Brand Names:
Aureomycin, Cyanamid

Drug Type: Antibiotic


Chlortetracycline is a broad-spectrum bacteriostatic agent that works by inhibiting protein synthesis. It is one of the few antibiotics approved for use in laying hens producing eggs for commercial use in the United States, Australia, Canada, and Ireland. Chlortetracycline is one of the older antibiotics from the tetracycline class. Other drugs from the tetracycline class include Oxytetracycline, Tetracycline, and Doxycycline. Tetracyclines have activity against gram-positive and gram-negative bacteria, including some anaerobes. It is also active against Chlamydia, Mycoplasmas, and some protozoa, and several rickettsiae. Specific bacteria within the tetracycline's activity range include Escherichia coli, Klebsiella spp, Pasteurella spp, Salmonella spp, Staphylococcus spp, and Streptococcus spp.

Egg Withdrawal Period:
  • In Australia: Chlortetracycline is labeled for use in the drinking water of chickens at doses up to 60 mg/kg (27 mg/lb) for < 5 days with a 0-day egg withdrawal.
  • In Ireland: Chlortetracycline can be fed as part of a medicated feed to laying hens at a dose of 20 to 25 mg/kg (9 to 11 mg/lb) for 5 to 7 days with a 4-day egg withdrawal.
  • In the United States and Canada: Chlortetracycline approved for use in laying hens producing eggs intended for human consumption when its given in accordance with each product manufacturer's directions.
Caution: Prolonged treatment can have catabolic and immunosuppressive effects, reduce normal gut flora, and cause the bird to become more susceptible to opportunistic secondary infections.
  • 5000 mg/kg soft feed for 45 days
  • 2500 mg/L drinking water
  • Photosensitivity
  • Decreased immunity
  • Disruption of normal gut flora
  • More susceptible to infection with secondary pathogens.
  • Calcium
  • Sodium bicarbonate: Concurrent use with tetracyclines may result in formation of non-absorbable complexes; also, concurrent use within 1 to 3 hours of administering may result in decreased absorption of oral tetracyclines because of increased intragastric pH.