Feline Seizures: Thinking Beyond the Episode

In the March open access episode of Chattering With International Cat Care, Yaiza Gómez-Mejías is joined by Dr Mark Lowrie to discuss his recent Clinical Spotlight Review in the Journal of Feline Medicine and Surgery on epileptic seizures in cats.

Together, they explore how signalment, careful neurological examination, and thorough metabolic screening shape the diagnostic pathway. The conversation highlights common pitfalls - including interpreting postictal changes, differentiating seizures from syncope or paroxysmal dyskinesia, and deciding when advanced imaging is warranted - offering practical guidance to help clinicians approach seizuring cats with clarity and confidence.

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Epileptic seizures in cats: practical approaches to diagnosis

View The Transcript Here

Host:

Yaiza Gómez-Mejías, LdaVet MANZCVS (Medicine of Cats), RCVS CertAP (Feline Medicine), iCatCare Veterinary Community Co-ordinator

Speaker:

Mark Lowrie, MA, VetMB, MVM, DipECVN, MRCVS, Director at Movement Referrals and Specialist in Veterinary Neurology

Creators and Guests

Host

Yaiza Gomez-Mejias

Veterinary Community Co-ordinator @ International Cat Care

What is Chattering with iCatCare?

Welcome to Chattering With iCatCare, the official monthly podcast of International Cat Care, hosted by Yaiza Gomez-Mejias (Veterinary Community Co-ordinator). Each month, we chatter about cats and cat-friendly practices with industry experts and contributors to The Journal of Feline Medicine and Surgery. Each episode contains highlights from our longer discussions and interviews, which are accessible to iCatCare members at portal.icatcare.org. If you would like access to our full episodes, would like to become an iCatCare Veterinary Society Member, or find out more about our Cat-Friendly schemes, visit icatcare.org.

Yaiza Gomez Mejias: [00:00:00] So welcome to another episode of Chattering with iCatCare. I'm Yaiza Gomez, iCatCare Veterinary Community Coordinator and today we are diving into epileptic seizures in cats. Identifying the underlying cause of feline seizures is often a challenge. The range of differential diagnosis is incredibly broad and it can be very difficult to identify. Joining us today is Dr Mark Lowrie, co-author of the recent Clinical Spotlight Review in the Journal Of Feline Medicine and Surgery. He will help us navigate the diagnostic approach to ensure that we don't miss anything important.

Hi Mark, and thanks for joining us today. Seizures are such a fascinating thing to talk about. In the review, you highlight that the cat signalment is a major diagnostic tool. How should the patient's age or breed influence our list of differentials?

Mark Lowrie: Signalment is really important in cats with seizures and age is [00:01:00] probably the biggest part of that. So if I'm seeing a young cat, maybe let's say under five years old with a normal interictal neurological exam and normal screening blood work, then I would say idiopathic epilepsy becomes just that bit more plausible.

I'm still careful in cats because idiopathic epilepsy is definitely less common than it is in dogs, but that age group, it does make it a lot more realistic. As you move through to cats into middle age that balance shifts quite quickly, so older cats are much more likely to have structural epilepsy or reactive seizures.

So my list of differential diagnoses leans heavily towards things like neoplasia, vascular disease, inflammatory or infectious encephalitis, and maybe some metabolic causes and then the other side of signalment of course is with breed, breed does matter as well. Particularly in pedigrees because there are some syndromes where the signalment is almost part of the diagnosis.

So signalment doesn't give you the answer, but it absolutely changes the weighting of your differential diagnoses before you've [00:02:00] even started the workup.

Yaiza Gomez Mejias: Getting back to the neurological examination, you emphasise the need to repeat it once the postictal phase has resolved. Why is that? Are there any transient changes likely to mislead us when we examine the cat just after having a seizure?

Mark Lowrie: Yeah, I mean, that's a really practical pitfall. The postictal period can produce these transient neurological abnormalities that look exactly like structural forebrain disease. Cats can be disorientated, they pace, appear centrally blind, they seem behavioural abnormal, and they can even look a little bit weak and ataxic.

So if you examine them right then it's very easy to over interpret that and conclude there must be a structural lesion. We always recommend repeating the neuro exam once the cat is clearly back to normal. The other reason is the owners may describe odd behaviour between seizures but sometimes what they're actually describing is a prolonged postictal change rather than a true interictal abnormality and I think it's really important to separate those two things out because it makes [00:03:00] a big difference to your diagnostic reasoning and I suppose there's one really important caveat here. Severe violent seizures can cause real injury. In those cases, deficits may persist beyond the postictal period, but in the average case, repeating the exam once the postictal phase is resolved prevents you being led down the wrong path, and usually I'd say a 24 to 48 hour period following the seizure is a reasonable timeframe to wait to repeat that examination.

