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Monday, 7 November 2011

Seizures in dogs and cats

Welcome to PercyPods Pet Emergency blogs. We hope that you and your pets have been well since the last blog. This week we are going to discuss another one of the more serious problems that can affect dogs and cats, namely seizures or what some people also call fits or convulsions. Although a single seizure is often not especially harmful to your pet, seizures can be life-threatening and so it is important for pet carers to be well informed about this problem.

What is a seizure?

Okay so let’s start by discussing what a seizure is. Basically the brain works because there is an electrical circuit flowing around it at all times. The brain controls a very large amount of the body’s actions and functions and all of these essentially rely on this electrical circuit flowing properly. A seizure occurs when there is an uncontrolled burst or sudden increase in this electrical circuit. It is a bit like if there is surge in the current in the electrical circuits in your house that blows a fuse. Depending on exactly where in the brain this burst occurs, how severe it is and how long it goes on for, there can be quite varied consequences. Some seizures are what we call ‘partial’ or ‘focal’ where only one or two parts of the brain and therefore the body tend to be affected and they are usually less severe and less of a concern. The other type of seizure, the type that is more concerning and that we are going to focus on here, is a ‘generalised tonic-clonic seizure’ and this type of seizure is more common in dogs than it is in cats.

What is a generalised tonic-clonic seizure?

So what is a generalised tonic-clonic seizure? As the name suggests, this type of seizure is one where most of the brain and the body is affected. The animal will fall over if standing, may lose consciousness, and their muscles become very tense or rigid which may cause their neck and legs to become extended; this is the ‘tonic’ phase and usually only lasts for a few seconds. This phase is then followed by the ‘clonic’ phase in which many of the muscles contract and relax rapidly. These convulsions may range from exaggerated twitches to violent shaking or vibrating. Paddling of the legs often occurs. The eyes may roll back or close and the tongue may be injured by strong champing of the jaws or from being bitten. Some animals will salivate or froth at the mouth while others may pass urine or faeces during the seizure.

In many cases a generalised seizures lasts for a few seconds up to a couple of minutes. However in more severe cases a condition known as status epilepticus may occur where your pet will continue to seizure for 5 minutes or more or will have repeated seizures one after the other without much time at all in-between to regain consciousness. Status epilepticus is a life-threatening emergency.

Will I notice anything before or after the seizure?

Now, as with humans, before a dog or a cat has a seizure, they may show what we call a ‘pre-ictal’ phase during which their behaviour changes before you notice the other signs described above; the actual seizure itself occurs in the ‘ictal’ phase hence we use the term ‘pre-ictal’ for the period before the full blown seizure starts. Many people who care for pets that suffer seizures come to recognise these signs and can therefore take appropriate measures before the seizure begins. So what are some of the reported pre-ictal signs? Well, animals may appear restless, agitated or nervous. They may hide or they may be more clingy than normal and later some may become unresponsive to you. The pre-ictal phase may last for just a few seconds or may go on for several hours.

You should also be aware that after a generalised seizure your pet may have what we call a ‘post-ictal’ phase. This phase may include a variety of abnormalities such as unusual behaviour, panting, disorientation, staring straight ahead, temporary blindness, inappropriate urination or passing of faeces, and in some cases more obvious neurological signs. The post-ictal phase usually lasts for less than an hour or maybe a few hours but it can go on for much longer even as long as 2 days believe it or not. There is no direct correlation between the severity of the seizure and the duration of the post-ictal phase.

Is there anything that I might confuse with a seizure?

Before we talk about some of the causes of seizures, we would just like to mention some of the things that dogs and cats can do which you might mistake for a seizure. There are quite a few and some are just part of normal animal behaviour while others are abnormal. One of the most common things to be confused with a seizure is what we call syncope. Syncope is basically like a fainting episode and usually occurs because of a problem with the heart or with the breathing. Animals often fall over suddenly but in many cases they recover quite quickly within seconds to a minute. However some animals pant and remain weak after the episode. Some animals get a condition known as vestibular disease which affects one of the nerves in the head. This causes signs such as an abnormal head position and loss of balance which can come on very suddenly and be mistaken for a seizure. Then there are those dogs that twitch or paddle their legs while sleeping. Some will even vocalise. This is especially common in young puppies although many older dogs show similar behavior. This is normal and is usually associated with very deep sleep.

