Drugs Approved for Use in Horses

Name of Drug Dose Route
Acepromazine 0.03-0.066 mg/kg for sedation IM
0.033-0.055 mg/kg followed by 0.055-0.066 mg/kg butorphanol IV
0.04 mg/kg followed by 0.6 mg/kg meperidine IV
0.02-0.055 mg/kg q8h for α-adrenoceptor blockade IM
Acetazolamide 2.2 mg/kg q12h-q6h PO
Acetylcysteine (10%) 2-5 ml/50 kg q6h Aerosol
10% topical solution q1-4h Ophthalmic
Aclometasone 0.05% Topical
Acyclovir 5-10 mg/kg q8h PO
Acyclovir 3% q3-4h Ophthalmic
Adrenocorticotrophic hormone 0.26 mg q8-12h (depot preparation) IM
0.125 mg/foal (tests adrenal function of premature foals) IV
Albendazole 25 mg/kg q12h for 5 days for Dictyocaulus arnfieldi PO
50 mg/kg q12h for 2 days for Strongylus vulvaris larvae PO
4-8 mg/kg q12h for 1 month for Echinococcus PO
Albuterol 1-2 μg/kg Inhalation
Alfaprostol 3 mg/450 kg for luteolysis; 2 doses 14-18 days apart IM
Allopurinol 5 mg/kg IV
alpha-tocopherol 1.5-4.4 mg/kg q24h PO
Altrenogest 0.044 mg/kg q24h for 8-12 days; for estrus synchronization follow with luteolytic dose of prostaglandin F PO
0.044 mg/kg to prevent aggression PO
0.44 mg/kg q24h for pregnancy maintenance PO
Aluminum hydroxide 200-250 ml q8h (antacid) PO
60 mg/kg PO
Amikacin 3.5-7.5 mg/kg q12h to q6h IM or SQ
15-20 mg/kg q24h IM or SQ
1-10 mg/kg q12h for foals Slow IV or IM
75-100 mg Subconjunctival
125-250 mg Intraartricular
2 g buffered with equal volume of 75% sodium bicarbonate Intrauterine
15 mg/ml; combine 250 mg amikacin with 15 ml artificial tears Ophthalmic
Aminocaproic acid 20 mg/kg diluted 1:9 in saline and administered over 30-60 min IV
Aminophylline 5-10 mg/kg q12h PO
Aminopropazine fumarate 0.5 mg/kg q12h IM or IV
Aminopyrine 2.5-10 mg/450 kg IV or IM
Ammonium chloride 20-520 mg/kg q24h (acidifier) PO
Amoxicillin 10-22 mg/kg q8h IM
Amoxicillin trihydrate 6-10 mg/kg q12h-q8h IM
Amphotericin B 0.05 mg/kg q2d for 1 month 

Introduce over 5 days; dissolve in 1 L 5% dextrose and administer over 1 hour via large-bore catheter

0.15% solution in 5% glucose topically 4-6 times daily Ophthalmic
Ampicillin Na 10-15 mg/kg q8h-q6h IV or IM
Ampicillin Na trihydrate 11-22mg/kg q12h or q8h IM or PO
50 mg Subconjunctival
50 mg/ml; reconstitute 1 g with 5 ml water and add 15 ml artificial tears Ophthalmic
Antidiuretic hormone 60 IU q6h for diabetes insipidus IV
Ascorbic acid 30mg/kg q12h in IV fluids IV
Aspirin 10-100 mg/kg q12h PO
Atipamezole 0.05-1.0 mg/kg IV
Atracurium 0.04-0.07 mg/kg IV
Atropine 0.01-0.1 mg/kg IV, IM, or SQ
Atropine HCl 0.5%-1.0% q6-48h Ophthalmic
Aurothioglucose 1 mg/kg IM
Azathioprine 2-5 mg/kg q24h loading dose, then q48h for maintenance PO
Azithromycin 10 mg/kg q24h for 5 days followed by q48h PO
Azlocillin 25-75 mg/kg q6h IV
Beclamethasone 3.75mg q12h Inhalation
Benztropine mesylate 8 mg Slow IV drip
Betamethasone 0.02-0.1 mg/kg IM or PO
4-10 mg Intralesional
Bethanecol 0.025-0.1 mg/kg q8h or q6h SQ
0.3-0.4 mg/kg q8h or q6h PO
Bismuth subsalicylate 0.5-1 ml/kg q4-6h in foals PO
1-2L/450 kg q12h PO
