Epilepsy in dogs: new developments

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Epilepsy in dogs: new developments and therapeutic approach to status epilepticus

This post provides an update on the latest developments in epilepsy in dogs. We will review some recent abstracts and discuss the therapeutic approach.

Veterinary medicine and care

Cryptogenic epilepsy in dogs        

1. Assessment of the prevalence and clinical features of cryptogenic epilepsy in dogs: 45 cases (2003–2011). Schwartz et al. J Am Vet Med Assoc 2013;242: 651-657 

A retrospective study of 214 cases to determine the prevalence and clinical features of epilepsy in dogs aged 7 or over.

21% (45) had a cryptogenic form of epilepsy, while 79% (169) were symptomatic cases. At the end of follow-up, most dogs (40 [89%]) with cryptogenic epilepsy were receiving one or more antiepileptic drugs (AEDs). Mean survival time following diagnosis was 52 months for the dogs with cryptogenic epilepsy. Seven dogs died in relation to seizures or AEDs.

New AEDs

2. Clinical efficacy and safety of imepitoin in comparison with phenobarbital for the control of idiopathic epilepsy in dogsTipold A et al. J Vet Pharmacol Ther 2014 

A multicentre study of 226 dogs into the safety and efficacy of imepitoin, a new antiepileptic drug, in comparison with phenobarbital.

Imepitoin twice daily at incremental doses of 10, 20 or 30 mg/kg showed similar results to phenobarbital in seizure control. Dogs in the phenobarbital group suffered more side effects, including elevated liver enzymes, which was not observed in the imepitoin group.

Risk factors affecting survival in dogs with epilepsy

3. Risk factors for survival in a university hospital population of dogs with epilepsy. Fredsø N et al. J Vet Intern Med 2014

This work studied the risk factors for survival in dogs with epilepsy and survival time in dogs with idiopathic or symptomatic epilepsy. 

It involved a retrospective analysis of dogs diagnosed with epilepsy between 2002 and 2008. A total of 102 dogs were selected, 78 with idiopathic epilepsy and 24 with symptomatic epilepsy.

The mean life span was 7.6 years (all), 9.2 years (idiopathic), and 5.8 years (symptomatic). Treatment with two antiepileptic drugs had no adverse effects on survival (p = 0.056).

The authors concluded that dogs with idiopathic epilepsy may have a similar life expectancy to that of dogs in general. They also surmised that if the therapeutic response to monotherapy is insufficient, the use of two AEDs does not worsen the prognosis.

Therapeutic approach to status epilepticus

Whenever a dog develops status epilepticus, antiepileptic treatment must be initiated alongside systemic stabilisation, anamnesis of case history and additional tests.

Here we review the BSAVA guides.

First-line treatment are: diazepam 0.5–2 mg/kg (i.v. or p.r.) or midazolam 0.07–0.22 mg/kg (i.v. or i.m.).

If, after starting this treatment, the situation of status epilepticus persists, the dose can be repeated three times or a diazepam infusion may be introduced (0.5–2 mg/kg/h diluted in 5% dextrose or 0.9% saline).

The second-line treatment is phenobarbital. The loading dose is 2–4 mg/kg i.v. or i.m., which can be repeated twice if seizures persist.

If this medication does not resolve the situation, it is a case of refractory status epilepticus. In this event, start a phenobarbital infusion at 2–4 mg/kg/h (maximum of 24 mg/kg/24 h). If the patient still remains in status epilepticus, start sedation with propofol 4–8 mg/kg as a bolus or pentobarbital 2–15 mg/kg as a bolus.

The final step if the dog remains in status epilepticus is a propofol infusion at 6–12 mg/kg/h or pentobarbital at 1–5 mg/kg/h. Once the situation has stabilised, doses should be reduced by 25% every 2 hours depending on the effect.

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