Pasture Heaves

(Chronic Obstructive Pulmonary Disease or COPD.)
NB All breathing problems are urgent. They need to be treated immediately to avoid permanent damage to lung tissue.
They should not be exercised until completely back to normal. Be prepared for it to take weeks or even months.
Stabled horses can develop respiratory allergies to dust and mould found in their bedding or hay. This is relatively easily rectified by turning out or removing the offending material and ensuring good ventilation.

What is more difficult to cure is ‘Pasture Heaves’, a very distressing respiratory condition associated with the inhalation of pollens and moulds present in the pasture grass.
It too is characterised by wheezing, coughing and general difficulty with breathing. Airways and lungs become inflamed and constricted. Mucous glands get active and airways are clogged with this thicker fluid.

Horses with heaves usually have no trouble taking in air but have major trouble with exhaling. They need to contract their abdominal or flank muscles to force the air out of their lungs. Repeated use of these muscles will cause a visible ‘heave’ line along the lower abdomen between the girth and the flank.

Breathing becomes noticeably audible from a distance even when the horse is at rest and you will see his sides ‘heaving’.  This is a distressing condition and often signals the end of the horse’s useful life. It is certainly one which is far easier to prevent than cure!
Interestingly there is a school of thought that the root cause is a chronic lack of salt.

A lack of salt leads to a lack of fluid which stimulates histamine production. One of histamines major roles in the body is to control the thirst response as well as redistributing body fluids to tissues in most need of water. (See Histamines)

When a horse has ‘No Puff’

This is a different issue to pasture heaves.

Some horses seem to have no puff. They are short of breath with very little exertion.

It is entirely possible that the metabolic alkalosis caused by the high potassium/chloride depleted diet causes what is known as hypoventilation as a means of correcting body pH.

Therefore, correcting body pH via the diet changes suggested should rectify the problem.

 

 The Mystery Cough

There are a number of conditions that affect the respiratory tract of the horse. Sometimes the cause is obvious due to an accompanying mucous discharge or because it can be associated with allergies or a physical disability but there are also some respiratory issues that don’t seem to be associated with anything and the cause is a real mystery.
For example those horses that exhibit a ‘dry’ cough associated with exercise. Maybe one or two coughs when you start trotting or cantering and then they are OK for the rest of the ride. But sometimes they continue to cough and are actually ‘exercise intolerant’.

We have also observed ponies developing ‘raspy’ breathing just prior to or during a laminitic attack.
Any breathing problems can be difficult to correctly diagnose but as a general rule if there is any change in your horse's breathing it is always advisable to contact your vet who will go through the process of eliminating all the usual causes:..

1.Bacterial and viral infections such as the common cold or the very serious equine influenza (viral), and Strangles (bacterial). Both these diseases are highly contagious and can spread very rapidly between horses. Other infections include pneumonia, herpes virus, adenovirus and rhinovirus. Foals and young growing animals are very susceptible.

2. Allergies Chronic Obstructive Pulmonary Disease (COPD) is very similar to asthma in humans caused by irritants like pollen, fungal spores and/or dust usually from hay and straw. The resultant narrowing of the airways leads to coughing and in more severe cases ‘heaves’ characterised by ‘raspy’ breathing or wheezing and general difficulty breathing. This is an extremely debilitating condition that leads to early retirement and loss of useful life.

3. Anatomical:  Sometimes physical problems develop within the structures of the airways between the nostrils and the lungs which can cause partial obstruction. Such obstructions impair breathing and cause abnormal noises such as ‘whistling’ and ‘roaring’. Usually these are successfully rectified with surgery.

4. Lungworm is a parasite that spends part of its lifecycle in the lungs and respiratory tract of horses and ponies and causes persistent coughing. Sharing grazing with donkeys increases the risk of being infected by this parasite.

When the cause is obvious, for instance where horses are stabled or otherwise confined and their bedding and/or forage is musty, dusty, or mouldy then the solution is obvious: remove the cause. Sometimes the problem is that easily resolved. However when even extensive veterinary investigation fails to identify a cause then we need to look outside the square.

Another possible cause of idiopathic respiratory issues including having ‘no puff’ or coughing on exercise can be a disturbance to body chemistry caused by diet related mineral imbalances. The cumulative effect of feeding potassium-rich forages plus high potassium hard-feeds can result in the body experiencing difficulty maintaining correct pH. This will cause automatic compensatory mechanisms involving the respiratory tract to be triggered in order to restore equilibrium.
The following are possible signs of such a respiratory problem:

• Coughing when eating feeds or starting exercise    
• Audible breathing, wheezing or ‘raspy’ sounds
• Exercise intolerance (no puff or out of breath with very little exertion, continual coughing)
• Increased respiratory rate (normal = 8-20 breaths per minute)
• Noticeable abdominal effort when breathing ('heaves')

Diet adjustments can reduce these signs significantly. Be aware of your horse’s potassium intake in order not to inadvertently add to his load. Horses obtain more than enough of this important mineral from their forage especially when green grass is included, let alone if you are piling in additional potassium-rich feeds. Adding salt to feeds helps to take the stress off the adrenal glands and kidneys whose function it is to maintain the correct potassium:sodium ratio.