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Merrist Wood College National Certificate in Horse Studies Equine Science Mechanical Systems Failure Beccy Manley 09.12.2001 Table of Contents- and Figures and Tables Table of Contents Figures and Tables ........................................ i Acknowledgements ......................................... ii Introduction .............................................. 1 Skeletal system ........................................... 2 Respiratory system ........................................ 3 Cardiovascular system ..................................... 4 Renal system .............................................. 5 Diagnostic decision tree .................................. 6 Strangles ................................................. 7 Conclusion ................................................ 8 References and Bibliography ............................... 9 List of Figures and Tables Illustration of skeleton .................................. 2 Illustration of synovial joint ............................ 2 Illustration of respiratory system ........................ 3 Illustration of heart ..................................... 4 Table of arteries and veins ............................... 4 Illustration of kidneys ................................... 5 Illustrtion of Strangles .................................. 7 For picture credits see reference page. i Acknowledgements I should like to express my thanks to E. Manley and H. Manley for their help and ideas in developing the content of this report. ii Introduction Horses suffer from many common ailments often easily caught infections that can prove fatal. Horses need to be fit and well to do their job. If the owner doesn't recognise the first signs of illness in their horse then the animal may suffer; never reach its full potential; ever return to work; cost the owner large vets bills. This report sets out to describe the basic function of four main systems in the horse making them easy to understand and interesting to read. It also sets out to help owners to find out what may be wrong with their horse using a diagnostic decision tree. Lastly it sets out to create a fact file on one common disease from the decision tree to highlight the importance of knowing the first signs of illness in horses. 1 Skeletal system The horse has an endoskeleton, which means skeleton under the skin. A normal horse has 205 bones but it can have 206 depending on whether it has 7 or 8 coccygeal vertebrae. Function To protect and support the body. Locomotion: for locomotion we need to have attachments consisting of bone, ligament, bone: muscle, tendon bone. Bones • Long bones: contain marrow for the manufacture of red blood cells. They have compact bone on the shaft allowing for strength and support and spongy bone at the head making them light. • Irregular bones: these are found in most joints and along the spine. They have protrusions and projections to allow for muscles, ligaments and tendons to be attached. • Flat bones are found in the skull and the scapula (shoulder). Joints Joints are formed when two or more bones come together and are held together by bands of flexible fibrous tissue, known as ligaments. There are three main types of joints: • Immovable, these are found in the junctions between the skull. • Slightly movable, these are found in the vertebrae forming the spinal column. • Freely movable: 1 Hinge type joint e.g. Fetlock 2 Plane type joint, where flat surfaced bones glide over each other 2 3 Pilot joint: this allows turning, (as in Atlas and Axis). 4 Ball and socket e.g. hip. Each freely movable joint is enclosed in a fluid filled joint capsule. 3 Respiration system Function Takes air to the lungs which then supplies oxygen. Diffusing oxygen in to the blood stream and carbon dioxide from the blood to the lungs. Regulates water and temperature. There are two types of respiration: Internal: metabolic break down of compounds e.g. carbohydrates this happens through the cells of the body. External: The transfer of gases between the environment and the blood, this takes place in the lungs. Upper tract (A) Buccal cavity (B) Nasal Cavity (open to pharynx) (C) Inferior maxillary sinus (D) Superior maxillary sinus (E) Frontal sinuses (F) Guttural pouch (G) Pharynx (H) Trachea (I) Bronchus (J) Alveolus (K) Lungs (L) Larynx The nostrils: Take oxygen in and out and have hair to filter dirt. The horse cannot breath through its mouth. Nasal cavities: Warm and clean the air with cilia (hair like) and they have tiny bones which are covered in mucus membranes. Pharynx: is used of respiration and digestion with the soft palate separating the mouth from the nasal cavities and the epiglottis acting as a stopper covering the oesophagus when it breathes and the larynx when it eats. Larynx: is in the entrance of the trachea and contains the vocal chords, as air goes over they vibrate and make a noise. Trachea: This goes form the larynx to the lungs and is held open by rings of cartilage. It is also part of the lower tract. Lower tract Bronchi: they divide in to each lung and are held open by rings of cartilage. Once in each lung they divide into a bronchiole tree. Narrow tubes with mucus membranes. Alveoli: alveoli are sacs found at the tip of ducts. They made up of lung tissue and cover a huge surface area. They have a very thin surface area so that the cells from the pulmonary artery can make a gaseous exchange. Gaseous exchange The de-oxygenated blood is found in capillaries, close to the surface of the alveoli. The carbon dioxide found in the blood diffuses into the air in the alveoli and expelled. Oxygen taken in from the air into the alveoli diffuses into the capillary walls and combines with the haemoglobin in the blood. 