Tail Anatomy 101
I want to show you how incredible your dog’s tail is, and why it’s so much more than a cute appendage for wagging. Tails are built-in communication tools and a physical extension of the spine that can give us clues to deeper issues. I work with dog’s tails in almost every treatment! I’m hoping this quick anatomy lesson will help you understand your pup a little better (and some of what I think about during treatment).
Getting Situated
I’ve popped in some pictures of the tail and pelvis because what we are going to be reviewing is super nerdy, and kinda hard to visualize. I’ve put some arrows on the images to show that the tail muscles blend in with the pelvis and the spine. In the image down below, you can get a more full picture of how some of the anatomy connects.
I’m going to dive into some of the individual muscles, but I want to give you a taste of the big picture. Your dog’s body works as one connected system, with a series of tension lines (like a suspension bridge). The tail is the starting point for 3 of these tensional lines (called Kinetic lines). These kinetic lines are built up of muscles, fascia, ligaments, tendons, and even some organs!
We can lay the stage for these kinetic lines, by looking at some of their individual parts and how the individual parts work together.
Tail Muscles
The individual muscles of the tail connect into the lumbar spine, the sacrum, the pelvis, and pelvic diaphragm.
If you’re curious, what we call our pelvic floor, would be more like a pelvic wall in our four legged friends. Just like in humans, the pelvic diaphragm is super important for gut support, posture, and balancing internal pressures.
One muscle in particular highlights the full body connection really well. The Sacrocaudalis dorsal lateralis (or in english the muscle of the sacrum and tail that’s on the top and the sides) is a big tail muscle, is actually functionally considered a continuation of the longissimus muscle, one of the big muscles of the spine (Evans, & Lahunta, 2012). During jumping, and climbing type motions the tail is going to be working with the big spinal muscles.
Dogs have significant muscles all around their tails. Each of the muscles have very fancy latin names, but essentially the tail muscles are:
Top side (Sacrocaudalis dorsal lateralis)
Top middle (Sacrocaudalis dorsal medialis)
Teeny tiny top spinal muscle (intertransversarius dorsales caudae)
Bottom side (Sacrocaudalis ventralis lateralis)
Bottom middle (Sacrocaudalis ventralis medialis)
Teeny tiny bottom spinal muscle (intertransversarius ventrales caudae)
Each of these muscles weave in with their neighbours. Even the teeny tiny bottom spinal muscle of the tail blends and connects with its neighbour - the pelvic diaphragm. Now, even these small muscles have a relationship with gut health, defecation, and internal pressures.
Tail Fascia
The fascia is another way that the tail relates to the spine, and the rest of the body. The tail fascia is a continuation of the gluteal fascia, the spinal fascia, the visceral (organ) fascia, and the abdominal fascia! (Elbrø, 2024)
We can look at the gluteal fascia as a great example of continuation in a dog's body. Quick note: in dogs the glutes are actually on the sides of the hips (see the pic at the top of the article). This fascia is so thick that it actually provides an attachment point for some of the tail muscles! This means that any hind limb motion is innately going to affect tail tension.
This deep gluteal fascia (similarly to humans) comes from the Thoracolumbar fascia (that’s a fancy way of saying it comes from the back) (Evans, & Lahunta, 2012), so again, the tail has such strong ties to the rest of the body.
Kinetic Lines
Recent research (2024!) has shown that dogs have similar myofascial kinetic lines as humans. What this means is that there are layers of muscles and fascia that all work together. The tail is connected to 3 of the deep kinetic lines which connect the tail to the head!
A deep dorsal (back) line, which runs with the super deep spinal muscles; a deep ventral (belly) line, that starts both in the tail and the hind limb and converges in the fascia of the organs; and finally, a deep lateral line, which again had multiple starting points, and actually formed a double helix pattern around the dog to support rotation. Finally there were also functional lines, spiral lines, and forelimb lines, and superficial lines. (Elbrø, 2024)
These deep kinetic lines work to coordinate spinal extension, flexion, lateral movement, and rotation. When you put it all together we have a full body system that directly ties your dog’s tail to their spine, viscera (aka organs), and core stability.
Force Transmission
From human research on force transmission through muscles and fascia, we know that these myofascial kinetic lines also transmit and distribute force (Huijing, 2003).
When your dog pushes off the ground with their back paw, that energy can ripple through the fascia, traveling up the leg, through the pelvis, and dissipate through the spine or the tail.
This is what researchers call direct and parallel force transmission:
Force can travel along muscle fibers and through tendons (direct transmission)
Or it can also spread through fascia layers to nearby muscles and tissues (parallel transmission)
In simpler terms this means that the tail doesn’t just hang out. It helps absorb, redirect, and distribute forces as your dog moves, balances, and adjusts to their environment.
This really builds a picture of how the tail is connected, and related to the rest of the body. It seems clear that the body can easily influence the tail, and vice versa.
Other research
There has been some other new research that shows that dog’s tails are not as biomechanically important as other tailed animals (Rottier et al., 2022). Compared to other animals who use their tails as an extra limb (Kangaroos, or some monkeys) or air rudders (cheetahs), dog’s tails are mostly for communication.
But what is that the whole picture? Looking at the research on force transmission and kinetic lines, I would argue that living anatomy deserves more nuance. The muscular and fascial research builds a picture that tails are important for dissipating force, and for fine tuning muscle tension in dog’s bodies. Even if tails aren’t essential for balance, or high velocity turning, they may influence spinal rhythm and pelvic motion.
Your dog’s cute tail is more than decoration—it’s a part of their spinal health. If you notice something off about their tail, there is a strong likelihood the rest of their body could need some love and attention. Check in with your vet first, but if you find you want some deeper support, osteopathy might be the right fit.
This was a dense read! If you made it this far congrats on being a curious and attentive pet parent! I hope that this anatomy lesson helps you to read your dog's body a bit more clearly. And in turn create a stronger bond between them and you.
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Amanat, S., Paracha, H., Alexandre, E., Mayer, J., & Granatosky, M. C. (2020). Canine locomotion. In Encyclopedia of Animal Cognition and Behavior (pp. 1-6). Springer, Cham.
Elbrø, V. S. (2024). Canine Myofascial Kinetic Lines: A Descriptive Dissection Study Including Related Function and Locomotion and Comparison of the Human and Equine Myofascial Kinetic Lines. Open Journal of Veterinary Medicine, 14(9), 229-256. 10.4236/ojvm.2024.149017
Evans, H. E., & De Lahunta, A. (2012). Miller's anatomy of the Dog-E-Book: Miller's anatomy of the Dog-E-Book. Elsevier health sciences.
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Huijing, P.A. (2003) Muscular Force Transmission Necessitates a Multilevel Integrative Approach to the Analysis of Function of Skeletal Muscle. Exercise and Sport Sciences Reviews, 31, 167-175. https://doi.org/10.1097/00003677-200310000-00003
Gillette, R. L., & Angle, T. C. (2014). Canine locomotion analysis. Canine rehabilitation and physical therapy, 201-210
Rottier, T., Schulz, A. K., Söhnel, K., Mccarthy, K., Fischer, M. S., & Jusufi, A. (2022). Tail wags the dog is unsupported by biomechanical Modeling of Canidae Tails Use during Terrestrial Motion. bioRxiv.
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