THE TRUTH ABOUT BITS - PART 7 : ABOUT THE LUNGS

The principal function of the lungs are to transport oxygen from the air into the blood, and to release carbon dioxide from the blood back into the air. Air passes through the nose, throat, and trachea [windpipe] until it reaches the lungs where millions of very small, thin walled air sacs called alveoli are located, and where the exchange of oxygen and carbon dioxide takes place.

The trachea in a horse is around eighty centimetres in length and it is held permanently open by around 60 'C' shaped rings of cartilage, which are approximately six centimetres in diameter. The trachea divides into two bronchi or tubes which are also supported by cartilage, and which lie within the right and left lung. The bronchi progressively subdivide into bronchioles, terminal bronchioles, respiratory bronchioles, alveolar ducts and finally, the very microscopic alveoli. These alveoli are very thin and made from a single layer of simple cells and are surrounded by a network of capillaries [small blood vessels], white blood cells, wetting agents, as well as nerves and lymph capillaries and vessels.

The body's job is to establish equilibrium or homeostasis continually in every cell, at all times, in every place in the body. Therefore in the lungs the exchange of gases takes place when there is an unequal content of gases either in the alveoli or in the capillary blood.

On inspiration air travels until is reaches the alveoli [see diagram above]. As there is then a higher concentration of oxygen in the alveoli than in the capillary blood, oxygen diffuses through the alveoli into the capillaries where it binds to the haemoglobin contained in red blood cells. The oxygen rich blood is then pumped around the body by the action of the heart, ready to meet the needs of various muscles and organs. Similarly, deoxygenated blood which is high in carbon dioxide arrives at the capillaries. Because there is a higher concentration of carbon dioxide in the capillaries than in the alveoli , the carbon dioxide diffuses into the alveoli which is then released on expiration of breath.

The lungs are made up of stretchy, spongy, honeycomb like material, and they fill and empty from activation and relaxation of the muscles of the ribcage and the diaphragm. The diaphragm extends across the bottom of the ribs, and during inhalation, the diaphragm contracts and moves backwards, and together with the chest wall expanding, this allows the lungs to fill. Exhalation is more passive - the diaphragm relaxes and moves forward, the chest wall relaxes, the lungs recoil and empty.

The effect of a bit in relation to the lungs

If the airway is unobstructed, air flows through the nose, throat, trachea and into the lungs with minimum effort of breathing, with minimum suction pressure which originates at the diaphragm, and therefore with a minimum of energy expended. When the airway is partially obstructed by tongue elevation, soft palate displacement and|or held poll flexion, the work of breathing enough air to satisfy the demands of the body, becomes harder or more forceful. Breathing becomes more frequent and there is a far greater suction pressure in the lungs with much more energy expended.

In normal circumstances with an unobstructed airway the act of breathing is unimpeded, however when an airway is obstructed either partially or fully, the suction pressure within the lungs becomes too excessive for the cartilage in the trachea to sustain. This often results in collapse of the trachea, thus preventing air flow either partially or completely. As the body's demand for air increases, the effort generated to breathe is increased, but the air flow becomes less, thus placing body systems in extreme stress and the horse in severe emotional and physical torment.

As each intake of air in an obstructed airway becomes more forceful, the suction pressure in the bottom of the lungs is also increased. The increase in suction pressure within the fragile and thin tissue of the alveoli causes fluid [which contains red blood cells] to be diffused into the lung and the capillary|alveoli barrier to rupture. The pressure within the lungs may be at such high levels, that the fluid is also sucked into the airway, which is exhibited as blood stained fluid discharging from the nose of a horse. The abnormal accumulation of fluid within the lung saturates the lung tissue causing a condition known as pulmonary edema. Pulmonary edema is not only evidenced in horses - many people who experience near drowning can also exhibit this condition, as sea water inhaled into the lungs becomes an irritant which causes the lungs to fill with fluid. Strangulation also causes pulmonary edema. As the person struggles to inhale enough air to sustain life, abnormal and excessive suction force is created in the lungs which results in fluid filling the lungs and capillary|alveoli rupture.