Boldenone undecylenate 1 mg/kg repeated at 3-week intervals IM
Botulinum antitoxin 100-150 IU/ml: 200 ml/foal or 500 ml/adult IV or IM
Bretylium tosylate 3-10 mg/kg IV
Buparavaquone 4-6 mg/kg, single dose IV
Butorphanol tartrate 0.01-2 mg/kg, see xylazine, detomidine, and acepromazine IV or IM
Caffeine 10 mg/kg loading dose, then 2.5-3 mg/kg q24h PO
Calcium chloride 1-2 g/450 kg, slowly to effect IV
Calcium gluconate 0.5 ml/kg of 10% solution Slow IV
Cambendazole 20 mg/kg for Strongyloides westeri PO
Captan 3% solution Topical
Carbenicillin Na indanyl 50-80 mg/kg q12h or q8h IV or IM
200 mg Subconjunctival
6g Intrauterine
Carbon disulfide 24 mg/450 kg PO
Carprofen 0.7 mg/kg q24h IV
Casein (iodinated) 5 g q24h PO
Cefaclor 20-40 mg/kg q8h PO
Cefadroxil 22 mg/kg q12h PO
25 mg/kg q4-6h for foals IV
Cefamandole 10-30 mg/kg q4-8h IV or IM
Cefazolin Na 15 mg/kg q12h or q8h IV or IM
50 mg Subconjunctival
50 mg/ml; reconstitute 1 gm with 5 ml water and add 15 ml artificial tears Ophthalmic
Cefepime 6 mg/kg q8h for adults IV
11 mg/kg q8h for foals IV
Cefixime 400 mg/kg q8h PO
Cefonicid 10-15 mg/kg q24h IV or IM
Cefoperazone 30-50 mg/kg q12h or q8h IV or IM
Ceforanide 5-10 mg/kg q12h IV or IM
Cefotaxime Na 15-25 mg/kg q12h-q8h IV or IM
Cefotetan 15-30 mg/kg q12h IV or IM
Cefoxitin 30-40 mg/kg q8h or q6h IM
20 mg/kg q6h IV
Ceftazidime 25-50 mg/kg q12h IV or IM
Ceftiofur 1-5 mg/kg q24h-q12h IV or IM
1 g Intrauterine
Ceftizoxime 25-50 mg/kg q12h or q8h IV or IM
Ceftriaxone 25-50 mg/kg q12h IV or IM
Cefuroxime 25-50 mg/kg q8h IV or IM
Cefuroxime axetil 250-500 mg/kg q12h PO
Cephalexin 10-30 mg/kg q8h-q6h PO
Cephalothin Na 20-40 mg/kg q8h-q6h IV or IM
100mg Subconjunctival
50 mg/ml; reconstitute 1 gm with 5 ml water and add 15 ml artificial tears Ophthalmic
Cephapirin 30 mg/kg q4-6h IV or IM
Cetizoxime Na 20-30 mg/kg q8h IV
Charcoal (activated) 1-3 g/kg as slurry (1 g in 5 ml water); repeat if necessary in 8-12 hours PO
Chloral hydrate 60-200 mg/kg for foal restraint IV
40-100 mg/kg PO
Chloramphenicol palmitate 4-10 mg/kg q8h or q6h (foal) PO
25-50 mg/kg q8h or q6h (adult) PO
Chloramphenicol succinate 25 mg/kg q8h-q6h IV or IM
50-100 mg Subconjunctival
Chlorhexidine 0.5%-2% Topical
Chlorpromazine 1 mg/kg IM
Cimetidine 6.6 mg/kg q4-6h IV
18 mg/kg q8h PO
2.5-4 mg/kg q8h for 2 months for tumor reduction PO
Cisapride 0.1 mg/kg IM
0.5-0.8 mg/kg q8h for 7 days PO
Clarithromycin 7.5 mg/kg q12h PO
Clenbuterol 0.8-3.2 μg/kg q12h PO
0.8 μg/kg q12h IV
200 μg for uterine relaxation IM or slow IV
Cloprostenol Na 250-500 μg/450 kg; can repeat in 30 min to 2 hours for parturition induction IM
Clotrimazole 500 mg suspension or cream q24h for 1 week Intrauterine
Cloxacillin 10-30 mg/kg q6h IM
Cocaine chloride 1-1.5 ml of 10 mg/ml Subconjunctival
Colistin 2500 IU/kg q6h Slow IV
Corticotropin 1 IU/kg IM
Coumaphos 0.06% wash, 0.1% dust Topical
Cromolyn sodium 80-300 mg Inhalation
Cyclophosphamide 200-300 mg/m2 q2-3wk IV
Cyclosporin A 0.2%-2.0% topical q6-12h Ophthalmic
Cyproheptadine 0.5 mg/kg q12h PO
