Second degree sunburn with bubbles all over my front legs- how long 2 heal? the skin will be normal as before? any scars? any risk for skin cancer?

Keep clean and moist: If healing occurs within 10 days and additional sun or injury or infection is avoided, then it is unlikely that scarring will occur. However this is no guarantee. Yes there is a risk of ski cancer but the risk is difficult to quantify.

Burn: A second degree burn takes weeks to heal and should be treated by a physician to reduce the chance if scarring and infection. Skin cancer risk is doubled following a blistering sunburn