8 questions to ask before treating poisoned veterinary patients

1. When did the ingestion occur? In most cases, vomiting can safely be induced within an hour of ingestion. If it has been several hours since the ingestion, most likely the toxicant has already moved out of the stomach and vomiting will be of limited or no benefit to the pet.1,2 Certain toxins can delay gastric emptying (e.g. salicylates, opioids, anticholinergics) or remain in the stomach for a prolonged period of time (e.g. chocolate, large wads of xylitol gum, grapes or raisins, large ingestions of tablets or capsules that form a bezoar). In these specific situations, vomiting induction can be performed in asymptomatic patients up to four hours after ingestion.1

2. Does the patient have any symptoms? Induction of vomiting in a pet that is already vomiting or symptomatic is not warranted. Pets that are sedate or have an altered state of consciousness may be at increased risk of aspiration pneumonia secondary to vomiting induction. In many situations, gastric lavage1 performed under intubation-to protect the airway-may be required. Pets that present in an excited state can have clinical signs further exacerbated during vomiting induction, thus worsening their condition. Again, as the patient is already symptomatic, they have likely already absorbed most of the drug or toxin.

3. Is there a species or breed concern with induction of vomiting? Brachycephalic breeds of dogs (e.g. bulldogs, Pekingese, Shih-Tzus) may present a higher risk of aspiration pneumonia and are candidates for sedation, airway protection, and gastric lavage. Species that can be safely induced to vomit include most dogs, cat, ferrets, and potbelly pigs. Rabbits, rodents (e.g. chinchillas, rats, gerbils), ruminants (e.g. sheep, cattle, llamas, goats), horses and birds can't safely be induced to vomit or may be anatomically unable to vomit.3

4. Is there an underlying medical concern or condition? Megaesophagus, laryngeal paralysis, or a previous history of aspiration pneumonia are a few examples of conditions that may increase the risk for aspiration pneumonia when inducing vomiting.1

5. Is the toxicant caustic or corrosive? Any substance that's corrosive and capable of causing burns and caustic injury can further injure the stomach, esophagus, and mouth when inducing vomiting. Examples are batteries, undiluted drain cleaners, toilet bowl cleaners, lime-removal products and concentrated pool products. With poisoning from this type of ingestion, vomiting induction is contraindicated.

6. Is the toxicant a hydrocarbon or petroleum distillate? These low-viscosity liquids are easy to aspirate into the lungs, and vomiting induction is not recommended. Some frequently encountered hydrocarbons and petroleum distillates include gasoline, kerosene, tiki torch fuels, motor oils and furniture polish oils.

7. Is the toxicant zinc, calcium, or aluminum phosphide? These are active ingredients in many commercially available mole and gopher baits. Ingestion of these phosphide rodenticides can result in the formation of a toxic phosphine gas in the stomach. This gas can harm owners and clinic staff when the pet vomits, potentially causing headache, nausea and bronchial-type reactions (like asthma). Induction of vomiting should occur outdoors or in a well-ventilated area after administration of an antacid (e.g. aluminum hydroxide, milk of magnesia).

8. How fast will the patient develop clinical signs with this toxicant? Large ingestion of human medications can result in rapid occurrence of life-threatening clinical signs. It is important to determine if and when pharmaceutical ingestion will result in sudden changes in blood pressure, heart rate, central nervous system mentation or neurologic abnormalities (e.g. seizures, hyperagitation, tremors). Since many medications (e.g. selective-serotonin reuptake inhibitors, quick-release drugs, sublingual pills) can cause clinical signs right away, pet owners should not be told to induce vomiting at home without appropriately consulting a veterinarian or Pet Poison Helpline.

Don't miss part two of this article: 7 effective emetics and how to use them.

References:

• Lee JA. Decontamination of the Poisoned Patient. In: Osweiler G, Hovda L, Brutlag A, Lee JA, ed. Blackwell's Five-Minute Veterinary Consult Clinical Companion: Small Animal Toxicology, 1st Ed. Iowa City: Wiley-Blackwell, 2010, pp. 5-19.

• Peterson ME. Toxicological Decontamination. In: Peterson ME, Talcott PA, ed. Small Animal Toxicology, 2nd Ed. St. Louis: Elsevier Saunders, 2006, pp. 127-141.

• Bihun C, Bauck L. Basic Anatomy, Physiology, Husbandry, and Clinical Techniques. In: Quesenberry K, Carpenter JW, eds. Ferrets, Rabbits, and Rodents, 2nd Ed. St Louis: Elsevier Saunders, 2004, pp 289-290.