Comparative Anatomy of Domestic Animals

Dog Vertebral Formula

C7T13L7S3Cd20-23

Horse Vertebral Formula

C7T18L6S5Cd15-21

Dog Vertebral Formula

C7T13L7S3Cd20-23

Horse Vertebral Formula

C7T18L6S5Cd15-21

Ruminants Vertebral Formula

C7T13L6S5Cd18-20

Pig Vertebral Formula

C7T14-15L6-7S4CD20-23

Dog Atlas

Alar foramen is absent; instead there is an alar notch

Horse Atlas

Has 3 foramina: intervertebral, alar and transverse

Ruminant Atlas

Transverse process is absent; lateral vertebral foramen is divided into two

Pig Atlas

Transverse foramen is situated in the posterior border

Dog Axis

Long; dens is typically tooth like

Horse Axis

Long; spinous process is bifed

Ruminant Axis

Long; dens is spout shaped

Pig Axis

Short; high spine directed

Dog 6th Cervical Vertebra

Transverse process has a well-developed ventral plate

Horse 6th Cervical Vertebra

Has trifid transverse process

Ruminant 6th Cervical Vertebra

Transverse process has a well-developed ventral plate

Pig 6th Cervical Vertebra

Transverse process has a well-developed ventral plate

Dog 7th Cervical Vertebra

Undivided; lacks transverse foramen

Horse 7th Cervical Vertebra

Undivided; lacks transverse foramen

Ruminant 7th Cervical Vertebra

Undivided; lacks transverse foramen

Pig 7th Cervical Vertebra

Divided; with transverse foramen

Dog Lumbar Vertebrae

Transverse process of L4-6 articulate with each other

Dog Sacral Vertebrae

Spinal processes are fused to form a median sacral crest

Dog Caudal Vertebrae

2 spines on ventral surface of Cd4 fuse ventrally to form hemal arch

Horse Caudal Vertebrae

2 spines on ventral surface of Cd1 fuse ventrally to form hemal arch

Dog Ribs

13 pairs; 9 sternal, 4 asternal; cylindrical shaft; 8 sternebrae; xiphoid process present; narrow xiphoid cartilage

Horse Ribs

18 pairs; 8 sternal, 10 asternal; narrow shaft; 6 sternebrae; xiphoid process absent; broad, leaf-like xiphoid cartilage

Ruminant Ribs

13 pairs; 8 sternal, 5 asternal; strongly curved dorsal third; 7 sternebrae; xiphoid process present; broad, leaf-like xiphoid cartilage

Pig Ribs

14 pairs; 7 sternal, 7 asternal; cylindrical shaft with distinct angle; 6 sternebrae; xiphoid process present; narrow xiphoid cartilage

Dog Scapula

Spine bisects lateral surface into equal halves; trapezius tubercle present; acromion present; equal infra and supraspinous fossae

Horse Scapula

Distinctly triangular; trapezius tubercle overhangs infraspinous fossa; tuber of spine present; no acromion; infraspinous fossa larger

Ruminant Scapula

Tuber of spine present; acromion present; infraspinous fossa larger

Pig Scapula

Well-developed tuber of spine; no acromion; equal infra and supraspinous fossae

Dog Humerus

Single undivided intertuberal groove; divided greater tubercle; undivided lesser tubercle; single lateral tuberosity; supratrochlear foramen present

Horse Humerus

Divided intertuberal groove with sagittal ridge; divided greater and lesser tubercles; massive lateral tuberosity; no supratrochlear foramen

Ruminant Humerus

Divided intertuberal groove with low ridge; divided greater and lesser tubercles; lateral tuberosity almost converts groove to foramen; no supratrochlear foramen

Pig Humerus

Single intertuberal groove; divided greater tubercle; undivided lesser tubercle; no supratrochlear foramen

Dog Radius and Ulna

Separated; radius neck distinct; olecranon has tuberculate summit

Horse Radius and Ulna

Fused by ossification; ulna fused 2/3 down to radius

Ruminant Radius and Ulna

Large animals: fused; Small ruminants: ulna slender and not fused

Pig Radius and Ulna

Connected by dense connective tissue; ulna massive and larger than radius

Dog Carpal Bones

7 bones including 1,2,3,4; accessory articulates with ulna and ulnar carpal

Horse Carpal Bones

7 bones; no 1st; accessory articulates with radius and ulnar carpal

Ruminant Carpal Bones

6 bones; fused 2 and 3; accessory articulates only with ulnar carpal

Pig Carpal Bones

8 bones; all present including 1st; accessory articulates only with ulnar carpal

Dog Metacarpal Bones

MC 1-5 all present

Horse Metacarpal Bones

MC III = cannon bone; MC II and IV = splint bones

Ruminant Metacarpal Bones

MC III and IV fused; MC V vestigial

Pig Metacarpal Bones

MC II to V present; MC III and IV functional

Dog Digits (Forelimb)

