# Fluoxetine: veterinary dose and monograph

> Fluoxetine is a veterinary drug. Selective serotonin reuptake inhibitor (SSRI) and the licensed veterinary behavioural drug (Reconcile) for canine separation anxiety — also widely used for compulsive disorders, fear-based aggression, and feline anxiety/urine marking. Indications include canine separation anxiety (licensed) with a behaviour-modification programme; compulsive/stereotypic disorders (acral lick, spinning, etc.); fear- and anxiety-based aggression. This monograph lists 4 reference doses for dogs, cats, horses and sugar gliders, each with route, frequency and source.

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

## At a glance

- **Drug class:** Veterinary drug
- **Also known as:** Reconcile, Prozac, Fludac, Flunil
- **Species with doses:** Dogs, Cats, Horses and Sugar gliders
- **General dose range:** 1–2 mg/kg PO q24h — check the species tables for the indication
- **Routes:** PO
- **Last reviewed:** 1 October 2026

## Indications

- Canine separation anxiety (licensed) with a behaviour-modification programme
- Compulsive/stereotypic disorders (acral lick, spinning, etc.)
- Fear- and anxiety-based aggression
- Feline anxiety, urine marking and some compulsive behaviours

## Fluoxetine 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

*Fluoxetine doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Separation anxiety / compulsive / aggression | 1–2 mg/kg | PO | q24h | — |

- Separation anxiety / compulsive / aggression: Papich 5e and Plumb’s p.545 (Reconcile label): 1–2 mg/kg PO once daily with behaviour modification; efficacy may take up to 4 weeks; continue 2 months after response, then taper. Up to 3 mg/kg daily (Landsberg). Avoid with MAOIs (amitraz, selegiline) and tramadol — serotonin syndrome.

### Cats

*Fluoxetine doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Anxiety / urine marking / compulsive | 0.5–1.5 mg/kg | PO | q24h | — |

- Anxiety / urine marking / compulsive: Papich 5e: 0.5–1 mg/kg/day PO (0.5–4 mg per cat; start ¼ tablet = 2.5 mg); urine marking 1 mg/kg, up to 1.5 mg/kg. Plumb’s p.545: aggression and generalised anxiety 0.5–1.5 mg/kg once daily; urine marking 0.5–1 mg/kg (2.5–5 mg per cat).

### Horses

*Fluoxetine doses for horses*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Behaviour disorders | 0.25–0.5 mg/kg | PO | q24h | — |

- Behaviour disorders: Papich 5e: horses 0.25–0.5 mg/kg PO once daily, mixed with grain.

### Sugar gliders

*Fluoxetine doses for sugar gliders*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Self-mutilation / compulsive behaviour | 1–5 mg/kg | PO | q12h | — |

- Self-mutilation / compulsive behaviour: Carpenter Exotic Animal Formulary 6th ed, Table 7-5 (p.501): sugar gliders 1 mg/kg PO q12h (up to 1–5 mg/kg PO q8–12h) for self-mutilation. Use the liquid form; pair with husbandry/pair-bonding correction.

## Contraindications

Concurrent MAO inhibitors / selegiline (serotonin syndrome — observe washout). Other strongly serotonergic drugs at high combined load. History of seizures (lowers threshold). Known hypersensitivity. Hepatic impairment (metabolised hepatically). Not a quick fix — requires behaviour modification.

## Species-specific warnings

> **Caution:** Cats: Effective for feline anxiety/marking but monitor appetite closely (anorexia risk); use low mg/kg and expect a slow onset/washout.

## Adverse effects

- Reduced appetite / weight loss, especially early (transient)
- Lethargy or, conversely, restlessness/agitation early
- GI upset
- Lowered seizure threshold (rare)
- Serotonin syndrome if combined with other serotonergic drugs

## Drug interactions

- MAO inhibitors / selegiline (Anipryl): contraindicated — serotonin syndrome (observe washout both ways)
- Other serotonergic drugs (tramadol, TCAs, trazodone, ondansetron): additive serotonin-syndrome risk
- CYP inhibitor: can raise levels of co-metabolised drugs
- Drugs lowering seizure threshold: additive risk

## Pregnancy and lactation

Limited veterinary data; generally avoided in pregnancy unless clearly necessary.

