Is the word cat not affected by the accusative like other words are (vala-vale, muña-muñe) it stays kēli and not pergaps kēlE?
[Late answer, but anyway ...]
Generally those nouns which end in an -i or an -o in the nominative singular are the same in the accusative singular. (And the nominative and accusative plural match each other too.) These are the 3rd declension (those governed by 'o') and the 5th declension (those governed by 'i').