What they did
Because no data describe the efficacy and adverse effects of emetics in dogs, researchers evaluated the efficacy of apomorphine vs. 3% hydrogen peroxide to induce emesis after toxin exposure, as well as any resulting adverse effects, in 147 dogs.

Information was gathered from the medical record database of the ASPCA Animal Poison Control Center (APCC) between January 2008 and April 2009. Callers were instructed to induce emesis (if medically indicated) by using either apomorphine (0.03 mg/kg intravenously once, or a crushed tablet dissolved in saline solution, instilled in the conjunctival sac, and rinsed away with water or saline solution after emesis) or 3% hydrogen peroxide (2.2 ml/kg orally, 45 ml maximum, repeated once after 10 to 15 minutes if vomiting did not occur). Unless the dog had already eaten within the preceding two hours, feeding a small meal before the induction of emesis was also recommended to improve success.

What they found
Hydrogen peroxide was administered to 84 dogs and apomorphine to 63 dogs. Emesis was successful in about 92% of dogs regardless of the type and dose of emetic used. The route of apomorphine administration was not significantly associated with the successful induction of emesis or occurrence of adverse events. The time to onset of emesis was similar between both groups—14.5 minutes for peroxide and 18.6 minutes for apomorphine. The duration of effect appeared longer for the peroxide group (42 vs. 27 minutes), but this was not statistically significant. Recovery of ingested agents was 48% for the peroxide group and 52% for the apomorphine group. The overall incidence of adverse events was low (14%) and consisted primarily of lethargy and nausea. An association between the frequency of administration of an emetic and frequency of adverse events was noted.

Take-home message
The researchers briefly mention other agents not recommended for use as emetics because of the potential for adverse events: sodium chloride salt (sodium toxicosis), ipecac syrup (cardiotoxicity), and xylazine (CNS depression, hypotension). In addition, mustard powder and dishwashing liquid are not recommended because of ineffectiveness, administration difficulty, and the possibility of severe adverse effects.

The authors also remind us that owners may not consult with a veterinary professional before administering an emetic and may give an incorrect dose or repeatedly and excessively attempt to induce emesis, induce emesis in patients that have ingested an agent that has antiemetic effects, or induce emesis in patients that have ingested agents for which inducing emesis would be contraindicated (caustic agent, CNS stimulant, hydrocarbon or petroleum distillate).

However, when used appropriately and under veterinary supervision, both apomorphine and 3% hydrogen peroxide provide similar efficacy for the induction of emesis with comparable risk of adverse effects, which were described as typically mild and self-limiting.

Khan SA, McLean MK, Slater M, et al. Effectiveness and adverse effects of the use of apomorphine and 3% hydrogen peroxide solution to induce emesis in dogs. J Am Vet Med Assoc 2012;241(9):1179-1184.

Abstract available at: http://avmajournals.avma.org/doi/abs/10.2460/javma.241.9.1179