Seizures, also called fits or convulsions, are among the most common neurological conditions for dogs. A seizure is a sudden abnormal surge of electrical activity in the nerve cells of the brain. It often results in involuntary muscle movements, loss of consciousness, change in behavior, confusion, restlessness, and vocalization.
After your dog has experienced a seizure, you are likely wondering what caused it.
This article discusses the potential causes of seizures in dogs and outlines a few of the difficulties in getting a diagnosis.
The 10 Typical Reasons Why Dogs Have Seizures
1. Epilepsy
Epilepsy and seizures can sometimes be used interchangeably. However, epilepsy is a condition used to describe a seizure disorder, whereas a seizure is the event itself. The difficult part of this diagnosis is that experts don’t exactly yet know what causes it. The word ascribed to epilepsy is “idiopathic,” which essentially means there is no known cause. To be diagnosed with epilepsy, other conditions need to be ruled out, especially if the canine patient is older than 5 years or younger than 6 months.
Epilepsy can be controlled with medication, and the dog usually requires lifelong treatment on anticonvulsant therapy. It is important to keep a seizure diary for a dog with epilepsy, noting the length, frequency, and circumstances of the seizures, and to ensure that you have an emergency plan in place if your dog’s seizure lasts longer than 3 minutes.
2. Poisons and Toxins
Certain toxins can cause a sudden onset of seizures. These include xylitol (the artificial sweetener), anti-freeze, dark chocolate, rat-bait poison, and caffeine. You are also likely to see other clinical signs, such as vomiting and diarrhea, tremors, lethargy, and sometimes bruising or bleeding. It is extremely important to receive prompt veterinary treatment if you believe that your dog has been exposed to a potential poison, as the prognosis is improved dramatically with early intervention and treatment. Some toxins have an antidote, but for others, patients simply can only be supported as the toxin works its way out of the body.
3. Brain Tumor
More common in middle-aged and older dogs, a brain tumor is always on a veterinarian’s differential list for sudden onset seizures and is something that is ideally ruled out through specialist diagnostics. Brain tumors can often cause other signs too, such as a change in behavior, pacing, restlessness, head tilt, circling, vision disturbances, vomiting, inappetence, and lethargy. An MRI or CT is normally required to visualize the lesion in the brain, and a biopsy to figure out what type of tumor it is. Depending on the type of tumor, how aggressive it is, and whether it has spread at the time of diagnosis, a dog can undergo treatment for brain tumors with a combination of surgery, radiation, and chemotherapy. In many cases, though, owners will elect for palliative treatment and humane euthanasia.
4. Head Trauma
A severe knock to the head can result in brain injury and seizures. There are many possible ways that a dog could attain a traumatic head injury: being hit by a car, falling from a height, being attacked by a larger animal, and suffering gunshot wounds. It will usually be accompanied by other obvious signs of traumatic injury, such as bleeding, difficulty breathing, collapse, lameness, etc. Patients with a history of a traumatic brain injury have an increased risk of developing epilepsy. This is notable in humans too. The prognosis for head trauma depends on the severity of the injury, but sadly, it can be fatal, so it is essential to seek treatment immediately.
4. Brain Tumor
More common in middle-aged and older dogs, a brain tumor is always on a veterinarian’s differential list for sudden onset seizures and is something that is ideally ruled out through specialist diagnostics. Brain tumors can often cause other signs too, such as a change in behavior, pacing, restlessness, head tilt, circling, vision disturbances, vomiting, inappetence, and lethargy. An MRI or CT is normally required to visualize the lesion in the brain, and a biopsy to figure out what type of tumor it is. Depending on the type of tumor, how aggressive it is, and whether it has spread at the time of diagnosis, a dog can undergo treatment for brain tumors with a combination of surgery, radiation, and chemotherapy. In many cases, though, owners will elect for palliative treatment and humane euthanasia.
