A strict liability rule reserved for official duties
Under Ind. Code §15-20-1-3, an owner is strictly liable for a bite only if the victim was carrying out official duties for a government or postal service — mail carriers, police officers, firefighters, and similar workers. Among Indiana's bordering states, this is the narrowest strict liability rule; Ohio, Michigan, and Kentucky all extend strict liability to ordinary bite victims.
Outside that narrow category, Indiana relies on negligence — but not a strict "one free bite" rule. Indiana courts have specifically held that dogs aren't entitled to one free bite before an owner can be held liable; a first bite can still support a claim given other evidence the owner failed to use reasonable care, including a violation of a local animal control ordinance (negligence per se).
A genuine exception to Indiana's usual premises rules: trespass is not a defense in dog bite cases — the negligence standard applies regardless of whether the victim was an invitee, licensee, or trespasser.