General Treatment
See the presenting problem map 
and quiz on seizures.
- The treatment of a seizure disorder will obviously depend upon the primary cause.
- If no cause can be found, or if the seizures are a life threatening problem regardless of cause, anticonvulsant medication should be initiated.
- In general anticonvulsants may either raise the seizure threshold or prevent the spread of the electrical activity.
- Guidelines have been established to aid the clinician as to when anticonvulsant medication should be initiated.
- This author begins anticonvulsant therapy with phenobarbital
at 3 mg/kg PO BID. - Phenobarbital levels should be assessed at 2 weeks after beginning therapy to determine whether therapeutic concentrations have been obtained.
The trough therapeutic concentration (within one hour of the next dose) seem to correlate best with clinical seizure control. - Therapeutic range from between 20 and 35 microg/ml. It is important to remember that this is a range based on a population of dogs.
- Individual dogs may be controlled at various levels within, and sometimes outside, the therapeutic range.
- Unless phenobarbital levels are increased to 40 microg/ml, one will not be able to assess whether phenobarbital will adequately control the individual dog's seizures.
There is no magic mg/kg dose of phenobarbital that is needed or toxic to individual animals. Therefore, assess phenobarbital concentrations before deciding that an animal is getting too little or too much phenobarbital. - Common side-effects include polyuria, polydipsia, polyphagia, transient sedation or hyperexcitability and ataxia. These are common 1-2 weeks after the onset of treatment or after increasing the oral dosage but usually resolve as tolerance develops. Polyuria, polydipsia, and polyphagia are the most common long-term side-effects. Other side effects include hematological abnormalities, eg neutropenia, anemia and thrombocytopenia.
- Hepatoxicity is rare. An increase in liver enzyme concentration is to be expected in all animals receiving phenylbarbitone and so liver function tests are required to monitor the effects on the liver. Hepatoxicity may be reversible if detected early and phenylbarbitone withdrawn. There is an increased risk of pancreatitis in dogs receiving both bromide and phenobarbitone.
- In most dogs, however, up to 13 mg/kg can be given safely.
- If toxic levels of phenobarbital are obtained, and seizure control is not adequate, then an additional anticonvulsant is added (see below).
- The author prefers to use potassium bromide or rarely, clorazepate /clonazepam.
Sources
Publications
Refereed papers
- Dewey C W, Guilliano R, Boothe D M et al(2004) Zonisamide therapy for refractory idiopathic epilepsy in dogs. JAAHA 40 , 285-291 PubMed.
- Ruehlman D, Podell M & March P (2001) Treatment of partial seizures and seizure-like activity with felbamate in six dogs. JSAP 42 , 403-408 PubMed.
- Levitski R E, Trepanier L A (2000) Effect of timing of blood collection on serum phenobarbital concentrations in dogs with epilepsy. JAVMA 217 , 200-204 PubMed.
- Platt S, Randell S C, Scott K C et al(2000) Comparison of plasma benzodiazepine concentrations following intranasal and intravenous administration of diazepam in dogs. AJVR 61 , 651-654.
- Patent J M (1998) Clinical management of seizures. VCNA 18 , 947-964.
- Nichols E S, Trepanier L A, Linn K (1996) Bromide toxicosis secondary to renal insufficiency in an epileptic dog. JAVMA 208 , 231-233 PubMed.
- Dyer K R, Shell L G (1993) Anticonvulsant therapy: a practical guide to medical management of epilepsy in pets. Vet Med 88 , 647-653.
- Speciale J, Dayrell-Hart B, Steinberg S A (1991) Clinical evaluation of gamma-vinyl-gamma-aminobutyric acid for control of seizures in dogs. JAVMA 198 , 995-1000.
Other sources of information
- Platt S R, Adams V, Garosi L S et al(2003) Gabapentin as adjunctive therapy for refractory idiopathic epilepsy in dogs. Proc ECVN Annual Symposium.
- Podell M (1997) In: Proceedings of 15th ACVIM.Lake Buena Vista, Florida, USA.