The biggest difference between seizures and non-seizures is the animal’s state of consciousness. If an animal is doing something that resembles a seizure while conscious, is aware of its surroundings, or is easily roused (as in sleep), it is not having a true seizure.

What are some of the causes of seizures?

Okay so before we go on to consider what you should do if your pet has a seizure, let’s first talk about what some of the causes of seizures are. There are many causes of seizures and we tend to divide them into two groups. The first group are causes that originate within the brain itself. These are causes that we refer to as intracranial and they include for example brain tumours, inflammation affecting the brain and bleeding into the brain. One of the most common causes of seizuring originating in the brain is known as epilepsy; this condition, similar to epilepsy in people, affects both dogs and cats although it is more common in dogs. It is seen especially in purebred and large dogs and tends to become apparent for the first time between one to five years of age. At the moment we are not sure why any one dog or cat develops epilepsy – it is a condition of unknown cause or so-called ‘idiopathic’ – but much research work continues in this area. Idiopathic epilepsy is inherited in some breeds of dog at least, for example in German Shepherd dogs. Inflammation affecting the brain, so-called encephalitis, may be due to an infection but it is often not found to be due to an infection rather a sterile non-infectious problem.

The second group of causes of seizures are ones that do not originate in the brain itself but are still able to disrupt the electrical circuit in the brain. We refer to these causes as extracranial and a very common example would be seizuring that occurs after a dog or cat is exposed to a poison that can cause seizures. There are several examples of such poisons, one of the most common affecting dogs being metaldehyde which is found in slug bait. In cats we quite commonly see seizuring when they are overdosed with an anti-flea preparation that contains substances called pyrethrins and pyrethroids. Both of these types of poisoning were discussed in episode 3 of these blogs so please have a read if you haven’t already.

Other extracranial causes of seizures include severely low blood glucose, so-called hypoglycaemia, which can occur for example in puppies and kittens, when a diabetic animal is overdosed with insulin, or in older dogs with tumours that produce insulin, so-called insulinomas. Hypocalcaemia (low blood calcium levels) is another metabolic cause of seizures especially common in lactating bitches after they have given birth. High blood ammonia levels can also lead to seizures. This metabolic disturbance is seen in animals with liver disease, for example so-called portosystemic shunts.

What should I do if my pet has a seizure?

Okay so now that we have considered what a seizure is and what some of the possible causes are, let’s focus on what you should do if your pet has a seizure or indeed if you recognise the signs which suggest that your pet is going to have a seizure soon. If your pet is having a seizure, the first thing to do is to make sure that he or she cannot injure themselves. Rather than trying to move your pet away from danger it is better if possible to move any potential hazards away from them. For example, move any pieces of furniture that they may injure themselves on or any bottles or ornaments that could fall on them. It is best if possible to avoid actually touching your pet, especially around the mouth, during a seizure as they may inadvertently bite you. However if your pet is not on the floor then you do need to take steps to make sure that he or she does not fall off the sofa or the bed or wherever they happen to be.

Try to stay calm and make note of as much information as you can in terms of what your pet is doing and then ring your practice immediately for advice. If your pet has had a seizure previously, your vet may have given you some tubes of a drug called diazepam that we use to stop a seizure. These tubes are designed to be given to your pet through their anus – their bum – into their rectum. If you have these tubes, you should administer the dose suggested by your vet and wait for a few seconds to a minute to see if the seizure stops and then call your practice.

Not all animals that have suffered a seizure need to be examined as an emergency. Your vet practice will want to get some information from you to help them decide on a recommendation. Of course your wishes are also very important in this. The sort of information that your practice will want to know includes:
  • What signs you noticed during the seizure and, assuming that the seizure has finished, how long it went on for; also, did you administer any diazepam rectally and if so, what effect did it have.
  • They will also want to know if your pet has had any more seizures that day and if so, when they occurred
  • You should also tell your practice whether your pet has had any seizures in the past and if so whether he or she is on any treatment for this
  • It is also important to your practice to know if you think your pet may have been exposed to something like a poison or a drug overdose
  • And lastly, they will want to know if your pet has any significant previous medical history
On the basis of this sort of information and your wishes, you can decide with your practice whether your pet should be examined at the practice or stay at home and continue to be monitored. If the decision is made to monitor your pet at home then you should monitor him or her very closely for another seizure and ring your practice immediately if it occurs again. Remember that your pet’s behaviour may be abnormal as we discussed before during this post-ictal period. A single isolated seizure in an otherwise healthy adult animal does not usually require emergency veterinary care, though an appointment should be scheduled promptly for a thorough work-up.

