Yes, Keppra (levetiracetam) and phenobarbital can be given together in dogs, and this is one of the most common drug combinations veterinarians use to manage epilepsy. The two medications work through different mechanisms in the brain, which means combining them often provides better seizure control than either drug alone. Many dogs end up on this combination when a single medication isn’t enough to keep seizures at an acceptable frequency.
Why Vets Combine These Two Drugs
Phenobarbital is typically the first medication prescribed for canine epilepsy. It’s effective, well-studied, and relatively inexpensive. But some dogs continue to have breakthrough seizures even at therapeutic doses. When that happens, veterinarians often add Keppra rather than simply increasing the phenobarbital dose, because higher phenobarbital levels carry greater risks of liver damage and excessive sedation.
Keppra works differently from phenobarbital at the cellular level, so the two drugs complement each other. This “add-on” approach is standard practice in veterinary neurology. Some dogs also receive Keppra on a short-term “pulse” basis: if your dog is prone to cluster seizures while already on phenobarbital, your vet may recommend keeping Keppra on hand to give a few doses after a seizure occurs, helping prevent additional seizures from following in rapid succession.
How Phenobarbital Affects Keppra Levels
One important thing to know about this combination is that phenobarbital speeds up how quickly your dog’s body processes Keppra. Phenobarbital activates liver enzymes that break down many other drugs, and Keppra is among them. This means a dog already taking phenobarbital may need a higher or more frequent dose of Keppra compared to a dog taking Keppra alone. Your vet will account for this when setting the initial Keppra dose and will adjust based on how your dog responds.
Keppra, on the other hand, does not significantly affect phenobarbital levels. So adding Keppra to your dog’s regimen is unlikely to throw off the phenobarbital dose that’s already been established.
Side Effects to Watch For
Both phenobarbital and Keppra can cause sedation on their own, and combining them can increase that effect, especially in the first week or two. You may notice your dog seems drowsier than usual, slightly uncoordinated, or less interested in food. Most dogs adjust within a few days to a couple of weeks as their body acclimates to the new medication level.
Phenobarbital carries the more serious long-term risks of the two drugs. It can affect liver function over time, increase thirst and appetite, and cause weight gain. Keppra is generally considered gentler on the body. Its most common side effects are mild sedation and occasional gastrointestinal upset. Some owners also report that their dog seems more anxious or restless when first starting Keppra, though this typically resolves quickly.
If your dog becomes profoundly sedated, can’t walk without stumbling, or stops eating for more than a day after starting the combination, contact your vet. These signs can indicate the combined sedative effect is too strong and a dose adjustment is needed.
Blood Monitoring on Combination Therapy
Dogs on both medications need regular blood work, and the monitoring schedule differs for each drug. According to the Texas A&M Veterinary Medical Diagnostic Laboratory, phenobarbital levels should be checked two to three weeks after starting therapy or changing the dose. Once your dog is stable, phenobarbital levels and liver values are typically rechecked every 6 to 12 months.
Keppra monitoring works on a faster timeline because the drug doesn’t accumulate in the body the way phenobarbital does. Levels can be checked within one week of starting or adjusting the dose. For the most accurate reading, blood is drawn about two hours after giving the pill to capture the peak level. Adding a new drug to your dog’s regimen is itself a reason to recheck levels of both medications, since the interaction between them can shift how each drug is processed.
What Combination Therapy Looks Like Day to Day
Phenobarbital is usually given twice daily, roughly 12 hours apart. Keppra in its standard form is given three times daily, about every eight hours, because it’s a short-acting drug that clears the body quickly. An extended-release version of Keppra exists that can be given twice daily instead, which simplifies the schedule. However, extended-release tablets cannot be split or crushed, so they don’t work for every size of dog.
Keeping a consistent schedule matters more with this combination than with either drug alone. Phenobarbital levels need to stay steady to maintain the seizure threshold, and Keppra’s short duration means a missed dose can leave a gap in protection. Setting phone alarms for dosing times is a simple strategy that makes a real difference.
It also helps to keep a seizure log noting the date, time, duration, and severity of any seizures your dog has. This gives your veterinarian concrete data to evaluate whether the combination is working or needs adjustment. Many owners find that adding Keppra meaningfully reduces seizure frequency, but the response varies from dog to dog, and fine-tuning doses can take several weeks.
Pulse Therapy for Cluster Seizures
Not every dog on this combination takes Keppra every day. Cornell University’s College of Veterinary Medicine notes that dogs prone to cluster seizures (multiple seizures within a 24-hour period) can benefit from “pulse” Keppra therapy. In this approach, your dog stays on phenobarbital daily, and you give a few doses of Keppra only after a seizure occurs to reduce the chance of another one following closely behind. This can be especially useful for dogs whose clusters tend to happen in a predictable pattern, such as every few weeks. Your vet will provide specific instructions on how many doses to give and how far apart to space them during a cluster event.