Clindamycin

Lincosamide antibiotic Antibacterial

Dosage & Administration Guidelines

Species Route Dose Frequency Duration & Clinical Notes
Dog PO 5-10 mg/kg q12h Duration: 5-14 days (up to 28 days for osteomyelitis)
Notes: Administer with food to reduce GI upset. For toxoplasmosis, dose may be higher (10-20 mg/kg q8-12h).
Cat PO 5-10 mg/kg q12h Duration: 5-14 days
Notes: Administer with food. For toxoplasmosis, use 10-12 mg/kg q12h for 2-4 weeks.
Horse PO 2.5-5 mg/kg q12h Duration: 5-14 days
Notes: Use with extreme caution due to risk of colitis. Monitor for diarrhea. Oral absorption is variable; consider IV for severe infections.
Horse IV 2.5-5 mg/kg q12h Duration: 5-14 days
Notes: Slow IV infusion over 30 minutes. Not FDA-approved for horses; extra-label use.
Cattle IM 5-10 mg/kg q24h Duration: 3-5 days
Notes: Extra-label use; observe withdrawal times. Not commonly used in food animals.
Cattle PO 5-10 mg/kg q12h Duration: 3-5 days
Notes: Extra-label use; risk of GI disturbances.
Small Ruminants (sheep/goats) PO 5-10 mg/kg q12h Duration: 3-5 days
Notes: Extra-label use; monitor for diarrhea.
Rabbit PO 10-15 mg/kg q12h Duration: 5-7 days
Notes: Use with extreme caution; risk of enterotoxemia. Administer with probiotics and monitor fecal output.
Bird (e.g., raptors) PO 25-50 mg/kg q12h Duration: 5-7 days
Notes: Limited data; use with caution.
Reptiles PO 5-10 mg/kg q24h Duration: 5-7 days
Notes: Dosing may vary by species; consult a specialist.

Clinical Indications & Species Uses

General Indications
  • Treatment of susceptible anaerobic bacterial infections
  • Treatment of Gram-positive aerobic infections when other antibiotics are not suitable
  • Treatment of toxoplasmosis (in combination therapy)
Dog (Canine)
  • Treatment of skin and soft tissue infections (pyoderma, abscesses, wounds)
  • Dental infections and periodontal disease
  • Osteomyelitis
  • Anaerobic infections (e.g., peritonitis, aspiration pneumonia)
  • Toxoplasmosis (in combination with other agents)
  • Bacterial enteritis (e.g., Clostridium perfringens-associated diarrhea)
Cat (Feline)
  • Skin and soft tissue infections (wounds, abscesses)
  • Dental infections
  • Osteomyelitis
  • Anaerobic infections
  • Toxoplasmosis (in combination with pyrimethamine or other agents)
  • Upper respiratory infections (secondary bacterial)
Horse (Equine)
  • Anaerobic infections (e.g., pleuropneumonia, peritonitis)
  • Bone and joint infections (osteomyelitis, septic arthritis)
  • Skin and soft tissue infections
  • Dental infections
Cattle (Bovine)
  • Anaerobic infections (e.g., foot rot, metritis, mastitis)
  • Respiratory infections (e.g., pneumonia) when anaerobes are involved
  • Skin and soft tissue infections
Small Ruminants (Sheep / Goat)
  • Anaerobic infections (e.g., foot rot, mastitis, metritis)
  • Skin and soft tissue infections
Rabbit & Small Mammals
  • May be used for anaerobic infections with extreme caution and supportive care
Avian & Poultry
  • May be used for anaerobic infections in some species (e.g., raptors) with caution
Exotic & Other Species
  • Reptiles: anaerobic infections, abscesses
  • Small mammals (e.g., ferrets, guinea pigs): anaerobic infections, but caution in herbivores due to GI dysbiosis

Pharmacology & Mechanism of Action

Drug Class: Lincosamide antibiotic | Pharmacological Group: Antibacterial

Mechanism of Action: Clindamycin is a lincosamide antibiotic that inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit, specifically the 23S RNA of the 50S subunit. This binding interferes with the peptidyl transferase reaction and blocks peptide bond formation, thereby inhibiting bacterial growth. It is primarily bacteriostatic, but may be bactericidal at higher concentrations. It has activity against Gram-positive aerobes, anaerobes, and some protozoa (e.g., Toxoplasma, Plasmodium).

Pharmacodynamics: Clindamycin exhibits time-dependent killing and has a post-antibiotic effect against susceptible organisms. It is effective against a wide range of anaerobic bacteria, including Bacteroides fragilis, Fusobacterium, and Clostridium perfringens, as well as Gram-positive cocci such as Staphylococcus aureus (including penicillinase-producing strains) and Streptococcus spp. It is also used for its immunomodulatory effects in some conditions, such as reducing toxin production in streptococcal infections.

⚡ Pharmacokinetics Summary

Absorption: Clindamycin is well absorbed after oral administration in most species, with bioavailability ranging from 50-90% depending on species and formulation. In dogs, oral bioavailability is approximately 70-90% when given with food. In horses, oral absorption is variable and may be lower. Intramuscular and subcutaneous injections provide rapid absorption.
Distribution: Clindamycin is widely distributed throughout the body, including bone, soft tissues, and body fluids. It penetrates well into abscesses and bone, but penetration into the central nervous system is poor. It crosses the placenta and is excreted in milk. Protein binding is approximately 60-95% depending on species.
Metabolism: Clindamycin is extensively metabolized in the liver, primarily to active and inactive metabolites. The major metabolite is clindamycin sulfoxide, which has some antibacterial activity. Metabolism may be species-dependent.
Excretion: Clindamycin and its metabolites are primarily excreted in the bile and feces, with only about 10% excreted in the urine. Enterohepatic recirculation occurs. In animals with hepatic impairment, elimination may be prolonged.
Half-Life: Dogs: approximately 4-5 hours; Cats: approximately 4-6 hours; Horses: approximately 1-2 hours; Cattle: approximately 2-3 hours; Rabbits: approximately 1-2 hours.
Bioavailability: Oral: Dogs ~70-90%, Cats ~50-70%, Horses ~30-50% (variable).
Protein Binding: Dogs: ~60-80%; Cats: ~70-90%; Horses: ~70-80%; Cattle: ~60-70%.

