The area you indicate is where the anal glands are located. Many dogs with anal gland issues will drag their rears on the ground or carpet. The anus area often is swollen and or has a bad odor. This may cause a dog to continue to lick the area.
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, 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.
Excellent site on anal glands
A tapeworm infestation can lead to excessive licking in the rectal area which can lead to inflammation. 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.
There is a condition "cold tail" that Labradors, English Pointers, English Setters, Foxhounds and Beagles sometimes get which causes them to hold their tail close to the body. You can read about it here. It can cause a localized swelling at the tail.
It is possible that this is what you are seeing with your dog. With cold tail it sometimes takes up to 2 weeks for the tail to recover. Some owners feel the administration of anti-inflammatory medication aid in a faster recovery.
Dog's have sebaceous glands and perianal glands at the base of their tails. Sometimes, these glands can become clogged and swollen. A warm compress on the spot and cleaning with Benzyl peroxide gel may help with the problem. I would also use some Neosporin or triple antibiotic cream on the area as well. Dogs with this swelling of the sebaceous gland may have a problem with hypothyroidism or a hormonal imbalance, so I would suggest you have your dog seen by your vet if you do not see improvement.
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