmacokinetics of two metabolites of ethanol were studied to better understand the behavior of this compound in the horse and provide a scientific basis for regulation of its administration. Six horses received a single intravenous (30 mL; 1200 mg) and oral (90 mL; 3600 mg) administration of ethanol (vodka, 40% ABV) in a balanced cross-over design. Blood and urine samples were collected at vari...
Swanton WE, Johnson R, Zhao Q, Schroeder C.To evaluate sedation and IV xylazine requirements to achieve 45% of baseline head height above ground measurements following oral (PO) administration of 2 trazodone dosages. Methods: 8 healthy, adult mares of various weights and breeds belonging to a university teaching herd were utilized in a blinded, crossover study design. Horses were randomly assigned to 1 of 3 PO treatments: control (no trazodone), trazodone at 3 mg/kg (low dose [LD]), or trazodone at 6 mg/kg (high dose [HD]). Before treatment, cardiac auscultation, EquiSed sedation score, and head height above ground (HHAG; cm) measureme...
Jacquay ET, Harris PA, Adams AA.It is unknown whether short-term transportation affects endocrine responses similarly in horses with and without insulin dysregulation (ID). Objective: To characterise the effect of short-term transportation on stress parameters and insulin responses to an oral sugar test (OST) in horses with and without ID. Methods: Longitudinal cohort study. Methods: Fourteen adult non-pregnant, non-PPID mares of mixed light breeds were grouped as either ID (n = 7) or non-ID (n = 7) based on endocrine testing. Over 2 weeks, horses were transported once, in groups of 3-4 in a horse trailer on a roun...
Kellerman TS, Marasas WF, Thiel PG, Gelderblom WC, Cawood M, Coetzer JA.Leukoencephalomalacia (LEM) was induced by the oral administration of fumonisin B1 (FB1) to 2 horses: a filly received 59.5 mg/kg of a 50% preparation of FB1, administered in 21 doses of 1.25-4 mg/kg over 33 days; a colt, 44.3 mg/kg of 95% pure FB1 in 20 doses of 1-4 mg/kg in 29 days. Both animals developed nervous signs such as apathy, changes in temperament, inco-ordination, walking into objects, and one showed paralysis of the lips and tongue. Characteristic lesions of LEM were present in the brains. These trials proved conclusively that FB1 can induce LEM in horses.
Laverty S, Sandy JD, Celeste C, Vachon P, Marier JF, Plaas AH.To examine the concentration of glucosamine in the synovial fluid and its pharmacokinetics in serum in a large animal model following dosing with glucosamine HCl at clinically relevant levels. Methods: Eight adult female horses were studied. After an overnight fast, glucosamine HCl (20 mg/kg of body weight) was administered by either nasogastric (NG) intubation or intravenous (IV) injection. Blood samples were collected before dosing and at 5, 15, 30, 60, 120, 180, 240, 360, 480, and 720 minutes after dosing. Synovial fluid samples were collected from the radiocarpal joints 48 hours before dos...
Ryan D, McKemie DS, Kass PH, Puschner B, Knych HK.The increasing availability of cannabidiol (CBD) and anecdotal reports of its anti-inflammatory effects has garnered it much interest in the equine industry. The objectives of the current study were to (1) describe the pharmacokinetics of oral CBD in exercising thoroughbreds, (2) characterize select behavioral and physiologic effects, and (3) evaluate effects on biomarkers of inflammation using an ex vivo model. This study was conducted in a randomized balanced 3-way crossover design with a two-week washout period between doses. Horses received a single oral dose (0.5, 1, and 2 mg/kg) of CBD...
Akerreta S, Calvo MI, Cavero RY.To collect, analyze and evaluate the ethnoveterinary knowledge about medicinal plants in a northern Iberian region (Navarra, 10,421 km(2), 620,377 inhabitants). Methods: Field work was conducted between 2003 and 2007, using semi-structured questionnaire and participant observation as well as transects walks in wild herbal plant collection areas. We performed semi-structured interviews with 667 informants (mean age 72; 55.47% women, 44.53% men) in 265 locations, identified the plant reported and analyzed the results, comparing them with those from other territories. Results: Out of 287 species ...