Cytosine arabinoside 200-300 mg/m2 q1-2 wk with chlorambucil or cyclophosphamide IM or SQ
D-penicillamine 3-4 mg/kg q6h for 10 days PO
Danthron 15-30 ml/kg PO
Dantrolene Na 10 mg/kg loading dose; then 2.5 mg/kg q2h, maintenance PO
2-2.5 mg/kg in saline for acute myopathy Slow IV
1-2 mg/kg q24h to prevent myositis PO
Dembrexine 0.3-0.5 mg/kg PO
Demecarium bromide 0.25% q12h Ophthalmic
Detomidine 0.005-0.02 mg/kg IV
0.01-0.02 mg/kg followed by 0.044-0.066 mg/kg butorphanol IV
0.02-0.04 mg/kg followed by 2.2 mg/kg ketamine IV
Dexamethasone 0.02-0.2 mg/kg q24h IV, IM, or PO
0.5-2 mg/kg for septic shock IV
100 mg/450 kg q24h for 5 days to induce parturition IV
Dexamethasone phosphate 0.1% q8h Ophthalmic
Dexamethasone suspension 0.1% q3-8h Ophthalmic
Dextran (6% solution) 8 g/kg q24h for up to 3 days IV
Diazepam 0.03-0.5 mg/kg; repeat in 30 minutes if necessary Slow IV
Dichlorphenamide 1 mg/kg q12h PO
Dichlorvos 35 mg/kg PO
0.93% solution Topical
Dicloxacillin 10 mg/kg q6h IM
Diethylcarbamazine 1 mg/kg q24h for 21 days for onchocerciasis PO
50 mg/kg q24h for 10 days for verminous myelitis PO
Digoxin 0.002 mg/kg q12h IV
0.01 mg/kg q12h PO
Dihydrostreptomycin 11 mg/kg q12h IM or SQ
Dimercaprol 2.5-5 mg/kg as 10% solution in oil q4h for 2 days, then q12h until recovery IM
Dimethyl glycine 1-1.6 mg/kg q24h PO
Dimethyl sulfoxide (DMSO) 0.5 mg/kg to 1.0 g/kg (10% solution in 5% dextrose); repeat lower doses q6-12h IV
50% solution Topical
Dinoprost tromethamine 10 mg/450 kg IM
Dioctyl sodium sulfosuccinate 10-20 mg/kg in 4-8 L water q48h PO
Dioctyl sodium sulfosuccinate 5% solution 10 ml in warm water as enema for retained meconium
Dioxathion 0.15% wash Topical
Diphenylhydantoin 1-10 mg/kg q2-4h IV, IM, or PO
Dipyrone 5-22 mg/kg IV or IM
Dobutamine 1-10 μg/kg per minute (250 mg in 500 ml saline infused at 0.45 ml/kg per hour) IV
Dolophine HCl 0.2-0.4 mg/kg IM
Domperidone 0.2 mg/kg IV
1.1 mg/kg q24h PO
Dopamine 1-5 μg/kg per minute (200 mg in 500 ml saline infused at 0.45 ml/kg per hour) IV
Doxapram 0.5-1.0 mg/kg q5min (do not exceed 2 mg/kg in foals) IV
0.02-0.05 mg/kg per minute up to 400 mg total for neonatal foal resuscitation IV
Doxepin hydrochloride 0.5-0.75 mg/kg q12h PO
Doxycycline 3 mg/kg q12h PO
0.3% topically q3-6h Ophthalmic
Ecothiophate iodide 0.03% q12h Ophthalmic
EDTA calcium disodium 75 mg/kg per day in divided doses for lead poisoning Slow IV
6.6% solution (1 ml/0.9 kg), q8-12h IV
Eltenac 0.5 mg/kg IV
Enalopril 0.5 mg/kg q12-24h PO
Enrofloxacin 2.5 mg/kg q12h PO
Ephedrine sulphate 0.7 mg/kg q12h PO
Epinephrine 1-1.5 ml of 0.33 ng/ml Subconjunctival
0.01-0.02 mg/foal (foal resuscitation) IV
0.1-0.2 mg/foal (foal resuscitation) Intratracheal
Erythromycin base 0.1 mg/kg per hour to enhance gut motility IV
Erythromycin estolate or ethylsuccinate 25 mg/kg q12h PO
Erythromycin lactobionate 2.5-5 mg/kg q8h or q6h IV
20-40 mg Subconjunctival
Erythromycin phosphate or stearate 37.5 mg/kg q12h PO
Estradiol 0.004-0.008 mg/kg q2d for urinary incontinence IM
