how often animals die when they get sick?

as often as they stop breathing when sick

Quite often I have seen a blue whale and a sperm whale beached by polluted sea water,there was nothing that the Marine Wildlife rescue could do.

Animals get disease just like humans.

Their potential lifespan is based on the type of disease they get. Colds are healed, cuts and scratches are healed. Bites and cancers can be fatal.

Hmm... Depends on the sickness. and depends on dog. Like labs labs are strong at fighting sickness. Most dogs are except chiwawa's. But I am sure your dog will be okay.. Ill pray for him.

In the wild, sick animals get killed and eaten by predators as they are easy targets.

It would depend on what they are sick with and their physical condition at the time.