Meulyzer M, Vachon P, Beaudry F, Vinardell T, Richard H, Beauchamp G, Laverty S.To compare the pharmacokinetics of glucosamine and the synovial fluid levels attained following treatment with glucosamine sulphate or glucosamine hydrochloride in a large animal model at clinically relevant doses. Methods: Eight adult female horses were used. Crystalline glucosamine sulphate (Dona) or glucosamine hydrochloride was administered at a dose of 20 mg/kg by either intravenous (i.v.) injection or nasogastric (n.g.) intubation. Plasma samples were collected before dosing and at 5, 15, 30, 60, 120, 360, 480 and 720 min after dosing. Synovial fluid samples were collected from the radio...
Davis JL, Salmon JH, Papich MG.To determine pharmacokinetics, safety, and penetration into interstitial fluid (ISF), polymorphonuclear leukocytes (PMNLs), and aqueous humor of doxycycline after oral administration of single and multiple doses in horses. Methods: 6 adult horses. Methods: The effect of feeding on drug absorption was determined. Plasma samples were obtained after administration of single or multiple doses of doxycycline (20 mg/kg) via nasogastric tube. Additionally, ISF, PMNLs, and aqueous humor samples were obtained after the final administration. Horses were monitored for adverse reactions. Results: Feeding ...
Stradaioli G, Sylla L, Zelli R, Chiodi P, Monaci M.The effect of orally administered l-carnitine on the quality of semen obtained from stallions with different semen qualities was investigated. Four stallions with proven fertility (high motility group, HM) and with normal seminal characteristics (>50% progressive motility and > 80 x 10(6) spermatozoa/ml), and four questionable breeders (low motility group, LM) with <50% of sperm progressive motility and < 80 x 10(6) spermatozoa/ml, received p.o. 20 g of l-carnitine for 60 days. Blood and semen samples were collected before treatment (T0) and after 30 (T1) and 60 days (T2). Semen ev...
Garré B, Gryspeerdt A, Croubels S, De Backer P, Nauwynck H.The purpose of the current study was to investigate the therapeutic efficacy of valacyclovir against EHV1 in a controlled study. Eight naïve Shetland ponies were inoculated with 10(6.5) TCID(50) of the neuropathogenic strain 03P37. Four ponies were treated with valacyclovir at a dosage of 40mg/kg bodyweight, 3 times daily, for 5 (n=2) or 7 (n=2) consecutive days, while the other four ponies served as untreated controls. The treatment regimen started 1h before inoculation. Ponies were monitored daily for clinical signs. At 0, 1, 2, 3, 4, 5, 7, 9, 11, 14, 17 and 21 days post inoculation (d pi),...
Toutain PL, Reymond N, Laroute V, Garcia P, Popot MA, Bonnaire Y, Hirsch A, Narbe R.To determine pharmacokinetic parameters for meloxicam, a nonsteroidal anti-inflammatory drug, in horses. Methods: 8 healthy horses. Methods: In the first phase of the study, horses were administered meloxicam once in accordance with a 2 x 2 crossover design (IV or PO drug administration; horses fed or not fed). The second phase used a multiple-dose regimen (daily oral administration of meloxicam for 14 days), with meloxicam administered at the recommended dosage (0.6 mg/kg). Plasma and urine concentrations of meloxicam were measured by use of validated methods with a limit of quantification of...
Chirino-Trejo JM, Prescott JF, Yager JA.Two groups of three one to three week old foals were immunized orally on four occasions over five weeks with two strains of Rhodococcus equi, a clinical isolate from a pneumonic foal and a laboratory passaged Congo red negative variant of this strain. Three nonimmunized foals of similar age acted as controls. Three weeks after the last immunization, all foals were challenged on five occasions over seven days by aerosol infection with about 10(10) of the pneumonic foal isolate on each occasion. Control foals became seriously ill and were euthanized. Immunization with either strain protected foa...
