CE Article #1 Five CommonToxins Ingested by Dogs and Cats Julie Ann Luiz, DVM University of Hawaii at Hilo Johanna Heseltine, DVM, MS, DACVIM Oklahoma State University ABSTRACT: Substances that are toxic to pets are present in most households. Early identification of intoxication is crucial to preventing or minimizing gastrointestinal absorption of toxins.The history, clinical signs, and laboratory test results can be used to make a presumptive diagnosis and begin therapy. nce absorbed from the gastrointestinal in veterinary medicine are derived from the (GI) tract, many toxins lack a specific human medical literature. Decontamination and Oantidote and are associated with severe treatment strategies for the toxins discussed in systemic effects that are difficult to treat. this article are summarized in Table 1 . Therefore, prompt decontamination is the first step in managing patients that have ingested Emesis Induction toxic materials. If the toxin ingested is known, If the owner suspects toxicosis and calls the therapy should be initiated before clinical signs clinic before presenting the animal, the veteri - develop. This article discusses the general prin - narian must consider the risks and benefits ciples for minimizing GI absorption of ingested of instructing the owner to administer an toxins and the clinical presentation and man - emetic .1 Productive emesis requires the pres - agement of toxicosis caused by five commonly ence of food or liquid in the stomach, espe - ingested household substances: anticoagulant cially for retrieval of small volumes of toxin .2 rodenticides, ethylene glycol (EG), marijuana, Removal of the poison from the stomach is chocolate, and metaldehyde. most effective within 1 hour of ingestion, is useful up to 2 hours after ingestion, and is of DECONTAMINATION STRATEGIES limited benefit more than 4 hours after inges - FOR ORALLY INGESTED TOXINS tion. 2,3 Early emesis may remove up to 80% of GI decontamination techniques are used to pre - the ingested material. 3 vent or limit the absorption of ingested toxins. Induction of emesis is contraindicated for Because many toxins lack a specific antidote, corrosive and caustic materials, as well as for decreasing the amount of petroleum distillates and other volatile materials toxin absorbed may be life- that may result in aspiration pneumonia .2,3 saving, and decontamination Vomiting should not be induced in patients •Take CE tests strategies should begin as soon that are depressed or have decreased conscious - • See full-text articles as possible after ingestion of a ness or those that have seizures or are likely to toxic substance. Most decont - seizure. 2,3 Emetics should not be administered if CompendiumVet.com amination methods practiced the patient has already vomited. 2 COMPENDIUM 578 November 2008 Five Common Toxins Ingested by Dogs and Cats CE 579 Ipecac and Hydrogen Peroxide Emetics that may be administered by the owner include syrup of ipecac and hydrogen peroxide, although these may not be effective. Syrup of ipecac (Table 2) causes gastric irritation and directly stimulates the chemoreceptor trigger zone, typically resulting in vomiting within 15 to 20 minutes. 2,3 If vomiting does not occur after dosing, one repeat dose may be given. Ipecac is ineffective in 50% of dogs treated. 3 Ipecac may cause exces - sive vomiting or central nervous system (CNS) depression. 3 Repeated dos - ing can result in cardiotoxicity. 2 The fluid extract is 14 times more potent than the syrup formulation and should not be used. 2 Hydrogen peroxide is a safer emetic that can be administered by owners using a syringe turkey baster. A 3% solution must be used because more concentrated formula - tions can cause severe mucosal irritation. 2 Potentially dangerous emetics that should not be used include table salt, dishwashing detergent, and cop - per sulfate. 2,3 Apomorphine and Xylazine Emetics for veterinary use include apomorphine hydrochloride for dogs and xylazine hydrochloride for cats. 2,3 Apomorphine is not consistently effective in cats, and a safe, effective dose has not been recommended for this species. 2 Apomorphine is a centrally acting agent that may be injected, or the oral tablet may be instilled subconjunctivally. After effec - tive emesis, the conjunctiva should be thoroughly rinsed because this med - ication is irritating. 2 Apomorphine may cause CNS depression, which , if severe, may be antagonized with naloxone (0.04 mg/kg IV) without alter - 2,3 ing the emetic effects. Xylazine is an α2-adrenergic agonist that causes emesis in cats but is not reliably effective in dogs. It may cause sedation and respiratory depression, which can be reversed with yohimbine (0.5 mg/kg SC or IM). 