Suspected and real intoxications are common causes of presentation to the emergency service. Different scenarios of patient presentation may occur:

• Asymptomatic animals with observed or suspected exposure to toxins
• Symptomatic animals with suspected exposure to toxins
• Symptomatic animals with observed exposure to toxins

For all presentation scenarios, a toxicologic analysis is helpful to identify the toxin. Vomited material, gastric content, urine, or serum can be sent in for analysis. It is of high importance to give the toxicologist a detailed history to enable a pre-differentiation of suspected toxins. Analysis usually requires several days. For some common toxins such as ethylene glycol and anticoagulants, point of care tests are available, which help to confirm a suspicion of intoxication in the emergency service. In patients with known exposure to toxins, the name and amount of the toxin ingested should be evaluated so that the properties of the toxin, such as toxic dose, lethal dose (LD) 50, LD 100, time to symptoms, time to maximal plasma levels, half-life, volume of distribution, water solubility, fat solubility (Log P), molecular weight, and protein binding can be identified.

For asymptomatic patients we should consider decontamination, antidote therapy if available, and enhancing excretion if possible.

In symptomatic patients the first step is to triage the patient and treat the most life-threatening symptoms. This is followed by decontamination, antidote therapy, and enhancement of excretion of the toxin.

Symptomatic treatment depends on the symptoms. Common signs observed at triage are cardiovascular abnormalities such as shock, bradyarrhythmia, and tachyarrhythmia, but also respiratory issues, seizures, anaemia, vomiting, and diarrhoea, hyper- and hypothermia, local tissue irritation and pain.

The type of decontamination depends on the contact area. Toxins exposed to the skin should be washed from the skin. It is also helpful to clip the contaminated fur. Usually these toxins are fat soluble. Therefore, washing should be performed using mild shampoo. Toxins leading to local irritation of the oral and oesophageal mucous membranes should be diluted with water. If the toxin is a known acid or base, some mild neutralizing agents such as bicarbonate for acids and citrate for alkalic substances help to decrease further injury. Decontamination should be performed as soon as possible after exposure to minimize tissue damage.

Gastrointestinal exposure can be decontaminated by inducing emesis, performing gastric lavage, or administering activated charcoal.

Efficacy of all decontamination techniques depends on timing, type, and formulation of the toxin. Some drugs in liquid or tablet formulation are fully absorbed within a few minutes. For these toxins, decontamination after a few hours is not helpful. Some other toxins such as metaldehyde may stay in the intestinal tract for a longer period, so decontamination may be helpful even hours after exposure. Induction of emesis should only be performed in animals without neurologic symptoms and with intact swallowing reflexes. Inducing emesis is not indicated if acids, alkali substances, alcohol, oily substances, or paraffin have been ingested. Using emetics, about 50% of the substance can be retrieved. This also depends on the physical properties of the substance. If it sticks to the gastric wall, often less than 50% of the toxin can be removed. Sometimes it is helpful to feed the patient before inducing emesis.

Emesis can be induced with apomorphine in dogs. It acts at the chemoreceptor trigger zone, and subsequently binds to µ-opioid receptors in the vomiting center and stops vomiting, thus it produces self-limiting vomiting. The effect is faster and shorter after IV application compared to subcutaneous or intramuscular routes. It may cause bradycardia, tachycardia, and sedation. The antiemetic effect, but not the cardiovascular effects, can be antagonized by naloxone. Maropitant and metoclopramide will also antagonize the emetic effect. It has also been proven to be effective after conjunctival application, but causes conjunctival irritation via this route.

Hydrogen peroxide (H₂O₂) is also effective in inducing emesis in dogs, but may cause bloat and leads to intestinal irritation and mucosal injury. Syrup of ipecac and sodium solutions are not recommended to induce emesis in dogs.

In cats, xylazine is used as a standard emetic drug. The effective dose 50 (ED 50) is 0.27 mg/kg, the ED 100 is 1 mg/kg. With higher doses, the incidence of sedation is high. Subcutaneous and IM application is more effective compared to IV. Alternatively, dexmedetomidine has been used at doses of about 10 µg/kg to induce emesis. The ED 50 and 100 to induce emesis in cats is unknown. The effect can be antagonized with atipamezole.

Activated charcoal adsorbs mostly fat-soluble substances due to the high surface area. It only has a minor effect for alcohol, paraffin, and alkalic substances. It decreases intestinal motility and will also adsorb other enterally administered substances and drugs. For some drugs with enterohepatic circulation, elimination can be enhanced by repeated dosing. The effective dose is about 1–4 g/kg. The effect is slightly reduced by adding food to the charcoal. Laxatives, such as sorbitol, added to charcoals shorten the passage time and enhance toxin elimination. The effect of charcoal has not been studied for many toxins. Ideally, one should search for studies on the effect of charcoal on toxin plasma levels in the target toxin and species.

Gastric lavage is often used to decontaminate the GI tract. The substance is often not removed completely. For lavage, the patient should be anaesthetized and intubated. Lavage should be performed with water or isotonic solutions. A volume of 10 mL/kg lavage fluid is recommended, which is infused and drained from the stomach via a large bore tube with a murphy eye. Adding bicarbonate may increase gastric pH and decrease metabolism of some substances in the gastric acid. Colonic lavage is also helpful to eliminate residual toxins, that may be resorbed in the colon.

For some toxins such as anticoagulants, paracetamol, organophosphate, and ethylene glycol, antidotes are available. These should be administered early in the course of treatment.

Elimination of the toxin from the circulation is mandatory if the animal was exposed to toxic or lethal doses of the substance. For small sized, water soluble toxins, fluid diuresis may be helpful. It is often recommended to add a diuretic to improve elimination. The effect of furosemide or mannitol has not been studied for many toxins and remains unclear. Alternatively, these small sized, water-soluble toxins with a low volume of distribution may be removed by haemodialysis or peritoneal dialysis. The effect has been proven for some toxins. Especially for fat soluble substances elimination via charcoal haemoadsorption is possible. In human medicine some of these toxins have also been treated with large bore haemodialysis. Protein bound toxins, such as many NSAIDs, have been successfully removed using plasmapheresis. The type of extracorporeal treatment has to be adapted to the physical properties of the toxins.

Intravenous lipids are commonly used these days to treat severe intoxications with fat soluble toxins characterized with a Log p>1. There is limited evidence on the effect of IV lipids in animals. Many case reports describe successful management. Metanalysis of experimental studies have proven a positive effect of IV lipids in cardiac arrest due to local anaesthetic intoxication. One prospective study in veterinary medicine has proven a positive effect in cats with permethrin intoxication. Side effects should be kept in mind. Additionally, toxin adsorption can be enhanced with IV lipid treatment if no decontamination has been performed in advance of the application.