The absence of a tail or anuria in dogs
When a dog has no tail or has a short tail, it is said to be anuran or brachyuran respectively.
Some dogs are born with a naturally short tail without this being considered an anomaly compared to the standard of their breed. But, the absence of a tail in dogs can also be secondary to a congenital anomaly or a racial predisposition of the dog.
Of course, the absence of a tail can also result from a tail docking, that is to say a voluntary cutting of the dog's tail by a veterinary surgical procedure. This practice is still authorized in France, under certain conditions.
Brachyuria in dogs
Brachyouria, or short tail, refers to a congenital shortening of the tail by a decrease in the number of coccygeal vertebrae. Tail shortening ranges from a tail reduced by a quarter of its length, compared to expected breed standards, to no tail at all.
Good to know
The number of coccygeal vertebrae varies from 18 to 22 in dogs.
In most cases, this "anomaly" does not generally cause any associated he alth problem but only aesthetic damage for the owner of the animal and sometimes a non-confirmation of the dog when its breed standard precise.
However, this anomaly can sometimes be associated with spina bifida, that is, an abnormality in the development of the dog's spine, resulting in neurological disorders such as hind limb ataxia.
For many dog breeds, brachyuria is caused by a mutation in the T gene, a gene present on a non-sex chromosome that normally codes for a protein involved in embryonic development.
The anomaly is hereditary and is transmitted according to an autosomal dominant mode of transmission. This implies that dogs that express the "short tail" trait only have one out of two mutated genes. Dogs that inherit two copies of the mutated gene in their genetic makeup are generally not viable and die in utero. For these reasons, it is therefore not recommended for breeders to breed dogs born with a short tail, and especially to cross a male and a female with a short tail.
The dog breeds likely to present the T gene mutation, and therefore an abnormally short or even absent tail are as follows:
- Australian Shepherd,
- Shepherd of the Pyrenees,
- Polish Plain Shepherd,
- Australian Cattle Dog,
- Bourbonnais Braque,
- Spanish Water Dog,
- Karelian Bear Dog,
- Croatian Shepherd Dog,
- Breton Spaniel,
- Mudi,
- Austrian Pinscher,
- Schipperke,
- Spitz of the Visigoths,
- Brazilian Terrier,
- Jack Russell,
- Welsh Corgi Pembroke,
- Miniature Australian Shepherd,
- Savoy Shepherd.
Dogs belonging to other breeds can also be born naturally with a short tail without a T gene mutation having been found. Other genetic causes, still unknown to date, are then certainly involved. These races include:
- the Boston Terrier,
- the English Bulldog,
- the Cavalier King Charles,
- the Parson Russel Terrier,
- the Rottweiler,
- and the Miniature Schnauzer.