I have a cat and though I can feel the electricity in her fur, I never get sparks from her. And she never seems to get sparks from any objects the way I get. Probably because she walks around grounded, while I wear shoes. And just some cat hair on your pcb can't do any harm. It's not conductive.
I occasionally got a shock from my cat -- which would startle us both! But, I was living in a desert, where the air got exceptionally dry -- especially in the winter!
But,
Grumpy_Mike is correct, electrostatic discharge should not affect electronics where the "
circuits are all connected up". On the other hand, ESD could damage parts, not in circuit, if not handled with proper ESD protocol.
And BTW: even if a part, exposed to ESD, still functions, it's still possible is was damaged in a way that it will fail long before MTBF.