Unfortunately chloramphenicol is one of few antibiotics which may cause human fatalities at therapeutic dosage levels. These toxic complications obviously limit its use in human medicine to cases of grave disease where it has unquestionable advantages over other antibiotics. Typhoid fever and systemic salmonella infections are among the diseases for which it has been required. It can, however, cause a fatal aplastic anaemia.
Sensitisation from previous exposure may be a contributory factor in the toxicity of chloramphenicol to humans, and it is therefore vitally important that human food should contain no chloramphenicol residues. It is also very important that the enteric bacteria of domestic animals should have minimal opportunity to develop transferable resistance to chloramphenicol.
The Report of the Joint Committee on the Use of Antibiotics in Animal Husbandry (commonly known as the Swann Report), placed special emphasis on chloramphenicol and expressed concern at its increasing use in veterinary medicine. Serious consideration was given at this time to the proposal that its use in animal husbandry and veterinary medicine be forbidden. "It is of interest to speculate on the possible implications of chloramphenicol use on domestic pets. Cats and dogs live in very close proximity to humans and have ample opportunity to transmit enteric bacteria in which transferable resistance may have been induced. Some authorities have argued that chloramphenicol should be avoided in these domestic situations." However, veterinary practitioners did retain the use of this antibiotic as an exceptional measure reserved for special situations.
In the certain chloramphenicol products for topical use were previously open-sellers, were included as Schedule 4 veterinary medicines.
There is no withholding period that has been recommended for chloramphenicol because its use in animals intended for food production is not allowed.
Veterinarians must not prescribe chloramphenicol as a feed or water additive for growth promotion purposes or to use or prescribe it for food producing animals in other than exceptional circumstances and then formally advise the owner about the responsibilities regarding keeping any treated animal out of the food chain.
"In the US, chloramphenicol does not have FDA approval for use in food-producing animals. Residues in foods of animal origin are illegal and regulatory laboratories claim the ability to detect levels in the low parts per billion range. Veterinarians responsible for illegal residues are vulnerable to law suits for damages. Veterinarians are able to purchase chloramphenicol legally for treatment of dogs, cats and zoo animals. It is also legal to use it in horses, cattle and swine not destined for human consumption but veterinarians are reminded that if the owner changes his mind and releases residue-containing animals into the food chain he can hold the veterinarian liable for any carcass condemnation if he has not been properly forewarned."
Quoted sections have come from Regulatory Control of Veterinary Drugs - Department of Primary Industry Pesticides Section, Document PB 237A, Australian Government Publishing Service, Canberra, 1983