This by itself does not mean that the dog is not a purebred or that there is anything wrong at all. As with most tail shapes, lengths and holds, the only time to be concerned is if there is a change and the Beagle cannot hold his tail as he naturally would otherwise (more ahead).
My Beagle is holding his tail funny/ in an odd way
If you take the time to really study a Beagle all throughout the day, you’ll definitely see times when the dog is briefly holding his tail at a funny angle or in a way that seems odd. However, in most cases this is just due to the dog’s mood or the activity that he is engaged in.
A Beagle may hold his tail down if he is feeling depressed or scared. Sometimes, the tail will go down due to submission and this can most certainly happen if a Beagle is being scolded by his owners.
There are 3 conditions that may cause a Beagle to hold his tail oddly (excluding actual injury to the tail itself):
Engorged anal glands. These small peanut sized glands (one located on each side of the anus), hold oils (commonly referred to a scent oils). Minuscule amounts are released when one dog encounters another and some is also released when the dog has a bowel movement. Sometimes, the oil will build up, causing the glands to become enlarged. This can cause somewhat intense itching (the dog may scoot his/her bottom along the ground in an attempt to relieve the itching).
Normally 1 of 3 things will happen: The oil may be reabsorbed (in which case the swelling goes down), the skin may break open due to the tight pressure (in which case a quite noxious odor
will be released along with the fluid – this should be looked at by the vet so that the tear can be treated and skin is not left open and vulnerable to infection) or a vet or groomer may express the glands.
Back problems – Since the tail is a continuation of the spine, issues in the back can radiate down into the tail. This includes pain due to a ruptured disk and other back pain issues.
Age related posture – As a Beagle ages, he loses some muscle and tendons may weaken. In addition, arthritis comes into play as well. All of these issues may cause an older, senior Beagle
to have what appears to be a weakened tail hold.
As with all holding and movement issues, you will want to make sure that the tail has not been injured and that it is just a matter of the Beagle choosing to hold it in an odd way as opposed to not being able to move it or hold it as he normally does (more ahead on tail injuries).