Yaiza Gomez Mejias: Could you clarify the fundamental differences between reactive seizure, structural epilepsy, and idiopathic epilepsy in cats?

Mark Lowrie: I would think of it as three different buckets or baskets. Each bucket has a different implication. Reactive seizures are where the brain is structurally normal but it's reacting to a systemic problem.

There could be something like metabolic disease, like hypoglycemia, hepatic encephalopathy, electrolyte [00:04:00] disturbances, severe hypertension, uremia, and of course always toxins. They're always on the list as causing metabolic disease, but the key idea is fix that systemic trigger and the seizures should resolve.

That's reactive seizures in one of the buckets. Then we move to structural epilepsy, so that means there's a lesion within the brain itself. That could be neoplasia, of course, inflammation or infection, vascular disease, malformation, and people refer to trauma. When I say trauma, I mean something that's caused significant damage to the brain, whether it be a fracture causing depression or contusion of the brain parenchyma itself.

But these are all things that would result in structural epilepsy. The important thing here is these cats have interictal neurological abnormalities. Although not always, especially early in the disease, they might not show problems. Another time when we may not see signs in between the seizures would be if they have a lesion in a silent area of the brain.

So a common part [00:05:00] would be the olfactory lobe. It's so important they've got their sense of smell. In cats, it's far more important than it is in ourselves. It's a lobe in cats. It's a nerve in ourselves. The other third aspect to talk about is idiopathic epilepsy, and it's a diagnosis of exclusion, so recurrent seizures, a normal interictal period, and no evidence of toxic metabolic or structural intracranial disease after appropriate investigation would really lead you down the path to saying, this is idiopathic epilepsy. And in cats, it is much less common in dogs, we do tend to be slightly more cautious about applying that label without thorough exclusion of other causes.

So we definitely see it but I think it's fair to say we don't have a strong handle on it in quite the same way we do in dogs, and we are a little bit more hesitant with how we label cats as idiopathic epileptics.
Yaiza Gomez Mejias: Oh, that's such clarifying answers. Thank you so much. Getting back to the article again, you describe recorded videos as invaluable, so what specific behaviours [00:06:00] or signs should we look for in these videos to distinguish a true seizure from other problems like syncope or paroxysmal dyskinesia?

Mark Lowrie: Well, you've got my favourite topic. Every time I have any patient come in, it's really helpful to get a video of what the owners are seeing at home. It really helps. Clearly for seizures it's more important because seizures are discreet episodes. As vets, we're fairly fortunate that it's rare we see them. It's the owners that suffer them at home.

So I like them to capture a video of the seizure and what I'm looking for, I'm looking for a peracute onset and end, a kind of stereotype pattern between the episodes, involuntary motor activity, that's really important. It can be hard to know if it's involuntary, but obvious paddling of the legs, it's clearly an involuntary reaction and ideally some evidence of altered awareness. That can be really hard to get on a video and so that's where I'd really be pressing the owner for their view on things. Be careful 'cause if you say, is your [00:07:00] cat aware? They'll often say yes because the cat's eyes are open and we know from seizures, all seizures, cat's eyes will be open. So it's really important to say, can your cat respond to you?
Another really important thing is autonomic signs. Hypersalivation is a big one in cats, so frothing at the mouth we might see, or just excess saliva, and I suppose urination and defecation can be supportive. Another thing we need to differentiate from is syncope and syncope tends to look different, it's usually a sudden collapse with a loss of tone.

So flaccid rather than increased tone and recovery is often rapid, and I'd describe it as clean, really, with little or no post-event confusion. Cats snap right back out of it. Also, syncope is more likely to be triggered by excursion or excitement, whereas many epileptic seizures occur when a cat is resting or relaxed.
But a syncope is something that is very much [00:08:00] cardiovascular or cardiorespiratory and the main one I'd think of would be cataplexy or narcolepsy. Now, that often comes on with excitement, exertion, and feeding's a common one, but I have seen videos of cats that have cataplexy where they're creeping up on their prey, maybe about to catch a mouse or a bird outside, and they're ready to go and as they start running, that excursion is enough to trigger an episode and they just completely collapse. So that's the one neurological time we will see decreased tone. If we see it at any other time that for me is syncope, and that's why I bring that up and mention it.