## Monitoring

- Behavioural response over 4–8 weeks (set owner expectations)
- Appetite/weight (early anorexia) and demeanour
- Concurrent serotonergic medications
- Taper when discontinuing long-term therapy

## Toxicity and overdose

Overdose causes serotonergic signs — agitation, tremor, hyperthermia, tachycardia, mydriasis, vomiting, and at high doses seizures and serotonin syndrome. A common scenario is a dog ingesting the owner's human fluoxetine. The long half-life means effects (and any serotonin syndrome) can be prolonged.

Management: Decontaminate if recent ingestion (emesis/charcoal). For serotonin syndrome: cyproheptadine (serotonin antagonist), active cooling, IV fluids, control agitation/seizures with benzodiazepines, and supportive monitoring (temperature, ECG). No specific antidote; effects can be prolonged.

## Clinical pearls

- The licensed go-to for canine separation anxiety — but it is one leg of a stool: behaviour modification (and often situational anxiolytics) are essential
- Counsel owners that it takes 4–6 weeks to work and is a months-long commitment
- Avoid combining with other serotonergic drugs (selegiline, tramadol, trazodone at high doses) — serotonin syndrome
- Watch for early appetite loss in cats and dogs; it usually settles
- Taper rather than stop abruptly, and remember the long washout when switching drugs

## Mechanism of action

Selectively inhibits the presynaptic serotonin (5-HT) transporter, increasing synaptic serotonin in the CNS. Over weeks this produces adaptive downstream receptor changes that reduce anxiety, impulsivity and compulsive behaviour — the delay reflecting the time needed for these neuroadaptations rather than the immediate reuptake block. The long-lived active metabolite norfluoxetine sustains the effect.

## Formulations and products

- 8 / 16 / 32 / 64 mg chewable (Reconcile, dogs)
- 10 / 20 mg capsule (human)
- Oral solution 4 mg/mL (20 mg/5 mL)
- Reconcile (Elanco) — 8 / 16 / 32 / 64 mg chewable, Chewable tablet
- Fludac — 10 / 20 mg capsule, Capsule (human-label)
- Flunil — 10 / 20 mg capsule; 20 mg/5 mL syrup, Capsule / syrup (human-label)

## Storage

Chewables/capsules/solution: 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.

## Other hormones, emergency drugs, supplements and other drugs

- [Ferrous Sulfate](https://vetmasterji.com/drugs/ferrous-sulfate)
- [Finasteride](https://vetmasterji.com/drugs/finasteride)
- [Fludrocortisone](https://vetmasterji.com/drugs/fludrocortisone)
- [Flumazenil](https://vetmasterji.com/drugs/flumazenil)
- [Fluticasone (Inhaled)](https://vetmasterji.com/drugs/fluticasone)
- [Fomepizole (4-MP)](https://vetmasterji.com/drugs/fomepizole)
- [Glipizide](https://vetmasterji.com/drugs/glipizide)
- [Glycopyrrolate](https://vetmasterji.com/drugs/glycopyrrolate)

## Frequently asked questions

### What is the dose of Fluoxetine for dogs?

Reference doses for Fluoxetine in dogs: 1–2 mg/kg PO q24h (Separation anxiety / compulsive / aggression). Confirm against the label and the patient before use.

### What is the dose of Fluoxetine for cats?

Reference doses for Fluoxetine in cats: 0.5–1.5 mg/kg PO q24h (Anxiety / urine marking / compulsive). Confirm against the label and the patient before use.

### What is the dose of Fluoxetine for horses?

Reference doses for Fluoxetine in horses: 0.25–0.5 mg/kg PO q24h (Behaviour disorders). Confirm against the label and the patient before use.

### When should Fluoxetine not be used?

Concurrent MAO inhibitors / selegiline (serotonin syndrome — observe washout). Other strongly serotonergic drugs at high combined load. History of seizures (lowers threshold). Known hypersensitivity. Hepatic impairment (metabolised hepatically). Not a quick fix — requires behaviour modification.

### What are the side effects of Fluoxetine in animals?

Reduced appetite / weight loss, especially early (transient); Lethargy or, conversely, restlessness/agitation early; GI upset; Lowered seizure threshold (rare); Serotonin syndrome if combined with other serotonergic drugs.

## Sources

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

---

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.