Lungs are organs which are designed to be filled with air, not fluid. At sporting events, the general public sympathises with the 'poor horse' with a 'blood nose'. Sadly for the horse, blood exhibited at the nose means only one thing - that it is being asphyxiated - strangled… from an obstructed airway, which results in pulmonary edema and capillary|alveoli rupture and sometimes a horrifying death. Examples of dysfunction of the lungs caused by an obstructed airway are :

• Interference with correct striding to breath ratio [common] : At canter or gallop a horse breathes in rhythm with every stride, which is referred to as respiratory-locomotor coupling. In the suspensory phase of the gait [when all four feet are off the ground], and also when the front feet are off the ground [with the back feet on], the organs in the abdominal cavity are pushed backwards, the diaphragm contracts and moves backwards, which enables the lungs to fill - in other words the horse inhales. When the front feet are on the ground [with the back feet off], the organs in the abdominal cavity are pushed forwards, the diaphragm relaxes, the lungs recoil, which enables the lungs to empty. In other words the horse exhales.
  
  Any interference in breathing, along with the horse's inability to move in a normal range of motion because of held reins causing bit pain and poll flextion, creates a direct and negative response to the horse's breathing to striding ratio which in turn relates negatively to exercising capabilities.


• Increased suction pressure in the lungs [common] : Partial or full obstruction of the airway either by displacement of the soft palate, elevation of the tonge and|or an abnormally bent airway means that the work of breathing becomes more difficult. Breathing is initiated by the action of the diaphragm - in simple terms, where the suction pressure is the greatest. Increased suction pressure in the lungs creates a chain of events which disables the function of the lungs, and when this occurs even for a small amount of time, a horrifying death becomes imminent


• Pulmonary edema [common in sporting events] : Many physiological processes of the lung are unable to be sustained when there is abnormally high suction pressure present. Fluid from the surrounding tissue is drawn into the lungs, and other fluid which would normally drain from the lungs becomes impossible. This chain reaction quickly fills the lungs with fluid, making them swollen, waterlogged, heavy and solid. Once the lungs fill with fluid, airflow is impossible, and death quickly follows. The body is so finely balanced, that at just one stride of gallop with a fully obstructed airway, the lungs will quickly fill with a large amount of blood stained fluid


• Pulmonary haemorrhage [common in sporting events] : Higher pressure in the capillaries through hard and prolonged exercise, combined with extreme vacuum pressure in the lungs, caused by an obstructed airway creates a rupture in the capillary|alveoli barrier. Capillary blood is sucked into the lungs and combines with edema fluid which is then sucked into the airway and exhibited as bleeding from the nose. Bleeding from the nose of a horse is an horrendous occurrence, however the majority of horses who are in severe respiratory distress do not exhibit this visual sign. Bleeding in the lungs is however experienced in 85% of racehorses, but because handlers cannot see or hear the distress a horse experiences - as a horse is not vocal or facially expressive as a human would be in a similar situation - the handler incorrectly assumes all is well. They are not educated to understand that at a biological level the situation is life threatening. And emotionally for the horse it must be absolute torture. What is equally distressing is how the general public supports horse racing and sporting events and accepts that bleeding from the nose is just something that happens, with no deeper thought about this horrifying phenomenon

Example of increased suction pressure from a partially obstructed airway

Imagine a vacuum cleaner - the motor equates to the lungs, and the pipe and end - the airway and mouth. Suction is initiated at the motor end [the lungs], and when the pipe is free from obstruction everything operates well with no disruption to the vacuum cleaner suction or pressure. When an item partially obstructs the pipe, or if the pipe kinks, the motor works harder to suck. The suction at the mouth end is almost non existent, whilst the suction pressure between the motor and the obstruction is enormous. Increased suction pressure, with decreased air flow, means the motor most probably over time will cause the cleaner to cease to function. Increased pressure in the lungs, and subsequent failure of the lungs, is caused from a partially or fully obstructed airway caused directly by simply placing a piece of metal in a horse's mouth.

The great debate - pulmonary edema or haemorrhage - induced by asphyxia or exercise?

There is much debate about whether bleeding in the lungs results from Exercise Induced Pulmonary Haemorrhage or if it results from Asphyxia Induced Pulmonary Edema.

