Abstract

Epilepsy is a reported neurological disorder in California sea lions (Zalophus californianus), often secondary to domoic acid exposure. Sea lions under managed care with previous wild exposure to domoic acid may later develop epilepsy and require lifelong medical management. Phenobarbital is historically the anticonvulsant drug of choice for pinnipeds but may not be effective or have unwarranted side effects in some patients.^1,2 Levetiracetam is a commonly used anticonvulsant in dogs as monotherapy or add-on medication.³ We describe the serum levels of oral extended-release levetiracetam in two California sea lions under managed care, suspected to have been exposed to domoic acid in utero. Sea lion A is 15 years old with a chronic history of seizures managed with phenobarbital since 2016 and levetiracetam extended release added in 2021 and titrated to effect; current doses are 0.73 mg/kg BID and 44.9 mg/kg BID, respectively. Sea lion B is 12 years old with an acute history of seizures managed with extended-release levetiracetam 23 mg/kg BID. Blood samples were collected under voluntary behavioral control to complete a sampling timeline of 0 to 12 hours. Serum levetiracetam and phenobarbital levels were evaluated by high pressure liquid chromatography, and data analyzed for each individual over time. Results demonstrated serum levels within the therapeutic range for canines.⁴ Clinically, use of levetiracetam has resulted in superior seizure control than phenobarbital alone in sea lion A, and successful prevention of further seizures in sea lion B, with no observed adverse effects.

Acknowledgements

The authors thank the veterinary, medical records office, and training staff at the National Marine Mammal Foundation and U.S. Navy Marine Mammal Program for their excellent care of the U.S. Navy’s marine mammals.

*Presenting author

Literature Cited

1.  Gulland FMD, Haulena M, Fauquier D, Langlois G, Lander ME, Zabka T, Duerr R. 2002. Domoic acid toxicity in Californian sea lions (Zalophus californianus): clinical signs, treatment and survival. Vet Rec. 150(15):475–480.

2.  Goldstein T, Mazet JA, Zabka TS, Langlois G, Colegrove KM, Silver M, Bargu S, Van Dolah F, Leighfield T, Conrad PA, Barakos J, Williams DC, Dennison S, Haulena M, Gulland FM. 2008. Novel symptomatology and changing epidemiology of domoic acid toxicosis in California sea lions (Zalophus californianus): an increasing risk to marine mammal health. Proc Biol Sci. 275(1632):267–276.

3.  Kelly D, Raimondi F, Shihab N. 2017. Levetiracetam monotherapy for treatment of structural epilepsy in dogs: 19 cases (2010–2015). Vet Rec. 181(15):401.

4.  Podell M, Volk HA, Berendt M, Löscher W, Muñana K, Patterson EE, Platt SR. 2016. 2015 ACVIM small animal consensus statement on seizure management in dogs. J Vet Intern Med. 30(2):477–490.