Invertebral disk disease (IVDD) and seizures

The normal canine/feline spinal cord is protected by blocks of bone known as vertebrae. Between each vertebra sits the intervertebral disk. This disk is composed of a fibrous outer coating and a gelatinous centre, and it helps to provide structural support to the spine. Over time the disk can degenerate, ultimately leading to intervertebral disk disease (IVDD). There are two main types of IVDD and both the back and neck can be affected. 

Diagnosis

X-rays can be very helpful in determining the presence of mineralized intervertebral disks, assessing bone structure, etc., but in order to diagnosis IVDD advanced imaging such as MRI or CT is required. These tests allow visualization of the disks and spinal cord, which are soft tissues, and enables us to accurately determine which segment of the spinal cord is affected. 

Treatment

IVDD can be managed conservatively or with surgery. The type of treatment depends on the severity of clinical signs and results of diagnostic tests. 

Conservative management involves strict cage rest for 4-6 weeks +/- pain medications. Strict cage rest means confining a pet to small crate at all times, aside from brief bathroom breaks. Running, jumping, climbing and playing must not be permitted.  

Surgical management typically involves a procedure known as a “hemilaminectomy” for the back and a “ventral slot” for the neck. A special drill is used to remove a small window of bone from the vertebrae, allowing for visualization of the spinal cord and removal of as much extruded disk as possible. Patients usually remain in hospital for several days after surgery, receiving intravenous fluids, pain medications and bladder management. Recovery continues with strict cage rest at home. A recheck examination is performed 4-6 weeks after surgery. 

Type I and Type II IVDD

Seizures are due to abnormal electrical activity within the brain. Causes for this abnormal activity include those that are extracranial (diseases of the body secondarily affecting the brain) and intracranial (primary diseases of the brain). Some extracranial causes include hypothyroidism, toxins, high or low red blood cell levels, low blood sugar levels and electrolyte problems. Intracranial causes can include infection, inflammation, strokes and tumours.

One of the most common causes of seizures in dogs is idiopathic epilepsy, meaning an underlying cause cannot be identified. This typically occurs in animals between the ages of six months and five years.

Clinical signs

Common signs of seizures are loss of consciousness, paddling of the limbs, stiffness of the limbs, urination and defecation, although this list is not inclusive; other signs such as focal areas of twitching and behavioural changes are possible. Some owners will notice their pet acting abnormally before or after a seizure. These periods are known as the pre-ictal and post-ictal phases, respectively. Animals may be aggressive, fearful, confused or blind in the post-ictal phase and this may last for several days.

Treatment

Treatment for seizures involves attempting to identify (through bloodwork, abdominal ultrasounds, MRI, spinal taps, etc) and treat any underlying causes. The seizures themselves are managed with anti-epileptic medications, of which several are available. It is important to understand that in most cases the seizures are never cured, but we hope to reduce the severity and frequency of the events.