Selegiline (L-Deprenyl): veterinary dose and monograph

At a glance

Drug class

Veterinary drug

Also known as

Anipryl, L-deprenyl, Selgin, Eldepryl

Species with doses

Dogs and Cats

General dose range

0.5–1 mg/kg PO q24h — check the species tables for the indication

Routes

PO

Last reviewed

1 October 2026

Indications

• Canine cognitive dysfunction syndrome (age-related cognitive decline)
• Pituitary-dependent hyperadrenocorticism (licensed but limited/variable efficacy)
• Feline cognitive dysfunction (off-label)

Selegiline (L-Deprenyl) 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

• Cognitive dysfunction syndrome: Plumb’s p.1055 (Anipryl label): 0.5–1 mg/kg PO once daily in the morning, rounded to whole tablets; 0.5 mg/kg then 1 mg/kg if no response after 4 weeks (Seksel). Effect develops over weeks. Do not combine with other MAOIs, SSRIs, TCAs, amitraz or tramadol.
• Pituitary-dependent hyperadrenocorticism (limited efficacy): Papich 5e and Plumb’s p.1055 (label): start 1 mg/kg PO each morning; if no response within 2 months, increase to 2 mg/kg once daily; reassess the diagnosis if still unresponsive. Efficacy is inconsistent — trilostane is more reliable.

Cats

• Cognitive dysfunction (off-label): Papich 5e: 0.25–0.5 mg/kg PO q12h (once daily may suffice). Plumb’s p.1055: 0.25–1 mg/kg PO once daily (Gunn-Moore; supported by AAFP); ageing-related vocalisation or sleep disturbance 0.5–1 mg/kg once daily (Seksel).

Contraindications

Concurrent serotonergic drugs (SSRIs like fluoxetine, TCAs, tramadol, mirtazapine, ondansetron) or other MAO inhibitors (e.g. amitraz) — SEROTONIN SYNDROME; observe washout periods. Concurrent opioids (especially pethidine) — dangerous reaction. Known hypersensitivity. Limited Cushing's efficacy — don't rely on it for that.

Species-specific warnings

Dogs: Do not combine with serotonergic behaviour drugs (fluoxetine/clomipramine), tramadol, mirtazapine, ondansetron, or amitraz (an MAOI) — serotonin syndrome. Check for amitraz-containing parasiticides.

Adverse effects

• Usually well tolerated
• GI upset (vomiting, diarrhoea), restlessness/agitation
• Behavioural change, disorientation
• Serotonin syndrome with serotonergic co-medication

Drug interactions

• SSRIs/TCAs/tramadol/mirtazapine/ondansetron and other MAOIs (incl. AMITRAZ): SEROTONIN SYNDROME — contraindicated; observe washouts
• Opioids (especially pethidine/meperidine): serious reaction — avoid
• Sympathomimetics: potentiated pressor effects
• Other dopaminergic drugs: additive effects

Pregnancy and lactation

Limited data; avoid in pregnancy unless clearly needed.

Monitoring

• Cognitive/behavioural response over 4–6 weeks (set owner expectations)
• Review ALL co-medications for serotonergic/MAOI interactions (including amitraz collars/dips)
• GI tolerance and behaviour
• For Cushing's use: recognise its limited efficacy and reassess

Toxicity and overdose

Generally well tolerated; overdose causes GI upset, restlessness/agitation, hypertension and, with serotonergic co-medication or at high doses, SEROTONIN SYNDROME (tremor, hyperthermia, agitation, seizures). The interaction risk is the dominant hazard, not direct organ toxicity.

Management: No specific antidote. For serotonin syndrome: cyproheptadine (serotonin antagonist), active cooling, benzodiazepines for agitation/seizures, IV fluids and supportive monitoring. Decontaminate large recent ingestions; manage hypertension. Observe long washout when switching to/from serotonergic drugs.

Clinical pearls

• The licensed treatment for canine cognitive dysfunction ("doggy dementia") — give once daily in the morning and allow weeks for the benefit; pair with environmental enrichment and diet
• It is an MAO INHIBITOR — the cardinal rule is NO serotonergic drugs (fluoxetine, tramadol, mirtazapine) and no other MAOIs, including AMITRAZ (tick collars/dips); washouts are essential
• Its Cushing's licence notwithstanding, trilostane/mitotane are far more reliable for hyperadrenocorticism
• Avoid opioids like pethidine concurrently (dangerous reaction)

Mechanism of action

At therapeutic doses it selectively and irreversibly inhibits monoamine oxidase-B, slowing the breakdown of dopamine (and phenylethylamine) in the CNS — enhancing dopaminergic neurotransmission, which underlies its benefit in cognitive dysfunction. It also reduces oxidative free-radical formation and may have neuroprotective effects. The Cushing's rationale is increased dopaminergic inhibition of pituitary ACTH (pars intermedia), but this effect is clinically modest. At higher doses MAO-B selectivity is lost, raising serotonin-syndrome risk with serotonergic drugs.

Formulations and products

• 2 / 5 / 10 / 15 / 30 mg tablet (Anipryl)
• 5 mg tablet (human, Selgin/Eldepryl)
• Anipryl (Zoetis) — 2 / 5 / 10 / 15 / 30 mg tablet, Tablet
• Selgin / Eldepryl — 5 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

• Propentofylline
• Protamine Sulfate
• Pyridostigmine
• Salbutamol (Albuterol)
• Sertraline
• Sodium Bicarbonate
• Succimer (DMSA)
• Terbutaline

Frequently asked questions