Association between Estrus and Onset of Seizures in Dogs with Idiopathic Epilepsy

Abstract

BackgroundCatamenial epilepsy in humans is defined as changes in seizure frequency over the course of the menstrual cycle. Three hormonally based patterns of seizure exacerbation have been determined.ObjectivesThe aim of this study was to evaluate whether there is an association between onset of seizures and the estrous cycle in intact bitches with presumptive idiopathic epilepsy and whether a pattern to the onset of seizures could be recognized.AnimalsForty‐five intact female dogs from a hospital population with a presumptive diagnosis of idiopathic epilepsy.MethodsIn a retrospective study, the database of a small animal hospital in Sweden was searched for medical records of intact female dogs diagnosed with epilepsy or seizures. The stage of the estrous cycle as reported either by the owner or the veterinarian at the time of the first seizure was noted.ResultsOf the 45 dogs with idiopathic epilepsy, 17 (38%) had their first seizure when in heat and six dogs (13%) had their first seizure 1–3 months after heat. Nine dogs (20%) had seizures reoccurring in relation to their estrous cycle.Conclusions and Clinical ImportanceThese findings suggest an association between estrus and onset of seizures in intact bitches with presumptive idiopathic epilepsy. Two hormonally based patterns could be recognized: one during heat and one during a specific time point at the end of diestrus. This could be explained by the proconvulsive effects of estrogen or loss of protective effect against seizures of progesterone, respectively.

Seizure‐precipitating factors in dogs with idiopathic epilepsy

“…In our study population, the estrous cycle affected seizure occurrence in 42% of the intact females. This is consistent with a previous study, which reported that the estrous cycle affected the onset of epilepsy as well as seizure frequency among roughly one‐third of intact females with idiopathic epilepsy . However, owing to the nature of our study, it is impossible to confirm that seizures truly occurred because of the estrous cycle.…”

“…The dogs were collected during 2016 and 2017 among the hospital population of the University Veterinary Teaching Hospital (UVTH) of the University of Helsinki , and during 2017 among the hospital population of the privately owned Referral Animal Hospital Aisti (RAHA), in Vantaa, Finland. The number of dogs was estimated based on studies on the effect of estrus in seizure frequency and reflex seizures in dogs . We selected dogs until reaching the goal of 50 dogs.…”

“…To our knowledge, only 2 studies exist on seizure‐precipitating factors in dogs with epilepsy. In intact female dogs with idiopathic epilepsy seizures tend to cluster during estrus and for the subsequent 1‐3 months . Various stimuli, such as visits to a veterinary clinic, a grooming facility, or a boarding facility, frequently trigger seizures in dogs .…”

Long‐term efficacy of imepitoin in the treatment of naive dogs affected by idiopathic epilepsy

“…It is interesting to note that the vast majority of intact females (14 out of 15) had the oestrus between four and seven months after the beginning of IMP treatment. In dogs, a recent study found an association between heat and the onset of seizures in intact females with presumptive IE, and hypothesised a possible role of the proconvulsant effects of oestrogen or the loss of the protective effect of progesterone against seizures (Van Meervenne and others 2014b). However, little is known about the influence of sex hormones on epilepsy in dogs and further research is needed to evaluate the possible role of sterilisation on epilepsy (Van Meervenne and others 2014a).…”

Associations between neutering and idiopathic epilepsy in Labrador retrievers and Border collies under primary veterinary care in the UK

“…A male predisposition has been reported within many breeds (Van Meervenne et al, 2014). Furthermore, seizure occurrence has been reported as associated with the oestrous cycle in bitches with idiopathic epilepsy, suggesting a beneficial effect of neutering (Shell, 1993;Knowles, 1998;Thomas, 2000;Van Meervenne et al, 2015).…”