Estrone sulfate 0.04 mg/kg q24h IM
Ethyl alcohol (50%) 5-10 ml/50 kg Aerosol
Ethylene diamine dihydriodide 0.5-1.5 g/450 kg q24h PO
Ethylenediaminetetraacetic acid (EDTA) 0.5% topical solution q2-4h Ophthalmic
Etodolac 10-15 mg/kg q24h IV or PO
Famotidine 3.3 mg/kg q8h PO
Febantel 6 mg/kg PO
Fenbendazole 5 mg/kg PO
10 mg/kg for Parascaris equorum PO
50 mg/kg q24h for 3 days for verminous arteritis PO
50 mg/kg for Strongyloides westeri PO
50 mg/kg q24h for 5 days for onchocerca PO
Fenoterol 2-4 μg/kg Inhalation
Fenoprostalene 0.5 mg/450 kg SQ
Fentanyl Two 10 mg patches
Ferrous sulfate 2 mg/kg q24h PO
Florfenicol Do not administer to horses until more data are available
Floxacillin 10 mg/kg q6h IM
Fluconazole 4 mg/kg q24h PO
Flumazenil 0.5-2.0 mg Slow IV
Flumethasone 0.002-0.008 mg/kg PO
Flunixin meglumine 0.25-1.1 mg/kg q24h-q8h PO, IM, or IV
Fluoroprednisolone acetate 5-20 mg/450 kg IM
Fluphenazine 25 mg/pony (at 320 days gestation for prevention of fescue toxicosis) IM
Fluprostenol 250 μg/450 kg IM
Flurbiprofen Na 0.03% q8h or q6h Ophthalmic
Fluticasone propionate 2000 μg/450 kg Inhalation
Folic acid 40-75 mg IM
Folinic acid 50-100 mg IM
Follicle stimulating hormone 10-50 mg/450 kg IV, IM, or SQ
Furazolidone 4 mg/kg q8h PO
Furosemide 1-3 mg/kg q12h IV or IM
250-500 mg 1-4 hours prerace IV or IM
Gentamicin sulfate 2-4 mg/kg q12h-q6h IV, IM, or SQ
6.6-8.8 mg/kg q24h IV, IM, or SQ
10-40 mg Subconjunctival
150 mg (unbuffered) Intraarticular
1-2 g buffered in equal volume of 75% sodium bicarbonate Intrauterine
6 mg/ml; combine 100 mg with 15 ml artificial tears Ophthalmic
Clucagon 25-50 mg/kg IV
Glycerin 1 g/kg PO
Glycerol 0.5-2 g/kg for brain edema IV
Glycerol (5%) 2-5 ml/50 kg Aerosol
Glycerol guaiacolate 110 mg/kg for convulsions IV
0.1-0.2 g/50 kg q6h expectorant PO
Glycopyrolate 0.005-0.01 mg/kg IV
Glycosaminoglycan polysulfated 250 mg once weekly Intraarticular
1 mg/kg q5days IM
Gonadotropin-releasing hormone 0.05 mg 2 and 0.5 hours prebreeding for low libido SQ
0.04 mg 6 hours prebreeding to induce ovulation IM
Griseofulvin 10 g/450 kg q24h for 2 weeks, then 5 g q24h for 7 weeks PO
Guaifenesin (5%-10%) To effect (— 50-110 mg/kg needed for induction) Slow IV
5% with 4.4 mg/kg thiamylal Rapid IV
Heparin 10 IU/kg loading dose IV
15 IU/kg per hour maintenance Slow IV
40-100 IU/kg q12h or q6h for acute laminitis IV
20-90 IU/kg for peritonitis prevention SQ
Heparin calcium 150 IU/kg loading dose, then 125 IU/kg q12h for 6 doses, then 100 IU/kg SQ
Heparin sodium 40-80 IU/kg IV
2 hours later, 40 IU/kg, then 40 IU/kg q12h SQ
Heparin (low-molecular-weight) 50 IU/kg q12h SQ
Hetastarch 5-10 ml/kg/day IV
Human chorionic gonadotrophin 2000 IU to synchronize ovulation IV
Hyaluronate Na 10-50 mg/joint (see manufacturer’s recommendations) Intraarticular
500 mg q4d for 7 doses IM
Hyaluronic acid 20-120 mg locally around inflamed tendon
20-50 mg Intraarticular
Hydralazine 0.5 mg/kg IV
Hydrochlorothiazide 250 mg/450 kg q24h PO
Hydrocortisone sodium succinate 1-4 mg/kg IV drip
