First of all, thank you for caring so much and showing concern for your friend's beardie. All of us here are very passionate about our dragons and the rest of our pets, they are members of our own families and we do get a lot of people that come on here for emergency help due to total neglect and/or abuse of their dragons, and only when their dragons are on death's door do they finally ask for help. Unfortunately it's typically too late at that point and there's not much they can do to help. Bearded dragons are desert reptiles, and as such their lives literally depend on adequate strength and amount of UVB and UVA light daily, living in proper temperatures daily, and eating appropriate live insects and greens daily with adequate calcium supplementation, and if they live in improper temperatures, under improper lighting, and being fed improper diets with improper calcium and multivitamin supplementation for very long, their bodies cannot function and they die. The thing you must remember with bearded dragons though is that there is a distinct difference between NEGLECT/ABUSE and just POOR ADVICE from pet shops and actually often times from breeders and exotics vets. There are people who come on here that have unlimited money to spend on their dragons set-ups, lighting, and diets, and still their dragons are very ill and die not because they were neglectful owners, but because they were given horrible and inaccurate advice by pet shop employees, breeders, and vets. They are told to buy UVB and basking lights that are totally inadequate for a dragon, or they are actually advised that they "don't need a
UVB light at all", or they are told that they can feed their new month-old baby dragon commercial pellets and lettuce or freeze-dried insects. It's terrible but this happens every day, multiple times a day. So it's quite possible that your friend has been given terrible diet and temperature advice and lighting recommendations, and these are the reasons her dragon is now sick.
I have found that the best way to approach this situation with a friend, family member, or even a neighbor who you are "dragon-sitting" for (this happens all the time and the person comes on the forums to ask questions after they see the way their neighbors are keeping the dragon they are watching while they are on vacation) is to do the research yourself, find out what your friend is doing that is wrong as far as her UVB and basking lights, her thermometers and her temperature zones, and her diet and supplementation, and then once you figure out what parts of her husbandry and diet needs corrected you can make a list and go over it with her. If you're able to purchase some things for her as Christmas gifts that's also an awesome way to help her and her dragon out. Telling her that you're thinking about getting a bearded dragon yourself so you started doing research on your own, and you have now learned that because beardies are desert reptiles they need very specific UVB lighting that is set-up in a specific way, they need a proper Digital thermometer in order to set up a proper temperature gradient across their enclosures, and they need a certain amount of live insects and fresh greens every day, depending on their age, and that a lot of live insects, such as mealworms, are not at all good to feed a bearded dragon as a daily, staple feeder insect because they cause impactions, etc. This way you don't offend your friend and you're able to educate her and yourself at the same time.
First of all, how old is your friend's dragon? If you know how long she's had him or where she bought him from this will usually tell you his age. For example, if she bought him at a Petco or PetSmart, then he was most likely a very young baby when she brought him home, usually the baby dragons they sell at Petco and PetSmart are around a month or so old. The reason his age is important is that a proper diet for him is totally dependent on how old he is. Dragons that are a year old or younger need pretty much an entire diet made up of tons of healthy, live insects every single day, several times throughout the day, and little to no greens or veggies. Although they should be offered fresh greens every day, most dragons under a year or so old will not eat them at all, or they only pick at them. This is because they do 90% of their growing and developing during their first year of life, and so they need a ton of live insect protein every single day in order to grow to a healthy size and develop appropriately. Unfortunately mealworms are not a live insect that should be fed as a daily staple insect to dragons, they are mostly hard, chitlin shell and fat, and if your friend's dragon does have an impaction that is causing the paralysis in his back legs, it's probably at least partly due to the mealworm shells causing an impaction that is pressing on his spinal column. Crickets, roaches, silkworms, and BSFL/Phoenix Worms/Calciworms/Nutrigrubs/Reptiworms (all the same thing) are the healthiest daily live feeder insects for dragons.
The other likely cause of his paralyzed back legs (and any stunted growth) is Metabolic Bone Disease (MBD), which is caused by not getting 13-14 hours a day of adequate
UVB light. This lack of adequate daily
UVB light results in the dragon not being able to absorb or process any of the calcium (or any other nutrition) from their food or supplements, and as a result their bone density weakens, and due to other nutritional deficiencies they have problems with muscle use, nerve issues, etc. See if you can find out what Brand/Model/Type (long tube, compact, or coil) of
UVB light your friend has, and if it's mounted inside the tank or on top of a mesh lid. Also find out what type and specifically what wattage and color her Basking Light is as well. And how many hours a day she leaves both lights on.
Also, how long is the dragon about from the tip of his snout to the very end of his tail? Is he at all skinny or is he a good, healthy looking size? Photos definitely will help...also, how big is his tank?
Does she use calcium and a multivitamin powder daily?
The other big question is regarding the temperatures inside his tank. Does she use a Digital Thermometer that has a Probe on a wire or a Temperature Gun that she measures her temperature zones with, or does she simply have the stick-on thermometers inside the tank? Does she know what the temperatures are for her dragon's Basking Spot Surface Temperature, the Hot Side Ambient (air) Temperature, and the Cool Side Ambient (air) Temperature?
These are the big questions, along with his age and the daily diet, that are going to tell us what is going on with her dragon...