Doses of Common Drugs

Glossary

PO = Per os (oral) administration
SC = Subcutaneous administration
IM = Intramuscular administration
IV = Intravenous administration
q24h = Administration every 24 hours (once daily)
q12h = Administration every 12 hours (twice daily)
q8h = Administration every 8 hours (three times daily)
q6h = Administration every 6 hours (four times daily)

Puff = Delivery of one metered dose (inhalations)
AHSA = American Horse Shows Association
BALF = Bronchoalveolar Lavage Fluid
DPI = Dry Powder Inhalation
EIPH = Exercise Induced Pulmonary Hemorrhage
FEI = Fédération Equestre Internationale
IAD = Inflammatory Airway Disease
MIC = Minimum Inhibitory Concentration

Antibiotics

Drug

Trade

Name

Dose

Route

Pharmaco-

kinetics

Side

Effects

Comments

Ref

Penicillin Compounds

Ampicillin

6.6 mg/kg q12h

IM

Efficient against

S. zooepidemicus

11 mg/kg q8h

IM

Ampicillin

Well absorbed PO by neonate foals

Can alter intestinal flora

Amoxycillin

20 - 30 mg/kg

PO

Serum concentrations maintained for 5 - 6 hours

Can alter intestinal flora and induce diarrhea in foals

Amoxicillin + Clavulanate

Penicillin sodium

22 000 IU/kg q6h

IV, IM or SC

Salts can have cardio-
depressant effects

Bactericidal, Gram +, Anaerobic coverage.

Recommended against Streptococci(Strangles, Pneumonia)

Procaine Penicillin G

22 000 IU/kg q12h

IM

or SC

Anaerobic coverage

Cephalosporins

Ceftiofur
(third-generation
cephalosporin)

Naxcel®

(Pfizer)

2 mg/kg q24h

IM

Needs to be refrigerated when reconstituted as its loss of potency is attained after 12 hours at room temperature

Possible local reactions

Efficient against S. zooepidemicus, Pasteurella sp., Actinobacillus. Doses can be increased if bacteria have a high MIC (Pseudomonas, Klebsiella, Enterobacter)

[1,
2]

Excenel®

(Pfizer)

2 mg/kg q12h in neonate foals (2-7 days old)

IM

Aminoglycosides

Gentamicin

6.6 mg/kg

q24h

IV

Does not cross blood/brain barrier

Nephrotoxicity

[3]

Gentocin®

(Schering

Plough)

50 mg/ml

Nebuli-

zation

12 times greater concentration in BALF with aerosol delivery than with IV administration

Mild inflammatory cell response in BALF

Bactericidal

Concentration-dependent antimicrobial activity

Kanamycin

7.5 mg/kg q8h

IV

or IM

More expensive than gentamicin

Amikacin

4.4 - 6.6 mg/kg

q8-12h or

21 mg/kg q24h

IV

or IM

Less nephrotoxic than gentamicin

Less resistance of gram- strains in comparison to gentamicin

[4,
5]

Trimethoprim-Sulfonamide

Borgal®
(Intervet)

Duoprim®
(Schering Plough)
Tribrissen®
Oral Paste
(Schering Plough)
Tribrissen 48%
(Schering-Plough)
Duphatroxim®
(Fort Dodge)
Trisuprime®
(Bayer)

12.5 - 30 mg/g q12h.

Often dosed 5/1

Sulfa/trimethoprim

PO

IM

IV

SC

Should be administered 30 minutes prior to feeding (best absorbed)

Can cause diarrhea

Bactericidal

Certain strains of S. zooepidemicus are resistant

Macrolides

Erythromycin

25 mg/kg q12h

Treatment duration: 4 - 6 weeks in cases of R. equi

PO

Can cause diarrhea

Used to treat Rhodococcus equi. Can be used in association with rifampin

[6]

Rifampin

3 - 5 mg/kg q12h

PO

Should not be used alone as microbial resistance can develop rapidly

Metronidazole

15 mg/kg q6 - 8h

PO

Effects on CNS (depression, circling, head tilting)

