Do you have a dog or cat that has seizures? If you do and the problem is serious enough to warrant treatment, chances are you are giving your pet phenobarbital or potassium bromide, either alone or in combination. In the majority of cases phenobarbital and potassium bromide do a great job of reducing seizure frequency and severity to acceptable levels (at least with dogs; seizures in cats can be really bad news). Up until recently, however, pets that did not respond well to these medications were out of luck. Thankfully, that situation is changing.
First, a bit of background. A seizure is a symptom, not a disease in and of itself. Sometimes veterinarians can find an underlying cause for a pet’s seizures. Electrical activity in the brain may be disrupted by tumors, inflammatory diseases, infections, metabolic abnormalities, and more.
If this is the case, treatment should be aimed at the primary problem, although medications to control seizures may also be necessary for either the short or long term. If no underlying cause for a pet’s seizures can be found, he or she will be diagnosed with primary epilepsy, in which case seizure control (not eradication - this is rarely possible) is the main goal of treatment.
Phenobarbital and potassium bromide have long been, and still are, the go-to drugs for seizure control in veterinary medicine. But they don’t work well in all situations. The problems associated with the drugs typically fall into two categories:
1. Pets continue to have frequent and/or severe seizures despite having serum levels of these drugs that fall at the high end of the therapeutic range.
2. Pets have unacceptably severe side effects, typically sedation, ataxia (difficulty walking), increased appetite, thirst and urination, or pronounced elevations in liver enzymes.
When phenobarbital and potassium bromide are not suitable options, it is time to look to the newer drugs like felbamate, gabapentin, levetiracetam, pregabalin, topiramate, and zonisamide. These have the advantage of fewer side effects even when used at the relatively high doses that may be needed to control a pet’s seizures. They can be used alone or in conjunction with phenobarbital and potassium bromide, in which cases the doses of the older drugs can often be lowered dramatically, which reduces their adverse effects.
But don’t run out and ask your vet for a new prescription if your pet’s seizures are well-controlled on phenobarbital and/or potassium bromide. I strongly believe in the "if it ain’t broke don’t fix it" approach, and most vets have so much experience with these older drugs that we know what problems to look for and how to deal with them if they arise. The same cannot be said with the newer medications that we are "borrowing" from the human medical community.
The newer meds are also more expensive than phenobarbital and potassium bromide. Thankfully, some are now available as generics, which puts them within financial reach for many more pet owners.
If your veterinarian is unfamiliar with or uncomfortable using these newer anti-seizure medications, ask whether a consultation with a veterinary neurologist might be in your pet’s best interests.
Dr. Jennifer Coates