Amitriptyline: veterinary dose and monograph

At a glance

Drug class

Veterinary drug

Also known as

Tryptomer, Amitone, Elavil

Species with doses

Dogs, Cats and Birds

General dose range

1–2 mg/kg PO q12–24h — check the species tables for the indication

Routes

PO

Last reviewed

1 October 2026

Indications

• Feline idiopathic/interstitial cystitis (refractory cases)
• Neuropathic pain (adjunct, multimodal)
• Anxiety, compulsive and urine-marking behaviours
• Pruritus with a behavioural/neuropathic component (adjunct)

Amitriptyline dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

Dogs

• Neuropathic pain / anxiety (adjunct): Papich 5e: 1–2 mg/kg q12–24h PO. Plumb’s p.77: neuropathic pain 1–2 mg/kg q12–24h (Hardie; Liptak); anxiety 1–2 mg/kg q12h, up to 4 mg/kg q12h (Virga); pruritus 1–2 mg/kg q12h.

Cats

• Idiopathic cystitis (refractory) / anxiety: Papich 5e: 2–4 mg per cat/day (0.5–1 mg/kg/day), can be divided q12h; idiopathic cystitis 2 mg/kg/day or 2.5–7.5 mg per cat per day (controversial). Plumb’s p.77: behaviour 0.5–1 mg/kg q12–24h or 5–10 mg per cat daily; FLUTD 2.5–12.5 mg per cat once at night, stop if no improvement in 2 months (Buffington; Bartges). Taper to stop.

Birds

• Feather-damaging behaviour / anxiety: Carpenter's 6th ed (Bird psychotropic table): 1–5 mg/kg PO q12–24h; grey parrots/cockatoos 1.5–9 mg/kg PO but plasma levels erratic and toxicity seen in ~1/3 of African greys — start low, titrate, monitor. ⚠ Severe extrapyramidal signs reported in a macaw at 5 mg/kg. Combine with environmental / behaviour modification. Plumb’s p.77 (Lightfoot 2001): 1–2 mg/kg PO q12–24h for feather plucking (anecdotal).

Contraindications

MAO inhibitors / selegiline (serotonin syndrome). Cardiac arrhythmia/conduction disease (TCA cardiotoxicity). Glaucoma, urinary retention (anticholinergic). Seizure disorders. Hepatic impairment. Known hypersensitivity.

Species-specific warnings

Cats: Anticholinergic urinary retention is a concern in cats with lower-urinary-tract disease — monitor urination; reserve for refractory idiopathic cystitis with environmental therapy.

Adverse effects

• Sedation (often prominent), anticholinergic effects (dry mouth, constipation, urinary retention)
• Weight gain / increased appetite
• GI upset
• Cardiac conduction effects at high dose
• Urine crystal/colour change (cats)

Drug interactions

• MAO inhibitors / selegiline: contraindicated — serotonin syndrome
• Other serotonergic drugs: additive serotonin-syndrome risk
• Anticholinergics: additive (urinary retention, ileus)
• Antiarrhythmics / QT-prolonging drugs: additive cardiac effects
• CNS depressants: additive sedation

Pregnancy and lactation

Limited data; avoid in pregnancy unless clearly necessary.

Monitoring

• Clinical response (FIC signs, pain, behaviour) over weeks
• Sedation, anticholinergic effects (urination, constipation)
• Cardiac status (older patients/high doses)
• Body weight/appetite; taper when discontinuing

Toxicity and overdose

As a TCA, overdose causes anticholinergic and CNS signs and dangerous cardiotoxicity (wide-QRS arrhythmias, hypotension, seizures) — potentially fatal. A common scenario is ingestion of human amitriptyline tablets. Cardiac effects dominate the lethal risk.

Management: Decontaminate if recent (charcoal). IV sodium bicarbonate is the cornerstone for TCA cardiotoxicity (narrows QRS, supports BP); IV fluids/vasopressors, benzodiazepines for seizures, ECG monitoring; cyproheptadine for serotonin syndrome. Intravenous lipid emulsion has been used in severe TCA toxicity. No single antidote.

Clinical pearls

• A useful triple-duty drug: feline idiopathic cystitis (refractory), neuropathic-pain adjunct, and anxiety/compulsive behaviour
• For FIC, it is a SECOND-LINE add-on to multimodal environmental modification (MEMO), water/diet changes — not a first step
• Sedation and anticholinergic effects are common — dose at night and watch for urinary retention/constipation
• Cardiotoxic in overdose: sodium bicarbonate is the key intervention; avoid in patients with arrhythmias
• Taper rather than stop abruptly after long-term use

Mechanism of action

Inhibits reuptake of serotonin and noradrenaline (raising CNS monoamines — anxiolytic/antidepressant and descending analgesic effects) and blocks muscarinic, histaminic, alpha-adrenergic and NMDA receptors and sodium channels. In feline idiopathic cystitis these combined actions (analgesia, anti-inflammatory, anti-anxiety, and effects on bladder sensory nerves/mast cells) underlie its benefit. The anticholinergic/antihistaminic actions cause its sedative/peripheral side effects.

Formulations and products

• 10 mg tablet
• 25 mg tablet
• 75 mg tablet
• Tryptomer — 10 / 25 / 75 mg tablet, Tablet (human-label)
• Amitone — 10 / 25 mg tablet, Tablet (human-label)

Storage

Tablets: 15–30 °C, dry, protect from light.

Before you use this dose

Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

Other hormones, emergency drugs, supplements and other drugs

• Altrenogest
• Aminophylline
• Atipamezole
• Atracurium
• Atropine Sulfate
• Azathioprine
• B-Complex Injection (B1 + B6 + B12)
• Bethanechol

Frequently asked questions