# Selegiline (L-Deprenyl): veterinary dose and monograph

> Selegiline (L-Deprenyl) is a veterinary drug. A selective monoamine oxidase-B (MAO-B) inhibitor licensed (Anipryl) for canine COGNITIVE DYSFUNCTION SYNDROME ("doggy dementia/senility") — it improves signs of age-related cognitive decline (disorientation, altered sleep-wake cycle… Indications include canine cognitive dysfunction syndrome (age-related cognitive decline); pituitary-dependent hyperadrenocorticism (licensed but limited/variable efficacy); feline cognitive dysfunction (off-label). This monograph lists 3 reference doses for dogs and cats, each with route, frequency and source.

Source: https://vetmasterji.com/drugs/selegiline · Last reviewed: 2026-10-01

## 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

*Selegiline (L-Deprenyl) doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Cognitive dysfunction syndrome | 0.5–1 mg/kg | PO | q24h (morning) | — |
| Pituitary-dependent hyperadrenocorticism (limited efficacy) | 1–2 mg/kg | PO | q24h | — |

- 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

*Selegiline (L-Deprenyl) doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Cognitive dysfunction (off-label) | 0.25–1 mg/kg | PO | q12–24h | — |

- 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

> **Caution:** 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

> **Caution:** 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.

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## Frequently asked questions

### What is the dose of Selegiline (L-Deprenyl) for dogs?

Reference doses for Selegiline (L-Deprenyl) in dogs: 0.5–1 mg/kg PO q24h (morning) (Cognitive dysfunction syndrome); 1–2 mg/kg PO q24h (Pituitary-dependent hyperadrenocorticism (limited efficacy)). Confirm against the label and the patient before use.

### What is the dose of Selegiline (L-Deprenyl) for cats?

Reference doses for Selegiline (L-Deprenyl) in cats: 0.25–1 mg/kg PO q12–24h (Cognitive dysfunction (off-label)). Confirm against the label and the patient before use.

### When should Selegiline (L-Deprenyl) not be used?

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.

### What are the side effects of Selegiline (L-Deprenyl) in animals?

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

## Sources

- Plumb's Veterinary Drug Handbook
- Merck Veterinary Manual, 11th edition
- Papich, Papich Handbook of Veterinary Drugs, 5th edition

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VetMasterJi is a clinical decision-support and education platform for veterinary professionals and students. It does not provide veterinary advice, diagnosis or treatment for specific animals. All drug doses, calculators and differentials are references that must be independently verified before clinical use; the attending registered veterinarian remains solely responsible for every clinical decision.