Anaerobic coverage. Cannot be used in food animals

[7]

Chloramphenicol

55 mg/kg q6h

PO

Half life is too brief to allow effective plasma concentrations when administered IV

IM injections cause pain and are contra-indicated in horses

Gram + and - anaerobic coverage. Should be manipulated with care as cases of fatal aplastic anemia have been reported in man. Cannot be used in food animals

[8,
9]

Tetracyclines

Oxytetracycline

6.6 mg/kg

q12 - 24h

IV

Doxycycline

10 mg/kg q12h

PO

IV administration reported to cause fatal diarrhea

[10]

Fluoroquinolones

Enrofloxacin

Baytril®

(Bayer)

2.5 - 5 mg/kg q12h

PO

or IV

Reports of arthropathy and possible cartilage damage in young horses (< 4 years)

Has not been approved for use in equine species

[11,
12]

Marbofloxacin

Marbocyl®

(Vetoquinol)

2 mg/kg q24h

IV,

SC

or PO

Concentration-dependent anti-Gram - activity

Time-dependent anti-Gram + activity

~100% bioavailability by SC administration, 62% by oral administration

Should be given prior to feeding

[13]

Bronchodilators

Drug

Trade

Name

Dose

Route

Pharmaco-

kinetics

Side

Effects

Comments

Ref

Anticholinergic Agents

Atropine

0.01 - 0.02 mg/kg

single dose

IV

Bradyarrhythmias, excitement, gut stasis

Single dose induces bronchodilation within 15 mins in heavey horses

[14,
15]

Glycopyrrolate

Robinul-V®

0.007 mg/kg

single dose

IV

Does not cross blood/brain barrier

Bradyarrhythmias, excitement, gut stasis

1 - 1.5 mg/horse

q12h

inhalation

Effects on respiratory mechanics 15 minutes after inhalation. Effect lasts at least 60 minutes

None reported. Absence of tachycardia in treated horses

[16]

Ipratropium bromide

Atrovent®

100 - 360 ug q6h

(5 - 18 puffs)

Inhalation

None reported

Must be delivered using a metered-dose inhalant system

2 - 3 ug/kg

Nebulization

Effect lasts 4 - 6 hours

Dose dependent effect

[17]

2.5 - 5 ug/kg

DPI

Onset of effect within 15 minutes

Delivered with a DPI mask

[18,
19]

Beta 2-Adrenergic Agonists

Albuterol sulfate

Torpex® (+3M device)

360 - 720 ug

q 6h

Inhalation

Onset of effect: 5 minutes

Effect lasts 30 minutes to 3 hours

[20,
21]

Clenbuterol

Ventipulmin® (Boehringer Ingelheim)

0.7 - 0.8 ug/kg q12h

PO

Increase dose by 25% if no response after 3 days. Maximal dose: 0.32 ug/kg

Low intensity sweating, muscle tremor, and/or nervousness at higher doses. Effects on cardiac contraction. Can cause abortion in pregnant mares.

Differences in individual response according to severity of clinical signs.

[22,
23]

IV, IM, Nebulization

Excitement, tachycardia, sweating, muscle tremors after IV injection.

Improves mucociliary clearance

[24]

Fenoterol

Berotec®

0.9 - 2 mg

Inhalation

Rapid onset of effect (< 5 mins)

Improves respiratory mechanical parameters

[25,
26]

Terbutaline

Brethine®

2 - 4 mg (10 - 20 puffs)

Inhalation

Nebulization

Low bioavailability if given PO (100 ug/kg)

Causes tachycardia, CNS stimulation, hyperventilation and lethargy after IV injection (10 ug/kg)

[27,
28]

Isoproterenol

0.1 - 0.2 mg/ horse

(until heart rate doubles)

IV

[15]

Pirbuterol

Maxair®

1.2 - 2.4 ug/kg

Inhalation

Onset of effect: 5 minutes

Effect lasts at least 7 hours

Causes agitation, tremors sweating and tachycardia, at doses exceeding 6 ug/kg

[29,
30]

