Minecraft: Can You recolor spawn eggs with resource packs?

Hi. I retextured cows so that they are black & white with my resource pack but I can't find a way to recolor the cow spawn egg. Is it even possible? Don't give me a mod because I HATE mods.

I wish I could help you, but I'm having the same problem.
All I know is that all spawn eggs use the same texture, but the colour comes from another file, probably similar to the colour-maps for grass and leaves which allows grass and leaves to be differently coloured from biome to biome. I however do not know the location of the file.