The dog thoracic vertebrae form the bony roof of the thoracic cavity. You may find a great variation in the number of thoracic vertebrae in various animals. This article will reveal the answer to the question: how many thoracic vertebrae does a normal dog have?
Quick answer: there are 13 (thirteen) thoracic vertebrae in the vertebral column of a dog. The first 9 thoracic vertebrae of the dogs show almost similar osteological features. And the last 4 vertebrae present minor differences from each other and the preceding nine bones.
You will also know the typical features of the dog thoracic vertebrae with the labeled diagram. I will also show you the differences among the thoracic vertebrae of various species like horses, cows, pigs, and rabbits with dogs.
So, let’s learn the anatomical features of typical canine thoracic vertebrae with their actual numbers.
How many thoracic vertebrae does a normal dog have?
The dog’s thoracic vertebrae is characterized by a long supraspinous process and a cylindrical body. But all the canine thoracic vertebrae do not show the typical osteological features.
First, let’s see the labeled diagram of the canine spine labeled diagram (vertebral column). This diagram represents the number of thoracic vertebrae in the dog.
- Number of thoracic vertebrae in a normal dog – 13 (thirteen),
You will find a similar number of thoracic vertebrae in cows and various species of rabbits. Let’s see the number of the thoracic vertebrae of the other various animals, including dogs, from Table 1 –
| Animal Species | Number of Thoracic Vertebrae |
| Dog | 13 |
| Cow | 13 |
| Horse | 18 |
| Pig | 14 / 15 |
| Rabbit | 12 / 13 |
Where is the thoracic vertebrae on a dog?
Answer: thoracic vertebrae are located on the spine or vertebral column of a dog. The thoracic vertebrae form the thoracic part of the vertebral column in a dog.
Again, these dogs’ thoracic vertebrae form the bony roof of the thoracic cavity. You know, there are different body cavities in the animal body, where the thoracic cavity is important as they contain various vital organs.
You may get an idea of the various body cavities from the dog body from the below-mentioned article –
Body cavities and organs with the labeled diagram – the major and minor cavities of an animal,
Again, you may also get the idea of the structure of the dog spine or vertebral column from the below-mention article –
Dog vertebral column and formula
You may have the question – how is the vertebral column formed in a dog? A dog’s vertebral column represents the series of vertebrae that articulate together to form the long column along the long axis of the body.
Here, the series of vertebrae means the irregular and unpaired bones of the cervical, thoracic, lumbar, sacral, and coccygeal regions.
Dog vertebral formula: when the number of various vertebrae expresses according to the regions, it is known as the vertebral formula. The vertebral dog formula may express as follow –
- Dog vertebral formula – C7 T13 L7 S3 C20
Here, C = dog’s cervical vertebrae, T = dog’s thoracic vertebrae, L= dog’s lumbar vertebrae, S = sacral vertebrae, and C = coccygeal vertebrae of the dogs. Again, the first letter of the word presents each group or region.
From this vertebral dog formula, you may easily count the number of various vertebrae from the spine.
Exception: typically, most of the dog shows 20 caudal vertebrae. But sometimes, you may find more or less number of caudal vertebrae in various dog breeds. Again, three caudal or coccygeal vertebrae fuse to form the sacrum in a dog.
Dog vertebrae numbers
Now, you may easily count the total number of vertebrae from the dog’s spine.
- Dog vertebra numbers – you will find 50 irregular bones in the dog vertebrae column (according to the vertebral formula).