Salmeterol

Serevent®

0.5 - 1 ug/kg

Inhalation

Onset of effect: 5 minutes

Duration of effect: 6 - 8 hours

Maximal effect: 30 - 60 minutes

[31]

Phosphodiesterase Inhibitors (Methylxanthine Derivatives)

Theophylline

1 - 5 mg/ kg q12h

PO

Narrow therapeutic margin

Toxic interaction with erythromycin

Causes tachycardia, increase in lactatemia and hyperoxia

[32]

20 mg/kg then 15 mg/kg q24h

PO

Narrow therapeutic margin

Toxic interaction with erythromycin

[33]

Aminophylline

(Soluble salt of theophylline)

9 - 15 mg/kg diluted in 1L of fluids delivered over 20 - 60 mins q12h or q8h

IV

Narrow therapeutic margin

Toxic interaction with erythromycin

Dose-related tachycardia, polypnoea and nervous symptoms (tactile, visual and auditory hypersensitivity, muscle tremor, sweating)

[15], [34-
36]

5 mg/kg q12h

PO

[37]

Pentoxifylline

16 g per horse (~36 mg/kg) q12h

PO

Poor absorption by gastro-intestinal tract

None reported

14 days administration improved respiratory mechanics at day 8, but had effect on BALF cytology

[38]

Alpha 2-Adrenergic Agonist

Xylazine hydrochloride

0.5 mg/kg single dose

IV

Bronchodilating effects are offset by an increase in respiratory resistance due to upper airway relaxation

Other alpha-2 adrenergic agonists have similar effects

[39]

Corticosteroids

Drug

Trade

Name

Dose

Route

Pharmaco-

kinetics

Side

Effects

Comments

Ref

Dexamethasone

0.08 - 0.164 mg/kg q24h

PO

50% biodisponibility when given PO. Effective within 6 hours, peak effect at 24 hours

Longer effect when given PO in comparison to IV. Feeding decreases bioavailability

[40,
41]

Azium® (Schering-Plough)

0.04 - 0.1 mg/kg q24h

IM, IV

Improvement of lung function at 2 hours (IV), with a peak effect at 4 - 6 hours. Dose should be gradually decreased to minimum necessary

Improves clinical signs, airway function and BALF cytology in heaves-affected horses in 3 - 7 days.

[41-
44]

Dexamethasone-21-isonicotinate

Voren® (Boehringer Ingelheim)

0.04 - 0.06 mg/kg, q3 days

IM

Long acting form of dexamethasone

Improves clinical signs and airway function in heaves-affected horses in 3 - 7 days. After 10 days of treatment, BALF cytology is not improved.

[41,
42]

Prednisone

1 mg/kg q12h for 1 week, decrease by 25% each week

PO

Very low biodisponibility

Ineffective for the treatment of pulmonary inflammation

[41,
42,
45-
47]

2.2 mg/kg q24h

PO

Well absorbed by gastro-intestinal system

[41]

Fluticasone

Flovent® (Glaxo-
Wellcome)

2 - 4 ug/kg q12h or

2 mg/horse q12h

Inhalation

Serum cortisol concentrations return to pretreatment values within a 2 day wash-out period.

Must be delivered using a metered-dose inhalant system. A 21 days treatment improves clinical signs, airway function and BALF cytology in heaves-affected horses in 3 - 7 days.

[41,
48-
50]

Beclomethasone

1.32 - 5 mg/horse q12h during 7 to 14 days

Inhalation

Adrenal suppression occurs at a dose of 528 ug/horse q12h but is restored after a 2 day wash-out period.

None reported although systemic absorption occurs through respiratory and gastro-intestinal tracts.