As we mentioned before, a condition known as status epilepticus may occur where your pet will continue to seizure for 5 minutes or more or will have repeated seizures one after the other without much time at all in-between to regain consciousness. Status epilepticus is a life-threatening emergency and your pet must be seen as soon as possible. Another situation in which your pet must be seen as soon as possible is if they have had what we call cluster seizures; this is when your pet has two or more generalised seizures within a 24 hour period.

If you do end up taking your pet to your practice while he or she is still seizuring, be careful not to get bitten when putting him or her into the car. Make sure that they are surrounded by plenty of padding so that they are protected from injury during the journey and if at all possible, take someone else with you in the car – your partner or a neighbour for example. Ideally the person who is calmest and least stressed should drive quickly but legally and carefully to the practice – it is clearly essential that you all reach the practice safely. Animals that are seizuring can become very hot so depending on how far the practice is it may be wise to have the air conditioning on in the car or some of the windows open.

What treatment will my pet need?

Okay so let’s end this blog by considering what treatment your pet may need, what your vet might need to do. As always, the treatment an animal needs will depend on the individual animal. The most important thing to start with is whether your pet is still seizuring at the time he or she arrives at your practice. If they are then the first priority is for your vet to control the seizures by administering anti-seizure drugs. Depending on how your pet responds, this may involve just one drug – usually diazepam or a similar drug called midazolam – or more and this may include your pet being anaesthetised. One of the other priorities in many cases is for your vet to measure your pet’s blood glucose concentration as this is a relatively common cause of seizures as we discussed before and one that can usually be easily treated at least in the short-term. Your vet may also discuss doing additional blood tests as well as analysing your pet’s urine and this is aimed at trying to look for some of the extracranial causes that we described before – remember those are ones that do not originate in the brain itself.

It is important for you to realise that in many cases the cause of a seizure cannot be determined without your pet being referred to a specialist where they can have advanced tests such as an MRI of the brain and collection of cerebrospinal fluid – this is the fluid that circulates around the brain and spinal cord.

So what about anti-seizure medication for your pet when they return home? Well, if and when this is started again depends on the individual animal and also on your wishes in terms of whether you want your pet to be referred to a specialist or not. Most animals that have only had one seizure are not started on medication with this decision being reviewed if another seizure occurs. Even then the decision to start medication will largely depend on how often the seizures are happening as some animals can go months between seizures without medication and starting long-term medication is not always the most sensible choice. On the other hand an animal that has had status epilepticus or cluster seizures may well be started on medication immediately.

The two most common anti-seizure medications used in dogs and cats are phenobarbital and potassium bromide; there are also a few others that are usually not used unless your pet fails to respond to one of these two drugs. You should note that depending on the cause of your pet’s seizure, despite being on treatment, the seizures may not disappear completely. Some animals will continue to have a seizure from time to time and the goal of therapy is to reduce the frequency and severity of seizures to a level the pet and its family can live comfortably with.

Okay so that brings us to the end of this blog on seizures in dogs and cats. It is quite a common and a serious emergency problem for which there are lots of different causes and the outlook very much depends on the cause. A number of different treatments may be needed and your vet will talk you through all of this as appropriate.

The next blog will be in approximately 2 weeks time when we will talk about heart disease in dogs and cats. Remember that if you have any comments or questions on this blog, or indeed any suggestions for future blogs, you can contact us in the usual ways. Via email on percypods@gmail.com; via the PercyPods Facebook page; or via Twitter on @PercyPods. Also don’t forget to subscribe for future episodes via the RSS feed. So thank you for reading and until next time, may you and your pets be safe.