Let’s find the summary of the numbers of dog vertebrae from Table 2 –
| Dog vertebrae name | Dog vertebrae number |
| Cervical vertebrae of a dog | 7 (Seven) |
| Thoracic vertebrae of a dog | 13 (Thirteen) |
| Lumbar vertebrae of a dog | 7 (Seven) |
| Sacral vertebrae of a dog | 3 (three); fused |
| Caudal vertebrae of a dog | 20 – 24 (Varies) |
Canine cervical vertebrae anatomy
The first two canine cervical vertebrae (atlas and axis) from the dog’s neck are structurally modified than others. You will find the full guide on the canine cervical vertebrae anatomy from the below-mentioned article of anatomy learner –
Again, the canine atlas and axis are structurally little different than these of the cow’s atlas and axis bones. For that, you may also read the following articles to understand the differences between these bones (atlas and axis) between dogs and cows –
- Atlas of ox – anatomy of the first cervical vertebra of cows, and
- Axis of ox – cows second cervical vertebrae with the labeled diagram,
Number of lumbar vertebrae in dog
The dog vertebral formula represents there are 7 lumbar vertebrae in the structure of the vertebral column. These canine lumbar vertebrae possess longer bodies than these of the thoracic vertebrae.
- Number of lumbar vertebrae in a dog – 7 (seven),
Again, you will find the unique osteological features in the structure of the transverse process of these vertebrae. The transverse processes of the canine lumbar vertebrae are longer and directed cranially and slightly ventrally.
You will see little variation in the structure of the canine and bovine lumbar vertebrae. To understand the main differences in the lumbar vertebrae between dogs and cows, you may read the below-mentioned article –
How many sacral and coccygeal vertebrae do dogs have?
Answer: you will find 3 sacral vertebrae in the structure of the dog sacrum. These three sacral vertebrae fuse to form the four-sided, wedged-shaped sacrum in dogs.
Again, the structure of the dog tail shows 20 – 24 caudal or coccygeal vertebrae. All these coccygeal vertebrae of the dog don’t possess the typical osteological features of a typical vertebra.
The below-mentioned article might help you to understand the structure of a dog tail, including the features of coccygeal vertebrae –
Thoracic vertebrae in dogs
In this section, you will learn the details features of the thoracic vertebrae in dogs. But make sure you know the structure of a typical vertebra from the animal’s spine.
You may get an idea of the structure of an animal’s typical vertebra from the following article –
Now, let’s identify the below-mentioned osteological features from the dog’s thoracic vertebrae –
- Body of the dog’s thoracic vertebra (cranial and caudal extremities),
- Pedicle and dorsal lamina of the canine thoracic vertebrae,
- Cranial and caudal costal fovea on the body of dog thoracic vertebra (for articulation with the head of ribs),
- Cranial and caudal articular processes of the canine thoracic vertebra,
- Shorter spinous process (paired) of the dog’s thoracic vertebra,
- The longer spinous process of the dog’s thoracic vertebra (single and caudally directed), and
- Costal fovea on the transverse process of the canine thoracic vertebra,
All these above-mentioned osteological features are identified in the dog thoracic vertebrae labeled diagram. Now, you will easily enlist the typical features from the canine thoracic vertebra.
Unique features of dog thoracic vertebrae
You will find the below-mentioned unique osteological features in the dog’s thoracic vertebrae –
- The body of the canine thoracic vertebrae are comparatively shorter and constricted in the middle,
- You will find two pairs of costal fovea (cranial and caudal) on the body of the canine thoracic vertebrae,
- The cranial aspect of the thoracic vertebra’s body is less convex, and the caudal end is less concave compared to the cervical vertebrae,
- The pedicles of the canine thoracic vertebrae are comparatively short and pierced by the addition of intervertebral foramen,
- You will find the two laminae that fuse in the middle, where the longer spinous process arises,
- The cranial aspect of the lamina of the dog thoracic vertebrae possess one pair of cranial articular process,
- You will find the short and irregular transverse process that also possesses a costal fovea for the articulation of the tubercle of ribs,
- The caudal articular process of the canine thoracic vertebrae is not also well-developed and locates ventral to the spinous process,
With these unique features, you will easily identify and differentiate the dog’s thoracic vertebrae from others.
Body of the dog’s thoracic vertebrae
The basic structure of the body of a dog’s thoracic vertebrae is similar to the cow’s thoracic vertebral bone. You will find the cylindrical body, which is more or less shorter than the bodies of cervical and lumbar vertebrae.
