Chlortetracycline

Chlortetracycline is an older tetracycline antibacterial used mainly in livestock feed or drinking water. Its practical role is control or treatment of specified susceptible infections at herd or flock level, including anaplasmosis control in cattle. Oral absorption is limited, so its clinical behavior differs from that of better-absorbed systemic tetracyclines.

Group

Tetracycline antibacterial

Mechanism of Action

Chlortetracycline enters susceptible organisms and reversibly binds the 30S ribosomal subunit. This prevents aminoacyl-transfer RNA from accessing the ribosomal acceptor site, interrupting peptide-chain elongation and bacterial protein synthesis. The resulting effect is primarily bacteriostatic. Its spectrum includes selected intracellular organisms and mycoplasmas as well as susceptible conventional bacteria, with activity determined by organism-specific resistance.

Dose Rates

Dogs

Use / stage	Dose	Route	Schedule	Instructions
Historical bacterial infection treatment	25 mg/kg	PO	Every 6–8 h	Rarely used; the monograph identifies no efficacy evidence.

Cats

Use / stage	Dose	Route	Schedule	Instructions
Historical bacterial infection treatment	25 mg/kg	PO	Every 6–8 h	Rarely used; the monograph identifies no efficacy evidence.
Cattery conjunctivitis recurrence prevention	50 mg/animal	PO	Every 24 h	Up to 30 days; Historical oral soluble powder in feed for mycoplasmal/chlamydial disease where topical therapy is impractical; delivered amount depends on intake.

Cattle

Use / stage	Dose	Route	Schedule	Instructions
Anaplasmosis prophylaxis	0.36–0.7 mg/kg	PO	Every 24 h	Oral feed/block delivery; individual intake determines the delivered amount.
Bacterial infection treatment	11 mg/kg	PO	Every 12 h	Up to 5 days; Oral tablets; course 3–5 days.
Feed or water medication	22 mg/kg	PO	Every 24 h	Total daily drug mass added to feed or water. Intake variation prevents assurance that each animal receives this amount.
Alternative oral infection treatment	10–20 mg/kg	PO		The source suggests once-daily use but does not explicitly assign the interval to this regimen; no interval is inferred.
Historical parenteral treatment	Reference only	IV		6–10 mg/kg IV or IM is described without a repeat schedule and without an established injectable product here.

Pigs

Use / stage	Dose	Route	Schedule	Instructions
Feed or water medication	22 mg/kg	PO	Every 24 h	Total daily drug mass added to feed or water. Intake variation prevents assurance that each animal receives this amount.
Alternative oral infection treatment	10–20 mg/kg	PO		The source suggests once-daily use but does not explicitly assign the interval to this regimen; no interval is inferred.
Historical parenteral treatment	Reference only	IV		6–10 mg/kg IV or IM is described without a repeat schedule and without an established injectable product here.

Rabbits

Use / stage	Dose	Route	Schedule	Instructions
Bacterial infections	50 mg/kg	PO	Every 12–24 h

Chinchillas

Use / stage	Dose	Route	Schedule	Instructions
Bacterial infections	50 mg/kg	PO	Every 12 h

Hamsters

Use / stage	Dose	Route	Schedule	Instructions
Historical injectable treatment	Reference only	IM		20 mg/kg IM or SC every 12 hours; no appropriate injectable preparation is established here.

Mice

Use / stage	Dose	Route	Schedule	Instructions
Historical injectable treatment	Reference only	SC		25 mg/kg SC or IM every 12 hours; no appropriate injectable preparation is established here.

Rats

Use / stage	Dose	Route	Schedule	Instructions
Historical injectable treatment	Reference only	SC		6–10 mg/kg SC or IM every 12 hours; no appropriate injectable preparation is established here.

Ratites

Use / stage	Dose	Route	Schedule	Instructions
Bacterial infections	15–20 mg/kg	PO	Every 8 h

Pigeons

Use / stage	Dose	Route	Schedule	Instructions
Ornithosis-complex adjunct	50 mg/kg	PO	Every 6–8 h	Often combined with tylosin. Calcium-rich grit/feed reduces absorption; maintain an appropriate nutritional plan.
Drinking-water medication	Reference only	PO		1000–1500 mg per gallon water; gallon standard is unspecified. Mix fresh at least every 12 hours in warm weather and account for intake.

Birds

Use / stage	Dose	Route	Schedule	Instructions
Feed treatment of chlamydiosis	Reference only	PO		Historical feed concentrations: 0.05% for small birds and 1% for larger psittacines. This does not establish an individual mg/kg dose; intake and exact feed composition matter.

Indications

Control of bovine anaplasmosis caused by susceptible Anaplasma marginale using an indicated medicated-feed program.
Treatment or control of specified susceptible bacterial respiratory infections in cattle, pigs or poultry with an appropriate medicated product.
Treatment or control of specified susceptible enteric bacterial infections in livestock, according to the species and product indication.

Contraindications

Avoid young animals except where the specific livestock use permits it.
Oral use in horses can cause diarrhea.
Do not use in guinea pigs because of enterotoxemia risk.
Use cautiously with renal or hepatic impairment; late-pregnancy exposure may impair fetal skeleton or tooth development.

Interactions

Calcium, magnesium, iron, zinc and aluminum reduce absorption by chelation.
Avoid concurrent nephrotoxic or hepatotoxic agents where possible.

Adverse effects

Tooth and bone deposition in growing animals
Renal injury with high exposure
Diarrhea

Preparations

Preparation	Form	Strength	Route
Chlortetracycline 25 mg tablet	Tablet	25 mg / tablet	PO
Chlortetracycline 500 mg tablet	Tablet	500 mg / tablet	PO

Monitoring and Administration

Dose delivery in feed or water depends on actual intake. Do not infer systemic efficacy from susceptibility results for better-absorbed tetracyclines.

Small-animal use is uncommon and lacks efficacy evidence. Keep dry formulations protected from light and incompatible minerals.

Powder concentrations include 25 or 64 g per pound of premix, and blocks may contain 2.5 g per pound; these are feed concentrations, not direct mL or tablet conversion strengths.