2,4,5 Gastric Lavage For patients in which induction of emesis is ineffective or contraindicated, GI decontamination may be achieved through gastric lavage, although this procedure requires the patient to be unconscious or anesthetized. 2,3 Gastric lavage is contraindicated for managing ingestion of caustic substances and volatile petroleum distillates and may be ineffective for congealed or chunky material. 2 The patient is positioned with the head lower than the chest. With a cuffed endotracheal tube in place, a stomach tube is passed no further than the level of the xyphoid. Warm water (5 to 10 mL/kg) is administered slowly, and the stomach contents are aspirated after a few minutes. The procedure is repeated 15 to 25 times and with the animal in different recumbent positions until the lavage fluid is clear. The end of the tube should be occluded or the tube kinked before removal. 2,3 Potential complications include electrolyte disturbances, esophageal perforation, propulsion of the toxin into the small intestine, and aspiration. 2 Activated Charcoal Administration Activated charcoal acts by adsorption—binding of the toxicant to an unab - sorbable carrier—and results in elimination of toxin in the feces. It provides November 2008 COMPENDIUM 580 CE Five Common Toxins Ingested by Dogs and Cats Table 1. Quick Reference for Decontamination andTreatment Recommended Toxin Decontamination Strategies RecommendedTreatment Anticoagulant • If asymptomatic and within several • Antidote: Vitamin K 1 (phytonadione) rodenticides hours of exposure, induce emesis • Dyspnea : Oxygen therapy • Administer activated charcoal • Hemothorax : Thoracocentesis • If symptomatic, detoxification is not useful • Anemia : Fresh whole blood transfusion or a • If symptomatic and continued or repeated combination of packed red blood cells and fresh- ingestions are suspected, administer frozen plasma activated charcoal and a cathartic agent • Active bleeding : Clotting factors supplied as fresh or fresh-frozen plasma Chocolate • If ingestion was recent, induce emesis • Seizures: Diazepam and sometimes phenobarbital or • Administer activated charcoal and a saline pentobarbital cathartic • Ventricular tachycardia: Lidocaine • Repeated administration of activated • Tachyarrhythmia: Propanolol or metoprolol charcoal q3 –8h for up to 72 hours is • Fluid therapy beneficial because methylxanthines • Urinary catheter placement to prevent reabsorption undergo enterohepatic recirculation of urinary methylxanthines through the bladder wall • If a massive dosage was ingested, perform gastric lavage Ethylene glycol • If asymptomatic and within 4 hours of • Fomepizole (4-MP) exposure, induce emesis • If 4-MP is not available : 7%– 20% ethanol • Administer activated charcoal and a saline • Supportive therapy : Fluid therapy, diuresis cathartic maintenance • Anuria : Furosemide, mannitol , or dopamine • Metabolic acidosis : Sodium bicarbonate • Symptomatic hypocalcemia : 10% calcium gluconate • Severe cases of renal failure : Peritoneal dialysis and hemodialysis Marijuana • If asymptomatic and ingestion was recent, • Supportive therapy : Fluid therapy induce emesis • Respiratory depression : Oxygen therapy • Administer activated charcoal and a saline • Agitation : Diazepam cathartic • Repeated administration of activated charcoal is beneficial because marijuana undergoes enterohepatic recirculation Metaldehyde • If patient is alert without excessive muscle • Seizures : Diazepam tremors or seizures, induce emesis • Muscle tremors and seizures : Methocarbamol • Administer activated charcoal and a • Seizures refractory to other therapies : Propofol cathartic • Supportive therapy : Fluid therapy • Perform gastric lavage if emesis is • Tachypnea or dyspnea : Oxygen therapy contraindicated • Metabolic acidosis : Sodium bicarbonate the most benefit when given within 2 hours of toxin against ethanol, methanol, isopropyl alcohol, acetone, ingestion but may still be useful up to 24 hours after petroleum distillates, pine oil, ammonia, and cyanide. 2,3 ingestion, especially for toxins undergoing enterohepatic It is available in granular and suspension formulations. recirculation. 2 It may be administered after emesis or Activated charcoal should not be given to patients at gastric lavage or when these procedures are contraindi - risk for aspiration pneumonia or those with suspected cated. Activated charcoal is generally accepted as the GI perforation. 2 When the granular formulation is used, adsorbent of choice, although it is relatively ineffective a dose of 1 to 4 g/kg is mixed in 50 to 200 mL of water COMPENDIUM November 2008 Five Common Toxins Ingested by Dogs and Cats CE 581 to make a slurry .2 The suspension dose is 6 to 12 Table 2. Products Commonly mL/kg. 6 Patients without clinical signs may be per - Used to Induce