Improvement not detected before 24 - 72 h. Less effective than PO dexamethasone. Must be delivered using a metered-dose inhalant system

[51-
54]

Beclovent®

1 - 3 ug/kg (12 - 15 puffs) q12h

Inhalation

(EADDS®)

Must be delivered using a metered-dose inhalant system

[49]

Vanceril® (Schering-Plough)

Inhalation

Must be delivered using a metered-dose inhalant system

[41]

Beclazone 250 inhaler®

500 ug/horse q12h

Inhalation

Treatment of SPAOD in a laminitis-prone horse. Must be delivered using a metered-dose inhalant system

[55]

Triamcinolone

Vetalog®

0.04 - 0,09 mg/kg

single dose

IM

Adrenal suppression maintained after 3 weeks of administration

Laminitis

A single dose improves heaves symptoms for up to 3 weeks

[56]

Budesonide

Pulmicort®

800 ug q12h

[57]

Flunisolide

Safety and efficacy has not been evaluated in horses

Non-Steroidal Anti-Inflammatory Drugs (NSAID). Indicated for symptomatic treatment of fever and pain in diseases such as respiratory viral diseases, strangles, etc.

Drug

Trade

Name

Dose

Route

Pharmacokinetics

Side

Effects

Comments

Ref

Phenylbutazone

3 - 4.4 mg/kg q12 - 24h

IV, PO

Inefficient against heaves or IAD

Flunixine Meglumine

Banamine® Binixine®

1.1 mg/kg q12 - 24h

IM, PO

Inefficient against heaves or IAD

1.1 mg/kg q12h

IV

Ketoprofen

Ketofen® Anaphen®

2.2 mg/ kg q12h

IV, IM

Dimethyl sulfoxide (DMSO)

100 ml mixed with 200 ml glycerin and 200 ml propylene glycol

Topical

Local treatment of upper airway inflammatory conditions (pharyngitis, epiglottic ulceration,…)

[58]

Sodium hyaluronate

Hyonate® (Bayer)

40 mg/ horse, two injections at 7 days interval

IV

Decreases BALF neutrophils in horses in remission from RAO. Possible antioxidant properties

[59]

Mucolytic Agents

Drug

Trade

Name

Dose

Route

Pharmacokinetics

Side

Effects

Comments

Ref

Acetylcysteine

2 g q12h

PO

Mucomyst® (Bristol)

20 - 60 ml of a 20% solution

Topical

Guttural pouch lavage in cases of empyema

[60]

Dembrexine

Sputolysin® Sputolosin®

(Boehringer Ingelheim)

0.33 mg/kg q12h

PO

Antitussive properties. Cannot be used in food animals

[61]

Bromhexine

Bisolvon®

60 mg/kg

PO

[62]

Immunomodulators

Drug

Trade

Name

Dose

Route

Pharmacokinetics

Side

Effects

Comments

Ref

Propionibacterium acnes

Eqstim® (Immunovet Inc.)

3 doses administered every 2 to 3 days

IV

Fever, anorexia, lethargy within 12 - 24 hours after first doses

Increases peripheral WBC.

Decreases BALF cytologic counts including lymphocyte and macrophage populations

[63-
65]

Purified mycobacterial cell wall extract

Equimune® IV, Vetripharm Inc.

1.5 ml repeated in 1 to 3 weeks

IV

Pulmonary lesions reported in 5 horses (granulomatous pulmonary fibrosis pneumonitis, bronchiolitis)

[66,
67]

Inactivated parapoxvirus

Baypamune®, Bayer

460 IU q8h at 48 h interval

IM

Delivery according to the predicted delay of highest infectious pressure.

1 week= IM injections at Day 0, Day 2 and Day 4

2 weeks= IM injections at Day 0, Day 2 and Day 9

Interferon alpha

Recommended for the treatment of IAD.

No effect on severity of clinical signs or duration of viral shedding in experimentally induced EHV-1 infection

[68-
71]

Interferon Alpha 2a recombinant

Roferon-A®

50 - 150 IU q24h for 5 days

PO

Recombinant is less effective than the natural interferon

Interferon Alpha n3 recombinant

Alferone®

50 - 150 IU q24h for 5 days

PO

Interferon Alpha 26 recombinant

Intron A®

50 - 150 IU q24h for 5 days

PO

Mast Cell Stabilizing Drugs

Drug

Trade

Name

Dose

Route

Pharmacokinetics

Side

Effects

Comments

Ref

Cromolyn sodium

Intal® (Rhone-Poulenc-Rorer)

