If you've had animals as long as I have then you're bound to have had at least one need subcutaneous fluids at one point or another in the pet's life. I, unfortunately, have had several. My Irish Wolfhound mix seem to need subcutaneous fluids every time she got sick and had to stay over night at the Veterinarian's office once to have IV fluids. They would take her in the back and give her what they called a "fluid pack" being a longer haired dog and that she would absorb the fluid quickly I never really knew why they called it that. That is until my Shar Pei mix, who has Shar Pei fever, need one when he was having a fever and he came back looking like a camel. My Veterinarian uses the Ringer's Solution because it's not suppose to sting as much when they have to give the subcutaneous fluids. Thankfully I've never had give subcutaneous fluids myself but from what I've heard it's supposed to be pretty easy to do because you aren't injecting the solution into a vein but under the skin to be absorbed into the bloodstream. Veterinarian's give subcutaneous fluids for different reasons; to keep the animal from getting dehydrated or to help flush waste from the kidneys, a lot of times animals get fluids is because of Kidney problems. All my animals that have had to get Ringer's Solutions subcutaneous fluids are noticeable better within a couple of hours, they weren't completely better but you could tell that they were feeling better. These fluids do what they are supposed to and help keep your pet's hydrated.