My Dad Was Scratched By A Dog On Thanksgiving Day

My dad was scratched by a dog on Thanksgiving Day (Oct) here in Canada and let the scratch go for sometime. Took him into the hospital as the doctor figured it was an infectious disease and he was treated with just some home care cleaning the wounds ad doing bandages for about a week. Hand cleared up, however Dad ended up in the hospital 2 weeks later and they couldn't find an infection that showed up on blood work, and Dad developed pneumia and passed on the 29th of December. I am wondering if the dog scratch may have had any play in a hidden diagnosis that was never found. The doctor here just kept saying, some kind of infection but couldn't tell us what it was.