A dog owner who destroys his own dog can be found guilty of destruction of evidence. For example, section 135 of the California Penal Code states:
135. Every person who, knowing that any book, paper, record, instrument in writing, or other matter or thing, is about to be produced in evidence upon any trial, inquiry, or investigation whatever, authorized by law, willfully destroys or conceals the same, with intent thereby to prevent it from being produced, is guilty of a misdemeanor.