4 Cardiovascular system Functions Circulates blood throughout the body. Transports energy substrates, electrolytes and hormones to tissues. Removes waste products, thermoregulation, lactate, Carbon dioxide and water. Blood White cells: Immune system, fight germs, make antibodies, remove germs and dead cells. Red cells: Carry oxygen and give blood its colour. Platelets: Clotting agent. Plasma: 90% water, straw colour, anti bodies, carbon dioxide, enzymes, hormones, amino acids salt and fibre (A) Anterior vena cave from head. that helps the healing process, (B) Aorta to body and head. (C) Pulmonary artery to lungs. (D) Pulmonary veins from lungs. (E) Left atrium. (F) Left ventricle. (G) Right ventricle. (H) Right atrium. (J) Posterior vena cava from body The Heart How it works: Oxygenated blood from the lungs goes to the Pulmonary vein into the left atrium in diastolic phase (relaxed). Then it goes in to the left ventricle until it is full, this causes pressure which pushes the blood out through the aorta into the body, this pressure is called systolic phase. The deoxygenated blood enters the right atrium through the vena cava in diastolic phase; it goes into the right ventricle until it reaches systolic phase then it goes through the pulmonary artery to the lungs. This is called the cardiac cycle. Facts The heart weighs 4kg. The average horse's heartbeat is 30-40 beats per minute. Reasons for the heart rate to increase are spooking, feeding, excess noise, posture, exercise, stress and illness. For illness the heart rate goes up because the body needs more blood to make antibodies. Blood vessels, arteries, veins and capillaries Arteries Carry blood from the heart to the body (oxygenated) Not Pulmonary Artery Blood carried at high pressure Thick walls No valves Veins Deoxygenated blood from body to heart Not Pulmonary vein Blood carried at a low pressure Thin walls Valves to stop back flow 5 Capillaries These are tiny tubes which connect the arteries to the veins, they allow material to go between the tissues. 6 The Renal system This system can be divided into two subdivisions they are: Kidneys, the manufacture of urine Excretory passages, all the structures of collecting urine and draining it out of the body, the Ureter, bladder and Urethra. The Kidney Controls the flux of ions out of the body Conserves water Excretion of nitrogenous wastes There are two parts to a kidney, the Cortex with urine producing nephrons and some tubules. The medulla is the deeper region, composed entirely of tubules. Renal blood supply The kidney is the place where blood is filtered Blood flow is the force behind urine formation. Blood enters the kidney via the renal artery and is distributed through smaller vessels. Ureter Thick muscle wall with two layers of muscle, one inner longitudinal one and an outer circular one. These act as a valve and prevent back flow. Conveys urine from renal pelvis to bladder. Urinary bladder Temporary storage organ for urine. It is made up of three layers of smooth muscle and elastic connective tissue. The lining is folded and puckered in a relaxed state (epithelium). Stretches. Urethra Conveys urine from bladder to exterior. In males it does two jobs, urinary tract and reproductive system. Urine release into urethra controlled by external sphincter. 7 8 Strangles Strangles is a common worldwide disease in horses and can be fatal. It is a disease of the upper respiratory tract and the lymph nodes of the head. It rapidly spreads from horse to horse through coughing, or by the horse eating or drinking infective droplets. Cause: It is caused by a bacterium called Streptococcus equi. Signs: Within 3-8 days of becoming infected, the horse will show a fever. The throat and larynx become inflamed and it becomes painful of impossible to swallow. There will be a typical yellow discharge from one or both nostrils and it may cough. The lymph nodes of the head become swollen and painful and may eventually burst with thick yellow pus. Infection in a few cases, spreads to other organs in the body and is called Bastard Strangles, it is usually fatal. Control: the best way to control strangles is to isolate the infected horses and disinfect all of the equipment that goes near it to avoid spreading it. Treatment: Penicillin is used to treat it. The abscesses may need to be opened and drained. 9 Recovery: Most horses do recover but it can be three months before they are fit enough to go back to work. 10 Conclusion Many things happen in the horse's body every day that people don’t think about, their body systems are like a humans. This makes them hard to look after the way we use them because there are so many risks involved in everything they are made to do. Decision trees are an easy way to find out if your horse has the symptoms of a common ailment, but there is also a bad side to it because someone could try and treat their horse without ringing the vet, to save money and the horse may be suffering from something worse. Strangles is a very infectious disease and is air borne so it is easily caught. Horse owners have to careful about how they handle infections and make sure that the horse is isolated. 11 References Skeletal system Text: Merrist Wood lecture Picture 1: Southwest Pony Club (1999) skeletal system [referenced in www document] http://www.websouthwest.co.uk/ponyclub/pages/respiratory_2.htm (accessed 28.11.01) Picture 2: C. Wayne McIlwraith, BVSc, PhD (?) Anatomy and Physiology of Equine Joints [referenced in www document] http://www.colostate.edu/depts/equine/graduate/orthopedics/ques tions/anatomyjoint.html (accessed 29.11.01) Respiration system Text: Merrist Wood lecture Picture: Southwest Pony Club (1999) respiratory system [referenced in www document] http://www.websouthwest.co.uk/ponyclub/pages/respiratory_2.htm (accessed 28.11.01) Cardiovascular system Text: Merrist Wood lecture Picture: Southwest Pony Club (!999) cardiovascular system [referenced in www document] http://www.websouthwest.co.uk/ponyclub/pages/respiratory_2.htm (accessed 28.11.01) Renal system Text: Dr. Thomas Caceci (?) urinary system [referenced in www document] http:education.vetmed.vt.edu/cirriculum/VM8054/Labs/Lab23/lab23 .htm (accessed 02.12.01) Picture: University of Bristol (05.09.00) Kidneys [referenced in www document] www.bris.ac.uk/Depts/Anatomy/calnet/potdse/page2.htm (accessed 02.12.01) Diagnostic decision tree Text: Southwest Pony Club (1999) diseases [referenced in www document] http://www.websouthwest.co.uk/ponyclub/pages/respiratory_2.htm (accessed 28.11.01) Strangles Text: (?) (?) OHAHS Health FAQ [referenced in www document] http://www.ohahs.org/strangles.html (accessed 28.11.01) Picture: Southwest Pony Club (1999) diseases [referenced in www document] http://www.websouthwest.co.uk/ponyclub/pages/respiratory_2.htm (accessed 28.11.01) 12