Equine Antibiotics

• Outlined are various Equine antibiotics, administration routes, frequency of dosage, potential problems, bacterial spectrum, and specific notes relevant to usage, and conditions each antibiotic is most suited to treat.

Oxytetracycline

• This is administered intravenously twice daily.
• Potential problem of dysbiosis with low risk.
• It covers Gram-positive and Gram-negative bacteria, but is bacteriostatic.
• Do not give IM or Orally
• Effective for respiratory and soft tissue infections.
• Use when patients are hospitalised only
• Used as a first-line treatment for septic arthritis and carpal/fetlock contracture in neonates.

Doxycycline

• This is given orally with feed twice daily.
• Can cause dysbacteriosis
• It covers Gram-positive, Gram-negative, and some anaerobic bacteria.
• Good penetration into pus.
• Given orally on discharge following IV oxytetracycline treatment in the hospital.
• Used to treat cellulitis and subsolar abscesses

Metronidazole

• Administered orally or IV twice daily or every 8 hours.
• Carries a risk to people handling it.
• Effective against anaerobes, especially for nasty infections.
• Must not be given to food-producing animals.
• Used to treat contaminated wounds and peritonitis.

Penicillin

• Given intramuscularly every 12 hours.
• Avoid IV/Oral route
• Reactions may occur if given IV.
• Use sodium penicillin in foals due to the high risk of procaine reactions.
• Narrow spectrum targeting Gram-positive and some anaerobic bacteria.
• Combine with gentamycin for broader spectrum coverage.
• Sodium/crystalline penicillin can be administered IV but is expensive.
• Works with Streptomycin (IM) for sinusitis
• Used to treat, endometritis, endocarditis, sepsis, septic arthritis and contaminated wounds.

Gentamycin

• Is given intravenously once a day.
• Nephrotoxic, so IV fluid therapy is needed to support kidneys.
• Use with care with NSAIDs due to nephrotoxic effects.
• Effective against Gram-negative bacteria, especially Pseudomonas.
• Works in tandem with penicillin for broader spectrum coverage.
• Helpful in guttural pouch empyema/chondroids, pneumonia, and peritonitis
• Treats endocarditis, pneumonia, septic arthritis, sepsis, and contaminated wounds.

TMPS

• This is given orally as a paste or powder, or intravenously twice daily.
• Inactivated by pus.
• Good against Gram-positive and Gram-negative bacteria, bactericidal effects.
• Not effective against Pseudomonas, Mycoplasma, Klebsiella, or anaerobes.
• Used in neonates after initial penicillin and gentamycin treatment.
• Do not use IV in horses that have had an alpha-2 as fatal reactions may occur.
• Inactivated by pus can cause cystitis, pyelonephritis and mastitis
• Treats patent urachus, umbilical infections, normal foals, and premature foals among other things

Ceftiofur

• This administered intramuscularly once a day.
• Antibiotic action is protected.
• Aims for Gram-positive, Gram-negative, and anaerobic bacteria.
• Culture and sensitivity (C&S) testing is required before use.
• Exhibits good penetration into the lungs.
• Effective for respiratory diseases.
• Often used in horses with compromised kidneys to treat sepsis, severe sepsis, neonatal pneumonia, and neonatal meningitis

Enrofloxacin

• Given intravenously or orally once daily.
• Offers protected action.
• Can cause cartilage damage in foals under two years of age.
• Resistance develops rapidly.
• Works against Gram-negative bacteria.
• Culture and sensitivity (C&S) testing is required before use.
• Do not use in skeletally immature animals!
• It has good penetration into tissues but not the cerebrospinal fluid (CSF).

Rifampicin

• Given orally twice a day.
• Should be avoided is category A.
• It is effective against Gram-positive, some Gram-negative, and anaerobic bacteria.
• Used in combination with another antibiotic to treat Rhodococcus equi.
• Do not use with fluoroquinolones.

Amikacin

• Administered intravenously once a day.
• Category C-caution.
• Targets Gram-negative, and some Gram-positive bacteria.
• Less nephrotoxic than gentamycin.
• Previously used intra-articularly but thought to be toxic to chondrocytes.
• Useful to treat Sepsis in foals