You may also read the ruminant thoracic vertebrae to compare it with dogs –
The mid-ventral part of the thoracic vertebral body shows constriction. You will see the most identifying features on the cranial and caudal aspects of the dog’s thoracic vertebral bodies.
And these are the cranial and caudal costal facets or fovea for the head of ribs. But, the eleventh thoracic vertebra of a dog lacks the caudal costal fovea. Again, the twelfth and thirteenth thoracic vertebrae always possess only the cranial pair of the costal fovea.
You may understand how the ribs, head, and tubercle make articulations with the body and the transverse process of thoracic vertebrae from the below-mentioned article –
Pedicles and lamina of canine thoracic vertebrae
The pedicles of the canine thoracic vertebral arch are comparatively short. You will find the deep notch on the caudal aspect of the pedicle of the canine thoracic vertebrae. But, the cranial pair of notches are frequently absent in the canine thoracic vertebrae.
The lamina of the dog thoracic vertebrae is a thin plate-like structure. These laminae fuse from the base of the spinous process. Two oval cranial articular processes are present on the cranial aspect of the lamina.
Processes of the dog’s thoracic vertebrae
The spinous process typically shows the massive and longer features in the dog’s thoracic vertebrae. You will find the more massive spinous process in the first thoracic vertebra, and they gradually decrease.
You will find the short spinous process in the ninth and tenth thoracic vertebrae, which incline caudally. The dog’s eleventh thoracic vertebra possesses a nearly perpendicular spinous process (this vertebra is known as an anticlinal vertebra).
Now, the spinous process of the 12th and 13th thoracic vertebrae possess the cranially directed spinous processes.
The transverse process of the dog’s thoracic vertebrae is irregular and shorter. You will find the fovea on the free end of the transverse process. And this fovea is designed for articulation with the tubercle of the dog’s rib.
The fovea on the transverse process decreases from the first to the last thoracic vertebrae. Sometimes you may find the mammillary processes on the second or third thoracic vertebrae. These are the small bony projection that projects dorsally from the transverse process of these thoracic vertebrae.
The articular processes are at the junction of the pedicles and laminae. The cranial articular processes remain widely separated on the first and second thoracic vertebrae.
The cranial articular processes face cranially and dorsally in most of the dog’s thoracic vertebrae.
How many accessory processes does a normal dog’s thoracic vertebrae have?
Answer: Typically, you will find the 1 pair of accessory processes on the caudal aspect of the 11th, 12th, and 13th thoracic vertebrae of the dogs. But, the dog’s thoracic vertebrae – first to tenth do not show accessory processes.
How many thoracic ribs do dogs have?
Answer: the dogs have 13 pairs of thoracic ribs in the structure of their chest. Among these 13 pairs, you will find 9 pairs sternal, 4 asternal, and one floating rib.
The heads of these ribs articulate with the costal fovea of thoracic vertebral bodies. Again, the tubercles of these ribs articulate with the fovea of the transverse process.
How to differentiate dog thoracic vertebrae from horses and cows?
Answer: you may easily differentiate the thoracic vertebrae of a dog from the cows and horses with the appearance of body, arch, and process. Here Table 3 will provide enough information that might help you to differentiate the dog’s thoracic vertebrae from the cows and horses –
| Features | Dog | Horse | Cow |
| Body | Wide Compressed dorsoventrally | Short Constricted at middle | Longer Constricted at middle |
| Arch | Notch shallow | Notch larger | Notch shallow |
| Spinous process | Cranial surface convex | Thick Blunt | Border thin Sharp |
| Accessory process | Present in last 3 vertebrae | Absent | Present in last 3 vertebrae |
Conclusion
So, the answer to how many thoracic vertebrae a normal dog has was revealed. And you already got the 13 numbers of thoracic vertebrae in the structure of the dog spine anatomy.
This guide also helps you to understand the basic structure of the 13 thoracic vertebrae from the dog spine. A little difference in the structure of these 13 thoracic vertebrae are also important for further studies.
