Watching your beloved pet appear helpless while foaming at the mouth or have twitching limbs and convulsive tremors can be terribly frightening. Most people understandably panic when this happens and fear the worst—that they may be losing their pet. Although possibly serious, seizures are relatively common with pets—more often dogs.
Most seizures can be controlled once the source of the problem is identified. A seizure is a physical manifestation of abnormal electrical activity in the brain. A seizure can occur when the nerve to muscle communication overloads. When the brain has an electrical charge that persists across a membrane seizures occur. Dogs do get epilepsy and this is the most common reason for seizures. However, metabolic, toxic and physical brain abnormalities (congenital or acquired) can also exist and cause seizures. Differentiating between all of those causes guides the treatment for seizures in pets.
Metabolic reasons for seizures include abnormal calcium, glucose or sodium levels. Some young pets might not have enough stored glucose called glycogen and significant exertion without a meal could bring their blood sugar too low. Severe infection can also bring down a blood sugar. Dogs with low blood sugar might need to be fed more often. Calcium is very carefully monitored and regulated by the parathyroid gland. The parathyroid helps the kidneys, intestines and bones supply short-term and long-term calcium levels to the body. Too little or too much of the parathyroid gland function causes changes in calcium and in some cases seizures when the muscles react to that excess or deficiency. Sodium helps maintain the pet’s internal water levels and imbalances of too much or too little may also cause seizures.
Toxins are another cause of seizures. The most common is snail bait containing the substance metaldehyde. This substance is a “tremerogen” which causes muscles to twitch. Dogs who eat this substance might start with fine tremors but if they have ingested enough the twitch will progress to full blown seizures and if left untreated these dogs can have their body temperature climb to greater than 107 which then can cause permanent damage in the brain and possible death. Make sure pets are not exposed to metaldehyde contained in snail bait around your house. There are safer brands that contain zinc or iron phosphate. Prescription medications, chocolate, coffee and many other household products can predispose pets to seizures. If your pet has behavior changes and may have been exposed to an unusual substance play it safe and call either poison control or your veterinarian for advice. A retrospective look at toxic and metabolic causes for seizures was published in 2011 and found many different extra-cranial (outside the brain) reasons for seizures in dogs: http://www.ncbi.nlm.nih.gov/pubmed/19939714
Anatomical abnormalities in the brain can include:
- Congenital (birth defects) where the brain is malformed or parts of the brain do not develop completely
- Brain tumors
- Brain injuries including trauma, stroke, hemorrhage or inflammation
In anatomical seizure cases the breed, age and previous history of the dog is essential information in figuring out the source of the seizures. Also dogs can develop anatomical brain changes or inflammation due to infectious diseases such as distemper, rabies or meningitis: bacterial or inflammatory. Often imaging the brain with magnetic resonance imaging (MRI) will help differentiate these causes. Cerebral spinal fluid can also be analyzed in these pets. Treatment varies from medication, antibiotics and supportive care, to (in cases of tumors) surgery and or radiation. It’s up to the owner to decide what is a viable option for them and their pet.
Epilepsy is often the diagnosis when other reasons for seizures are not identified. Obtaining a good history, evaluating the environment and breed of a pet as well as doing a blood panel, a thorough physical examination including neurologic exam are all necessary before settling on a diagnosis of idiopathic (spontaneous) epilepsy. Age of the pet also plays a role. Most epileptic pets have their first seizure between the age of 6 months and 5 years. Once again dogs can break the mold and have their first seizure at a later date and often an MRI is recommended to be sure there is not an anatomical insult in that older pet’s brain. Breeds in which the condition can be inherited include Beagles, Dachshunds, Keeshonden German Shepherd Dogs, Belgian Tervurens, and others. Breeds with a high incidence, but in which inheritance has not yet been established, include Cocker Spaniels, Collies, Golden Retrievers, Labrador Retrievers, Irish Setters, Poodles, Miniature Schnauzers, St. Bernards, Siberian Huskies, and Wire Fox Terriers. Even mixed breeds can be afflicted with epilepsy. You can read more at http://pets.webmd.com/dogs/dog-epilepsy.
Phenobarbital has historically been used for treatment of seizures. It is effective but does have a potential to be damaging to the liver if not carefully monitored. Potassium bromide is another medication being used for control of seizures in dogs. However, it causes an irreversible inflammatory bronchitis in cats so should not be used in that species. In recent years newer medications with fewer side effects have become affordable as generics. These medications: zonisamide, longer acting Valium analogs and levetiracetam (keppra) are emerging as safer and effective medications for managing seizures in pets.
Veterinary neurologists are one of the many specialty disciplines in our field and exclusive studying of the brain and spinal cord diseases allow them to help guide diagnostics and therapy in affected patients. Many internal medicine specialists also manage challenging seizure cases when the family veterinarian has exhausted their options for good control of the disease.
Blog Post Author:
Merrianne Burtch, DVM, DACVIM