Paroxysmal dyskinesia, so a sort of movement disorder, they're getting more and more common now, and we do see them in sphynx cats. We see them in other breeds too, but the sphynx is the one that we've recognised the first, if you like, but they can look really dramatic. The cat's typically conscious throughout, so is able to respond to an owner but the episodes can last much longer than a seizure, and there's no real postictal period.

These [00:09:00] episodes can go on for 10, 20 minutes, and if you have a cat suffering a generalised tonic-clonic seizure for 10 to 20 minutes, you would fully expect a long postictal phase. But with the paroxysmal dyskinesia, again, they come straight back out of it and come back to normal. But the movements in dyskinesia can be sustained, sort of twisting, flailing, almost dance like in the legs as well with how they're moving the legs, rather than the more classic tonic-clonic pattern where you've got quite violent paddling movements.

So the summary for me is the video lets you slow it down and ask, is this stereotyped? Is this the same sort of episode each time? Is there altered awareness? Are there autonomic signs? And how does the cat recover after the event?

Yaiza Gomez Mejias: Thank you and that summary helps as well. Just one little thing about the response, how should we advise the owner to evaluate whether the cat is responsive? Because in that moment the situation is quite stressful and is [00:10:00] there any tip?

Mark Lowrie: First time round, forget it. I think when you see your cat have one of these episodes, very very stressful. By the second, third, fourth time, they will start to see a pattern and I think that allows us to reassure and say, look, each time this happens, if this is a seizure event, sudden death from seizures is exceptionally unusual. I'll never say it doesn't happen, but is exceptionally unusual. Things like dyskinesias, they're benign. I mean there, there's plenty of problems and comorbidities they might be associated with, but actually for the cat itself, it's a completely benign procedure other than the discomfort of the episode itself. So if it's a young cat enjoys playing with a toy or something, maybe getting that, just see is the cat able to follow it and see what's happening? 'Cause cats are pretty tough. They like to know what's going on around them and they hide disease as best they can until the last moment.

So these sorts of interactions, doing things you know your cat would normally respond to you for, even stroking a cat you might find they just are trying to come up and get comfort from you by [00:11:00] knowing you're there. All these things show some form of awareness, whereas a generalised tonic-clonic seizure with loss of awareness, in fairness, you would know because you wouldn't be able to get near the cat. It would show a very different behaviour. It would be scrambling, potentially could hurt you, which with many cats, they would be devastated if they did that to you normally, but it shows there's an involuntary loss of awareness at doing that.

So they're the sorts of things I'd be looking at, but every cat is different here and it's important for the owners to know their cat, to know what the right method is to try.

Yaiza Gomez Mejias: Are there any specific clinical markers during a seizure that can point us toward either idiopathic or structural causes?

Mark Lowrie: Yeah, there are some patterns that maybe nudge you one way or the other, but nothing is absolute.

For me, features that increase suspicion of structural epilepsy include focal seizure types. That's always been described as something that might be more associated with structural disease, not always. If you have a cat with partial seizures, [00:12:00] I wouldn't be jumping and saying this must be a structural cause 'cause very often we can rule it out and find it is more an idiopathic event.

But focal seizures types, behavioural or psychomotor seizures, so tail chasing, this kind of thing, even intermittent unprovoked, episodic aggression. You can have a lovely, lovely cat that suddenly becomes quite aggressive and upset in an instant.

And then I suppose the other really important one that might increase structural epilepsy is seizures that change over time. Some way in which the character of the seizures changes. If the episodes are becoming more complex, more frequent, or are accompanied by progressive interictal changes, those structural diseases really rise up the differential diagnoses list and a big question I always ask my owners of cats with seizures is, I've asked them to take a moment to forget about the seizures and tell me about their cat in between the seizures. Is their cat normal day-to-day as they've always remembered them or has there been some change? Because [00:13:00] actually for me, that's far more important than the seizures themselves.

It can be hard because owners are obviously tunnel vision on the seizures, but it's actually the behaviour around the seizures, for me, is far more informative than the seizures themselves. Then I suppose on the other hand, a cat with generalised seizures, a completely normal interictal neurological exam and behaviour, and no progression over time.

