Levetiracetam

Levetiracetam is an antiseizure drug used in veterinary medicine for maintenance seizure control and emergency management. It is commonly added when other medications provide inadequate control, and selected patients receive it as primary therapy. Immediate-release, extended-release and injectable preparations support different clinical applications in dogs, cats and other species.

Group

Anticonvulsant

Mechanism of Action

Levetiracetam binds synaptic vesicle protein SV2A, which participates in neurotransmitter release. This interaction modulates vesicle function and can reduce abnormal synchronous neuronal activity and repetitive firing. The full downstream mechanism remains incompletely defined, but its action differs from direct potentiation of benzodiazepine-sensitive GABA receptors. These effects help limit seizure propagation and recurrence.

Dose Rates

Dogs

Use / stage	Dose	Route	Schedule	Instructions
Epilepsy immediate-release	20 mg/kg	PO	Every 8 h	Higher doses or shorter intervals may be needed with phenobarbital, especially in dogs.
Epilepsy extended-release	Reference only	PO		30 mg/kg every 12 hours using intact XR tablets. Use only an intact XR tablet for this schedule; do not substitute immediate-release products.
Emergency seizures	20 mg/kg	IV		May repeat 20 mg/kg boluses to a cumulative 60 mg/kg; cumulative repeat dosing requires manual tracking. The statement “duration of injection approximately 3 hours” is ambiguous and is not treated as an administration-time instruction.
Rectal seizure rescue	40 mg/kg	RECTAL	Once	100 mg/mL solution; volume may be impractical in larger dogs.
Epilepsy immediate-release	7.1–23.8 mg/kg	PO	Every 8 h	Separate adjunctive range for phenobarbital/bromide-refractory epilepsy.
Epilepsy immediate-release	10–20 mg/kg	PO	Every 8 h
Emergency seizures	60 mg/kg	IV	Once	Single loading dose, distinct from repeated 20 mg/kg boluses with a cumulative ceiling.

Cats

Use / stage	Dose	Route	Schedule	Instructions
Epilepsy immediate-release	20 mg/kg	PO	Every 8 h	Higher doses or shorter intervals may be needed with phenobarbital, especially in dogs.
Epilepsy extended-release	Reference only	PO		500 mg/cat once daily using one intact XR tablet. Approximately 94 mg/kg is the reported exposure, not a separate universal weight-based prescription.
Transdermal seizure treatment	60 mg/kg	TOPICAL	Every 8 h	Compounded Lipoderm 350-400 mg/mL; systemic concentrations are low and highly variable, so oral efficacy cannot be assumed.

Horses

Use / stage	Dose	Route	Schedule	Instructions
Short-term seizure treatment	30 mg/kg	IV	Once
Seizure treatment	30 mg/kg	PO	Every 24 h

Indications

Adjunctive maintenance treatment of epilepsy in dogs and cats with inadequate control on other antiseizure drugs.
Primary maintenance treatment in selected patients where levetiracetam is an appropriate choice.
Emergency adjunctive treatment of cluster seizures or status epilepticus in dogs and cats.
Selected short-term pulse treatment to reduce further seizures during a cluster-seizure episode.

Contraindications

Adjust treatment for reduced renal clearance.
Do not split or crush extended-release tablets.

Interactions

Phenobarbital can accelerate clearance and may necessitate adjustment.

Adverse effects

Lethargy, reduced appetite and feline hypersalivation
Occasional behavioural change

Toxicity

Excess exposure generally intensifies central depression; assess renal function and provide supportive treatment.

Preparations

Preparation	Form	Strength	Route
Levetiracetam immediate-release 250 mg tablet	Tablet	250 mg / tablet	PO
Levetiracetam immediate-release 500 mg tablet	Tablet	500 mg / tablet	PO
Levetiracetam immediate-release 750 mg tablet	Tablet	750 mg / tablet	PO
Levetiracetam immediate-release 1000 mg tablet	Tablet	1000 mg / tablet	PO
Levetiracetam 100 mg/mL oral solution	Oral Liquid	100 mg / mL	PO
Levetiracetam 100 mg/mL injection	Injection	100 mg / mL	IV

Monitoring and Administration

Track seizure frequency and clinical response. Drug-level interpretation is less standardized than for some older anticonvulsants.

Immediate-release oral doses are well absorbed; food has little effect. XR tablets must remain whole.

Spritam disintegrating tablets may be dispersed in a small spoonful of liquid immediately before administration.

Compounded transdermal delivery gives low and variable systemic concentrations.

Levetiracetam XR 500 mg tablet: 500 mg per 1 tablet. Swallow whole; XR regimen only.

Levetiracetam XR 750 mg tablet: 750 mg per 1 tablet. Swallow whole; XR regimen only.

Levetiracetam 60 mg/kg IV has been used after lorazepam 0.2 mg/kg IV for status epilepticus. Keep a seizure diary; concentration testing around one week after initiation and at 6-12-month intervals may help individual adjustment, but the animal therapeutic range is not firmly established.