Amphetamines toxicity in pets

Amphetamines are sympathomimetic amines that stimulate the central nervous and cardiovascular systems by activating alpha and beta receptors and increasing the release of norepinephrine and serotonin. This results in elevated catecholamine levels in synapses. They also stimulate the medullary respiratory center and reticular activating system.

Amphetamines increase catecholamine concentrations by promoting their release, inhibiting reuptake, and reducing metabolism. They also enhance serotonin release, contributing to their stimulatory effects.

Amphetamine toxicity causes stimulation across multiple body systems, with symptoms appearing within minutes (methamphetamine) or hours:

• Neurological: Restlessness, hyperactivity, tremors, seizures.

• Cardiovascular: Tachycardia, hypertension.

• Respiratory: Rapid breathing (tachypnea).

• Gastrointestinal: Vomiting, hypersalivation, diarrhea.

• Ophthalmic: Dilated pupils (mydriasis).

If left untreated, prolonged symptoms can lead to hyperthermia and myoglobinuria, requiring urgent veterinary care.

Detoxification

• Emesis: Induce vomiting if ingestion occurred <15 minutes ago and the pet is asymptomatic.

• Gastric Lavage: Consider if a large quantity of pills was ingested.

• Activated Charcoal: Administer if ingestion exceeds a lethal dose to limit absorption after emesis or gastric lavage.

• Urine Acidification: Enhance elimination by acidifying urine to pH 4.5–5.5 using:

  • Ammonium chloride: 100–200 mg/kg/day PO, divided QID.

  • Ascorbic acid: 20–30 mg/kg PO, SQ, IM, or IV.

Monitoring

• Regularly check body temperature, respiratory rate, heart rate, blood pressure, acid–base status, and perform ECG to monitor for arrhythmias.

Treatment

• IV Fluids: Regulate body temperature and protect kidneys from myoglobinuria.

• For Agitation: Use phenothiazines:

  • Acepromazine: 0.05 mg/kg IV or IM, titrated as needed.

  • Chlorpromazine: 0.5 mg/kg IV, IM, or SQ.

  • Cyproheptadine (serotonin antagonist):

    Dogs: 1.1 mg/kg PO or rectally, Cats: 2–4 mg total dose per cat.

• For Tachycardia: Administer beta-blockers (e.g., propranolol 0.02–0.06 mg/kg IV).

• For Tremors: Use methocarbamol 50–100 mg/kg IV, titrated as needed.

• For Seizures: Use barbiturates, such as phenobarbital 3–4 mg/kg IV.

Notes

There is no specific antidote for amphetamine toxicity; treatment is supportive and symptom-based. Immediate veterinary care is essential.

With prompt treatment, CNS and cardiac symptoms can be managed, and the prognosis is generally good. However, signs may persist for up to 72 hours if extended-release products were ingested. An urgent veterinary visit is critical after ingestion to ensure proper care and monitoring.