Читать книгу Farm Animal Anesthesia - Группа авторов - Страница 43

Chloral hydrate was one of the first general anesthetics used in large animal practice. Chloral hydrate itself does not have a CNS‐depressing effect; it depends on its metabolite, trichloroethanol, to produce sedative and anesthetic effects. This latency of action as well as the narrow margin of safety of the drug makes it an undesirable anesthetic for use in clinical practice. Nonetheless, chloral hydrate is a very reliable sedative. In horses, chloral hydrate is often administered as an alternative when other tranquilizers or sedatives fail to produce the desired calming effect. Chloral hydrate does not have an analgesic effect, thus an additional analgesic is required if the animal is in pain or the procedure being performed is painful. Chloral hydrate is very irritating to the tissue. Therefore, IV injection of the drug is better via an IV catheter to prevent accidental perivascular injection and the consequential severe tissue damage. Chloral hydrate has been used to sedate unapproachable but confined cattle via oral administration. Water should be withheld for 24–36 hours prior to offering the animal diluted chloral hydrate drinking solution to ensure complete consumption of the drug. The dose recommended for oral administration is 100–150 g in 8–12 l of water per animal for sedation and 5–7 g per 100 kg (220 lb) for light to moderate narcosis [146].

In pigs, oral chloral hydrate (13 g/50 kg [110 lb]) produced sedation within 20–30 minutes following administration via a stomach tube [147]. Though intraperitoneal administration (4–6 ml of 5% solution/kg) has been reported in the pig, the technique is not recommended as peritonitis is a common complication [148]. However, Jennings reported intraperitoneal chloral hydrate administration (0.3 mg/kg in 5% solution) produced sedation within 30 minutes with a duration of 60 minutes. No tissue irritation or signs of peritonitis were observed [146]. Chloral hydrate (1–4 ml of 5% solution) has been used in combination with azaperone (4 mg/kg IM) in 500 pigs to produce general anesthesia for 2 hours with complete recovery to standing within 4–5 hours [149].