I see that you haven't responded to my request for more information but I want you to have some answers.
There are a few reasons why a dog will lick their tail region and bottome excessively. Often they will also drag their bottom on the floor as well. Some dogs will lick the rear excessively if there is fecal matter stuck to the hairs in the area. Keeping the hair trimmed back in the area will help stop excessive licking.
Full anal glands can also cause excessive licking. Frequently they will drag their rear on the carpet to help relieve the pressure. The anal glands are 2 sacs on either side of the anus at about the 4' o'clock and 8 o'clock positions. If your dog is continually licking their anus and dragging it, it could also indicate that they are full. This problem can usually be resolved by emptying out the glands. To empty them or express them, you will want to cover the area with a tissue and press your finger on the dog's anal glands with an upward motion. A foul smelling liquid should come out. If nothing comes out and your dog appears to be in pain, you should take him to the Vet. Your vet can do this easily, as he is experienced at it. With some dogs the glands fill up and become an issue on a regular basis and many have their glands expressed monthly as a result. Excellent site on anal glands
If no lump in area It could also be tapeworm infestation. Tapeworms release segments that exit the anus and spread tapeworm eggs into the environment. They can cause severe itching in some dogs. They can usually be seen in the stool and are small about 1/2 inch moving things. If the stool has dried, they look like rice in the stool or stuck in the hair around the anus. Drontal plus is also a prescription product and is used for the treatment of Tapeworms, though dewormers with praziquantel work well against tapeworms. Usually this isn't an ongoing issue unless the dog continues to become reinfected. Dogs can contract tapeworms by ingesting an infected flea.
I hope this information is helpful to you. If you would like any additional information or have more questions please don’t hesitate to press the reply to expert or continue conversation button so I can address any issues you still have . If you do find this helpful, please take this opportunity to rate my answer so I am compensated for my time.
If you have questions in the future that you wish me to answer, you may click here and bookmark the page or make it a favorite. It is best to put my name "JANE" in the question as well.
Since there have been recalls on certain foods, please check the following site to be sure the food your animals eat is not affected. If it is affected, contact your vet as soon as possible. Have your dog seen if they have any symptoms.
The last is allergic condition -- flea allergy being the most common allergy leading to itching around the base of the tail and rectal region.
I hope you find this information helpful.
A Perianal Adenoma is also a possibility. You can read about this here: