Sambar are one of the few deer species known to fight rather than flee, typically against dholes or feral dogs. If nearby, they'll use bodies of water to their advantage, standing knee-deep and striking out with their front hooves or antlers. If in a group, they'll back into a defensive unit, protecting one another's vulnerable hindquarters.
However, they often fall prey to Bengal tigers, especially in India. In fact, tigers have been said to mimic sambar alarm calls, luring in curious deer.
The red or "sore" spot on their necks is not a wound, but a gland that produces white or reddish fluid. It's most prominent during the rut and on pregnant or lactating hinds.