Hydroxyethyl starch See Hetastarch
Hydroxyzine HCl 0.5-1 mg/kg q12h IM or PO
Hyoscine 0.14 mg/kg IV
Idoxuridine 0.1% q2-6h Ophthalmic
Imidocarb diproprionate 2 mg/kg q24h for 2 days for Babesia caballi IM
4 mg/kg q3d for 4 treatments for Babesia equi IM
Imipenem 15 mg/kg q6-8h for foals IV
Imipramine 100-600 mg q12h for 2 weeks to improve ejaculation PO
0.55 mg/kg q8h IM or IV
1.5 mg/kg q8h PO
Insulin 0.5 IU/kg IM or SQ
Insulin — protamine zinc 0.15 IU/kg q12h IM or SQ
Interferon-α 2A (1,000 IU/ml) 1 ml q24h for 3 weeks, one week off, then repeat PO
Iodide Na 20-40 mg/kg q24h for several weeks PO
lodochlorhydroxyquin 10 g/450 kg (repeat for 3-4 days then gradually reduce dose if response is obtained) PO
Ipratropium 2-3 μg/kg Inhalation
Iron cacodylate 1 g IV
Isoflupredone acetate 10-14 mg IM
Isoniazid 5-20 mg/kg q24h PO
Isoproterenol HCl 0.4 μg/kg by slow infusion (discontinue when heart rate doubles) IV
0.05-1 μg/kg per minute for foal resuscitation IV
Isoproterenol (0.05%) 5-10 ml/50 kg q6h Aerosol
Isoxsuprine HCl 0.4-1.2 mg/kg q12h IM
Itraconazole 3 mg/kg q12h for up to 2 months PO
1 % with 30% DMSO topically q4-6h (not for use with subpalpebral lavage system) Ophthalmic
Ivermectin 0.2 mg/kg PO
0.2 mg/kg twice at 4-day intervals for lice and mange PO
Kanamycin 7.5 mg/kg q8h IV or IM
1-2 g Intrauterine
Kaopectate 2-4 qt/450 kg q12h PO
Ketamine See xylazine and detomidine
Ketoconazole 30 mg/kg q24h or q12h (dissolve in 0.2 N HCl) PO
Ketoprofen 2.2 mg/kg IV or IM
L-asparginase 10,000-40,000 IU/m2 q2-3wk IM
Lactase 6,000-9,000 FCC units q3-6h PO
Lactulose 0.2 ml/kg q12h PO
Levallorphan tartrate 0.02-0.04 mg/kg IV
Levamisole 8-11 mg/kg q24h PO
Levothyroxine 10 mg in 70 ml Karo syrup q24h PO
Lidocaine 0.2-0.5 mg/kg bolus q5min up to 1.5 mg/kg total dose IV
1.3 mg/kg bolus over 5 minutes, then 0.05 mg/kg per minute for up to 24 hours for treatment of ileus IV
1-2 mg/kg followed by 20-50 μg/kg/min for ventricular arrythmias in foals IV
Lime sulfur 3%-5% Topical
Lindane 3% spray Topical
Loperamide 0.1-0.2 mg/kg q6h PO
Magnesium hydroxide 200-250 ml q8h (antacid) PO
Magnesium sulfate 0.2-1 g/kg dissolved in 4 L warm water q24h PO
4 mg/kg boluses q2min up to 50 mg/kg total dose IV
Malathion 0.5% wash, 5% dust Topical
Mannitol (20%) 0.25-2.0 g/kg Slow IV
Mebendazole 8.8 mg/kg PO
20 mg/kg q24h for 5 days for Dictyocaulus arnfieldi PO
50 mg/kg q24h for 5 days for onchocerciasis PO
Meclofenamic acid 2.2 mg/kg q12h PO
Megestrol acetate 65-85 mg/kg q24h PO
Meperidine See acepromazine
Metaclopramide HCl 10 mg/kg IV
Methadone 0.05-0.2 mg/kg IV
Methetharimide 10-20 mg/kg IV
Methicillin 25 mg/kg q4-6h IM
100 mg Subconjunctival
Methionine (D-L) 1 g/kg q24h PO
Methocarbamol 5-55 mg/kg q6h Slow IV
40-300 mg/kg for convulsions Slow IV
Methoxychlor 0.5% wash Topical
Methylcellulose flakes 0.25-0.5 kg/450 kg in 10 L water PO
Methylene blue 8.8 mg/kg as 1 % solution IV
Methylprednisolone acetate 0.2-0.7 mg/kg IM
Methylprednisolone sodium succinate 2-4 mg/kg IV
