Streptomycin Sulfate

Aminoglycoside antibiotic Antibacterial

Dosage & Administration Guidelines

Species Route Dose Frequency Duration & Clinical Notes
Dog IM 10-15 mg/kg q12h Duration: 5-7 days (or as clinically indicated)
Notes: Monitor renal function and hearing. Use with caution in dehydrated animals.
Dog SC 10-15 mg/kg q12h Duration: 5-7 days
Notes: SC administration may be less painful than IM.
Dog PO 20-40 mg/kg q8h Duration: 3-5 days
Notes: For local effect in enteritis; not absorbed systemically.
Cat IM 10-15 mg/kg q12h Duration: 5-7 days
Notes: Use with caution in cats with renal disease.
Cat SC 10-15 mg/kg q12h Duration: 5-7 days
Notes: SC administration may be used.
Cat PO 20-40 mg/kg q8h Duration: 3-5 days
Notes: For local effect in enteritis.
Horse IM 10-15 mg/kg q12h Duration: 5-7 days
Notes: Monitor renal function. Not for IV use in horses due to risk of neuromuscular blockade.
Horse Intrauterine 2-5 g per infusion q24h Duration: 3-5 days
Notes: For metritis/endometritis; dilute in sterile saline.
Cattle IM 10-15 mg/kg q12h Duration: 5-7 days
Notes: Observe withdrawal times for milk and meat.
Cattle SC 10-15 mg/kg q12h Duration: 5-7 days
Notes: SC administration may be used.
Cattle Intramammary 200-500 mg per quarter q12h Duration: 3-5 days
Notes: For mastitis; use only with approved intramammary formulations.
Cattle Intrauterine 2-5 g per infusion q24h Duration: 3-5 days
Notes: For metritis/endometritis.
Sheep/Goat IM 10-15 mg/kg q12h Duration: 5-7 days
Notes: Use with caution; observe withdrawal times.
Sheep/Goat SC 10-15 mg/kg q12h Duration: 5-7 days
Notes: SC administration may be used.
Rabbit IM 10-15 mg/kg q12h Duration: 5-7 days
Notes: Monitor renal function; avoid in rabbits with renal disease.
Rabbit SC 10-15 mg/kg q12h Duration: 5-7 days
Notes: SC administration may be used.
Rabbit PO 20-40 mg/kg q8h Duration: 3-5 days
Notes: For local effect in enteritis.
Poultry IM 10-20 mg/kg q12h Duration: 3-5 days
Notes: Not approved for use in laying hens in many countries; observe withdrawal times.
Poultry PO (water) 50-100 mg/L drinking water Continuous Duration: 3-5 days
Notes: For flock treatment; ensure adequate water intake.
Reptiles IM 5-10 mg/kg q24h Duration: 5-7 days
Notes: Dose based on limited studies; adjust based on species and renal function.

