I'm severely allergic to most animals, including fish, horses, cats and dogs. I've owned fish and dogs all throughout my life, but only became allergic to them after a stem cell transplant in 2003. Now, we can no longer have either, except for a pure poodle. We can't even have a cross, like a Weimerdoodle.
We tried. We got this adorable pup that we named Charlie, and after explaining my circumstances to the breeder, he offered to let us have the pup but if there was ever a risk to my health in the first year, we would be able to give him back to a good, safe home. Unfortunately, within just a few weeks, I became severely ill - barely able to breathe, an unfortunate vomiting and pneumonia type illness, that could only be explained by the poor dog. So, we sadly had to give Charlie back to the breeder, who was kind enough to promise that he would be rehomed.
Eventually, we found a pure poodle, in our Bracken, and my health has been fine with him.