The proponents of EIPH explain that the phenomenon of bleeding in the lungs is the result of capillary haemorrhage caused from strenuous and prolonged exercise, which causes higher pressure in diseased and dysfunctional capillaries which in turn causes them to rupture. It is also thought that bleeding from the lungs is an unavoidable consequence of competitive training and racing, and that it is a hazard that the racing industry and general betting public need to accept.

This theory is widely disputed by various people, and particularly by Dr Robert Cook, a veterinary science professor and published author who lives in the USA, and who has completed significant amounts of research on the horse's nose, mouth, throat and lungs for over fifty years. He is a world authority on the harmful effects of bits, an active voice in advocating changes to FEI rules, and is an inspiration to millions of people worldwide. It is his opinion based upon years of research and his own personal experiences, that the correct terminology should be Asphyxia Induced Pulmonary Edema or AIPE for the following reasons :

• Proponents of EIPH state that the small airway is diseased and dysfunctional which contributes to easy rupture and haemorrhaging. However diseases of the small airway are not evidenced in race horses who bleed. Firstly the bleeding is too common, too persistent and too long standing in a horse, to be caused by a disease. Secondly, there are no other signs of disease, such as fever, coughing or nasal catarrhal discharge; and thirdly bleeding does not coincide with epidemics of viral respiratory diseases. It is also theorised that chronic allergic bronchiolitis may be the culprit, however if this is so, then horses in New Zealand and Australia should not show signs of bleeding from the lungs, where bronchiolitis is rare. This however is not the case. Similarly, medications which are traditionally used to alleviate the symptoms of chronic small airway diseases have no effect on horses who bleed from the lungs. Also these horses do not have nor later develop a persistent cough, which is a characteristic of this type of disease
  
  The explanation that persistent chronic disease in the small airway of horses who exhibit bleeding from the nose is a contributing factor in this phenomenon is extremely questionable, and is not consistent with the symptoms nor pathology of chronic small airway disease


• The term 'exercise' induced is also very questionable. When a post mortem is carried out immediately on a horse who has died on the race track, the lungs will be found to be swollen, waterlogged, heavy, solid and a dark red in colour. The surface of both lungs present with a symmetrical rash on both sides, which matches the distribution of the dark red discolouration from congestion and haemorrhage in the depths of the lungs. Horses at rest, in stables, being transported, and under anaesthetic who have died from accidental asphyxia exhibit exactly the same distribution of lesions and with the same waterlogged lungs, as those who have died on the race track. Because the pathology is identical to an at rest but asphyxiated horse, this phenomenon is clearly not caused by exercise, and should be correctly termed 'asphyxia' induced


• The term 'haemorrhage' is again very questionable. Medical terminology for a waterlogged lung is pulmonary edema and at autopsy the pathology is identical to that of pulmonary edema with the bronchi of the lungs filled with sticky pink foam. If the fluid was blood, then it would have the ability to clot, which this fluid does not. Whilst it is acknowledged that there is a higher than normal pressure within the capillaries, the rupture of the capillary|alveoli barrier is an occurrence which results from extremely high suction pressure within the already fluid filled lungs. The haemorrhage is a secondary response, after the lungs have already begun filling with fluid, which then mixes together and is sucked into the airway. Because the fluid is not blood, the term haemorrhage is incorrect. The more correct terminology is pulmonary edema.

In conclusion - the meaning of cruelty is defined as 'the infliction of unnecessary suffering'. After reading this seven part article, it is hoped at the very least it has raised some questions. The results of clinical research of the prolonged agony that a bit causes a horse in it's mouth, throat, airway and lungs as well as psychological torment is however, unquestionable. It is fact. The commonly occurring behaviours exhibited by horses - whether they be small and subtle to more violent and dangerous and experienced by riders the world over should be evidence enough - that how we are treating horses and the methods that we are using are not working. In a plea for understanding the horse does the only thing it can to impart it's distress. The use of a bit, along with other abusive practices should never be condoned. Not once, not a few times. Not ever. Having a respectful, harmonious, responsive, effortless relationship with a horse is easy - and it's safer. By using a bit one is committing an act of horrendous cruelty upon an animal who is naturally obliging and peaceful and at the mercy of humans. The time is NOW for a global change. MAKE THAT CHANGE!