What is the tail?
The tail is the posterior elongated part of a dog that extends beyond the trunk or main part of the body.
Where is the tail located?
The tail is located at the end of the vertebral column. In other words, it is the hind-most part of the backbone.
What is the general structure of the tail?
The canine tail usually consists of between six and 23 highly mobile vertebrae, largely enclosed by a versatile musculature making the various segments, especially the tip, capable of finely graded movements that lift the tail, move it from side to side, or draw it down toward the anus or between the hind legs. Part of the musculature is formed from muscles associated with the rectum, the anus and the pelvic diaphragm. The tail is served by four to seven paired nerves. These muscles have many tendons that insert from the fifth or sixth caudal vertebra then onto the next and so on to the end of the tail.
What are the functions of the tail?
You can tell a lot about what dogs are feeling by watching their tails. Dogs use their tails for communicating; they express happiness, aggression, stress and all of the emotions in between. By looking at the position and movement of the tail, you can usually tell what they are saying. When he wags his tail high and wags it back and forth, he’s usually feeling pretty good; when he is interested in something, his tail is horizontal to the ground; a tucked tail indicates the dog is frightened or submissive; when the tail goes from horizontal to upright and rigid, he is feeling threatened or challenged; and a tail that is low and wagging just slightly means your dog is feeling worried or insecure.
The tail has another vital role in communicating. Every time your dog moves his tail, it acts like a fan and spreads his natural scent around him. One of his most important odors comes from the anal glands, two sacs under the tail that contain a smelly liquid that is as unique among dogs as fingerprints are to us. Every time the dog wags his tail, the muscles around the anus contract and press on the glands, causing a release of the scent. A dominant dog that carries his tail high will release much more scent than a dog that holds his tail lower. Likewise, a frightened dog holds his tail between his legs to keep others from sniffing him, so he does not draw attention to himself.
The tail is important as a means of counterbalance when the dog is carrying out complicated movements such as leaping, walking along narrow structures, or climbing. Dogs that run at great speeds usually have long thin tails in proportion to the rest of the body, and they use their tails as counterbalance when making turns. Their tails give them both agility and ability to turn quickly to keep up with their prey. Tail muscles are also important in stabilizing the vertebral column and supporting the action of the extensor muscles of the back as well as those of the croup and buttocks.
Some dogs also use their tails as rudders when swimming. Swimming dogs have tails that are thick, strong and very flexible, which helps them to move easily through the water and make quick turns.
Some dogs use their tails for insulation. Nordic breeds have brushy or plumed tails with long dense fur. When lying down they pull their tails over their faces to keep out the cold. They also use their tails as rudders when pulling a sled across the ice.
What are the common diseases of the tail?
Trauma
Cauda equina syndrome
Alopecia
What types of diagnostic tests are used to evaluate the tail?
Various tests are used to diagnose disorders of the tail. These include:
- Myelogram
- Radiographs (X-rays)
- Trichogram (microscopic exam of the hair)
- Skin scrapings
- Fungal culture
- Skin biopsy
