In what cases should I use 条 for 猫?
Misusing quantifiers is a practice of rhetorics. Consider the examples of 一滩猫 and 一坨代码. 滩 gives a metaphor noting the liquidity of a cat, and 坨 implies that the code is badly programmed to look like shit.

In orthographic usages, 条 cannot quantify 猫. However, if you have a specific rhetorical purpose, you may quantify anything with any quantifier you prefer.

In this very particular case, when 条 is used to quantify 猫, it would seem that you are giving an explicit implication that the cat is pretty long or very thin; and note that context matters.