Seizures can occur in dogs for many different reasons. A seizure occurs when the cerebral cortex, a part of the brain, functions in an abnormal way. The cause of this malfunction may be a result of an abnormality located within the brain itself or a result of a disease that starts in another part of the body but still is able to affect the brain.
Extracranial Causes of Seizures in Dogs
Extracranial causes of seizures are the causes that originate elsewhere in the body but are still able to affect the dog's brain and cause seizure activity. The seizure occurs because either the metabolism or the electrophysiology of the brain is changed by the disease.
In most extracranial cases of seizures, the entire cerebral cortex is affected resulting in a generalized seizure rather than a focal or partial seizure.
The most common extracranial causes of canine seizures are:
- hypoglycemia (low blood sugar level)
- liver disease (also termed hepatic encephalopathy)
- kidney disease
- hypocalcemia (low blood calcium level)
- hypothyroidism (disease of the thyroid gland that causes abnormally low thyroid hormone production)
- poisons, including organophosphates, chocolate (theobromine), caffeine, strychnine and others
- hyperthermia (elevated body temperature, "heat exhaustion")
- veterinary parasites, such as fleas and hookworms
Intracranial Causes of Canine Seizures
Intracranial causes of seizures are diseases that cause either structural or functional changes inside of the dog's brain.
Common intracranial causes of canine seizures that cause structural changes in the brain include:
- nutritional imbalances such as thiamine deficiency
- infectious diseases such as canine distemper virus infection (CDV), rabies and other viral, bacterial, fungal, protozoal or rickettsial infections
- congenital disease such as hydocephalus
- brain tumors
- degenerative brain conditions such as storage diseases
- trauma to the brain
- cerebral infarction (lack of blood flow to part of the brain)
In most cases, if the cause of your dog's seizures is a structural intracranial lesion, the disease will be progressive, getting worse with time.
Functional changes inside of your dog's brain may result in what is known idiopathic epilepsy. Idiopathic epilepsy is a disease in which your dog has recurrent seizures but no specific cause can be located for the seizures.
If your dog has had a seizure, he should be examined by your veterinarian. In some cases, diagnostic tests will indicate a clear cause for the seizure or seizures. Where no cause can be located, the disease is diagnosed as idiopathic epilepsy.