For me, that fits really well with an idiopathic epilepsy. But the honest answer to the question that you've asked is cats can be really deceptive and that's why we tend to lean much more towards imaging in cats than we do in dogs. MRI is something I would go to much faster than I would in a dog with seizures.
Yaiza Gomez Mejias: MRIs seems to be the modality of choice for the brain, isn't it?

Mark Lowrie: MRI really is clearly preferred. MRI is by far and away the best tool for the subtle parenchymal disease of the brain. Things like inflammation and many of the lesions that we worry about in seizuring cats. But CT, it still has a role when MRI isn't available and when maybe cost constraints are real for an owner [00:14:00] or when you are particularly suspicious of things that CT is relatively good at detecting.
Certain mass lesions, acute haemorrhage or bony chain. It's got advantages CTs much quicker and that sometimes matters in unstable patients or where anaesthetic time needs to be minimised. But the key practical point is if we do a CT and it's normal, it doesn't rule out significant intracranial disease in a seizuring cat.

So you just need to frame expectations appropriately with the owners if you're going down the route of CT. I think it's important they're informed and they then make the informed decision as to whether to do CT or MRI.

Yaiza Gomez Mejias: There are other two tests that we tend to rely on and that's the bloods. But you said in the review that the blood test results are often unremarkable even in metabolic screening.
Are there any other red flags apart from the bloods, which could point to metabolic disorders?
Mark Lowrie: Yeah, with the role I do, I will get cats come in that usually have had [00:15:00] some blood tests and that first round of blood work is normal but the blood test you'd perform on a cat might be different to the blood test I perform and what another vet might perform.

So we all have our panel of chosen tests to run and there are probably strong similarities, but there'll be the odd one there that might be slightly different and if you miss out a particular blood test, it's easy to overlook that. Packed cell volume would be a great example. I think, to be fair, that's the one that's, if you're going to perform hematology, you probably get your hematocrit and packed cell volume.

But if you don't perform that, that might be the only test you've got there of something like polycythemia, which is a definite cause for seizures in cats. So it's very important about dotting the I's and crossing the T's when it comes to blood work and that's the first thing I'd say. But let's say we've done thorough tests and the blood work is normal.

There are still clues that could help you keep metabolic disease on the radar. For me, the overall pattern of a metabolic cause for seizures would be waxing and waning [00:16:00] systemic illness. So a cat that kind of has days when it's well, days when it's not so well, outside of the seizures is important. They might be a bit lethargic.

You might have gastrointestinal signs, generalised weight loss, polyurea, polydipsia and the one I mentioned earlier on, but really want to emphasise again is hypertension. Such a hard diagnosis in cats, partly because when you've just had one or two seizures, the hypertension may be very intermittent, and so ignoring all the practicalities of blood pressure measurements, you may be testing that count on a day when the blood pressure is normal.

But it's really repeated measurements that we want to check, and I think if you've got a cat with seizures where you've not found any other cause, so I suppose those where you are thinking idiopathic epilepsy is most likely I would be keeping a very strong monitor on that cat's blood pressure and potentially get it in every six months, every three months for blood pressure monitoring.

Those clinical features for me matter as much as any single lab value. Some metabolic triggers [00:17:00] can be intermittent. So the red flags are often the history and the pattern rather than one sort of headline abnormality, if you like, on a single blood panel.

Yaiza Gomez Mejias: So in seizures, is there any biochemistry parameter you would emphasise as an expert in this matter?

Mark Lowrie: Obviously, renal parameters, so urea and creatinine are vital, liver enzymes are good on there, but you know what, they're not as important as you might think, but for the liver I'm most interested in the things the liver produces. So the four things for me would be glucose, urea, cholesterol, and albumin.
Alongside that, I really do want that fasted bile acid test. I'd also be looking at electrolytes and I've mentioned hematocrit PCV. I think that's a really important one in cats because it can get overlooked. You can do hematology, but really check that value 'cause if that's high, that could be everything you need to know about that cat and you may have got a metabolic cause. They're probably the general ones I'd be really wanting to make sure have been covered.

Yaiza Gomez Mejias: Thank you so much. I think that this brings us to [00:18:00] the end of our discussion on the complexities of feline seizures. I'd say one of my takeaways is that systematic approach and prioritising a thorough history and clinical judgment is very relevant for an effective management, not just the advanced techniques. If you want to see the different seizure types we have discussed today, I highly encourage you to visit the Journal of Feline Medicine and Surgery website to view the supplementary videos provided by Dr Lowrie and his team. Thank you for listening. We will be back again next month with more about feline medicine and the JFMS.