Monday, 2 November 2015

All About ... Recurrent Airway Obstruction

If you regularly read my blog you will know that Basil has some level of Recurrent Airway Obstruction (RAO) .  This used to be called Chronic Obstructive Pulmonary Disease (COPD) and Fidget was a sufferer.  It is not known as COPD now because several aspects of the disease differ from COPD in humans.  Basil's RAO seems to be triggered by some type of pollen - which we haven't managed to identify yet - and also stress.  He does not generally cough a great deal and has little mucus  but he noticeably has more trouble breathing and his sinuses grow in size!

Have a look at my  blog about the Respiratory System to understand more about how this works.

What is

RAO is common, it limits performance and is an allergic respiratory disease. There are 2 forms of RAO in horses one which is associated with stabled horses which are fed hay and also summer pasture associated RAO seen in pasture kept horses.

  • Respiratory difficulty 
  • Flared nostrils 
  • Heave line:- When the abdominal muscles help with breathing they can increase in size and so leading to the heave line.   
  • Rapid breathing 
  • Laboured expiration 
  • Wheezing:- occurs when the air is flowing through narrowed airways. 
  • Crackles:- due to excessive mucus production. 
  • Chronic cough 
  • Nasal discharge 
  • Cough during feeding or exercise 
  • Loss of performance

Usually seen when susceptible horses are exposed to common allergens.  It is thought to be the lungs hypersensitivity to inhaled allergens.  These are often mould or dust found in straw or hay but can be a certain type of pollen, often oil seed rape is the culprit.  The small airways become inflamed and narrow, mucus is produced and these lead to the signs mentioned earlier.

The average age at which a horse develops RAO is 9 years old.  This is approximately when I first noticed Basil and Fidget with the signs, which gradually got worse as they got older.  It can occur in any breed but there does seem to be a genetic susceptibility.

Usually RAO is diagnosed from a physical examination and the horse's history as there is little to be seen from blood tests.  Radiographs may show changes to the diaphragm.

Treatment & Prevention
Environmental management is the most important treatment and preventative measure.  This is a long term commitment as horses with RAO will always be susceptible.  Horses that suffer only mildly can often be kept healthy without drugs.   

The most common causes are dusts present in hay and straw.   Sufferers should be kept at pasture as much as possible with fresh grass as the source of roughage.  Round bale hay has been found to be particularly allergenic.  

Horses that must be stabled should be fed soaked/steamed hay or haylage.  Straw should not be used as bedding, an alternative low in dust should be chosen.  The horse should not be stabled close to an indoor arena or a haystore.  The bedding should not be thrown around and sweeping should be avoided close to a sufferer.  

Horses with summer associated RAO should be kept in a dust free stable environment. 
Corticosteroid can be given to reduce the pulmonary inflammation but these should be avoided in horses or ponies at risk of laminitis (Fidget NEVER had these).  Bronchodilators (eg: Ventipulmin) can relieve obstruction of the airways by relaxing the muscles around the walls of the airways. They can be given as powder in food or inhaled using a special mask.

In a perfect world we would be able to follow the advice to the letter BUT it is rarely that easy.  Fidget's RAO was due to dust but keeping him out all year and 24/7 was not an option as he had a tendency to being fat and was at risk of laminitis.  He had to have soaked hay and I avoided producing any dust near him.  His was fairly easy to manage.  
Basil's is more tricky in some ways.  We have not yet managed to identify the pollen that sets him off, although I think it is something in the hedgerow.  When I restrict their grass, in late spring, he rummages in the hedge and this seems to be when he sets his RAO off.  I really don't feel it is fair to keep him in 24/7, it is something I don't agree with for horses.  He has soaked hay and I am hoping to be able to buy a steamer soon instead.  Although the hay isn't really his trigger reducing the allergens can't be a bad thing!  I am looking into herbal breathing supplements too to see if there is something I can give him to help the situation.  Watch out for my blog about that soon!

Did you see last week's video 'New Rugs'  on my You Tube channel.   
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Until next time!

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