Seizures in Dogs
by Dr. Audrey Harvey, BVSc (Hons)
Seizures in dogs are basically any sudden body movement that is out of control. It is caused by abnormal activity in the brain. These movements can affect his whole body, or they may cause fairly mild twitching in just one area. He may lose consciousness, and he may urinate or defecate during the seizure.
Seeing your beloved dog having a seizure is one of the scariest things any dog owner can experience.
If your dog has a seizure, it's important that you take your dog to your veterinarian to find out the cause, and have him treated. Seizures in dogs that last longer than 3 or 4 minutes can cause fluid accumulation in the lungs or brain, both of which are very serious conditions. Also, the extreme muscle activity that usually happens during a seizure can increase his body temperature, which can damage his internal organs.
Causes of Seizures in Dogs
There are a number of causes of seizures in dogs. Low blood sugar in toy breeds such as Chihuahuas or Yorkshire Terriers can lead to convulsions. Small breeds that are feeding a large litter of pups can develop low blood calcium because of their high rate of milk production. One of the main symptoms of hypocalcemia, or low blood calcium, is seizures.
Liver problems result in an accumulation of toxins, such as ammonia, in the blood. Infections such as distemper lead to brain inflammation and seizures. High ammonia levels will affect a dog's brain, thus seizures are one symptom of liver disease.
Many chemical toxins also cause these symptoms; one example is metaldehyde, a chemical that is commonly used in snail bait. Lead poisoning is also characterized by seizure activity. A bump on the head may lead to convulsions due to swelling of the brain.
The age of your dog can give you a hint as to the possible cause of his seizures. Young dogs less than 12 months old usually have seizures because they have been born with something wrong. Hydrocephalus, or water on the brain, can be responsible for seizures in young dog, as can a portosystemic shunt. This is a liver abnormality in which blood bypasses the liver and therefore toxins aren't removed. The symptoms are similar to those of liver disease, and often include seizures.
Middle aged dogs up to 5 years tend to have epilepsy, which is seizure activity with no obvious cause. Epilepsy is a diagnosis of exclusion; all other possible causes of your dog's symptoms must be ruled out before he is considered to be epileptic.
Older dogs often have some medical condition which is causing their seizures. Some examples include brain tumors, strokes or again, liver failure.
These guidelines are very general, and won't necessarily apply to every dog, but they are useful to keep in mind.
Types of Seizures and their Symptoms
There are several ways of categorizing seizures in dogs. One way is to group them based on their cause.
•Primary seizures occur when there is no obvious cause, and if a dog has repeated primary seizures, they are considered to have epilepsy.
•Secondary seizures occur in association with a recognizable brain abnormality, such as a tumor.
•Seizures in dogs that occur associated with non-brain disease or toxicity are known as reactive seizures. In these cases, the dog's brain is physically normal.
We can also describe seizures based on a dog's behavior during a convulsion, and what part of his body is affected.
The Grand Mal
, or generalized, seizure is the one we're most familiar with in dogs, and the most frightening. Their entire body is involved. Their muscles repeatedly contract and relax, as their legs and head are extended, and they froth at the mouth. They may yelp, and they often paddle their legs. Loss of consciousness occurs, and can pass urine or feces.
Sometimes these seizures occur one after the other without a pause, and this is known as status epilepticus. This is a medical emergency, and you need to contact your veterinarian immediately.
Cluster seizures are like status epilepticus, in that they are repeated Grand Mal seizures, but there is a period between the seizures where the dog regains consciousness.
Partial seizures, also known as focal seizures, involve just one area of the brain. This means that only part of the body is affected. A common example is twitching or movement of one part of the face. These seizures can become generalized, and affect the whole body.
The last type of seizure is the psychomotor seizure. These originate in the part of the brain responsible for behavior, and are characterized by snapping at imaginary things in the air above them, howling, or walking around in circles. As with partial seizures, they too may lead into a generalized seizure.
Many owners of epileptic dogs describe an aura; behavioral changes that indicate that a seizure is imminent. Their dog appears nervous, and may whine and pace the floor.
The period after a seizure is called the post-ictal phase, and it usually lasts around an hour. A dog will appear dazed and restless, and may not recognize their owner. They may also have a temporary inability to see or hear.
Diagnosing the cause of Seizures in Dogs
It can be difficult getting to the bottom of your dog's seizure problem. The first step is to look at his history – when did the seizures begin? Did anything significant happen before they started, for example did he go fishing and possibly swallow a lead sinker, or was he involved in a fall or a car accident, which may have caused trauma to his head.
From there, a number of diagnostic tests will need to be done. Basic blood tests will indicate if infection is present, and if there is any organ dysfunction, such as liver disease. If there is nothing obvious on these tests, then a cat scan or MRI will be performed to look for brain abnormalities. A sample of the cerebrospinal fluid that bathes the brain and spinal cord will also be analyzed to check for unusual cell counts that can indicate infection or inflammation.
These tests are not cheap, but are essential to make sure that your dog's condition is properly diagnosed, and that he gets the best possible treatment.
If the tests all return normal results, then a diagnosis of epilepsy is reached, and anti-epileptic drugs will be prescribed.
Treating Seizures in Dogs
If your dog is having a seizure, you need to stay calm. Clear the space around him so he doesn't hurt himself. Don't go near his mouth. He won't swallow his tongue, but he may inadvertently bite you. If the seizure lasts longer than 3 or 4 minutes, carefully pick him up and take him to a veterinarian
Initial treatment will be sedation or anesthesia with diazepam or propofol, to stop the convulsion. Hypoglycemia is treated with intravenous glucose. Similarly, hypocalcemic convulsions will respond well to intravenous calcium injections.
Phenobarbital and Potassium Bromide for Dogs
Epileptic dogs are usually prescribed phenobarbital. This drug reduces the seizure activity in your dog's brain. It can take a few weeks for drug levels in your dog's blood to reach effective levels, and at this point, blood tests should be done to make sure that your dog is getting enough medication. These tests should be repeated every 6 months. This drug can affect your dog's liver, so at the same time as you have his phenobarbital levels tested, you should also have blood tests done to check how well his liver is functioning.
Unfortunately, about one third of epileptic dogs don't respond to phenobarbital alone, and seizures still occur. If this is the case with your dog, he can take potassium bromide in conjunction with phenobarbital. This combination is successful in most cases of epilepsy in dogs.
There are some human anti-epileptic drugs which can be used for seizures in dogs. Their disadvantages are that they are expensive, and their dosing schedule is inconvenient. Not all dog owners can medicate their dog three or four times a day. However, if nothing else works, then they may be worth trying.
If your dog suffers from seizures, you will need to medicate him for the rest of his life. Fortunately, most dogs with properly managed epilepsy enjoy a normal lifestyle, and their condition doesn't affect them too much at all.
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