What Causes Seizures

Seizures have many causes, and the aim of both holistic and conventional veterinarians is to determine and treat the root cause. Some causes are metabolic, such as hypoglycemia (low blood sugar), especially in toy breed puppies, and hypocalcemia (low calcium levels), which is common in females who are nursing puppies. Hypocalcemia and hypoglycemia can also be responsible for seizures in young puppies with intestinal parasites.

Brain Tumors

Brain tumors in dogs older than five or six years of age are often responsible for seizures. The seizures may range from partial to grand mal. Cluster seizures may also develop. Onset of seizures or neurologic changes will often be gradual. A dog with a brain tumor may experience some of the following symptoms:

  • Appetite. The dog may be ravenous or entirely uninterested in food.

  • Difficulty breathing. Breathing seems labored and stops and starts while the dog is asleep.

  • Fatigue. The dog lacks energy and tires quickly during exercise.

  • Gait is unsteady, stumbling, or staggering. The dog may have difficulty climbing stairs or walking on uneven ground.

  • Geriatric separation disorder. A dog awakens at night for no reason and may whine, pace, or seem restless.

  • Loss of bladder or bowel control. This is apparent in dogs that were previously housetrained.

  • Mental confusion. The dog may forget familiar commands, fail to recognize family members or familiar people, become disoriented in familiar places, and have a glazed expression.

  • Pain. The dog may whine and whimper seemingly without reason.

  • Personality change. The dog may have obsessive behaviors and may be less affectionate or very docile.

  • Sensory problems. The dog may experience loss of sight, hearing, or even sense of smell.

  • Lead Poisoning

    Lead poisoning is the most common toxic cause of seizures. Dogs can ingest lead if they lick or eat oil-based paint chips, batteries, linoleum, roofing materials, champagne bottle foil, golf ball coverings, and pie, fishing, or drapery weights. The amount of lead necessary to instigate a seizure depends on the dog's seizure threshold.


    Encephalitis, or inflammation of the central nervous system, will also cause seizures. Some seizures are triggered by immune-mediated encephalitis, a low-grade inflammation of the brain that is caused by a reaction to proteins and organisms in a vaccine. Noninfectious causes of encephalitis include granulomatous meningoencephalitis (GME) and chronic encephalitis that mostly affects Pugs and a few other flat-faced breeds.

    Other Causes

    The following conditions can also be responsible for causing seizures:

    • Blood glucose levels too high or too low

    • Congenital defects

    • Fevers and heat stroke

    • Head trauma

    • Infections such as distemper

    • Liver disease and hypothyroidism

    • Low oxygen levels in the blood

    • Toxins, such as insecticide, rat poison, antifreeze, or chocolate

    • Various forms of cancer

    Congenital causes of seizures include hydrocephalus and lissencephaly. Hydrocephalus, the most common congenital brain malformation, involves the increased accumulation of fluid (cerebral spinal fluid) in the ventricles of the brain. Seizures are one symptom of this disease. Puppies with hydrocephalus will often seem dull and be slow to learn. They may have gait abnormalities as well. Another congenital defect that causes seizures in Lhasa Apsos, wire-haired Fox Terriers, and Irish Setters is lissencephaly, a brain malformation. This neurologic abnormality may show up during the first year of life and includes behavioral, visual, and convulsive disorders. In Lhasa Apsos, signs of alternating depression and excitability, aggression toward owners, and seizures may be apparent.

    Setting Off a Seizure

    Dogs with low seizure thresholds are prone to them. Stress or prolonged excitement can instigate a convulsion. A dog could have a seizure during a game of chase, when the family returns home, or if he receives a really tasty treat. Other triggers include any sudden, subtle, or radical changes in food or environment.

    Use caution when vaccinating breeds that are prone to epilepsy, and with any dog that has a history of seizures. Monovalent vaccines should be used for the puppy series, and adults should be vaccinated with only the core vaccines and vaccines that are appropriate to the risk of disease. Titers can be used to measure a dog's immunity to disease after vaccination.

    Some dogs react so violently to thunderstorms, changes in barometric pressure, or extreme cold weather that they will seize. For other dogs, separation anxiety, car rides, visits to the veterinarian, or extreme fatigue or nervousness will bring on a seizure.

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