It's a scary thing to see a pink bulge coming from the rear end of your pet bearded dragon while they are straining but this prolapse of the cloaca can occur due to a number of reasons.
Bearded Dragon Prolapse Due to a Lack of Calcium
More often than not a lack of calcium in your bearded dragon's bones causes their cloaca to prolapse. Not having enough calcium can be due to a diet low in nutrition or from not having enough UVB rays in their habitat. Since calcium makes bones strong, bones become soft and pliable when there isn't enough calcium in them so if the pelvis is soft enough, a bearded dragon will prolapse because the bones aren't strong enough to keep everything that should be inside, inside. Having said this, it is important to gut load crickets, dust the crickets with a calcium and vitamin D3 supplement if there isn't any in the gut load, and provide appropriate UVB lighting for your pet bearded dragon.
Being infected with an abundance of parasites is another common reason why your pet bearded dragon will strain and prolapse their cloaca. You should have a fecal sample checked by your exotics vet to rule out having too many parasites. If the fecal test is positive, a deworming may be necessary to lessen or clear the parasitic infection and help prevent further prolapses from occurring.
Bearded Dragon Prolapse Due to Diarrhea
If your bearded dragon is straining because they have diarrhea from eating watery foods or for another reason he could prolapse. Offering foods that are more nutrient and fiber dense should help prevent prolapses if this is the cause.
Bearded Dragon Prolapse Due to Laying Eggs
If your female bearded dragon has recently laid eggs, is in the process of laying eggs, or is trying to lay eggs (she doesn't have to have been with a male to lay eggs) she could be straining to pass the eggs and in turn prolapse. Offering appropriate calcium in the diet and UVB lighting in the enclosure will help her body have normal contractions. Hormone supplements (such as Releaves) may lessen the frequency of egg production but otherwise there may not be much you can do to make your female beardie stop laying eggs.
Replacing the Prolapse in Your Bearded Dragon
If your bearded dragon prolapses the first thing you should do is moisten what came out. Lubricating gel, Vaseline, and water can all keep the important tissues healthy while you replace, or get help replacing, the prolapse. Sometimes by applying sugar to the prolapse you can help shrink it since the sugar absorbs excessive fluid. This may make replacing the prolapse easier.
To replace the prolapse, keep it lubricated and apply gentle pressure directly to the pink tissues. If possible, work from the outside in and try to gently push the tissue back into the cloacal opening. If you are concerned about tearing tissues, hurting your bearded dragon, or you are having any trouble, you should rush him to your exotics vet. Sometimes anesthesia is necessary to relax your beardie or a suture pattern called a purse string may need to be placed to keep the prolapse in place after pushing it back in.
Once the prolapse has been replaced you'll want to determine the cause and make sure it doesn't come out again. If a prolapse is out for an extended period of time and is not kept lubricated the tissues may die and surgery may be necessary to remove dead tissue.