Triage and the decision to decontaminate
Merck notes that some patients may need immediate lifesaving measures at the initial examination [1]. Its key points advise considering the route of exposure and the type of substance first, so that decontamination is appropriate and "unlikely to result in more harm" [1].
Per Merck, "Emesis is contraindicated when the swallowing reflex is absent; the patient is not neurologically stable; the ingested substances are corrosive agents, volatile hydrocarbons, or petroleum distillates; or the risk of aspiration pneumonia is high" [1].
Merck also lists methods it calls inappropriate: oral salt, syrup of ipecac, and manual stimulation of the throat. It adds that owners should be advised against home remedies such as dish soap, raw eggs, hot sauce and mustard [1].
The cited sources do not assign tasks to specific team members. How a practice divides triage and intake work is outside what these sources address.
Inducing emesis in dogs and cats
Merck explains the species difference by receptor type. Dopamine D2 receptors drive emesis in dogs, which makes dopamine agonists more reliable in that species. Alpha-2 adrenergic receptors play the larger role in cats [1].
| Species | Agent | Dose as stated by Merck [1] |
|---|
| Dog | Hydrogen peroxide | "3% solution, 1-2 mL/kg, PO, up to 45 mL" |
| Dog | Apomorphine | "0.04 mg/kg, IM, or 0.03 mg/kg, IV" |
| Dog | Ropinirole eye drops | 2.7-5.4 mg/m2 in the conjunctival sac, may repeat once 20 minutes later |
| Cat | Xylazine | 0.44 mg/kg, IM |
| Cat | Dexmedetomidine | "5-10 mcg/kg, IM or SC" |
| Cat | Hydromorphone | 0.1 mg/kg, SC |
Merck limits hydrogen peroxide to dogs and to situations "when veterinary care or prescription options are not available" [1]. It warns that apomorphine should not be given orally because its oral bioavailability is negligible [1].
In cats, Merck notes that yohimbine or atipamezole can reverse excessive sedation or cardiovascular collapse from xylazine or dexmedetomidine. It describes hydromorphone as generally more cardiac sparing, with sedation reversible by naloxone [1].
Lavage, adsorbents and binders
Merck frames gastric lavage as an option in three situations: when emesis is not recommended, when emesis did not work, or when signs are life-threatening. It adds that effort and cost often outweigh the benefit. Merck states that gastric lavage "should be considered only in extreme cases and done under appropriate sedation or general anesthesia with a protected airway" [1].
Merck calls activated charcoal "usually" the adsorbent of choice. Merck gives the dose as "1-2 g/kg, PO; may be repeated at 4- to 6-hour intervals as needed" [1].
Some toxins undergo enterohepatic recirculation (cycling between liver, bile and gut). For these, Merck describes multidose charcoal at "1 g/kg of plain activated charcoal, PO, every 6-8 hours for 24 hours after exposure" [1].
Merck's listed contraindications to charcoal include [1]:
- caustic or hydrocarbon ingestion
- planned endoscopy or abdominal surgery
- suspected obstruction
- high aspiration risk
- severe dehydration
- hypernatremia
- hypovolemic shock
- ileus
- recent intestinal surgery
- protracted vomiting
Merck lists ibuprofen, carprofen and vitamin D3 among the toxins that may benefit from cholestyramine, a bile acid-binding resin. Merck gives the dose as "0.3-1 g/kg, PO, every 6 hours for 3 days for both dogs and cats" [1]. It advises checking the product for xylitol before giving it to dogs [1].
Merck describes intravenous lipid emulsion as a bolus at "1.5-4.0 mL/kg, IV, followed by 0.25 mL/kg/minute CRI for 30-60 minutes" [1]. It cautions that calcium channel blocker and bromethalin cases have worsened after lipid emulsion [1].
Food toxins
The Frontiers review by Cortinovis and Caloni (2016) summarizes the following thresholds and management points [2].