30 mg/kg, then 5.4 mg/kg per hour for 23 hours for CNS trauma IV
20 mg Subconjunctival
Up to 100 mg Intrabursal or intraarticular
Methylsulfonylmethane 30 g/450 kg q24h PO
Methysulfmethoxine 15-20 mg/kg q24h PO
Metoclopramide 0.25 mg/kg q8h or q6h IV drip or SQ
0.6 mg/kg q4h PO
Metronidazole 15 mg/kg q6h IV or PO
Mezlocillin 25-75 mg/kg q6h IV
Miconazole 2% vaginal cream topically q4-6h (not for use with subpalpebral lavage system) Ophthalmic
1 % solution used topically q4-6h Ophthalmic
Midazolam 0.05-0.2 mg/kg IV or IM
Mineral oil 10 ml/kg q24h PO
Minocycline 3 mg/kg q12h PO
Misoprostol 1-4 μg/kg q24h PO
Morphine sulfate 0.2-0.4 mg/kg IM
0.25-0.75 mg/kg IV
Moxalactam 50 mg/kg q8h IV or IM
Moxidectin 0.4 mg/kg PO
Nafcillin 10 mg/kg q6h IM
Naloxone 0.01-0.02 mg/kg IV
Naproxen 10 mg/kg q24h or q12h PO or IV
Natamycin Topically q4-6h; dilute to 3.33% for use with subpalpebral lavage system Ophthalmic
Neomycin 1 g/horse q6h PO
2 g/horse q12h PO
0.5 g/foal q6h PO
1.5g/foalq12h PO
3-4 g Intrauterine
5 mg/kg q8h for 2 days to reduce ammonia production in the bowel PO
Neostigmine 0.004-0.02 mg/kg SQ
Netilmicin 2mg/kg q12h-q8h IV or IM
Niclosamide 100 mg/kg PO
Nitrofurantoin 3 mg/kg q12h IM
Nizatidine 6.6 mg/kg q8h PO
Norepinephrine 0.01 mg/kg IM
Nystatin 500,000 IU in 30 ml saline q24h for 7-10 days Intrauterine
Omeprazole 1.5 mg/kg q24h IV
Ouabain 2.5-3 mg/450 kg q2h until heart rate slows or intoxication develops; do not exceed 10 g total IV
Orbifloxacin 2.5 mg/kg q24h PO
Oxacillin 25-50 mg/kg q12h or q8h IV or IM
Oxfendazole 10 mg/kg PO
Oxibendazole 10-15 mg/kg PO
15 mg/kg for Strongyloides westeri PO
Oxymorphone 0.02-0.03 mg/kg IM
Oxytetracycline 5-20 mg/kg q24h IV
44-70 mg/kg (single dose for tendon contracture in foals) IV
Oxytocin 2.5-5 IU/450 kg as bolus q20min IV
80-100 IU in 500 ml saline Slow IV
10-20 IU/450 kg IM or IV
1-3 IU/450 kg for milk letdown IV
0.5-10 IU/kg to induce parturition IV
Pancuronium 0.04-0.066 mg/kg IV
Paromomycin 100 mg/kg q24h PO
Penicillamine d 3-4 mg/kg q6h for 10 days PO
Penicillin G
Penicillin Na 10,000-50,000 IU/kg q6h IV or IM
Penicillin K 10,000-50,000 IU/kg q6h IV or IM
20,000 IU/kg q6h PO
5 x 106 IU Intrauterine
Penicillin procaine 20-50,000 IU/kg q12h or q8h IM
Penicillin benzathine 10,000-40,000 IU/kg q48-72h IM
Penicillin V 110,000 mg/kg q12h-q6h PO
Pentazocine 0.8 mg/kg IV
Pentobarbital 2-20 mg/kg for convulsions IV
Pentosan sulfate 250mg q7-10d Intraarticular
Pentoxifylline 8.4 mg/kg q12h PO
Pentylenetetrazol 6-10 mg/kg IV
Pergolide mesylate “High dose” 0.006-0.01 mg/kg q24h PO
“Low dose” 0.002 mg/kg q24h PO
Permethrin 2% Topical spray
Perphenazine 0.3-0.5 mg/kg q12h PO
Phenobarbital 5-25 mg/kg in 30 ml saline for convulsing foals IV over 30 minutes
9 mg/kg q8h for maintenance IV
Phenothiazine 55 mg/kg PO
27.5 mg/kg with piperazine PO
Phenoxybenzamine HCl 0.7-1 mg/kg in 500 ml saline q8h or q6h IV
Phenylbutazone 2-4.4 mg/kg q12h PO or IV
Phenylephrine 10% Ophthalmic
0.1-0.2 μg/kg/min; total dose not to exceed 0.01 mg/kg IV