Clinical Indications & Species Uses

General Indications
  • Treatment of infections caused by susceptible aerobic gram-negative bacteria
  • Combination therapy for severe infections (e.g., with penicillins for synergistic effect)
  • Local therapy for enteritis (oral) or uterine infections (intrauterine)
Dog (Canine)
  • Treatment of infections caused by susceptible gram-negative bacteria (e.g., E. coli, Klebsiella, Pasteurella, Salmonella)
  • Bacterial enteritis (when oral therapy is desired for local effect)
  • Leptospirosis (in combination with penicillin)
  • Brucellosis (in combination with doxycycline or other agents)
  • Tularemia
  • Plague (Yersinia pestis)
  • Mycobacterial infections (as part of combination therapy)
Cat (Feline)
  • Treatment of susceptible gram-negative infections (e.g., E. coli, Salmonella, Pasteurella)
  • Bacterial enteritis (oral for local effect)
  • Leptospirosis (in combination with penicillin)
  • Tularemia
  • Plague
  • Mycobacterial infections (as part of combination therapy)
Horse (Equine)
  • Treatment of susceptible gram-negative infections (e.g., E. coli, Klebsiella, Salmonella)
  • Septicemia in neonates (in combination with other antibiotics)
  • Metritis and endometritis (intrauterine infusion)
  • Respiratory tract infections (e.g., pneumonia caused by gram-negative bacteria)
  • Leptospirosis (in combination with penicillin)
  • Ulcerative lymphangitis (in combination with penicillin)
Cattle (Bovine)
  • Treatment of susceptible gram-negative infections (e.g., E. coli, Pasteurella, Salmonella)
  • Bovine respiratory disease complex (BRD) (in combination with other antibiotics)
  • Metritis and endometritis (intrauterine infusion)
  • Mastitis (intramammary infusion in some formulations)
  • Leptospirosis (in combination with penicillin)
  • Foot rot (in combination with other agents)
Small Ruminants (Sheep / Goat)
  • Treatment of susceptible gram-negative infections (e.g., E. coli, Pasteurella, Salmonella)
  • Respiratory infections (pneumonia)
  • Enteritis
  • Metritis
  • Mastitis (intramammary infusion in some formulations)
  • Leptospirosis (in combination with penicillin)
Rabbit & Small Mammals
  • Treatment of susceptible gram-negative infections (e.g., Pasteurella multocida, E. coli)
  • Respiratory infections (snuffles)
  • Enteritis (oral for local effect)
  • Septicemia
Avian & Poultry
  • Treatment of susceptible gram-negative infections (e.g., E. coli, Salmonella, Pasteurella)
  • Colibacillosis
  • Fowl cholera
  • Salmonellosis
  • Mycoplasmosis (in combination with other agents)
Exotic & Other Species
  • Reptiles: Treatment of susceptible gram-negative infections (e.g., Salmonella, Pseudomonas)
  • Small mammals (ferrets, guinea pigs): Treatment of susceptible gram-negative infections
  • Fish: Treatment of bacterial infections (e.g., furunculosis, columnaris) via bath or injection

Pharmacology & Mechanism of Action

Drug Class: Aminoglycoside antibiotic | Pharmacological Group: Antibacterial

Mechanism of Action: Streptomycin is an aminoglycoside antibiotic that acts by irreversibly binding to the 30S ribosomal subunit of susceptible bacteria, specifically the S12 protein and 16S rRNA. This binding interferes with the initiation complex of protein synthesis, causing misreading of the genetic code and inhibiting protein elongation. The result is the production of nonfunctional or toxic proteins, disruption of the bacterial cell membrane, and ultimately bacterial cell death. Streptomycin is bactericidal and exhibits concentration-dependent killing. It is most effective against aerobic gram-negative bacteria and some mycobacteria, requiring oxygen-dependent active transport across the bacterial cell membrane.

Pharmacodynamics: Streptomycin exhibits rapid, concentration-dependent bactericidal activity. The post-antibiotic effect (PAE) is prolonged, especially at high concentrations, allowing for extended dosing intervals. It is active primarily against aerobic gram-negative bacilli, including Escherichia coli, Klebsiella spp., Pasteurella spp., Salmonella spp., and some strains of Pseudomonas aeruginosa. It also has activity against Mycobacterium tuberculosis and some gram-positive organisms such as Staphylococcus aureus (though resistance is common). Its activity is reduced in acidic environments, anaerobic conditions, and in the presence of pus or debris. Synergistic effects are seen when combined with beta-lactam antibiotics (e.g., penicillin) against enterococci and with other cell wall-active agents.

⚑ Pharmacokinetics Summary

Absorption: Streptomycin is poorly absorbed from the gastrointestinal tract; oral administration results in negligible systemic absorption. After intramuscular (IM) or subcutaneous (SC) injection, absorption is rapid and complete, with peak serum concentrations achieved within 30-90 minutes. In neonates and young animals, absorption may be more rapid. Topical application to wounds or mucous membranes may result in some systemic absorption, especially if applied to large denuded areas.
Distribution: Streptomycin is distributed widely in the extracellular fluid. It penetrates poorly into the cerebrospinal fluid, even in the presence of inflamed meninges. It crosses the placenta and can accumulate in fetal tissues. It does not penetrate well into the intracellular space, abscesses, or the eye. Volume of distribution is approximately 0.2-0.3 L/kg in most species. It is minimally bound to plasma proteins (about 30-35%).
Metabolism: Streptomycin undergoes minimal metabolism; it is primarily excreted unchanged by the kidneys. No significant hepatic metabolism occurs.
Excretion: Streptomycin is eliminated primarily by glomerular filtration, with active tubular secretion playing a minor role. In animals with normal renal function, the elimination half-life is approximately 2-3 hours in dogs and cats, 2-4 hours in horses, and 1.5-3 hours in cattle. In neonates or animals with renal impairment, the half-life can be significantly prolonged, increasing the risk of toxicity. Biliary excretion is minimal.
Half-Life: Dogs: 2-3 hours; Cats: 2-3 hours; Horses: 2-4 hours; Cattle: 1.5-3 hours; Rabbits: 1-2 hours; Birds: 1-2 hours (variable).
Bioavailability: Oral: <1% (negligible); IM/SC: ~100%.
Protein Binding: Approximately 30-35% bound to plasma proteins.

