Results When treatment was started it was at the beginning always phenobarbital, the mean dosis was 3.19 mg/kg/day (ranged 4-10mg/kg/day). Information about phenobarbital level measurement was available 63 times for 31 cats, and the mean of last measured level was 29,7 µg/ml (range 11-73). The number of seizures per year was categorized into 4 groups: seizure free (excellent controlled), 1-5 (good controlled), 6-10 (acceptable controlled) and over 10 seizures per year (pure controlled). The portion between seizure-free/good/acceptable/pure controlled cats was 6/17/8/69% in the first year, 42/9/12/36% in the second year, 48/14/3/34 in the third year, 40/15/15/30 in the fourth year, and 38/23/8/31 in the fifth year of therapy (Figure 1.). The portion of seizure-free cats was nearly 50% in the most observed years and over 10 seizures per year decreased after the second year of treatment and was about 30%. Treatment was continued in 28 out of 36 cats (77.8%) throughout their live or study. In 6 cats (16.7%) when drugs were discontinued or reduced the seizure returned and drug was restarted again. Only in 2 cats (5.6%) could be discontinued the antiepileptic drugs without returning of seizure. The duration of seizure event decreased in 26 (72.2%) and was unchanged in 8 cats (22.2%) after beginning of the treatment. The treatment effect on duration of seizure and subjective severity are summarized in Table 2. Significant correlations were found between number of seizures in 2nd year and days between disease onset and start of treatment (r = 0,418; p = 0,015) as well as recovery time (which is the number of the year when the cat first time seizure-free was for the period of one year) (r = 0,888; p = 0,001). Interestingly, if seizure-free status could be achieved for a year, cats remained usually seizure-free for many years (Figure 2.).

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