Phenytoin 5-10 mg/kg for convulsing foals IV
1-5 mg/kg for maintenance q4h IV, IM, or PO
10-22 mg/kg q12h for digoxin-induced arrhythmias PO
Physostigmine 0.1-0.6 mg/kg IM or slow IV
Pilocarpine HCl 4% gel q12h-q6h Ophthalmic
Piperazine 88-110 mg/kg PO
Pipercillin 15-50 mg/kg q12h-q6h IV or IM
Pirbuterol 1-2 μg/kg Inhalation
Polymixin B or E 5000-10,000 IU/kg q6h PO
1 x 106 IU Intrauterine
Ponazuril 5 mg/kg q24h for 28 days PO
Potassium chloride 40 g in 4-6 L water q12h PO
20-40 mEq/L of fluid IV
Potassium iodide 2-20 g q24h PO
Potassium permanganate 1 % solution for mouthwash
Povidone iodine 5% solution topically q24h (irritating to conjunctiva) Ophthalmic
Pralidoxime chloride 20-50 mg/kg Slow IV or IM
Praziquantel 0.5-1.0 mg/kg for tapeworms PO
Prednisolone acetate 1% topical q1-6h Ophthalmic
Prednisolone 0.2-4.4 mg/kg q24h or q12h PO or IM
Na succinate 2-5 mg/kg for septic shock IV
Primidone 1-2g/foal q12h-q6h PO
Procainamide 35 mg/kg PO
Progesterone 150 mg q24h to suppress estrus IM
300 mg q24h to maintain pregnancy IM
Progesterone repositol 1000 mg/450 kg once weekly for abortion prevention IM
Promazine 0.25-1 mg/kg IV
1-2 mg/kg granules PO
Propafenone 0.5-1.0 mg/kg IV
Propantheline bromide 0.014 mg/kg IV
Proparacaine 0.5% Ophthalmic
Propofol 2.4 mg/kg for anesthesia induction in foals, then 0.3 mg/kg per minute for maintenance IV
Propranolol 0.38-0,78 mg/kg q8h PO
0.05-0.16 mg/kg q12h IV
Prostaglandin-E2 analogues 1-4 μg/kg q24h for gastric protection PO
Prostaglandin F 10mg IM
Prostalene 2 mg/450 kg, 2 doses 2 weeks apart SQ
Psyllium mucilloid 1 g/kg q24h-q6h PO
Pyrantel embonate 38 mg/kg for tapeworms PO
Pyrantel tartrate 2.64 mg/kg q24h for control of intestinal nematodes PO
Pyrantel pamoate 6.6 mg/kg PO
13.2 mg/kg for tapeworms PO
Pyrilamine maleate 1 mg/kg IV, IM, or SQ
Pyrimethamine 0.25 mg/kg q12h for 3 days then q24h for 27 days (for equine protozoal myeloencephalitis) PO
Quinidine sulfate 22 mg/kg q2-6h PO
Quinidine gluconate 2.2 mg/kg q10min until 8-10 mg/kg total IV
0.7-3 mg/kg per hour IV
Ranitidine 6.6 mg/kg q8h PO
1.5 mg/kg q8h IV
Reserpine 2-5 mg/kg q24h PO
Rifampin 10-20 mg/kg q24h PO
3-5 mg/kg q12h with erythromycin for Rhodococcus equi PO
Romifidine 0.08-1.0 mg/kg IV
Ronnel 2.5% spray Topical
Saline (hypertonic) 7.5%, 4 ml/kg for hypovolemia IV over 20 minutes
Selenium (Na selenite) 5.5 mg/450 kg IM
Silver sulfadiazine 1% cream topically q4-6h (not for use with subpalpebral lavage system) Ophthalmic
Sodium bicarbonate 30-150g/day PO
Sodium hypochlorite 0.5% Topical
Sodium iodide 20-40 mg/kg q24h PO
Sodium sulfate Up to 3 g/kg dissolved in warm water PO
Sodium thiosulfate (20%) 0.22 ml/kg Slow IV
Spectinomycin 20 mg/kg q8h IM
Stanozolol 0.5 mg/kg, up to 4 doses q1-2 wk IM
Stilbestrol 30 mg/450 kg IM
Stirofos 1 % wash Topical
Streptomycin 11 mg/kg q12h IM or SQ
Succinylcholine 330 mg/kg IV or IM
Sucralfate 1-4g q12h-q6h PO
Sulfonamides 100-200 mg/kg on day 1, then IV, IM, or SQ
