I have two special needs dogs. Oscar and Penelope.
Oscar, a 12yr old Chihuahua mix, has luxating patellas in his hind legs and has epilepsy. His seizures are incredibly scary to watch, poor boy. He chewed through an electrical cord as a puppy when he was staying with my in-laws, and I often wonder if that was the culprit. We're just careful about paying with him as any bump to the head seems to trigger a seizure.
Our other dog, Penelope (aka Miss P), is a 3 yr old Chihuahua who has a luxating patella and severe allergies. She's been diagnostically tested and the allergy print out is 3 pages long, which includes all grasses and trees! She did have surgery on her knee (very expensive) but it didn't help despite the long, long, slow recovery process.
We try to walk the dogs every day, or second day, at the right pace for them not to 'skip' and properly use their knees. We also take them swimming in the summer.
As for Miss P's allergies, we always have baby Benadryl, an allergy cream, and a head cone on hand. She has a strict diet of potato and duck kibble and treats.
My husband and I love them both. Oscar came to Canada with us from Australia (so did our Cornish Rex) and Penelope came into our lives after we moved here. She was passed over at the SPCA and given a final chance through a small dog rescue. We were her foster family and fell in love, needs and all. Here's a quick pic of Miss P the other day when she got into the forbidden grass clippings. Note the neon green feet and guilty face.