5 digits; each with 3 phalanges; 2 proximal and 1 distal sesamoids

Horse Digits (Forelimb)

1 digit (digit 3); with hoof; 2 proximal and 1 distal sesamoid

Ruminant Digits (Forelimb)

4 digits (2-5); digits 3 and 4 bear weight; with hoof

Pig Digits (Forelimb)

4 digits (2-5); each with 3 phalanges; with hoof

Dog Ilium

Faces laterally; thick and convex cranial border; widely separated tuber sacrale; >1 gluteal line

Horse Ilium

Faces dorsally; sharp and concave cranial border; close tuber sacrale; only 1 gluteal line

Ruminant Ilium

Faces dorsally; sharp and concave cranial border; close tuber sacrale; only 1 gluteal line

Pig Ilium

Faces laterally; thick and convex cranial border; widely separated tuber sacrale; only 1 gluteal line

Dog Ischium

Tuber ischiadicum = thickened ridge; lower than acetabulum

Horse Ischium

Tuber ischiadicum = thickened ridge; same level as acetabulum

Ruminant Ischium

Trituberculate process; higher than acetabulum

Pig Ischium

Caudally directed process with lateral tubercle; lower than acetabulum

Femur - Trochanter Major (Dog)

Trochanter major is undivided; at same level as head of femur.

Trochanter Major (Horse)

Trochanter major is divided into cranial and caudal parts; higher than head of femur.

Trochanter Major (Ruminants)

Trochanter major is undivided; higher than head of femur.

Trochanter Major (Pig)

Trochanter major is undivided; same level as head of femur.

Intertrochanteric Line (Dog)

Poorly developed.

Intertrochanteric Line (Horse)

Poorly developed.

Intertrochanteric Line (Ruminants)

Poorly developed.

Intertrochanteric Line (Pig)

Absent.

Third Trochanter (Dog)

Absent.

Third Trochanter (Horse)

Present.

Third Trochanter (Ruminants)

Absent.

Third Trochanter (Pig)

Absent.

Supracondylar Fossa (Dog)

Present.

Supracondylar Tuberosity (Horse)

Present.

Supracondylar Tuberosity (Ruminants)

Present.

Supracondylar Tuberosity (Pig)

Present.

Patella (Dog)

Medial cartilaginous attachment of medial parapatellar cartilage.

Patella (Horse)

Medial cartilaginous attachment of medial parapatellar fibrocartilage.

Tibia and Fibula (Dog)

Fibula is as long as tibia.

Tibia and Fibula (Horse)

Only the proximal half of fibula remains.

Tibia and Fibula (Ruminants)

Fibula is vestigial; presence of malleolar bone.

Tibia and Fibula (Pig)

Fibula is as long as tibia.

Tarsal Bones - Total (Dog)

7 bones.

Tarsal Bones - Total (Horse)

6 bones.

Tarsal Bones - Total (Ruminants)

5 bones.

Tarsal Bones - Total (Pig)

7 bones.

Metatarsal Bones (Dog)

Metatarsals 2, 3, 4, 5.

Metatarsal Bones (Horse)

2, 3, 4 present; MTIII is cannon bone; MTII and MTIV are splint bones.

Metatarsal Bones (Ruminants)

MTIII and MTIV fused.

Metatarsal Bones (Pig)

2, 3, 4, 5 present.

Digits (Hindlimb) - Dog

Digits 2, 3, 4, 5 = 4 digits with 3 phalanges each.

Digits (Hindlimb) - Horse

Digit 3 = 1 digit with 3 phalanges.

Digits (Hindlimb) - Ruminants

Digits 2, 3, 4, 5 = 4 digits; 3 and 4 have 3 phalanges.

Digits (Hindlimb) - Pig

Digits 2, 3, 4, 5 = 4 digits, each with 3 phalanges.

Basihyoid (Dog)

With lingual process.

Basihyoid (Horse)

With lingual tuberosity.

Basihyoid (Ruminants & Pig)

Not specified.

Epihyoid (Dog)

Longest.

Epihyoid (Horse)

Smallest.

Epihyoid (Ruminants)

Replaced by ligamentum epihyoidium.