26 Feb 2018
Fabio Stabile
Job Title
The Belgian shepherd dog breed has a rare genetic condition that can cause epileptic seizures. Image: Ysbrandcosijn / Adobe Stock
Canine epilepsy is a complex brain disorder caused by abnormal, excessive/synchronous neuronal activity that manifests itself with the clinical sign of epileptic seizures1,2.
Epileptic seizures are generally episodic and short-lasting events (less than five minutes), typically manifesting with behavioural, motor and autonomic components1.
Canine epilepsy can be caused by a variety of conditions. In many cases, the primary cause is unknown, meaning investigations performed in these patients do not lead to the diagnosis of an underlying pathology causing seizure activity1. Hence, by exclusion, these cases are diagnosed with canine idiopathic epilepsy (IE).
From breed-specific studies on epilepsy, both genealogical analysis and reports of over-representation of epileptic individuals in canine families has raised evidence that, for many pure-breed dogs, a familial predisposition to develop canine IE exists (Panel 1)1,2.
A genetic defect associated with the condition is still unknown and it is reasonable, therefore, to consider the condition could be multifactorial (for example, inherited genetic and environmental, developmental, and other provoking factors)1,2,25.
Other causes of canine epilepsy include developmental CNS disorders, structural brain disorder (for example, trauma, inflammatory and infectious CNS disease, and vascular and neoplastic disease) and reactive causes of seizures. Only some rare purely genetic conditions causing epileptic seizures have been reported so far in the lagotto Romagnolo, Belgian shepherd dog and boerboel breeds4,20,24,27.
Terminology, definitions and classification associated with epilepsy in the veterinary literature were lacking in uniformity until 2015, when the International Veterinary Epilepsy Task Force (IVETF) published multiple consensus articles on the definitions, classifications, diagnostic investigations and treatment of IE.
The following definitions should be uniformly used by all vets and are reported as suggested by the IVETF.
Considered as a disease per se, IE can be classified into three groups, reflecting scientific advancements in the research field of epilepsy.
Semiology is referred to as the clinical manifestation of an epileptic seizure. These are classified in focal onset epileptic seizures and generalised epileptic seizures.
IE is the most common chronic neurological condition in dogs, with an estimated prevalence of 0.6% in the first-opinion canine population in the UK28. IE has been defined as two or more unprovoked epileptic seizures at least 24 hours apart, without identifiable underlying aetiology other than a suspected genetic origin1,2.
The IVETF has identified three tiers of confidence for the diagnosis of IE.
IE can impact considerably on the lifestyle of owners of affected dogs. The onset of epilepsy may be related to behavioural changes, which can impact on the pet and owner relationship, and quality of life29. Recurrent epileptic seizure activity associated with IE is unpredictable and can be linked with dramatic clinical manifestations, such as loss of consciousness, recumbency, tonic-clonic movements of limbs and jaw, hypersalivation, urination and defaecation, followed by transient blindness, aggressive behaviour and ataxia.
Ultimately, many scientific studies have highlighted IE can also affect a dog’s lifespan7,30-33. Treatment is often for life and requires regular administration of antiepileptic medications, and sometimes emergency management of severe seizures (for example, cluster seizures or status epilepticus), which may require hospitalisation31-33.
In the veterinary literature few studies on canine IE have identified:
The diagnosis and treatment of canine epilepsy is a field of rapid and continuous evolution. Many veterinary centres in the UK and Europe continue studying this sometimes frustrating disease to increase confidence in its diagnosis and to improve on – or develop new treatment – options for these patients.
