| Both long-acting and short-acting barbiturates may be encountered. The long-acting group includes phenobarbital, mephobarbital, and primadone—all commonly used as anticonvulsants or sedatives. The short-acting (butabarbital, pentobarbital,
secobarbital) and ultra short-acting (thiamylal and thiopental) barbiturates are used mainly for induction of anesthesia and seizure control. All are readily absorbed from the gut and have extensive liver metabolism; metabolites are primarily excreted via the kidneys. The onset of clinical signs varies from 15 min to several hours, and duration can be up to several days for the long-acting class. The most common
signs are sedation, ataxia, respiratory depression, coma, loss of reflexes, hypotension, and hypothermia. |
| Management is aimed at life support while attempting to remove unmetabolized drug from the system. Emesis should be induced if the exposure is very recent and the animal is asymptomatic. Gastric lavage while protecting the airway can remove much of the drug still in the stomach. Activated charcoal readily adsorbs barbiturates; small doses repeated every 4-6 hr can further decrease the body burden, even if overdose has resulted from use of an injectable product. IV fluids can be
given to support blood pressure. Respiratory effort and effectiveness needs to be closely monitored; treatment may require a respirator. Support for maintaining body temperature may be necessary. |
