Cow disappeared

[Nummy]

My cow just disappeared and din't appear back when bull was finished and walked away.

I'm using enders with custom mods, but I tried restarting server and using default client, but cow just isn't there anymore.
Is this common to happen?

[HasseKebab]

RIP

[Tonkyhonk]

try searching her for at least a few screens around, no matter walls. some stud males make females jump away while/after mating. i once found my cow 3 screens away all out of walls and over cliffs, one female sheep even jumped two brickwalls to get away, ive lost one pig quite recently too, couldnt find her at all. so yes, its rather common especially when your pen is crowded.