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 cephalic vein, the jugular vein, the femoral vein, and the medial saphenous vein (Figure 3.15).
The cephalic veins are located on the anterior surface of the forearm. They run from the dorsomedial foreleg proximally along the foreleg. They are easy to locate and very accessible for venipuncture. The cephalic vein is used for collection of large volumes of blood in larger dogs.
The lateral saphenous veins are small, superficial veins that run diagonally across the lateral surface of the distal part of the tibia.
The jugular veins are large superficial veins located on either side of the trachea on the neck.
The femoral vein is used for blood collection in cats and extends from the groin on the medial aspect of the thigh.
The medial saphenous vein is also used in cats and extends from the hock to the stifle on the medial aspect of the calf. It becomes the femoral vein at the stifle (Figure 3.16).
Muscles
There are several muscles that can be utilized to administer intramuscular injections. Again, the veterinary assistant does not administer these injections but plays a large role in assisting the veterinarian or veterinary technician by properly restraining the animal. In order to properly restrain, it is important for the veterinary assistant to be familiar with the location of the various muscles (Figure 3.17).
Lumbodorsal or dorsal lumbar muscle – located on either side of the midline.
Triceps – located caudal to the humerus.
Quadriceps – located anterior to the femur.
Biceps – the posterior muscle of the hind leg.
Semimembranosus/semitendinosus muscle group – located in the rear leg, also known as the hamstring muscles.
Figure 3.15 Veins.
Source: Courtesy of Dr Lori Renda‐Francis, LVT.
Figure 3.16 Saphenous vein.
Source: Courtesy of Dr Lori Renda‐Francis, LVT.
Figure 3.17 Muscles.
Source: Courtesy of Dr Lori Renda‐Francis, LVT.
Internal organs
Digestive system
The most cranial structure is the mouth. The mouth, or oral cavity, is a very important part of the digestive system in dogs. This is where digestion begins. The tongue and front teeth help a dog pick up pieces of food, and teeth in the back of the mouth grind the food into smaller particles. A dog has a total of 42 teeth, including incisors and canines, located in the front, and the premolars and molars, which are located in the back. As a dog chews, food is broken up into smaller particles for better digestion by enzymes in the stomach and small intestines. It passes through a small tube called the esophagus that connects the mouth to the stomach via the diaphragm.
The stomach is a sac‐like structure that stores large volumes of food. From the stomach, the food enters the small intestine. There are three parts to the small intestine. The duodenum attaches to the stomach. The middle part is the longest part and is called the jejunum, and the last part is the smallest part and is known as the ileum. It connects to the large intestine. The large intestine connects the small intestine to the anus. Its primary function is to absorb water from feces as needed in order to keep the animal hydrated. Its other function is to store fecal matter that is awaiting passage from the body. The last structure of the intestine is the rectum, which leads to the most caudal structure – the anus (Figure 3.18).
The liver and pancreas are two essential organs that have multiple functions. Both have ducts that secrete special chemicals into the intestine to aid indigestion. They are next to each other anatomically, and a disease of one can sometimes affect the health of both. The gallbladder is a pear‐shaped structure lying between the lobes of the liver (Figure 3.19).
Urogenital system
The canine urogenital system is a combination of the urinary and reproductive tracts. It includes the urinary and reproductive organs. The function is to provide reproduction and eliminate liquid wastes. The urogenital system is made up of the kidneys, bladder, ureters, and urethra along with the reproductive organs such as the testicles, penis, scrotum, uterus, ovaries, and vulva (Figure 3.20).
The
