Epilepsy is the most common chronic neurological disorder in dogs, with a formerly reported prevalence of between 0.5% and 5% in the canine population.
Epilepsy is not one single disease process but can be elicited by multiple causes and can be classified as genetic (primary or idiopathic), structural and of unknown origin/etiology.
Let’s get to grips with what it is and some of the causes.
What is Epilepsy?
Epilepsy occurs naturally in many species including rodents, cats, dogs, horses, cattle, goats, non-human and human primates.
It is the most common acquired chronic neurological disorder in humans having a a worldwide incidence of approximately 50–100 cases per 100,000 persons (higher in undeveloped countries) and a prevalence of 4–10 per 1000 persons.
In humans there are over forty epileptic syndromes and related conditions.
In dogs, however, epilepsy is not usually differentiated into syndromes. Most dogs with recurrent seizures have no identifiable underlying cause and are classified as having idiopathic epilepsy.
The lack of canine epilepsy classification may be due to the difficulty of seizure description and classification, and partly because electroencephalography (EEG) is not routinely used in veterinary neurology clinics.
To that end, we simply define epilepsy as a chronic neurological condition characterised by recurrent epileptic seizures
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Idiopathic epilepsy in dogs
Most dogs with recurrent seizures are thought to have idiopathic epilepsy, in short, no underlying cause of the seizure can be identified.
In these cases the first seizure usually occurs between 6 months and 6 years of age, but occasionally seizures have been known to start as young as 3 months and as late as 10 years of age.
There appears to be a hereditary basis for idiopathic epilepsy, with several breeds being affected:
- Beagles
- German Shepherds
- Labrador Retrievers
- Golden Retrievers
- Bernese Mountain Dog
- Viszlas
- Keeshonds
- English Springer Spaniel
Recently a mutation found on the Epm2b gene has shown to be causal in miniature wire-haired dachshunds.
The Theory of Epilepsy
The pathophysiology of epilepsy is often suggested to be an imbalance between excitation and inhibition in neurotransmitters; increased excitation or decreased inhibition may lead to epileptiform activity in the brain. It is considered that there is a fine balance between the excitatory glutamate neurotransmitter and the inhibitory GABA neurotransmitter.
This theory has been tested in dogs and researchers found significantly less GABA and more glutamate in cerebral spinal fluid (CSF) from epileptic patients when compared to normal controls.
Sadly, there appears to be a double-edged sword too, many receptors in the brain undergo altered expression following seizures and this may lead to changes in excitability of the brain and be involved in further pathogenesis of seizure disorders.
Temporal Lobe Epilepsy In Dogs
Temporal lobe epilepsy is the most common partial seizure disorder in adult humans and there are reports of it occurring in dogs.
It has also been suggested that “fly-biting” or “fly-catching”, a behaviour in which dogs snap aimlessly into the air as if trying to catch a fly, may have a temporal lobe origin.
Treatment
Since epilepsy is often associated with inhibition and excitation in the brain, antiepileptic drugs (AEDs) are used to alter the excitability of the brain and aim to reset the balance.
There are many mechanisms thought to be involved in the action of antiepileptic drugs.
- They may functionally block voltage-gated sodium channels
- They may directly or indirectly enhance inhibitory GABAergic transmission
- They can inhibit excitatory glutamatergic neurotransmission
- They can modulate calcium ion channels
Vagus Nerve Stimulation
The method used in humans was devised in canine models and has since been used with mixed results. It is based on the idea that repetitive electrical stimulation of the canine cervical vagus nerve interrupts or abolishes motor seizures.
Findings Here
Epilepsy and Diet
The Keto Diet
The ketogenic diet—a high‐fat, low carbohydrate, and moderate protein protocol—has been used to treat epilepsy for nearly 100 years in both children and adults.
A randomised controlled trial on childhood epilepsy showed promising results with 38 and 7 % of children on KD diets having >50 and 90 % seizure reduction, respectively. In comparison, only 6 % of the children on control diets achieved >50 % seizure reduction, with no children achieving >90 % seizure reduction.
Findings Here
It therefore makes sense that a ketogenic diet has been considered for use in dogs.
One study of 21 dogs found that seizures were reduced significantly in dogs fed a proprietary ketogenic diet for 3 months. No improvement was seen in dogs fed a standard diet for the same duration.
For 3 subjects, seizures appeared to stop entirely, demonstrating a 100% reduction in seizure frequency. In 7 dogs, seizures decreased by at least 50%, and another 5 dogs experienced a lower seizure frequency overall.
Findings Here
A Whistle Stop Tour of Keto
A Keto Diet for Pet Cancer
Omega-3 Supplementation
Omega-3 fatty acid deficiency has an interesting role in seizure outcome. It is thought that Omega-3 fatty acids can enhance GABAergic transmission in animals with epilepsy by stimulating the formation of new hippocampal interneurons or by altering expression of calcium-binding proteins.
When trialled in a patient with drug-resistant epilepsy, seizures reduced by 85%.
Findings Here
Essential Fats For My Dog’s Diet
Epilepsy and Allergy
In humans there are a number of reports that associate allergy with epilepsy. For example, children with allergic symptoms have a 76% increased subsequent risk of epilepsy. It has been found that in these individuals, hypoallergenic diets can reduce the frequency of seizures.
Again, we must consider that this may apply to dogs.
One study followed dogs with allergic disease. It included eight refractory epileptic dogs and seven were found to have gastrointestinal or skin allergies in conjunction with their refractory seizures. Introduction of an exclusion diet reduced seizures to an “acceptable level” in seven out of eight dogs. Behavioural abnormalities associated with seizures were eliminated in all cases.
Findings Here
Elimination Diets For Dogs
Epileptogenic Toxins
Many researchers posit that it’s not only certain foods that are epileptogenic, but toxins can also be problematic.
Whilst we’re not talking about chemical weapons such as sarin and VX, glutamatergic hyperstimulation can occur after exposure to excitatory amino acid toxins. Not only this, but toxins can affect GABA regulation too. When we say toxins we’re talking pesticides, industrial chemicals, and natural toxins.
Findings Here
Does My Pet Need To Detox
Other Causes To Consider
Whilst many dogs suffer epilepsy where no underlying cause of the seizure can be identified, the list of potential causes is fairly lengthy.
Both human and animal data is suggesting factors including:
- Temperature
- Light
- Sound
- Nutrition
- Maternal effects
- Infectious agents
- Brain trauma
- Gender
- Circadian rhythms
- Hormones
- Age
Canine epilepsy is complex and there are many questions we still don’t have the answer to. But we do know that in optimising overall health, nutrition can play a role. Check out our services to see how we can help.
Thanks for reading,
MPN Team
