Tonic-Clonic Seizure Symptoms in Dogs

A tonic-clonic seizure in dogs is one that affects the whole brain. This type of seizure is commonly seen in dogs with epilepsy, but can occur in dogs without this condition. Knowing the symptoms of a tonic-clonic seizure can help a pet owner know when a dog is about to or is having an episode.

Seizures in Dogs Explained

Neurons in a dog's brain communicate with each other through electrical and chemical signals that will either excite or shut-down a neuron. When a dog's brain function is normal, the turning off and on of neurons is well balanced. But when too many neurons are turned on, a seizure occurs. Many times a dog that has a seizure is at rest or asleep, but some dogs can have a seizure after being stressed out.

There are three stages to a tonic-clonic seizure: the aura (pre-ictal phase), seizure (ictal phase) and the post-seizure (post-ictal phase).

Tonic-Clonic Seizure Symptoms in Dogs

Symptoms of a seizure include the events that occur before, during and after an event. Before a dog has a tonic-clonic seizure, he'll begin to feel dizzy or light-headed and may not be able to see or hear well. He may also act strange, upset, or nervous and will begin repeating motions, may hide or demand his owner's attention.  These symptoms are done in the aura (pre-ictal) phase. These actions occur because the seizure is beginning in one area of the dog's brain, the focus, which will eventually spread to the whole brain. The aura phase can last a few minutes up to a couple of hours.

The ictal phase is when a dog has the actual seizure. The "tonic" part of the seizure occurs when a dog's muscles become rigid, causing the canine to fall over with his legs sticking straight out and his head tilted back. This episode lasts about 30 seconds before the seizing begins. Signs a dog is in the ictal phase include the loss of consciousness, the twitching of muscles and some involuntary vocalizations. The dog's eyes may remain open during a seizure, but he won't be able to see anything. A dog won't be able to control his bodily functions at this time and it's not usual for a canine to drool, urinate, empty his anal glands and even defecate.

The "clonic" phase of the seizure is when a dog unconsciously begins moving rhythmically. He may look like he is chomping on a big invisible bone or is running while lying down. A dog's tongue may also turn blue as he isn't able to breathe well. This will typically last a couple of minutes. At the end of the seizure (the post-ictal phase), a dog will remain still for a while and may be disoriented when he wakes up

Taking careful notes of what happens to a dog before, during and after a tonic-clonic seizure can help a veterinarian confirm the type of seizure, especially if it was the first time a dog had an episode such as this. Knowing the symptoms of a seizure can also help a pet owner know when a dog will have one, what's normal during an episode and what's considered an emergency.