50-100 mg/kg subsequently (check labels on each product)
Sulfonamides, potentiated 30 mg/kg q12h or q8h PO
Sulpiride 3.3 mg/kg q24h PO
Suprofen 1% q12h-q8h Ophthalmic
Telazol 1-2 mg/kg for anesthesia induction IV
Terbutaline 0.02-0.06 mg/kg q12h IV, PO, or inhalation
Testosterone (aqueous) 0.1-0.2 mg/kg q48h for 2 weeks for inadequate libido SQ
Tetanus antitoxin 100 IU/kg q3-5days for treatment of tetanus IM, SQ, or IV
Tetracycline 6.6-11 mg/kg q12h IV
Tetramethrin 0.4% solution, wipe-on Topical
Theophylline 1 mg/kg q6h PO
Thiabendazole 44 mg/kg PO
88 mg/kg for Parascaris equorum PO
440 mg/kg q24h for 2 days for verminous arteritis PO
4% solution in saline or 90% DMSO Topical
Thiamine HCl 0.5-5 mg/kg IM
Thiamylal Na 2-4 mg/kg IV
Thiopental 4-10 mg/kg as 10% solution IV
Thyroxine l 0.01 mg/kg q24h PO
Ticarcillin 40-80 mg/kg q8h IV or IM
6g Intrauterine
Ticarcillin clavulanate 50 mg/kg q8h-q6h IV
Ticarcillin/clavulanic acid 6 g/200 mg Intrauterine
Tilmicosin Do not administer to horses until more data are available.
Timolol maleate 0.5% q12h Ophthalmic
Tobramycin 1-1.7 mg/kg q8h (human dose) IV or IM
10-30 mg Subconjunctival
6 mg/ml; combine 100 mg with 15 ml artificial tears Ophthalmic
Tocopherol acetate 6000 IU/250-500 kg q24h PO
Tolazoline 0.5 mg/kg IV
Toxaphene 0.5% wash Topical
Tranexamic acid 1 g IV
Triamcinolone 0.02-0.1 mg/kg IM
1-3 mg/site up to 18 mg total Intralesional
1-2mg Subconjunctival
Trichlorfon 40 mg/kg PO
Trichlormethiazide 200 mg/450 kg PO
Trifluorothymidine 1% q1-2h Ophthalmic
Triflupromazine 0.2-2.0 mg/kg IV
Trifluridine 1 % q2-6h Ophthalmic
Trimethoprim-sulfadiazine 15 mg/kg q12h IV
15-30 mg/kg q12h PO
2.5-5 g q24h Intrauterine
Tripelennamine HCl 1 mg/kg IV or IM
Tromethamine 300 mg/kg IV
Tropicamide 0.5%-1% Ophthalmic
Tylosin 10 mg/kg q12h IM
Vancomycin 20-40 mg/kg q12h-q6h IV or PO
Vedaprofen 2.2 mg/kg q12h IV
Verapamil 0.025-0.5 mg/kg q30min IV
Vidarabine 3% ointment at least q6h Ophthalmic
Vincristine 0.01-0.025 mg/kg q7d IV
Vinegar 250 ml/450 kg q24h for enterolith prevention PO
Vitamin B complex 20-30 ml q24h PO
Vitamin C See Ascorbic acid
Vitamin E 1500-2000 IU q24h for equine degenerative myeloencephalopathy prophylaxis PO
6000-9000 IU q24h for treatment of equine degenerative myeloencephalopathy PO
Vitamin K1 0.5-1 mg/kg q4-6h for warfarin toxicosis SQ
1-2 mg/kg (divided at several sites) for sweet clover poisoning SQ
0.5-2 mg/kg for foals IM
Voltaren Topical q1-6h Ophthalmic
Xylazine 0.2-1.1 mg/kg IV
0.33-0.44 mg/kg followed by 0.033-0.066 mg/kg butorphanol IV
1.1 mg/kg followed by 1.75-2.2 mg/kg ketamine IV
0.6 mg/kg with 0.02 mg/kg acepromazine IV
0.66 mg/kg to ejaculate ex-copula IV
Yohimbine 0.12 mg/kg for xylazine or detomidine antagonism Slow IV
0.075 mg/kg to restore intestinal motility IV

IM, intramuscular; IV, intravenous; PO, by mouth; SQ, subcutaneous; q, ery; h, hour; d, day; wk, week.

It is recommended that the manufacturer’s literature be checked before a drug is used. Many drugs have not been approved for use in horses.