Garrison KL, Sahin S, Benet LZ.This study was conducted to determine the number of drugs exhibiting flip-flop pharmacokinetics following oral (p.o.) dosing from immediate-release dosage forms and if they exhibit a common characteristic that may be predicted based on BDDCS classification. The literature was searched for drugs displaying flip-flop kinetics (i.e., absorption half-life larger than elimination half-life) in mammals in PubMed, via internet search engines and reviewing drug pharmacokinetic data. Twenty two drugs were identified as displaying flip-flop kinetics in humans (13 drugs), rat (nine drugs), monkey (three ...
Doucet MY, Bertone AL, Hendrickson D, Hughes F, Macallister C, McClure S, Reinemeyer C, Rossier Y, Sifferman R, Vrins AA, White G, Kunkle B, Alva R....To compare efficacy and safety of paste formulations of firocoxib and phenylbutazone in horses with naturally occurring osteoarthritis. Methods: Randomized controlled clinical trial. Methods: 253 client-owned horses with naturally occurring osteoarthritis. Methods: Horses were treated with firocoxib (0.1 mg/kg [0.045 mg/lb], PO, q 24 h) or phenylbutazone (4.4 mg/kg [2 mg/lb], PO, q 24 h) for 14 days. Physical examinations and lameness evaluations were performed prior to treatment and after 7 and 14 days. Clinical improvement was defined as a reduction of at least 1 lameness grade or a combined...
Yocom AF, O'Fallon ES, Gustafson DL, Contino EK.Cannabidiol (CBD) products are widely marketed to horse owners, trainers, and veterinarians and are readily available to the consumer despite minimal pharmacokinetic or safety data being available. The objectives of this study were to determine the plasma pharmacokinetics, short-term safety, and synovial fluid levels of CBD following oral administration in horses. A prospective, randomized, controlled study design was used. Twelve horses were administered sunflower lecithin oil-based CBD at either 1 mg/kg (Group 1) or 3 mg/kg (Group 2) for a 24-hour pharmacokinetic study. Horses then received ...
Bell RJ, Mogg TD, Kingston JK.In recent years, gastric ulceration has been recognised as a common, possibly performance-limiting disease of adult horses. Here, we aim to provide the reader with a useful review of recent literature covering all aspects of equine gastric ulcer syndrome (EGUS) in adult horses. The anatomy and physiology of the stomach, with particular reference to secretion of acid and mucosal protective mechanisms, are reviewed, as are the differing theories relating to the aetiopathogenesis of gastric ulceration. We also explore the possible influence of various management factors on development of the dise...
Merritt AM, Sanchez LC, Burrow JA, Church M, Ludzia S.Ulceration of the squamous gastric mucosa is commonly associated with intensive training programmes in horses, but only one compound ('Gastrogard') has been subjected to controlled scrutiny as to therapeutic efficacy. Objective: To compare the gastric acid inhibitory efficacy of one manufactured ('GastroGard') and 3 generic pharmacy-compounded preparations of the proton pump inhibitor omeprazole (OME) in the mature horse. Objective: All OME preparations tested would induce a clinically acceptable effect. Methods: Six healthy mature gastrically cannulated horses of various breeds, 3 mares and 3...
Clode AB, Davis JL, Salmon J, Michau TM, Gilger BC.To determine penetration of topically and orally administered voriconazole into ocular tissues and evaluate concentrations of the drug in blood and signs of toxicosis after topical application in horses. Methods: 11 healthy adult horses. Methods: Each eye in 6 horses was treated with a single concentration (0.5%, 1.0%, or 3.0%) of a topically administered voriconazole solution every 4 hours for 7 doses. Anterior chamber paracentesis was performed and plasma samples were collected after application of the final dose. Voriconazole concentrations in aqueous humor (AH) and plasma were measured via...
Rendle DI, Rutledge F, Hughes KJ, Heller J, Durham AE.Metformin is a potential therapeutic agent for the treatment of insulin resistance (IR). In laboratory animals, orally administered metformin reduces intestinal glucose absorption and may therefore affect insulinaemic responses to oral carbohydrate ingestion. Objective: To determine whether pretreatment with metformin reduces plasma glucose concentration and insulin responses following consumption of dextrose in horses. Methods: Therapeutic cross-over study. Methods: Seven healthy Standardbred and Thoroughbred geldings were subjected to an oral dextrose challenge test on 4 occasions: with and ...
