Basic Horse Anatomy for Owners and Riders
Before owning a horse, it’s essential to get a basic knowledge of equine anatomy. Having this understanding will enable you to detect diseases or problems in your horse at an early stage and communicate effectively with a vet to find a quick solution.
What You Should Know About a Horse Skeleton
The horse skeleton is a framework of its body that protects its vital organs, such as its intestines, lung, and heart.
The equine skeleton comprises bones that are joined by ligaments to form joints. The ligaments are resilient connective tissues that offer support to the joints. They don’t have enough blood supply, making them take long periods to heal after an injury.
A synovial lining secretes synovial fluid to protect the joints. This fluid is essential, as it lubricates the joint to minimize friction. It provides nutrition and oxygen for the joints and absorbs shock.
Ensure to treat traumatic injuries affecting the joint as an emergency. If left unattended, it can cause infection to set in, resulting in lameness and inflammation. Other frequent (but less severe) conditions include windgalls and bog spavin. Developmental orthopedic diseases and degenerative joint diseases are more severe conditions that can result in lameness.
The Bones of a Horse Skeleton
The horse’s skeleton averagely has 205 bones which include:
- 34 skull bones
- 53 bones in the spine, which may vary depending on the breed:
- Five lumbar vertebrae
- Seven cervical vertebrae (the neck)
- 18 coccygeal vertebrae (tail)
- Five sacral vertebrae
- 18 thoracic vertebrae (the ribs)
- The ribcage includes 18 rib pairs that curve around the horse’s internal organs and attach to its sternum (the breast bone).
- The horse’s forelimbs include:
- Short and long pastern
- Split and cannon bones
- Coffin bone (foot)
- Eight carpal bones (knee)
- Scapula (shoulder blade)
- The hindlimbs include:
- Fibula and tibia
- Split and cannon bones
- Coffin bones
- Short and long pastern
- Seven tarsal bones
- Ilium, pubis, and ischium (pelvis)
The Muscles of a Horse
Horses have three different muscle types, which vary in terms of regulation of contraction, function, and structure.
The smooth muscle is an involuntary muscle that functions automatically without the horse’s conscious effort. Many parts contain smooth muscles, including the kidneys, bladder, and so on.
The cardiac muscle is also involuntary and controls the heart.
The skeletal muscle is voluntary and is responsible for movement.
Every skeletal muscle is attached to tendons that connect them to the bone. Although tendons are resilient, they’re also inelastic and can become damaged or strained.
Other Equine Body Systems
Horse Cardiovascular System
The cardiovascular system consists of blood, veins, heart, capillaries, and arteries. The heart circulates blood through arteries, capillaries, and veins. The horse’s blood supplies nutrition and oxygen to its internal organs, including the muscles. Common cardiovascular issues in horses include abnormal heart murmurs and rhythms.
The Lymphatic System
The lymphatic system is part of a horse’s immune system that contains lymph nodes and lymphatic fluid. Its principal function is to produce immune cells. The lymphatic fluid contains white blood cells, the primary tools of the body’s immune response. It eliminates toxins, such as bacteria and fat, from tissues in the body and transfers them to the horse’s circulatory system. When a horse’s body is balling with bacteria, the lymph nodes get enlarged. Such enlargement under its lower jaw indicates a head infection, such as tooth root infection or bacterial infection.
The Endocrine System
The endocrine system involves hormone-producing glands. The hormones regulate the horse’s body, including metabolism, tissue function, reproduction, and mood.
The Gastrointestinal System
The gastrointestinal system is where the horse’s body consumes and breaks down food, providing nutrition for other parts of the body, and excreting the wastes. It consists of the large intestine, small intestine, anus, mouth, stomach, esophagus, rectum, and pharynx.
Gastrointestinal diseases can lead to reduced appetite, weight loss, diarrhea, and colic (abdominal pain).
The Nervous System
The nervous system is a horse’s most complex system. It controls every other body system and consists of the motor and sensory nerves, spinal cord, and brain. The central nervous system is the center of every nervous control. Other nerves controlled by the peripheral nervous system are outside the spinal cord and brain. The nervous system also manages the involuntary operations, including the respiratory and cardiovascular systems, and the horse’s digestion, sleeping, and resting. Issues with the nervous system can lead to several signs, including altered behavior, seizures, and coordination difficulties.
The Reproductive System
The reproductive system in a mare controls the mating behavior, gestation, estrous cycle, lactation, and birth. It consists of the vulva, vagina, cervix, uterus, ovaries, and fallopian tubes. The system also has two mammary glands with two ducts each that open externally.
In stallions, the reproductive system controls sexual behavior and consists of the penis, urethra, and testes.
The Respiratory System
The respiratory system controls the flow of oxygen in a horse. It also helps to excrete toxins and feed the muscles. It consists of the lungs, larynx, diaphragm, mouth, bronchial tubes, trachea (windpipe), and nose.
The Urinary System
The urinary system in a horse controls the balance of fluid in its body. It consists of the urethra, ureters, bladder, and kidneys. The kidneys primarily remove waste products and filter the blood. The waste moves to the bladder through the ureters and exits through the urethra (male horses) and the vulva (mares).
The horse skin is a protective layer that senses the external environment, assists their immune system by protecting them from disease, and maintains the body temperature. A horse’s skin changes continuously and includes three layers: the subcutaneous, dermis, and epidermis layers.
Horses have the most prominent eyes among land animals, and they’re the human eye size. The eyes are at both sides of a horse’s head, so their sight range is almost 360 degrees. Horses understand colors (though not as much as humans). Their eyes consist of the eyelids, eyeballs, and surrounding nerves and muscles, and their eye problems include uveitis (eye inflammation) and corneal ulcers.