© Stuart M Bennett 2002


Alpha-Chloralose is an immobilising agent used on mice and pest birds. Classified as a soporific, which is a central nervous system depressant designed to immobilise target species at sublethal levels. The compound is slowly metabolised, resulting in a recovery within a few hours from ingestion. Possible accumulation in species that have undergone multiple treatments. Secondary risks to predators a factor if target species not removed promptly after administration of the compound.

It is also classified as a narcotic. Primary and secondary toxicity listed as low when the target species is removed. There is no probable aquatic risk due to the use pattern and lack of solubility in water.

Alpha chloralose is a hypnotic agent that has historically been popularized for its lack of baroreceptor depression, i.e. produces a stable, "physiologically awake animal" that is immobilized and "anesthetized." Recent studies of alpha chloralose in rats have shown that it produces a slow onset of sedation rather than a surgical plane of anesthesia which is characterized by myoclonia, hyperacusia, persistent muscle tone, convulsions, mild hypothermia and mild acidosis. This drug is probably a hypnotic rather than a true anesthetic, with unproven analgesic potency. It appears that the most ethically and scientifically acceptable use of this agent in rodents is to provide long-lasting anesthesia for procedures involving no painful surgical intervention. When using chloralose in rodents, a more potent but short-acting anesthetic (e.g. a thiobarbiturate), possibly in combination with a narcotic, can be administered to produce a depth of anesthesia sufficient to allow surgical procedures to be completed, following which unconsciousness can be maintained with alpha chloralose.

Chemical Name: (alpha)-D-Glucochloralose or alpha-chloralose

Other Names: Alpha-D-glucochloralose; Chloralose; Anhydroglucochloral; 1,2-O-(2,2,2-Trichloroethylidene)-alpha-D-glucofuranose; Alfamat; Aphosal; Chloroalosane; Dulcidor; Glucochloral C8H11O6Cl3; Glucochloralose; Glucofuranose, 1,2-o-(2,2,2-trichloroethylidene)-, (R)-; Murex; Somio; (R)-1,2-O-(2,2,2-trichloroethylidene)-alpha-D-glucofuranose;

Chemical Formula: C8H11Cl3O6

Chemical Structure:



Oral Mouse LD50 32 mg kg-1
IPR Mouse LD50 190 mg kg-1
Oral Rat LD50 400 mg kg-1


When Alpha-chloralose technical is used to stupefy birds it is a requirement to inform DEFRA. Also when laying the bait, it should be laid in numbered piles, which are on a plan, so that recovery of unused bait is effective. Sometimes DEFRA will have a representative on site. At the same time the number of operatives on site must be enough to enable recovery of all birds. It must be remembered that the birds do not stupefy immediately, and a careful watch must be maintained to ascertain where each flies to, so it can be recovered. Another thing to think about is the public reaction if the narcotising is in a town or city and birds start dropping in the high street, it may not be a suitable control method. Protected birds must be put into a warm recovery box in a quiet situation and then released gently. Pest birds must be dispatched correctly ideally using CO2.


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