Decontamination in toxicology cases (Proceedings)
All patients should be stabilized prior to attempts at decontamination. Once stabilization has been accomplished, decontamination should be considered to prevent systemic absorption of the toxicant. The specific method of decontamination chosen in each case must be guided by the species exposed and the exposure circumstances. When a patient has ingested a potentially toxic dose of a substance, the clinician has many options for decontamination including dilution, induction of emesis, gastric lavage, the use of adsorbents, cathartics, and administration of enemas. In many cases, the best treatment plan will include more than one of these methods.
Dilution using a small amount of milk or water is recommended in cases where irritant or corrosive materials have been ingested. A dose of 2-6 ml/kg is suggested, which for an average-sized cat, would be approximately only 1 – 2 teaspoons. Using only a small amount is important since using excessive amounts could lead to vomiting and re-exposure of the esophagus to the damaging material. Juicy fruits and vegetables can be fed to accomplish dilution in some patients, especially birds and reptiles. Dilution is not appropriate in patients who are at an increased risk for aspiration, including those who are actively seizing or obtunded. Dilution with milk, yogurt and cottage cheese has been useful in cases of oral irritation following ingestion of plants containing insoluble calcium oxalate crystals (Philodendron species, for example.
Emetics are usually most effective if used within 2-3 hours after the ingestion but in some cases, emesis may be effective even after that time frame. If the substance ingested could coalesce to form a bezoar in the stomach or a timed-released medication was ingested, emesis may be effective later than 3 hours after the ingestion. Chocolate and chewable medications are examples of products which may form bezoars. Emetics generally empty 40-60% of the stomach contents. Feeding a small moist meal before inducing vomiting can increase the chances of an adequate emesis.Animals which are able to vomit safely include dogs, cats, ferrets, and potbelly pigs. Emetics should not be used in birds, rodents, rabbits, horses or ruminants. Rodents are unable to vomit. Rabbits have a thin-walled stomach putting them at risk for gastric rupture if they vomit.
Induction of emesis is contraindicated with ingestion of corrosive agents including alkalis and acids. The protective epithelial lining of the esophagus may be damaged initially when one of these products is swallowed. The muscular layer of the esophagus may be exposed and at risk for ulceration, perforation and scarring if vomiting does occur. Emesis is also not recommended after petroleum distillate ingestion due to the risk of aspiration. The clinician must also take into account when deciding whether to induce emesis, any pre-existing conditions of the patient that can cause vomiting to be hazardous including severe cardiac disease or seizure disorder. In all instances the attending veterinarian must carefully weigh the benefits of emesis against the risks. Emesis may not be needed if the animal has already vomited and is not appropriate if the animal is already exhibiting clinical signs such as coma, seizures or recumbency, which make emesis hazardous. Additionally, if the patient has ingested a CNS stimulant and is already agitated, the additional stimulation of vomiting could lead to seizures.
Hydrogen peroxide, apomorphine hydrochloride and xylazine hydrochloride are commonly used emetics in the veterinary clinical setting. Preliminary data obtained from the ASPCA Animal Poison Control's toxicology database indicate that hydrogen peroxide and apomorphine are effective emetics in dogs. Emesis was successful in ninety-two percent of dogs when administered either 3% hydrogen peroxide or apomorphine. No significant adverse effects were reported in dogs after emetic use. Apomorphine was poorly effective as an emetic in cats and using it in cats is controversial. Xylazine was an effective emetic in only fifty-seven percent of cats. When emesis was successfully induced, sixty-eight percent of patients vomited some portion of the ingested toxicant.