200 mg q12h

Nebulization

Prophylactic effect only on mast cell degranulation

[72,
73]

Disodium cromoglycate

Intal®

80 mg q12h 1st week, then q24h

Nebulization

Delayed action

Prophylactic effect only on mast cell degranulation

Nedocromil

Tilade®

80 mg q12h 1st week, then q24h

Nebulization

Prophylactic effect only on mast cell degranulation

Anthelmintics

Drug

Trade

Name

Dose

Route

Pharmacokinetics

Side

Effects

Comments

Ref

Mebendazole

10 mg/kg q24h

PO

Efficient against P. equorum(adults) and S. vulgaris(adults)

20 mg/kg q24h for 5 days

PO

Efficient against D. arnfieldi

Fenbendazole

Panacur® (Hoechst-Roussel)

10 mg/kg q24h for 5 days

PO

Efficient against adults and larvae of P. equorum and S. vulgaris

Thiabendazole

88 mg/kg

PO

Efficient against P. equorum

Albendazole

25 mg/kg q12h

for 5 days or

50 mg/kg q12h

for 2 days

PO

4 - 8 mg/kg q12h for 1 month

PO

Treatment of hydatid cysts caused by Echinococcus granulosus

Ivermectin

Eqvalan®

200 ug/kg

PO

Efficient against P. equorum(adults) and S. vulgaris(adults and larvae) and D. arnfieldi

Antifungal Agents

Drug

Trade

Name

Dose

Route

Pharmacokinetics

Side

Effects

Comments

Ref

Potassium iodide

10 - 15 g q24h for a 450 kg horse

5 - 10 g q24h for a pony

for 30 - 60 day

PO

Treatment should be stopped with signs of iodism (lacrimation, coughing, scurfy coat with hair loss). Contraindicated in pregnant mares and in very young foals.

Enilconazole

33.3 mg/ml solution

Topical

Indicated for treatment of guttural pouch mycosis

[9,
74]

Miconazole

10 mg/kg in 250 ml of saline q24h

Topical

Indicated for treatment of guttural pouch mycosis

[9,
74]

Itraconazole

5 mg/kg q24h

PO

Reported as systemic therapy of guttural pouch mycosis

[74]

Nystatin

Topical

Treats mycotic rhinitis (Aspergillosis) or guttural pouch mycosis

[75,
76]

Natamycin

Topical

Treats mycotic rhinitis (Aspergillosis)

[76]

Amphotericin B

0.3 mg/kg day 1, dose increased by 0.1 mg/kg on each subsequent day, for at least 21 - 35 days

IV

Very nephrotoxic

Mycotic rhinitis, fungal pneumonia

[77,
78]

Others

Drug

Trade

Name

Dose

Route

Pharmacokinetics

Side

Effects

Comments

Ref

Furosemide(diuretic)

Lasix®

1.0 mg/kg

Inhalation,

IV

Kaliuresis

Bronchodilator

Reduces acute pulmonary edema

[9,
79]

0.5 mg/kg 30 minutes to 4 hours prior to racing

IV

Used to prevent or reduce severity of EIPH. Prohibited by FEI, the AHSA and most non-American racing rules

[80-
83]

Nasal strips

Flair® Equine Nasal strips

Reduces EIPH severity

[83]

Respiratory Analeptics

Doxapram

0.3 - 1 mg/kg

IV

Half life: 2 - 3 hours

Increases heart rate and cardiac output

Causes transient hyperventilation (approximately 5 minutes)

[84-
87]

Topical lavage solution

0.05% to 5% povidone-iodine solution q12 - 24h for 5 - 10 days

Topical

Sinus, guttural pouch lavage

Local Anesthetics

Drug

Trade

Name

Dose

Route

Pharmacokinetics

Side

Effects

Comments

Ref

Lidocaine

15 - 20 ml of a 4% solution

Topical

Local pharyngeal, tracheal or bronchial anesthesia, for instance during endoscopic examination

Xylazine

5% solution

Topical

Local pharyngeal, tracheal or bronchial anesthesia, for instance during endoscopic examination