Available Formulations & Strengths

Injectable Solution 200 mg/mL, 250 mg/mL, 400 mg/mL (IM, SC)
Oral Powder Various (e.g., 100 g per kg) (PO (mixed in feed or water))
Oral Solution Various (e.g., 100 mg/mL) (PO)
Intramammary Infusion 200 mg per syringe (often combined with other antibiotics) (Intramammary)
Intrauterine Bolus or Solution Various (e.g., 1 g, 5 g) (Intrauterine)
Ophthalmic Solution Not commonly available; may be compounded (Ophthalmic)

Contraindications & Clinical Warnings

Contraindications:
  • Hypersensitivity to streptomycin or other aminoglycosides
  • Pre-existing renal disease or severe renal impairment
  • Pre-existing hearing impairment or vestibular dysfunction
  • Neuromuscular disorders (e.g., myasthenia gravis) due to risk of neuromuscular blockade
  • Dehydration or hypovolemia (increased risk of nephrotoxicity)
  • Concurrent use of other nephrotoxic or ototoxic drugs (e.g., other aminoglycosides, loop diuretics, amphotericin B)
  • Pregnancy (especially in animals with compromised renal function) unless benefits outweigh risks
  • Do not administer intravenously in horses (risk of severe neuromuscular blockade and cardiac arrest)
Warnings & Clinical Precautions:
  • Use with caution in neonates and geriatric animals due to immature or declining renal function.
  • Monitor renal function (serum creatinine, BUN) and urine output before and during therapy.
  • Monitor for signs of ototoxicity (head tilt, ataxia, hearing loss) especially in dogs and cats.
  • Avoid prolonged use to minimize risk of superinfection.
  • In food animals, observe strict withdrawal times to avoid violative residues.
  • Use with caution in animals with electrolyte imbalances (e.g., hypocalcemia, hypokalemia) as neuromuscular blockade may be potentiated.
  • Do not mix with other drugs in the same syringe unless compatibility is known.
  • In horses, avoid intra-arterial injection; use only IM or intrauterine routes.
  • In poultry, avoid use in laying hens if eggs are intended for human consumption (check local regulations).
  • Streptomycin may cause pain at injection site; consider SC administration in some species.

Adverse Effects & Reactions

Common:

  • Pain and swelling at injection site
  • Local tissue irritation
  • Gastrointestinal upset (nausea, vomiting, diarrhea) when given orally
  • Superinfection (e.g., fungal overgrowth) with prolonged therapy

Serious / Severe:

  • Nephrotoxicity (acute tubular necrosis, increased BUN/creatinine, proteinuria)
  • Ototoxicity (cochlear and vestibular damage leading to hearing loss, ataxia, head tilt)
  • Neuromuscular blockade (respiratory depression, muscle weakness, paralysis)
  • Anaphylactic reactions (rare but possible)
  • Bone marrow suppression (rare)

Rare:

  • Allergic dermatitis
  • Eosinophilia
  • Hepatotoxicity (rare)
  • Peripheral neuropathy
  • Electrolyte disturbances (hypokalemia, hypocalcemia, hypomagnesemia)

Key Drug Interactions

Interacting Drug / Class Clinical Effect & Mechanism Severity
Other aminoglycosides (e.g., gentamicin, amikacin) Additive nephrotoxicity and ototoxicity; increased risk of toxicity. High
Loop diuretics (e.g., furosemide) Increased risk of ototoxicity and nephrotoxicity; may potentiate electrolyte imbalances. High
Neuromuscular blocking agents (e.g., succinylcholine, atracurium) Enhanced neuromuscular blockade, leading to respiratory depression and paralysis. High
Polymyxin B or colistin Additive nephrotoxicity and neuromuscular blockade. High
Amphotericin B Increased risk of nephrotoxicity. High
Cephalosporins (especially first-generation) Additive nephrotoxicity. Moderate
Methoxyflurane or other halogenated anesthetics Increased risk of nephrotoxicity. Moderate
Penicillins (e.g., penicillin G) Synergistic antibacterial effect against enterococci and some gram-positive organisms; however, in vitro inactivation may occur if mixed in same solution. Mild (beneficial interaction)
Nonsteroidal anti-inflammatory drugs (NSAIDs) May reduce renal blood flow and increase risk of nephrotoxicity. Moderate

