Why Do Dogs Arch Their Backs?

Adrienne Farricelli

Why do dogs arch their backs? We are used to seeing cats arch their backs, to such an extent that a black cat with an arched back has become the staple image for many Halloween decorations, but what about dogs who arch their backs, why do they do that?

Why do dogs arch their backs? We are used to seeing cats arch their backs, to such an extent that a black cat with an arched back has become the staple image for many Halloween decorations, but what about dogs who arch their backs, why do they do that? One may assume, that just like cats, dogs must arch their backs for the purpose of appearing larger and more intimidating, but turns out, when a dog arches his back and acts abnormally, one of the first and foremost concerns should be evaluating the possibility of an underlying health problem.

A Matter of Pain

In a healthy dog, the back in general tends to be straight from shoulder to tail. When a dog holds his back arched, veterinarians call this posture " kyphosis" which is meant to depict an abnormally rounded back.

Why do dogs assume this arched-up posture? According to NeuroPetVet, a website created and maintained by Dr. Mark Troxel, a board-certified veterinary neurologist, this position helps alleviate discomfort which may be localized in the dog's neck or back. Because this position relieves the dog's aches, using this posture is reinforcing to the dog so he'll tend to rely on this alternate position for as long as the pain is there.

A Spinal Issue

Based on Original graphic:  <a href="https://en.wikipedia.org/wiki/Dog_anatomy#/media/File:Skeleton_of_a_dog_diagram.svg">Przemek Maksim,</a> Wikimedia Commons CC BY-SA 3.0
Based on Original graphic: Przemek Maksim, Wikimedia Commons CC BY-SA 3.0

A dog's spine is composed by several small bones known as vertebrae. Between the vertebrae are several 'intervertebral disks' which are meant to cushion and provide flexibility to the dog's neck, spine, and tail.

In a dog with a perfect spine, the disks do what they were meant to do, allowing the dog to engage in day-to-day activities with no problems.

However, when a dog ages or through trauma, the disks are prone to rupture or herniate causing pressure on the spinal cord. Affected dogs may therefore develop what vets refer to as a "pinched nerve" or herniated disk in the dog's neck or middle or lower back.

When the disk is inflamed, it puts pressure on the dog's spinal nerves which is something quite painful, causing the dog to arch its back and likely also cry out in pain, along with keeping the head lowered and becoming reluctant to move, explains veterinarian Dr. Jeff.

Such dogs may also be hesitant to go up or down stairs, and on and off furniture, adds veterinary technician Julie Ann from Vet Info. When vets suspect a spinal problem, they may perform some neurological tests and manipulate each vertebrae for signs of pain.

An Abdominal Issue

Abdominal pain can cause an arched back posture too.
Dogs with abdominal pain often vomit, lose appetite and act lethargic.

It's important to note that the symptoms of abdominal pain and back pain can be quite similar. This is why veterinary neurologist Dr. Mark Troxel suggests that vets palpate the abdomen of a dog presenting with an arched back so to evaluate for possible signs of abdominal pain.

Even in the case of abdominal pain, the arched back and tucked-up abdomen is meant to provide relief. When a vet palpates the problem area, this may cause the dog to flinch and instinctively arch the back or tuck his tummy even more, which can help pinpoint the problem.

By palpating the abdomen, vets are looking for any abnormalities such as an enlarged spleen, liver or the presence of any masses, explains Dr. Vivian Carroll.

Along with an arched back, dogs suffering from some form of abdominal pain are likely to also have some other symptoms such as reduced appetite or loss of appetite, vomiting and diarrhea, suggests veterinary technician Julie Ann. The only way to better know what the problem is, is having the dog see the vet. After palpating the spine and abdomen, the vet is provided with important clues that may help determine where the pain is coming from. Further testing may be required to come to a diagnosis.

Time is of The Essence

An arched back warrants veterinary attention.
An arched back warrants veterinary attention.

Both spinal and abdominal problems require immediate veterinary attention because of the pain involved and the risks for complications if not treated in a timely manner.

For example, according to Animal Neurology Insights. in the case of intervertebral disk disease, time is of the essence and could ultimately make an impact as to whether the problem can be corrected.

Bloat, pancreatitis, dog intestinal blockages,  or a fecal impaction of the colon are other serious and potentially life threatening conditions that can cause abdominal pain and a hunched-up posture in dogs.

A Sign of Fear

On a lighter note, a hunched posture in dogs can be seen when they are fearful and feel particularly vulnerable. Unlike the cat, that by arching his back is trying to look larger, it's almost as if these dogs want to appear smaller than they really are, almost wishing to become invisible.

The fearful dog may retreat to a corner, keep the back hunched, tail tucked, head lowered and avoid eye contact, as Karen Overall describes the body language of a fearful black collie, in her book "Manual of Clinical Behavioral Medicine for Dogs and Cats."

The Breed Standard

The arched back in greyhounds provides tremendous flexibility.
The arched back in greyhounds provides tremendous flexibility.

On an even lighter note, in some breeds, a curved back is desired and it's part of the standard of many sighthounds. In this case though, the arched back isn't just a posture but a permanent feature as it's part of the dog's conformation.

For example, according to the American Kennel Club standard for the Italian greyhound," the back is curved and drooping at hindquarters, the highest point of curve at start of loin, creating a definite tuck-up at flanks."

The greyhound standard calls for loins with "a good depth of muscle, well arched," the borzoi standard calls for a "back - rising a little at the loins in a graceful curve."

Did you know? The arched loins characteristic of many sighthounds is also what allows them to run so fast. According to Sharon Sakson, a dog show judge, it is thanks to that slight arch over the loin that sighthounds can "fold their legs back up under them, like a spring, so there is more explosive energy when they launch into the next phase of the gallop."