Nibbles and Bits — January 2012

There are few things as scary to witness as a seizure. To watch a pet convulsing is stressful to the owner and also to the pet once he comes around. Understanding the causes and treatment of seizures demystifies the event and helps us to manage these pets.

Seizures in pets are generally the grand mal type typified by convulsions. During these, they are not conscious and all the muscles start contracting uncontrollably. They will often urinate or defecate during the seizure. Afterwards, they will go through a “post-ictal” period where they will be disoriented and often act blind. This period can last anywhere from a few seconds to several hours, depending on how long the seizure itself was.

There are a host of reasons pets can have seizures. Probably the most common is epilepsy. Animals with epilepsy will spontaneously have convulsions. They can vary in length and frequency and can often become worse as they get older. It is more common in certain breeds, most notably Labradors and Springer Spaniels and may be hereditary. Generally, most pets with epilepsy will start having seizures between the ages of one and four years, but if they are infrequent and short, no one may witness them early on so the onset may appear to be later in life. Epilepsy is a diagnosis of exclusion, which means there is no test specifically for it. Other causes need to be ruled out and then epilepsy is the diagnosis that is left.

Diseases of the liver can also cause seizures. The liver is responsible for filtering toxins out of the blood and build-up of these, ammonia in particular, can cause seizures. Low blood sugar, which can be seen in diabetics which get too much insulin, or in a tumor of the pancreas called an insulinoma, which secretes insulin, causes seizures because the brain isn’t getting enough glucose. Brain tumors can certainly cause seizures as well, although this is a less common cause.

Toxins can also cause seizures. Certain molds in particular can cause severe seizures. This can happen when pets get into the garbage and binge on moldy bread or other items. Also, there is one type of rat poison, called bromothalin, that can cause seizures. While most rat and mouse baits respond to Vitamin K as an antidote, this type does not have any antidote. If you must use rat or mouse baits, it is best to stay away from this one if you have pets. Other toxins include strychnine, Japanese yew plant, metaldehyde (found in some snail baits) and illicit drugs such as cocaine and methamphetamine. Another very common toxicity we see, although it causes severe tremors which look like seizures, is permethrin in cats. Permethrin is a common tick-killing agent found in many topicals for use in dogs only. Dogs tolerate it quite well, but when it is inadvertently applied to cats, they clean themselves and ingest the product. They are unable to metabolize it like dogs can and it causes protracted muscle tremors. Always make sure to read the label carefully.

Treating seizures involves managing the underlying cause if one is present. If the cause is epilepsy, then anticonvulsant medications are used if the seizures are frequent enough (usually every 2 weeks) or long enough (twenty minutes or more). Phenobarbital is the primary drug in most cases. Another common drug we use if phenobarbital is not effective enough or if there are problems with it is potassium bromide. Both of these medications need to be monitored periodically with blood tests to make sure proper levels are in the bloodstream.

The vast majority of pets with epilepsy can be managed with medication and go on to lead normal lives. If you have any other questions about seizures or epilepsy, please contact our office and we’d be happy to go into further detail.

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