Epilepsy and its treatment in dogs

Introduction

Epilepsy is the most common medical neurological disorder in dogs, and even due to anti-epileptic drugs, many dogs still suffer from seizures. It is important to study canine epilepsy and its cause, so a treatment can be offered. In this research paper we will address different causes, treatments and risk factors related to canine epilepsy.

Physiology of epilepsy

At a cellular and molecular level, the pathogenesis and pathophysiology of epilepsy are being studied thoroughly, but still little is known about the cause of epilepsies in dogs (Chandler, 2005). Epilepsy is defined as recurring seizures caused by an abnormality in brain function. These repetitive seizures are a result of the brain’s response to abnormal systemic metabolism, such as hypoglycemia, hypocalcemia, uremia, etc (Cui et al, 2017). The frequency and severity of seizures vary. Certain factors such as sleep deprivation, stress and hormonal factors show an increase in seizures (Forsgård et al, 2018). There are also recorded a correlation between the severity of a seizure and breed. Epilepsy is not terminal. Quality of life is the most important factor for a chronic medical disease like epilepsy. Euthanasia may be used as an option if the dog's quality of life is dramatically reduced or the financial and emotional burden exceeds the owner's limitations (Podell et al, 2016).

Types of canine epilepsies

Epilepsy can be inherited (genetic epilepsy), from structural defects in the brain (symptomatic epilepsy) or it can be caused by an unknown cause (idiopathic epilepsy) (“Epilepsy Research Initiative”, 2021). Identification of the type of epilepsy is important as it will tell what treatment is best suited.

Some gene mutations can be identified and help in the diagnosis of epilepsy. Most studies, however, have yet to identify causative gene mutations, implying that inheritance may involve several or many susceptibility genes and reflect additional environmental interactions (Ekenstedt et al, 2011). The symptomatic type of epilepsy can be caused either by abnormal brain structure, brain abnormalities such as tumors, head trauma or infectious diseases such as rabies or tetanus (Cui et al, 2017). Idiopathic is the most common type of epilepsy, and also the hardest type of epilepsy to identify as there is no direct cause for the seizures (Hülsmeyer et al, 2015).

Diagnosis and identification

For diagnosis, at least two unprovoked seizures are necessary, or one seizure paired with other symptoms, such as an acute head injury, past stroke, or an abnormality on an electroencephalogram (EEG) brain scan (Hülsmeyer et al, 2015). But this is only successful in some cases as most cases of epilepsy in dogs are from unknown causes.

Gene mutations

There are two types of canine epilepsies for which gene mutations have been identified: progressive myoclonic epilepsies and idiopathic epilepsy (Ekenstedt et al, 2011). So far, nine genes have been identified as being associated with progressive myoclonic epilepsies in a variety of dog breeds (Ekenstedt et al, 2011). Genetic idiopathic epilepsy research has been less effective, with only one relevant gene identified (Ekenstedt et al, 2011). For these ten kinds, genetic testing is available to help with diagnosis, prognosis, and breeding options (Ekenstedt et al, 2011). Process of elimination As mentioned much is still unknown about the cause of epilepsy in dogs. Therefore, it is also difficult to accurately diagnose. As with idiopathic epilepsy, it is a process of elimination (Unger et al, 2021). When all other neurological disorders resulting in seizures have been disproven the answer is usually idiopathic epilepsy.

Process of elimination

As mentioned much is still unknown about the cause of epilepsy in dogs. Therefore, it is also difficult to accurately diagnose. As with idiopathic epilepsy, it is a process of elimination (Unger et al, 2021). When all other neurological disorders resulting in seizures have been disproven the answer is usually idiopathic epilepsy.

Factors influencing susceptibility for canine epilepsy

Through studies and research veterinarians have learned that some specific breeds are more genetically predisposed to epilepsy. There is also evidence supporting that age is a major risk factor. Knowing the risk factors is necessary ...

Breed

The idiopathic type of epilepsy, which often has a genetic base, is more common in some breeds than others. Different breeds of Shepherds, Beagles, Border Collies, Labrador Retrievers, Basset Hounds, Poodles and English Springer Spaniels are among the breeds most commonly diagnosed with epilepsy (Erlen et al 2018).

Age

Most of the research done on canine epilepsy is in agreement that there is an increasing seizure risk with aging.

References

• Cherubini G (2016): Canine Epilepsy: Demystifying the Myths. Journal of the Kennel Club
• Cui ZJ, Liu YM, Zhu Q, Xia J, Zhang HY (2017): Exploring the pathogenesis of canine epilepsy using a systems genetics method and implications for anti-epilepsy drug discovery. Oncotarget 9: (17) 13181-13192
• Ekenstedt KJ, Oberbauer AM (2013): Inherited epilepsy in dogs. Topics in companion animal medicine 28: (2) 51-58
• Ekenstedt KJ, Patterson EE, Michelson JR (2012): Canine epilepsy genetics. Mammalian genome: Official Journal of the International Mammalian Genome Society 23: (1-2) 28-39
• Erlen A, Potschka H, Volk HA, Sauter-Louis C, O´Neill DG (2018): Seizure Occurrence in Dogs Under Primary Veterinary Care in the UK: Prevalence and Risk Factors. Journal of Veterinary Internal Medicine 32: (5) 1665-1676
• Forsgård JA, Metsahonkala L, Kiviranta AM, Cizinauskas S, Junnila J, Laitinen-Vapaavuori O, Jokinen TS (2019): Seizure-precipitating factors in dogs with idiopathic epilepsy. Journal of Veterinary Internal Medicine 33: (2) 701-707

• Hulsmeyer VI, Fischer A, Mandigers PJ, DeRisio L, Berendt M, Rusbridge C, Bhatti SF, Pakozdy A, Patterson EE, Platt S, Packer RM, Volk HA (2015): International Veterinary Epilepsy Task Force´s current understanding of idiopathic epilepsy of genetic or suspected genetic origin in purebred dogs. BMC Veterinary Research 11, 175

• Podell M, Volk HA, Berendt M, Loscher W, Munana K, Patterson EE, Platt SR (2016): 20 ACVIM Small Animal Consensus Statement on Seizure Management in Dogs. Journal of Veterinary Internal Medicine 30: (2) 477-490
• Shell L (2016): Maintenance Anticonvulsant or Antiepileptic Therapy
• Unger DM, Wiest R, Kiefer C, Raillard M, Dutil GF, Stein VM, Schweizer D (2021): Neuronal Current Imaging: An Experimental Method to Investigate Electrical Currents in Dogs with Idiopathic Epilepsy. Journal of Veterinary Internal Medicine 35: (6) 2828-2836