Available Formulations & Strengths

Oral Capsule 25 mg, 75 mg, 150 mg, 300 mg (PO)
Oral Solution 25 mg/mL, 75 mg/mL (PO)
Injectable Solution 150 mg/mL (as phosphate) (IV, IM)
Topical Gel (for dental use) 10% (various) (Topical (oral))

Contraindications & Clinical Warnings

Contraindications:
  • Hypersensitivity to clindamycin or lincomycin
  • Rabbits, hamsters, guinea pigs, and other hindgut fermenters (risk of enterotoxemia)
  • Horses (relative contraindication due to risk of colitis; use only when no alternative)
  • Ruminants (relative contraindication due to risk of GI dysbiosis; use with caution)
  • Concurrent use with erythromycin or other macrolides (antagonism)
Warnings & Clinical Precautions:
  • Use with caution in animals with hepatic or renal impairment
  • May cause gastrointestinal disturbances (vomiting, diarrhea) in dogs and cats; administer with food
  • In horses, monitor for signs of colitis (diarrhea, fever, depression); discontinue immediately if diarrhea occurs
  • In rabbits and rodents, use only if absolutely necessary and with supportive care (e.g., probiotics)
  • Prolonged use may result in superinfection with resistant organisms (e.g., Clostridium difficile)
  • Use in food animals requires adherence to withdrawal times and extra-label regulations
  • Avoid use in neonates unless necessary

Adverse Effects & Reactions

Common:

  • Vomiting
  • Diarrhea
  • Anorexia
  • Drooling (especially in cats due to bitter taste)

Serious / Severe:

  • Pseudomembranous colitis (especially in horses, rabbits, and rodents)
  • Clostridium difficile-associated diarrhea
  • Esophageal stricture (if oral capsules lodge in esophagus, especially in cats)
  • Hepatotoxicity (rare)

Rare:

  • Allergic reactions (urticaria, anaphylaxis)
  • Blood dyscrasias (neutropenia, thrombocytopenia)
  • Neuromuscular blockade (with high doses)

Key Drug Interactions

Interacting Drug / Class Clinical Effect & Mechanism Severity
Erythromycin and other macrolides Antagonistic effect due to competition for binding site on 50S ribosomal subunit High
Neuromuscular blocking agents (e.g., atracurium, pancuronium) May enhance neuromuscular blockade, leading to prolonged paralysis Moderate
Kaolin-pectin or other adsorbents May reduce absorption of oral clindamycin Moderate
Cyclosporine Potential increased risk of nephrotoxicity (limited data) Mild

Overdose & Toxicity Management

Signs of Toxicity:

  • Severe vomiting
  • Diarrhea (possibly bloody)
  • Inappetence
  • Lethargy
  • In severe cases, seizures or coma (rare)

Emergency Treatment Protocol: Treatment is primarily supportive. Discontinue the drug. Provide fluid therapy to correct dehydration and electrolyte imbalances. Administer antiemetics if vomiting is severe. In cases of suspected enterotoxemia (especially in horses, rabbits), consider oral administration of activated charcoal (if recent ingestion) and supportive care including probiotics, fluid therapy, and possibly metronidazole for Clostridium difficile overgrowth. There is no specific antidote.

Food Animal Withdrawal Times

🥩 Meat: 10 days🥛 Milk: 3 days

Withdrawal times are not established for clindamycin in food animals in many countries. In the US, clindamycin is not approved for food animals, so extra-label use requires extended withdrawal periods (e.g., 10 days for meat, 3 days for milk) as a general guideline. Always consult a veterinarian and follow local regulations.

Storage, Handling & Regulatory Information

Storage Temperature: Store at controlled room temperature 20-25°C (68-77°F), with excursions permitted between 15-30°C (59-86°F).

Handling & Special Conditions: Protect from moisture. Keep container tightly closed. Do not refrigerate oral solutions unless specified by manufacturer.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Approved for use in dogs and cats for certain indications (e.g., skin infections, dental infections). Not approved for food animals or horses.

Extra-Label (Off-Label) Use: In the US, clindamycin is not approved for use in food animals. Extra-label use in food animals is permitted under AMDUCA (Animal Medicinal Drug Use Clarification Act) only with a valid veterinary-client-patient relationship, and requires extended withdrawal times. In horses, it is not approved but may be used extra-label. In dogs and cats, it is approved for certain indications (e.g., skin infections).

Clinical Pearls & Practice Notes

💡 Clinical Insights: Clindamycin is a valuable antibiotic for anaerobic infections and certain Gram-positive infections in companion animals. It is particularly useful for osteomyelitis, dental infections, and deep pyoderma. In cats, it is a first-line treatment for toxoplasmosis. However, its use in horses, rabbits, and ruminants is limited by the risk of severe enterocolitis due to disruption of the normal gut flora. When used in these species, it should be reserved for cases where no safer alternative exists and with close monitoring. Always administer with food to reduce GI upset. For long-term therapy, monitor liver enzymes and blood counts. In food animals, adhere to withdrawal times and extra-label regulations. Clindamycin is not effective against Gram-negative aerobes, so it is often combined with other antibiotics for mixed infections.

References & Literature

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