Kvaternick V, Pollmeier M, Fischer J, Hanson PD.The primary objective of this study was to determine the pharmacokinetic profile of firocoxib, a novel second generation coxib, in horses. Horses were administered either a single oral or intravenous dose of firocoxib at 0.1 mg/kg in a two-period crossover study with 12 animals. The dosage was based on previously determined pharmacodynamic parameters. Oral firocoxib was well absorbed with an average bioavailability (absolute) of 79% and a Cmax of 75 ng/mL at 3.9 h. The average elimination half-life was 30 h. Following intravenous administration the average Cmax was 210 ng/mL and the eliminatio...
Sánchez de Medina A, Serrano-Rodríguez JM, Díez de Castro E, García-Valverde MT, Saitua A, Becero M, Muñoz A, Ferreiro-Vera C....Intravenous pharmacokinetics and oral bioavailability of cannabidiol (CBD) with different formulations have not been investigated in horses and may represent a starting point for clinical studies. Objective: To describe pharmacokinetics after intravenous and oral administrations with oil and micellar formulations and simulate different treatments. Methods: Single intravenous experiment and two-way randomised oral experiments, Latin-square design. Methods: Eight healthy horses received intravenous CBD at 1.00 mg/kg dose, oral CBD in sesame oil and in micellar formulation, both at 10.00 mg/k...
Weese JS, Anderson ME, Lowe A, Monteith GJ.This study was designed to evaluate whether Lactobacillus rhamnosus strain GG (LGG), an extensively studied probiotic organism in humans, can colonize the intestines of adult horses and foals. Lactobacillus rhamnosus strain GG was administered to adult horses at doses of 1 x 10(9) CFU/50kg bodyweight (BW)/day (group 1, 7 horses), 1 x 10(10) colony forming units/ 50kg BW/day (group 2, 7 horses) and 5 x 10(10) colony forming units/50kg BW/day (group 3, 7 horses) for 5 d. Foals received 2 x 10(10) colony forming units/50kg BW/day (group 1, 7 foals) or 1 x 10(11) colony forming units/50kg BW/day (...
Waller AP, Geor RJ, Spriet LL, Heigenhauser GJ, Lindinger MI.Oral acetate supplementation enhances glycogen synthesis in some mammals. However, while acetate is a significant energy source for skeletal muscle at rest in horses, its effects on glycogen resynthesis are unknown. We hypothesized that administration of an oral sodium acetate-acetic acid solution with a typical grain and hay meal after glycogen-depleting exercise would result in a rapid appearance of acetate in blood with rapid uptake by skeletal muscle. It was further hypothesized that acetate taken up by muscle would be converted to acetyl CoA (and acetylcarnitine), which would be metaboliz...
Hustace JL, Firshman AM, Mata JE.To determine pharmacokinetics and oral bioavailability of metformin in healthy horses. Methods: 4 adult horses. Methods: 6 g of metformin was administered 3 times IV and PO (fed and unfed) to each horse, by use of a crossover design, with a 1-week washout period between treatments. Plasma metformin concentration was determined via high-pressure liquid chromatography. Results: Mean +/- SD distribution half-life of metformin following IV administration was 24.9 +/- 0.4 minutes with a volume of distribution of 0.3 +/- 0.1 L/kg. Mean area under the curve was 20.9 +/- 2.0 h.microg/mL for IV adminis...
Waters LJ, Hanrahan JP, Tobin JM, Finch CV, Parkes GMB, Ahmad SA, Mohammad F, Saleem M.Three mesoporous silica excipients (Syloid® silicas AL-1 FP, XDP 3050 and XDP 3150) were formulated with a model drug known for its poor aqueous solubility, namely phenylbutazone, in an attempt to enhance the extent and rate of drug dissolution. Although other forms of mesoporous silica have been investigated in previous studies, the effect of inclusion with these specific Syloid® silica based excipients and more interestingly, with phenylbutazone, is unknown. This work reports a significant enhancement for both the extent and rate of drug release for all three forms of Syloid® silica at a ...
