Allergic to Nana's dog

As a Nana I excel -- to the dismay of my children. The dismay on their faces when their screaming urchins react like perfectly behaved toddlers when I grace them all with my presence is so confusing to me. If I were them I would build a wing in my house and summon me as tantrusms erupt.
So, it was with sheer delight that my daughter announced to me, my granddaughter Kaitlyn was allergic to my dog. Kaitlyn has been breaking out in rashes all over her body for about a year. She is at my home at least once a week. But sometimes the rash does not occur. And the dog is always around. So, I just accept this and say, "oh, too bad she can't come to Nana's anymore."
I rescued the poor pooch and will not turn my back on her. "I'll give her Claritin on the days she goes to your house" is snapped back at me. It was not my fault that this allergy thing happened. None of my kids are allergic to dogs. My daughter's husband is allergic to cats and dogs so he is the real culprit. But of course I am the guilty party simply because I have a dog. I have had a dog every single day of my life. So, this was not planned by Naughty Nana -- but I take the rap and mommy and daddy's faces are smug. They all begrudge me as usual. I am feeling sad and threatened until as I am leaving my granddaughter runs up and hugs me and says, "I love my doggy Nana."