yep this happened to my neighbor she got sick when her dog was sick in the hospital with giardia and was in the hospital as well for a week. She bought her dog from the pet store i got dexter from
She sued the guy and won in small claims court as he sold her a sick dog and refused to pay for medical treatment for her dog. Her dog and her are fine but it scared her too death so giardia from what i understand can passover to humans and is highly contagious. I am so sorry this happened to your mom but giardia is pretty common but we do not see it too often that it has affected humans on here but i know it definitely affected my neighbor.
Don't feel bad i had alot of red flags with dd but did not pay attention as i was new to all this and now i have dog with ISSUES so it happens but giardia can be treated. I thought i was doing better getting an akc dog the second time around not a pet store dog -ughhhh
Check out puppy lemon laws here and ladymom has the info. I think the most you will get is the vet bill paid not reimbursement of dog for giardia as that is not a genetic disease but check it out