Why are some dogs born without tails?
So what’s behind these naturally occurring bob tails? Well, there is a few different things at play here. There are some known and unknown genetic mutations that cause this trait in some breeds.
Let’s look at the known genetic mutation known for causing short tails.
Okay everyone, buckle your seat belt because there is some incoming nerdy science here for a second. Bear with it, it will be over soon.
According to a study published in the Journal of Heredity in 2009, titled Ancestral T-Box Mutation is Present in Many, but Not All, Short-Tailed Dog Breeds, identified that one reason for dogs being born with a short tail is the presence of the mutated T-gene C189G. There were 18 breeds identified in the study as carrying the C189G mutation.
The presence of this gene mutation causes a short tail, which can be a completely short bobtail or a mid-sized short tail. The breeds in which the study identified the C189G gene are not always born with a short tail, but there are significant odds that some puppies in those breed’s litters will be born with short tails.
One other important piece of information that this study identified, especially for breeders, is that in these 18 breeds identified as carrying the C189G gene, two copies of this gene mutation are lethal. Meaning if both parents have short tails, some of the puppies will inherit the gene from both parents, which is lethal to the puppy. The study showed that about one in four puppies would inherit the gene from both parents and die before birth.
| Australian Shepherd | Jack Russell Terrier |
| Austrian Pinscher | Karelian Farm Dog |
| Australian Stumpy Tail Cattle Dog | Mudi |
| Bourbonnais Pointer | Polish Lowland Sheepdog |
| Brazilian Terrier | Pyrenean Shepherd |
| Brittany Spaniel | Savoy Sheepdog (Berger de Savoie) |
| Corgi | Schipperke |
| Croatian Sheepdog | Spanish Waterdog |
| Danish-Swedish Farmdog | Swedish Vallhund |
Are Boxers Born with Short Tails?
Boxers are not being born with short tails, and certainly not without tails either. They are traditionally docked at a young age to meet the AKC breed standards.
An undocked Boxer is even being penalized for not having a short tail. This docking is purely for appearance and serves no other purpose.
Some bobtail boxers were being bred over time and exported to other countries but they are extremely rare.
You will find them most often in countries like Australia where breeding clubs demand them to be bred this way.
The regular Boxer should have a long tail.
Why do people cut dogs tails?
Historically, tail docking was thought to prevent rabies, strengthen the back, increase the animal’s speed, and prevent injuries when ratting, fighting, and baiting. Tail docking is done in modern times either for prophylactic, therapeutic, cosmetic purposes, and/or to prevent injury.
While many dogs can still swim despite having essentially no tail, most of the strongest swimmers have long, deep, otter-like tails. … Lacking this, some dogs struggle to keep a true course, which can cause them to wander into dangerous places.
Tail docking is the removal of a dog’s tail in part or whole for cosmetic reasons or to prevent possible injury. … The practice is illegal in England, Wales, Scotland and Northern Ireland, however, there are some exemptions, such as removal of the tail by a vet for medical reasons or for certain breeds of working dogs.
Some Dogs Are Born With A Short Tail #shorts
Dogs differ greatly in their morphological characteristics including various tail phenotypes. Congenitally short-tailed dogs are present in many breeds; however, the causative mutation located in the T-box transcription factor T gene (C189G) had only been described in the bobtailed Pembroke Welsh Corgis. We investigated here the presence of the T gene mutation in 23 other breeds (360 dogs, including 156 natural short tailed) in which natural bobtailed dogs exist. In the 17 breeds in which the C189G mutation was observed, there was a perfect correlation between this mutation and the short-tail phenotype. However, 6 breeds did not carry the known substitution or any other mutations in the T gene coding regions. No dogs were found to be homozygous for the C189G mutation, suggesting that the homozygous condition is lethal. In order to study the effect of the T gene mutation on litter size, we compared the number of puppies born from short-tailed parents to that born from long-tailed parents. In the Swedish Vallhund breed, we observed a 29% decrease in the litter size when both parents were short tailed. Given that the T gene mutation is not present in all breeds of short-tailed dog, there must be yet other genetic factors affecting tail phenotypes to be discovered.
Illustration of Bourbonnais Pointer dogs showing a tailless (anury) phenotype on the left, a short-tail (brachyury) phenotype in the middle, and a long-tail phenotype on the right (photo: Michaël Comte).
In Pembroke Welsh Corgis, the length of the natural bobtail varies from a complete tailless to a short tail with half the length of a normal tail and occasional kinks. For comparison, another likely recessively inherited type of bobtail exists in Bulldogs where all dogs in the breed have short tails with multiple kinks (Whitney 1947). There are also occasional reports of short-tailed dogs born from long-tailed parents in some breeds, revealing multiple patterns of inheritance or variations in penetrance.
We studied here the presence of the T gene mutation in a large number of breeds to investigate its possible ancestral origin and to identify whether other genetic causes exist in association with short tails. We tested 23 different breeds and showed that the C189G mutation is present in all short-tailed dogs of 17 breeds, supporting a correlation of mutation with the phenotype. We also showed that breeding of 2 bobtailed Swedish Vallhund dogs with the T gene mutation decreases litter size, which confirms a major role of T gene during embryogenesis.