Epilepsy in working dogs – Presented by Prof Holger Volk

Most veterinary surgeons will describe epilepsy as a pure seizure disorder. However, epilepsy is far more. Epilepsy is a brain disease(1) with seizures being the clinically most prominent sign. Most will recognise a generalised tonic-clonic convulsion, but relatively few will be able to spot focal motor or sensory seizures (ictal behaviour changes). However, apart from the seizures other clinical signs of epilepsy, which are increasingly recognised affecting the interictal period, are changes in cognition and behaviour(2-4). It is thought that there are shared pathophysiological pathways explaining the bidirectional relationship between neurobehavioural disorders and epilepsy(5); for example in human medicine, a patient with depression is more likely to develop epilepsy and a patient with epilepsy depression(6, 7). It is yet unknown if this bidirectional relationship exists in our veterinary patients.

Neurobehavioural comorbidities are been taken more and more serious in human patient, as they can have a bigger impact on health related QoL (HRQoL) than seizures. This is the case especially for inter-ictal anxiety and depression(8). Only few studies have studied interictal behaviour changes in dogs with epilepsy. In the first study, around two-thirds of dogs developed a behaviour change during the course of their idiopathic epilepsy(9).  Drug-resistant dogs were found to have greater amount of unfavourable behavioural changes than drug responders in the same study(9), a finding also been seen in rodent models of epilepsy, where drug-resistant rats had greater behaviour changes(10).  Not surprisingly, anxiety is the main behaviour change reported in dogs with IE (9, 11), and in two more recent studies changes in impulsivity and other clinical signs comparable with attention deficits hyperactivity disorder in people have been noted (12, 13). An increasing level of evidence also exists that dogs with idiopathic epilepsy might have changes in trainability, spatial memory and accelerated memory loss(3, 14, 15). As such, epilepsy management should in the future not only focus on reducing seizures, but also consider on reducing the effects of potential behavioural comorbidities(16). 

In conclusion, epilepsy is a complex disease which might not also cause seizures but also behaviour and cognition changes which might limit their use as a working do. Management needs to be tailored to the individual patient and the focus should  be not only on getting  better seizure control, but also on improving comorbidities.