Idiopathic Epilepsy

Seizures are common in dogs and can be caused by non-epileptic conditions or epilepsy. For owners of dogs with newly diagnosed epilepsy, most common concerns relate to the possible source of seizures, the risk of seizure recurrence, and prognosis.

Epilepsy is the most likely diagnosis in dogs presenting with new-onset seizures. Idiopathic Epilepsy (IE) is a common neurological disorder in both pets and humans. Even with the development of new antiepileptic drugs for humans, appropriate treatment options in dogs remain limited. Dogs experiencing repeated bouts of severe seizures are given therapeutic medication to control their frequency and severity. Idiopathic epilepsy has been reported in many dog breeds, such as The Standard Poodle, Dalmatian, Cavalier King Charles Spaniel, English Springer Spaniel, Belgian Tervuren, Cocker Spaniel, Miniature Schnauzer, Collie, and Basset Hound. A growing body of evidence supports a hereditary basis for idiopathic epilepsy. For a diagnosis of epilepsy to be made, other causes of seizures, including poisoning, infection, tumors, and head trauma must be ruled out. Although dogs of all ages can be affected, the peak value for the onset of first seizure is between one and five years. Early diagnosis and treatment are important in preventing of worsening of future seizures.

Generalized myoclonic epilepsy with photosensitivity in young Rodesian Ridgeback dogs were described by the owners as severe startling or even resembling an electric shock. Myoclonic twitches mainly occurred when the animals were in a recumbent position and relaxed, drowsy, or in the first stages of sleep, and with the eyes either closed or open. Occasionally twitches occurred also when the dogs were sitting, standing, or walking. Myoclonic jerks were predominantly confined to the trunk, proximal limb musculature (especially the thoracic limbs), cervical musculature producing nodding movements of the head (Movie S2), and the face (masticatory muscles resulting in chewing movements, eyelid and ear twitches. Some dogs appeared confused or scared following the episodes and seemed to be very agitated after the events, rising up and wandering around restlessly. Hence, sleep appeared impaired in these dogs.2

The diagnosis of idiopathic epilepsy is based on typical seizure history and exclusion of structural forebrain disease and metabolic-toxic disorders. Conventional therapy involves various anticonvalsant medications, including phenobarbital, potassium bromide, and valium. Generally, conventional anti-epileptic medicine is not prescribed, unless the pet has at least one seizure per month. Phenobarbital is commonly used to control seizures in dogs and cats with epilepsy. Side effects of phenobarbital include increased thirst, urination, and appetite. Occasionally, excessive sedation, wobbly gait, and anemia are seen, especially as the dosage increases. Dogs and cats that are given phenobarbital are periodically reevaluated to monitor side effects. Potassium bromide appears to have fewer side effects than phenobarbital. Many veterinarians are now using potassium bromide as the initial (and often only) medical therapy for dogs with epilepsy. Side effects may include tremors, stupor, wobbly gait, lack of appetite, vomiting, and constipation.

Lhasa apso puppies

The course of idiopathic epilepsy is highly individual and might not necessarily require long-term treatment. This must be considered when advising owners about what to expect with regard to treatment and prognosis. The consequences of a diagnosis of idiopathic epilepsy are very individual and some dogs may not need antiepileptic treatment.1

Dogs placed on low-salt diets may have increased bromide toxicity as a result of decreased chloride ion levels. Extra salt in the diet, as well as use of diuretics, may decrease the blood levels of bromide and increase the frequency of seizures. Dogs taking potassium bromide should be reevaluated regularly, usually every 3 to 6 months. Valium is the most commonly used as an injection for pets when have an ongoing seizure. Valium is not usually used as a sole medication for treating dogs with epilepsy. Phenobarbitone and potassium bromide are effective in most canine patients, although dosing regimes need to be carefully tailored to the individual, with serum concentration measurement. However, a significant proportion of patients remains resistant to these drugs. Work is currently underway to test the efficacy of newer antiepileptic drugs in the treatment of canine epilepsy, and preliminary data suggest that human drugs such as levetiracetam and gabapentin are of benefit in dogs with resistant epilepsy.

References

  1. A prospective observational longitudinal study of new-onset seizures and newly diagnosed epilepsy in dogs. BMC Vet Res. 2016; 13: 54.
  2. Generalized myoclonic epilepsy with photosensitivity in juvenile dogs caused by a defective DIRAS family GTPase 1. Proc Natl Acad Sci U S A. 2017 Mar 7; 114(10): 2669–2674.

 

 



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