Trazodone
Trazodone is used for situational anxiety and to facilitate calm confinement in small animals. Response and sedation vary between patients.
Group
Serotonin antagonist/reuptake inhibitor; anxiolytic
Mechanism of Action
Combines serotonergic receptor antagonism and reuptake inhibition with sedative and alpha-1-blocking effects.
Dose Rates
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Situational anxiety | 5–8 mg/kg | PO | Every 12 h | Maximum 300 mg/dose; Maximum 900 mg/day; Typical starting regimen; adjust only after observing response. Frequency may be individualised to every 8-24 hours. |
| Anxiety – low-dose titration — Initial | 1 mg/kg | PO | Every 12 h | Up to 7 days; First week, followed by up to 3 mg/kg every 12 hours if needed. |
| Anxiety – low-dose titration — Maintenance | 3 mg/kg | PO | Every 12 h | After the initial week; titrate to lowest effective amount. |
| Chronic anxiety adjunct – alternative | 1–4.8 mg/kg | PO | Every 12 h | Source describes gradual weekly titration rather than immediate use of the upper endpoint. |
| Event-related anxiety adjunct | Reference only | PO | 2-5 mg/kg PO about one hour before the trigger in addition to a daily behavioural regimen; maximum 14 mg/kg/day. This weight-dependent daily cap is retained here rather than discarded for calculation. |
Cats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Situational anxiety | 50–100 mg/animal | PO | As needed | As needed; 50 mg is usually sufficient in the cited source. Peak effect approximately 2-2.5 hours. |
Indications
- Situational anxiety
- Adjunctive treatment of anxiety disorders
- Short-term feline handling or travel sedation
Contraindications
- Hypersensitivity; do not combine with MAO inhibitors.
- Avoid IV administration in dogs.
Interactions
- SSRIs, TCAs, tramadol and other serotonergic drugs increase serotonin-syndrome risk.
- CNS depressants increase sedation; antihypertensives may increase hypotension.
- Azoles and some macrolides can increase exposure; NSAIDs may add bleeding risk.
Adverse effects
- Sedation, ataxia, vomiting/diarrhoea, paradoxical excitement or aggression.
- Hypotension; serotonin toxicity with interacting regimens.
Toxicity
Stop exposure and provide supportive care; monitor temperature, blood pressure, cardiac rhythm and neurologic signs.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Trazodone hydrochloride immediate-release 50 mg tablet | Tablet | 50 mg / tablet | PO |
| Trazodone hydrochloride immediate-release 100 mg tablet | Tablet | 100 mg / tablet | PO |
| Trazodone hydrochloride immediate-release 150 mg tablet | Tablet | 150 mg / tablet | PO |
Monitoring and Administration
Trial the chosen oral dose before a critical event when feasible. Give at least one hour before an anticipated canine trigger; feline peak sedation is often around 2-2.5 hours.
Start low and titrate from the observed response. Extended-release human tablets are not assumed equivalent to immediate-release tablets.