| Toxin | Reported thresholds | Decontamination and treatment notes |
|---|
| Chocolate (theobromine, caffeine) | Mild signs at 20 mg/kg, severe at 40-50 mg/kg, seizures at 60 mg/kg, per ASPCA APCC data | Emesis or lavage, multiple doses of charcoal, supportive care |
| Xylitol (dogs) | Hypoglycemia at doses as low as 0.03 g/kg; lowest dose linked to liver failure 0.5 g/kg | Early emesis in asymptomatic animals only; charcoal not recommended; IV dextrose for hypoglycemia |
| Grapes and raisins (dogs) | Any quantity considered a potential clinical problem | Prompt emesis and repeated charcoal; IV fluids at least 48-72 h; renal monitoring at least 72 h |
| Allium (onion, garlic) | 5 g/kg onion in cats, 15-30 g/kg in dogs | Emesis within 2 h if asymptomatic; charcoal after vomiting stops; transfusion if severely anemic |
| Macadamia nuts (dogs) | Signs reported from 0.7 g/kg | Emesis if recent and asymptomatic |
| Ethanol | Not stated | Emesis only with "extreme caution"; yohimbine and hemodialysis described |
On chocolate, the review gives theobromine content by type [2]:
- unsweetened baking chocolate and cocoa powder: more than 14 mg per gram
- semisweet dark chocolate: about 5 mg per gram
- milk chocolate: about 2 mg per gram
It describes prognosis as usually good when decontamination is achieved within 2-4 hours [2].
On grapes, the review cites a Veterinary Poisons Information Service analysis of 180 reports. In that analysis, the review reports, some dogs remained free of signs after eating as much as 1 kg of raisins, whereas others died after "just a handful." On that basis the authors advise that any ingestion "should be handled aggressively" [2].
On xylitol, the review describes a retrospective study of 192 dogs seen at three US university hospitals. In that study, 30 dogs became hypoglycemic, none developed liver failure, and all survived [2]. The doses in that study were estimated. The authors found no significant difference in estimated dose between hypoglycemic and euglycemic dogs [2].
The review states that no specific antidote exists for Allium toxicosis [2]. It also notes that Akita, Shiba and Jindo dogs may be more susceptible to oxidative damage from onions [2].
Human analgesics
Merck reports that cats are especially susceptible to acetaminophen because of limited glucuronidation [3]. It places feline toxicosis generally at 40-50 mg/kg, with some cats showing signs at 10 mg/kg. In dogs, it says signs do not appear unless the dose exceeds 100 mg/kg [3].
For acetaminophen, Merck describes early emesis followed by a single dose of charcoal with a cathartic [3]. Merck gives the N-acetylcysteine loading dose as "140 mg/kg of a 5% sterile solution," IV or PO, followed by "70 mg/kg, PO, every 6 hours for an additional five to seven treatments" [3].
Merck also lists ascorbic acid and methylene blue for methemoglobinemia. It advises rechecking liver enzymes at 24 and 48 hours [3].
Merck gives these ibuprofen thresholds in dogs [3]:
- 100-125 mg/kg (single dose): can cause GI signs
- 175-300 mg/kg: renal failure may occur
- above 400 mg/kg: CNS effects can appear
- above 600 mg/kg: potentially lethal
It states that cats are affected at roughly half the canine dose [3]. For massive ibuprofen ingestions, Merck describes "administration of activated charcoal with a cathartic, followed by oral cholestyramine every 6-8 hours for 3 days" [3].
According to Merck, naproxen has a 74-hour half-life in dogs because of enterohepatic recirculation [3]. For that reason it describes following single-dose charcoal with cholestyramine and monitoring for hypernatremia [3].
For aspirin, Merck reports a half-life of 37.5 hours in cats and states that there is no antidote. It also advises rechecking renal function at 24, 48 and 72 hours [3].
Anticoagulant rodenticides
Merck explains that these compounds block vitamin K recycling, which depletes clotting factors II, VII, IX and X [4]. Bleeding typically appears 3-7 days after a toxic dose [4].
For patients without signs, Merck lists inducing vomiting when the ingestion happened no more than 4 hours earlier, with emetics chosen for the species. It adds that charcoal is "not pursued by all clinicians" because a vitamin K1 antidote is available [4].
Merck gives vitamin K1 as "2.5 mg/kg, PO, every 12 hours for 28 days, or 5 mg/kg, PO, every 24 hours for 28 days" [4].
It suggests a 2-week course is typically sufficient for warfarin [4].
When exposure is uncertain and vitamin K1 is withheld, Merck describes checking prothrombin time (PT) 48 hours after ingestion [4]. After treatment ends, it describes rechecking PT 2-3 days later [4].
For patients with clinical signs, Merck adds [4]:
- fluid resuscitation
- fresh frozen plasma or whole blood
- PCV/TP and PT monitoring every 6-12 hours
It advises against IV vitamin K1 unless the product is labeled for veterinary IV use, citing the risk of anaphylactoid reactions [4].
Gaps in the cited sources
The four sources do not cover lily exposure in cats, a full ethylene glycol protocol, or bromethalin and cholecalciferol rodenticide management. Merck mentions ethylene glycol only to illustrate how ethanol and fomepizole work as antidotes [1]. The sources also do not describe staffing roles, triage scripts, or poison control center workflows.
