A seizure may be described as a sudden attack, spasm or convulsion. It is an abnormally-occurring, involuntary behavior. There are three different categories of seizures: generalized or grand mal seizures, partial seizures, and psychomotor seizures. Generalized or grand mal seizures involve the entire body and are characterized by stiffness and possibly stiffness/contraction cycles, along with loss of consciousness and possible urination or defecation. These are the most common type of seizures occurring in small animals. Partial seizures involve a specific region of the body as they originate from a specific area in the brain, though they may generalize to involve the whole body. Psychomotor seizures are mostly behavioral and involve involuntary howling, circling, snapping and so on. These type of seizures may be followed by a generalized seizure.

Sometimes it's difficult to distinguish seizures from fainting. The difference is that seizures are commonly followed by a post-ictal period lasting anywhere from a few minutes to several hours in which the animal may seem disoriented or even blind. Seizures may be caused by different factors and the first step in diagnosis is determining whether the cause is from within the brain, as with infection or trauma, or outside of the brain, as with external poisons, low blood sugar or circulating metabolic toxins. A blood test or ophthalmic exam can be performed to determine this.

The age of the pet determines the next step. In pets aged one year and younger, infections of the brain are the most frequent cause of seizures, which can be diagnosed with a tap. Pets aged one to five typically have no cause to the seizures and are labeled epileptic. Epilepsy is a term which simply means seizure disorder. Certain dog breeds are more prone to epilepsy, including Basset Hounds, Cocker Spaniels, Collies and Schnauzers. Epileptic pets may be prescribed medication to help suppress frequent seizures. In pets aged five and older, tumors are often the cause of seizures and can be diagnosed with a CAT scan or MRI. If caught early, most tumors are operable, otherwise corticosteroids may be used to reduce the amount of swelling on the brain.