Animal poisoning: signs, antidotes and first-line treatment

Organophosphate / Carbamate insecticides

Species

dogs, cats, cattle, goats and sheep

Typical source

Crop sprays, dips, contaminated feed, malicious poisoning

Urgency

Critical — treat immediately

Antidote

Atropine sulfate

Antidote dose

0.2–0.5 mg/kg — ¼ IV, remainder SC/IM; repeat to effect (dry secretions). Add pralidoxime (2-PAM) 20 mg/kg slow IV for OPs if available.

Also known as

malathion, chlorpyrifos, carbofuran, OP poisoning

Clinical signs: Hypersalivation (SLUDGE); Miosis; Muscle tremors → paralysis; Diarrhea, urination; Bradycardia; Dyspnea, pulmonary edema.

• Wash off dermal exposure with soap + water
• Do NOT atropinize to fixed dose — titrate to secretions
• Diazepam for seizures
• Avoid phenothiazines

Anticoagulant rodenticide

Species

dogs and cats

Typical source

Rodent bait ingestion (direct or relay)

Urgency

Urgent

Antidote

Vitamin K1 (phytomenadione)

Antidote dose

2.5–5 mg/kg/day PO with fatty food, 2–4 weeks (second-generation agents need the full 4 wk); check PT 48 h after stopping.

Also known as

bromadiolone, brodifacoum, warfarin, rat poison

Clinical signs: Lethargy, pallor; Hemorrhage: epistaxis, melena, hematomas; Dyspnea (hemothorax); Signs delayed 2–5 days post-ingestion.

• Emesis if <2–4 h since ingestion
• Activated charcoal 1–4 g/kg
• Whole blood / plasma if actively bleeding
• Avoid IM injections while coagulopathic

Urea / NPN toxicity (ammonia poisoning)

Species

cattle, buffalo, goats and sheep

Typical source

Fertilizer access, over-supplemented urea feed, poorly mixed ration

Urgency

Critical — treat immediately

Antidote

Cold water + weak acid (vinegar) orally

Antidote dose

2–6 L of 5% acetic acid (vinegar) + 20–40 L cold water per adult cow via stomach tube; repeat as rumen pH rebounds.

Also known as

non-protein nitrogen, fertilizer ingestion

Clinical signs: Onset 20–60 min; Muscle tremors, ear twitching; Frothy salivation, bloat; Ataxia → recumbency, bellowing; Convulsions, death in 1–2 h.

• Rumenotomy and rumen lavage in valuable animals
• IV isotonic saline + calcium borogluconate for tremors
• Treat herd-mates that shared the feed

Nitrate / nitrite poisoning

Species

cattle, buffalo, goats and sheep

Typical source

Lush oat/sorghum/sudan fodder, drought-stressed crops, fertilizer runoff water

Urgency

Critical — treat immediately

Antidote

Methylene blue

Antidote dose

1–2% solution at 4–15 mg/kg slow IV; repeat in 20–30 min if needed (ruminants tolerate repeat dosing).

Also known as

oat hay poisoning, nitrate accumulator plants

Clinical signs: Chocolate-brown mucous membranes and blood; Dyspnea, tachypnea; Weakness, ataxia; Abortion in survivors.

• Minimize stress/handling during crisis
• Remove suspect fodder from the whole herd
• Test remaining fodder before reintroduction

Snake envenomation (viperine)

Species

dogs, cattle, horses and goats

Typical source

Field grazing, farm dogs — usually face/limb bites

Urgency

Critical — treat immediately

Antidote

Polyvalent anti-snake venom (ASV)

Antidote dose

Species-appropriate polyvalent ASV IV per manufacturer; dose to venom load (not body weight) — pretreat for anaphylaxis risk.

Also known as

russell viper, saw-scaled viper, snake bite

Clinical signs: Rapid painful swelling at bite site; Fang marks, oozing; Coagulopathy: prolonged clotting, hematuria; Hypotension, shock; Neuro signs if elapid (ptosis, paralysis).

• Immobilize patient, keep bite below heart level
• NO tourniquets, incision, or suction
• IV fluids for shock
• Fresh whole blood if coagulopathic
• Tetanus prophylaxis

Chocolate (theobromine/caffeine)

Species

dogs

Typical source

Dark chocolate, cocoa powder, baking chocolate (dose scales with cocoa %)

Urgency

Urgent

Antidote

No specific antidote — supportive care

Clinical signs: Vomiting, diarrhea (2–4 h); Restlessness, panting; Tachycardia, arrhythmias; Tremors, seizures at high dose.

• Emesis if <2 h (apomorphine 0.03 mg/kg IV)
• Activated charcoal, repeat q4–6h (enterohepatic recycling)
• IV fluids; beta-blocker (propranolol 0.02–0.06 mg/kg slow IV) for tachyarrhythmia
• Diazepam/methocarbamol for tremors

Paracetamol (acetaminophen)

Species

cats and dogs

Typical source

Well-meaning owner medication — cats are exquisitely sensitive (any dose is toxic)

Urgency

Critical — treat immediately

Antidote

N-acetylcysteine (NAC)

Antidote dose

140 mg/kg PO/IV loading, then 70 mg/kg q6h × 7 doses. Adjunct: ascorbic acid 30 mg/kg + SAMe.

Also known as

acetaminophen, crocin

Clinical signs: Cats: methemoglobinemia — brown MM, dyspnea, facial/paw edema; Dogs: hepatic necrosis — icterus, vomiting (>100 mg/kg); Chocolate-colored blood.

