Complex sentence: However, the age at diagnosis is only one factor in diagnosing canine epilepsy, as one study found cause for seizures in one-third of dogs between the ages of one and three, indicating secondary or reactive rather than primary epilepsy.
Split into simpler sentences: However, the age of diagnosis is only one factor in diagnosing canine epilepsy. One study found a cause for the seizures in one-third of dogs between the ages of one and three, indicating secondary or reactive rather than primary epilepsy.