5. Liver Disease
The liver can be considered the body’s chemical weighing station in the body. It is responsible for detoxifying the blood, creating and storing energy, producing bile acids to aid in the digestion of food from the stomach, and creating proteins required for clotting. A side effect of decreased liver function is a neurological disease called hepatic encephalopathy, a result of the liver being unable to process substances that are toxic to the body, such as ammonia. It can cause seizures in affected dogs, alongside other neurological signs like head pressing, blindness, and muscle tremors. Due to the presence of the underlying liver disease, canine patients may also experience weight loss, vomiting, increased thirst and urination, and jaundice. The most common methods of hepatic encephalopathy in dogs are portosystemic shunts and hepatic lipidosis.
6. Hypoglycemia
Hypoglycemia, or low blood sugar, can cause seizures. It’s especially problematic for very young puppies. Certain drugs and toxins can result in low blood sugar, as can liver disease, specific tumors, infections and sepsis, pancreatitis, and overdosing on insulin in diabetic patients. The treatment and prognosis are dependent on the underlying cause of hypoglycemia, but once the blood sugar levels have been restored to normal, the seizures (and other clinical signs) should effectively cease.
7. Infections
Certain infections like distemper virus or parasitic infections like neospora are other causes of seizures, particularly for dogs under 6 months and unvaccinated pets. Diagnosis is made through analysis of cerebrospinal fluid, which needs to be collected via a needle into the spine under general anesthesia. They may also show other signs of fever, changes in behavior, neck pain and stiffness, and other neurological deficits. It is important to keep up with regular worming protocols, to not feed your dog contaminated raw or undercooked meat, and to ensure that they are up to date with their vaccinations.
8. Hydrocephalus
Hydrocephalus is the build-up of fluid inside the brain, specifically the cerebrospinal fluid (CSF). CSF exists in small amounts in healthy animals, surrounding the brain and spinal cord to support those tissues, but abnormal buildup can result in pressure on the brain and subsequent neurological signs, such as seizures. Dogs may be born with this condition or acquire it later in life over time. It is thought that it is caused by certain prenatal infections, exposure to toxins, genetic malformations, tumors, infections, and brain hemorrhage. Treatment of hydrocephalus is dependent on the underlying cause of the disease, the patient’s age, and the severity of clinical signs, but the overall goal is to stop the progression of the disease, either through medications or neurosurgery.
9. Heatstroke
Seizures aren’t the first thing that you would associate with hot weather and overheating, but they are a serious manifestation of severe heatstroke in dogs. When the body is unable to cool itself down due to sustained exposure to high temperatures, it damages the body’s tissues, causing organ damage to many of the systems. When the central nervous system is affected, it can eventually result in disorientation and seizures.
Alarmingly, heatstroke can progress extremely quickly and cause death in less than an hour. This is why it is especially important to not leave your dog in a car in hot (or even cool!) weather or to walk them in the middle of the day during the harsh summer months. The first signs of heatstroke are normally excessive panting, red gums, dehydration, and a fast heart rate, progressing to vomiting and diarrhea (sometimes with blood), weakness, collapse, and eventually, seizures and death. Dogs with heatstroke require emergency veterinary treatment immediately.
10. Autoimmune Disease
Autoimmune disease is where the body’s immune system is somehow activated to attack its own tissues and in some cases, its very own nervous tissue. This results in inflammation of the brain and its lining, termed meningoencephalitis (MUA). Alongside seizures, affected dogs may experience many other neurological signs, such as blindness, weakness, wobbliness, disorientation, change in behavior, and difficulty swallowing. Typically, MUA can be diagnosed on MRI and analysis of the cerebrospinal fluid, with treatment to suppress the immune system. The response to treatment is variable, but it is the hope that with appropriate therapy, they can have a good quality of life for many years, though they may need to always be on medication.
Conclusion
While this list doesn’t cover all causes of seizures, these are the main ones often seen in clinical practices. If your dog has suffered from one or more seizures, hopefully, this list has provided you with insight into the possible reasons that your dog may be having them and why vets proceed with the diagnostics that they do, such as blood and urine tests, X-rays, ultrasounds, and referrals for MRI and CTs. If you have any concerns with your pet, please call your veterinarian for advice.
Featured Image Credit: Kittima05, Shutterstock