• Never give paracetamol to cats — client education
• Oxygen for methemoglobinemia
• Hepatoprotectants + IV fluids

Ivermectin toxicosis

Species

dogs

Typical source

Livestock-strength ivermectin dosed to herding breeds (Collie, Aussie — MDR1 mutation), or massive overdose

Urgency

Urgent

Antidote

IV lipid emulsion (ILE) 20%

Antidote dose

1.5 mL/kg IV bolus, then 0.25 mL/kg/min CRI for 30–60 min; repeat once if signs persist.

Also known as

macrocyclic lactone, MDR1 breeds

Clinical signs: Mydriasis, apparent blindness; Ataxia, hypersalivation; Depression → coma; Tremors, bradycardia.

• Supportive nursing — recovery can take days
• Recumbent care: turning, eye lube, bladder management
• Avoid further P-gp substrate drugs

Zinc phosphide (rodenticide)

Species

dogs, cats and cattle

Typical source

Grain-based rodent baits — releases phosphine gas in the acidic stomach

Urgency

Critical — treat immediately

Antidote

No specific antidote — supportive care

Also known as

phosphine, rat cake

Clinical signs: Vomiting (garlic/rotten-fish odor); Abdominal pain, bloat; Dyspnea, pulmonary edema; Seizures, shock, hepatic failure.

• VENTILATE — vomitus off-gasses phosphine (protect staff, treat outdoors/windows open)
• Antacid (aluminium hydroxide) to slow gas release
• Gastric lavage with 5% sodium bicarbonate
• IV fluids + aggressive supportive care

Oleander / cardiac glycoside plants

Species

cattle, goats, sheep, horses and dogs

Typical source

Garden clippings fed to livestock, browsing ornamental hedges

Urgency

Critical — treat immediately

Antidote

Digoxin-specific Fab fragments (rarely available in field)

Also known as

kaner, nerium

Clinical signs: Vomiting/colic, bloody diarrhea; Bradycardia or tachyarrhythmias, AV block; Weakness, cold extremities; Sudden death.

• Activated charcoal 1–4 g/kg, repeat q6–8h
• Rumenotomy in valuable ruminants with large ingestion
• Atropine for bradyarrhythmia; lidocaine for ventricular tachyarrhythmia (dogs)
• Avoid calcium-containing fluids

Lantana camara poisoning

Species

cattle, goats and sheep

Typical source

Browsing lantana scrub during fodder scarcity

Urgency

Moderate

Antidote

No specific antidote — supportive care

Clinical signs: Photosensitization — swollen, peeling muzzle/udder skin; Icterus; Anorexia, ruminal stasis, constipation; Dark urine.

• Remove from source + shade housing (UV avoidance)
• Activated charcoal 2 g/kg reduces hepatotoxin absorption early
• IV fluids + rumen transfaunation
• Treat secondary skin infection

Lead poisoning

Species

cattle, dogs and birds

Typical source

Discarded batteries, old paint, sump oil — calves are notorious

Urgency

Urgent

Antidote

Calcium disodium EDTA

Antidote dose

75 mg/kg/day slow IV divided BID–TID × 3–5 days; repeat after 2-day rest if needed. Add thiamine 2–4 mg/kg IM (cattle).

Also known as

battery, paint

Clinical signs: CNS: blindness, head pressing, circling; Bellowing, convulsions (cattle); GI: colic, anorexia; Chronic: weight loss, anemia with basophilic stippling.

• Remove source from paddock
• Magnesium sulfate PO precipitates lead in gut
• Seizure control with diazepam/barbiturate
• Food-safety: treated livestock carry residue — advise on withholding

Ethylene glycol (antifreeze/coolant)

Species

dogs and cats

Typical source

Radiator coolant puddles — sweet taste attracts dogs and cats

Urgency

Critical — treat immediately

Antidote

Ethanol 20% (or fomepizole where available)

Antidote dose

Ethanol 20%: dogs 5.5 mL/kg IV q4h × 5 then q6h × 4; cats 5 mL/kg q6h × 5 then q8h × 4. Must start <8–12 h post-ingestion.

Clinical signs: Stage 1 (0–12 h): "drunken" ataxia, PU/PD, vomiting; Stage 2 (12–24 h): apparent recovery, tachypnea; Stage 3 (24–72 h): oliguric renal failure, oral ulcers; Calcium oxalate crystalluria.

• Time-critical — treat on suspicion
• IV fluid diuresis + bicarbonate for acidosis
• Once anuric, only dialysis helps — grave prognosis

Permethrin toxicosis (cats)

Species

cats

Typical source

Canine spot-on flea products applied to cats or close contact with treated dogs

Urgency

Critical — treat immediately

Antidote

No specific antidote — supportive care

Also known as

pyrethroid, dog spot-on applied to cat

Clinical signs: Severe muscle tremors, twitching; Hyperesthesia, ear flicking; Seizures; Hyperthermia from tremor.

• Methocarbamol 55–220 mg/kg IV to effect — drug of choice for tremors
• Bathe with lukewarm water + dish soap once stable (NOT hot/cold)
• IV lipid emulsion 20% (1.5 mL/kg bolus then CRI) speeds recovery
• Treat hyperthermia; good prognosis with 24–72 h support

Aflatoxicosis (moldy feed)

Species

cattle, dogs, birds and pigs

Typical source

Moldy maize/groundnut cake, poorly stored monsoon feed

Urgency

Moderate

Antidote

No specific antidote — supportive care

Clinical signs: Chronic: ill-thrift, drop in yield, rough coat; Icterus, hepatomegaly; Acute high dose: hemorrhage, hepatic encephalopathy; Milk residue risk (M1) in dairy animals.

• Replace the entire suspect feed lot
• Hepatoprotectants: SAMe, silymarin; vitamin K1 if bleeding
• High-quality protein diet during recovery
• Advise milk testing / withholding for dairy herds

Note

An assist for emergency triage, not a substitute for a poison-control consultation where one is available. Doses must be checked against the patient and the product.

Frequently asked questions