the study of the structure of the body and the relationship of its parts. Examination of the structures of various animal species is referred to as comparative anatomy.
Physiology – the study of the normal functions and activities of organisms.
Pathology – the study of the causes and effects of diseases or injury.
Embryology – the study of the origin and development of an individual organism. It begins after conception, or fertilization of the egg, and continues through parturition, or birth.
Histology – the microscopic study of the minute structure, composition, and function of cells and tissues.
Biology – the study of all forms of life.
Body systems
The animal’s body is composed of different systems. A system is a combination of organs that performs a particular function. The systems of the body and their functions are listed below.
Musculoskeletal system – includes all the muscles, bones, and joints. It permits motion and movement of the body.
Integumentary system – includes skin, hair, nails, sweat, and sebaceous glands. The skin is considered the largest organ in the body and has many functions. It covers and protects the body, aids in temperature regulation, and has functions in sensation and excretion.
Cardiovascular system – includes the heart and blood vessels. The main function is to transport the blood to the body.
Respiratory system – includes the mouth, nose, trachea, and lungs. It is responsible for absorbing oxygen and discharging carbon dioxide. It also aids in regulating body temperature.
Digestive system – includes the mouth, teeth, salivary glands, esophagus, stomach, intestines, pancreas, colon, liver, and gallbladder. Its function is to digest and absorb food and excrete wastes.
Urogenital system – includes the kidneys, urinary bladder, genitals, ureters, and urethra. It provides for reproduction and urine excretion.
Endocrine system – includes the thyroid glands, adrenal glands, and parathyroid glands. These glands are responsible for manufacturing hormones.
Nervous system – includes the brain, spinal cord, and nerves. With the special senses, it processes stimuli and enables the body to act and respond.
External anatomy
The head consists of several different anatomical parts. The forehead area is just above the eyes and just before the stop. The indentation in a dog’s forehead just above level of the eyes is the stop. The depth of the stop will vary depending on the breed of dog. The muzzle is the area between the stop and the nose. The length of the muzzle will vary depending on the breed of dog. The nose is located on the front of the face. It is black in most breeds. The mouth is located below the nose and, again, depending on the breed of dog, the shape and size will vary. Finally, the flew consists of the upper lips. The flew may be larger and longer in specific breeds such as the boxer or St Bernard. The ears are located on or near the top of the head and can vary in size, placement, and shape depending on the breed (Figure 3.11).
Figure 3.11 External anatomy of the head.
Source: Courtesy of Dr Lori Renda‐Francis, LVT.
Anterior portion
The shoulder is the muscular upper section of the upper arm, and the point of the shoulder consists of the front of the joint where the upper arm and shoulder blade come together. The brisket is the front portion of the body located between the forelegs and below the chest. The forearm is the top area of the upper front leg. The wrist is located lower on the front paw and is also known as the carpus. The paws include the toes, feet, and paw pads of all four of the dog’s legs. The elbow is the joint that connects the upper arm and the forearm (Figure 3.12).
Posterior portion
The stifle is the joint that connects the lower thigh to the upper thigh. The thigh is the area of the hindquarters located between the hip and the stifle. The tarsus is the joint that connects the crus (the lower leg) to the metatarsals, which are the beginning of the foot. The back of the upper thigh is referred to as the hamstrings. The tail is just below the croup and comes in a variety of shapes and lengths depending on the breed. The croup is the area of the back from the root of the tail to the front of the pelvis. The loin is the area on both sides of the vertebrae between the last few ribs and the hindquarters (Figure 3.13).
Middle portion
The underside of the abdomen is the belly. The area from the withers to the root of the tail is the back. The withers are the top of the shoulder blade and the highest point of the body and are located just behind the neck. The ruff is the thick, dense hair located around the top of the neck. The crest is the upper arched area of the neck (Figure 3.14).
Figure 3.12 External anatomy, anterior portion.
Source: Courtesy of Dr Lori Renda‐Francis, LVT.
Figure 3.13 External anatomy, posterior portion.
Source: Courtesy of Dr Lori Renda‐Francis, LVT.
Figure 3.14 External anatomy, middle portion.
source: Courtesy of Dr Lori Renda‐Francis, LVT.
Common veins
While veterinary assistants do not perform venipuncture techniques, they do have a significant role in assisting the veterinarian or veterinary technician in successful collection. The main role of the veterinary assistant during venipuncture is to properly restrain the animal for the procedure. Therefore, it is important for the veterinary assistant to know which veins are commonly used and where they are located and to be able to describe them using correct anatomical terminology.
For dogs, the most frequently used sites for blood collection are the cephalic vein, the jugular vein, and the lateral saphenous vein. The most commonly used veins in cats are the