Overdose & Toxicity Management

Signs of Toxicity:

  • Nephrotoxicity (increased BUN/creatinine, oliguria, proteinuria)
  • Ototoxicity (hearing loss, ataxia, head tilt, nystagmus)
  • Neuromuscular blockade (muscle weakness, respiratory depression, paralysis)
  • Cardiovascular collapse (hypotension, bradycardia)
  • Gastrointestinal signs (vomiting, diarrhea) if oral overdose

Emergency Treatment Protocol: Treatment is primarily supportive. Discontinue the drug immediately. For recent oral overdose, consider gastric lavage or activated charcoal (though absorption is poor). Maintain adequate hydration with intravenous fluids to promote renal excretion. Monitor renal function and electrolyte levels. In cases of severe neuromuscular blockade, administer calcium gluconate (e.g., 10% solution, 0.5-1 mL/kg IV slowly) and neostigmine (0.04 mg/kg IV) or other anticholinesterase agents. Hemodialysis or peritoneal dialysis may be considered in severe cases, especially in animals with renal impairment. Provide respiratory support if needed. There is no specific antidote for aminoglycoside toxicity.

Food Animal Withdrawal Times

πŸ₯© Meat: 30 daysπŸ₯› Milk: 72 days

Withdrawal times vary by country and formulation. In the US, the label withdrawal time for streptomycin in cattle is 30 days for meat and 72 hours (3 days) for milk. For sheep and goats, withdrawal times may be longer; consult local regulations. For poultry, do not use in laying hens if eggs are intended for human consumption; withdrawal time for meat is typically 30 days. Always follow label instructions and local regulatory requirements.

Storage, Handling & Regulatory Information

Storage Temperature: Store at controlled room temperature, 20-25Β°C (68-77Β°F); avoid freezing.

Handling & Special Conditions: Protect from moisture. Keep container tightly closed. Do not use if solution is discolored or contains particulate matter. For oral powders, store in a dry place.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Streptomycin is FDA-approved for use in cattle, swine, sheep, and poultry in certain formulations (e.g., injectable, oral, intramammary). However, many products have been withdrawn from the market; availability may be limited. It is not approved for use in dogs and cats but is used extra-label.

Extra-Label (Off-Label) Use: In the US, extra-label use of streptomycin in food animals is permitted under AMDUCA (Animal Medicinal Drug Use Clarification Act) only with a valid veterinarian-client-patient relationship and a written prescription. Extra-label use in feed is prohibited. Extended withdrawal times must be established. In the EU, similar regulations apply under Directive 2001/82/EC. Always consult a veterinarian for extra-label use.

Clinical Pearls & Practice Notes

πŸ’‘ Clinical Insights: Streptomycin is an older aminoglycoside antibiotic that is still used in veterinary medicine, primarily for its activity against gram-negative bacteria. It is often combined with penicillin for synergistic effects against enterococci and for the treatment of leptospirosis. Due to its potential for nephrotoxicity and ototoxicity, it should be used with caution, especially in animals with renal impairment or in neonates. Therapeutic drug monitoring is not routinely performed, but renal function should be assessed before and during therapy. In food animals, strict adherence to withdrawal times is essential. Because of the availability of newer and safer aminoglycosides (e.g., gentamicin, amikacin), streptomycin is less commonly used in small animal practice but remains a valuable option in certain situations, particularly for local therapy (e.g., oral for enteritis, intrauterine for metritis). Always consider culture and sensitivity testing to ensure susceptibility. In horses, intravenous administration is contraindicated due to the risk of severe neuromuscular blockade and cardiac arrest. For poultry, use in laying hens is prohibited in many countries due to egg residues. Overall, streptomycin should be used judiciously to minimize the development of antimicrobial resistance.

References & Literature

  • πŸ“š Plumb's Veterinary Drug Handbook
  • πŸ“š Papich Veterinary Pharmacology and Therapeutics
  • πŸ“š Compendium of Veterinary Products (CVP)