Neirinckx E, Vervaet C, De Boever S, Remon JP, Gommeren K, Daminet S, De Backer P, Croubels S.Species differences in oral bioavailability, first-pass metabolism and pharmacokinetics of biopharmaceutics classification system (BCS) class I compound acetaminophen were studied. The absolute bioavailability was 42.2%, 39.0%, 44.5%, 75.5% and 91.0% in chickens, turkeys, dogs, pigs and horses, respectively. After hydrolysis of metabolites by beta-glucuronidase/sulfatase, apparent bioavailability increased significantly in all species (turkeys: 72.4%, dogs: 100.5%, pigs: 102.2%), except horses (91.6%). Mean metabolic ratios of [acetaminophen glucuronide]/[acetaminophen] between 0 and 1h were s...
Terry RL, McDonnell SM, Van Eps AW, Soma LR, Liu Y, Uboh CE, Moate PJ, Driessen B.Gabapentin is being used in horses although its pharmacokinetic (PK) profile, pharmacodynamic (PD) effects and safety in the equine are not fully investigated. Therefore, we characterized PKs and cardiovascular and behavioral effects of gabapentin in horses. Gabapentin (20 mg/kg) was administered i.v. or p.o. to six horses using a randomized crossover design. Plasma gabapentin concentrations were measured in samples collected 0-48 h postadministration employing liquid chromatography-tandem mass spectrometry. Blood pressures, ECG, and sedation scores were recorded before and for 12 h after gaba...
Cudmore LA, Muurlink T, Whittem T, Bailey SR.Pro-inflammatory cytokines, such as IL-1β and TNFα, play a major role in activating leukocytes and endothelial cells during the systemic inflammatory response to endotoxin in the horse. β2 agonist drugs, such as clenbuterol, inhibit leukocyte activation. This study aimed to determine the effects of oral clenbuterol on clinical and leukocyte responses, including production of TNFα, in an in vivo endotoxin challenge model. In a randomised crossover design, horses received either clenbuterol or a placebo product prior to the administration of low dose endotoxin (30 ng/kg over 30 min). Clinica...
Tyma JF, Epstein KL, Whitfield-Cargile CM, Cohen ND, Giguère S.OBJECTIVE To determine the effects of oral omeprazole administration on the fecal and gastric microbiota of healthy adult horses. ANIMALS 12 healthy adult research horses. PROCEDURES Horses were randomly assigned to receive omeprazole paste (4 mg/kg, PO, q 24 h) or a sham (control) treatment (tap water [20 mL, PO, q 24 h]) for 28 days. Fecal and gastric fluid samples were collected prior to the first treatment (day 0), and on days 7, 28, 35, and 56. Sample DNA was extracted, and bacterial 16S rRNA gene sequences were amplified and sequenced to characterize α and β diversity and differential ...
Noble G, Edwards S, Lievaart J, Pippia J, Boston R, Raidal SL.Safety of meloxicam, a potent NSAID with selective COX-2 inhibition, has not been evaluated in horses. Objective: To evaluate pharmacokinetics and safety of single and repeated oral doses of meloxicam in adult horses. Methods: Forty-nine healthy, university-owned adult lightbreed horses. Methods: Study conducted in 2 parts. Part I addressed pharmacokinetics of single oral dose meloxicam (0.6 mg/kg) in 16 horses. Part II, 33 horses were randomly assigned to 5 treatment groups to assess prolonged administration (0.6 mg/kg PO q24h for 6 weeks, n = 7) or higher doses (1.8 mg/kg, n = 7, or 3.0 mg/k...
Garré B, Shebany K, Gryspeerdt A, Baert K, van der Meulen K, Nauwynck H, Deprez P, De Backer P, Croubels S.The purpose of this study was twofold. The first aim was to evaluate the oral bioavailability and pharmacokinetics (PKs) of acyclovir in horses after intravenous (i.v.) administration and after oral administration of acyclovir and its prodrug, valacyclovir. Second, we aimed to combine these PK data with pharmacodynamic (PD) information, i.e., 50% effective concentrations (EC(50) values) from in vitro studies, to design an optimal dosage schedule. Three treatments were administered to healthy adult horses: 10 mg of acyclovir/kg of body weight delivered as an i.v. infusion over 1 h, 20 mg of acy...
