If your kittens were not able to nurse during the first three days of life, they will not have received proper immunity from their mother. (vcahospitals.com)
This is especially important for kittens under six months of age, in which positive results are often caused by immunity from the mother. (riverbarkvet.com)
First of all, puppies can get varying amounts of disease immunity from their mothers. (professorshouse.com)