Factsheets

Horses


Overview
Horses are part of an ever growing industry, with over 600,000 horses in the UK, 1.4 million riders and 5 million people with an active interest in the equine industry*. Most people acquire a horse out of choice, so if you make this decision you should think carefully before going ahead. A horse needs lots of love and care, including regular worming, vaccinations and dental care. Owning a horse is time consuming and can be costly; not only will you will need to consider where you will keep your horse, you must also consider the ongoing costs of owning a horse which include accommodation, bedding, feed and healthcare.

In the unlikely event that your horse goes missing it is going to be very difficult for anyone to know who it belongs to, unless your horse carries some form of permanent identification. It is wise to get your horse microchipped or freezemarked, this will avoid heartache in the long run, should your horse go missing or is stolen.

Horses are herd animals, and thrive on being together with other horses. Don’t forget that your horse will need somewhere to graze, a stable for warmth in the winter time, a constant supply of water, feeding daily and regular exercise. It can cost hundreds of pounds a month to care for a horse, including accommodation, food, veterinary care and insurance; there will be other costs, including buying tack and rugs and extra livery charges when you go on holiday.

Horses can live into their thirties, over this time your horse will need lots of care and attention. Being able to provide all of this will ensure you and your horse make the most of your time together.

* Research conducted in 2004 by the Henley Centre for DEFRA and the British Horse Industry Confederation.

Whistling and roaring

Many horses of all types and ages have been observed to make an abnormal noise upon exercise. These horses and ponies are often referred to as whistlers or roarers. The noise produced can vary from barely audible to a loud roaring noise and is due to turbulent airflow through an abnormal airway. This finding is common in racing Throroughbreds, and can be a cause of poor performance in athletic horses. In less severe cases, the problem may go undetected and may have no effect on the average horse's athletic capabilities.

What is the larynx, what does it do?

The larynx forms an essential part of the upper respiratory tract. The main function of the larynx is to prevent inhalation of food into the lower airway. Its opening comprises a pair of arytenoid cartilages that support the vocal folds and the epiglottis which provides a protective flap over the airway during swallowing.

What causes whistling and roaring?

The abnormal inspiratory noise which can be heard when affected animals are exercised is due to narrowing or asymmetry of the larynx. The correct term for this phenomenon is recurrent laryngeal neuropathy (RLN) or laryngeal hemiplegia.

This upper respiratory disease occurs due to injury to the left recurrent laryngeal nerve (the nerve responsible for innervating the left side of the larynx). Causes of injury to this nerve are multiple and may include trauma to the neck, guttural pouch disease, strangles and neoplasia. In the majority of cases however, the cause remains unknown. Damage to this nerve results in the failure of abduction (opening) of the left arytenoid cartilage; this causes a decrease in airway diameter and disturbance to the flow of air along the upper respiratory tract.

How is RLN diagnosed?

RLN affected horses tend to have a reduced exercise capacity and make an abnormal respiratory noise on exercise. Your vet will palpate the larynx externally to see if he/she can feel any asymmetry of the muscles of the larynx. A slap test may be performed over the withers which reveals failure of contraction of the muscle responsible for opening the left side of the larynx in horses suffering from RLN.

The gold-standard diagnostic technique is endoscopic examination of the larynx. Endoscopy involves passing a fibre-optic camera via the nostrils and along the upper airway so that the larynx can be visualised directly. Asymmetry of the larynx and failure of opening of the arytenoids cartilages confirms the diagnosis of RLN. In mild cases, endoscopy during exercise may be necessary to appreciate the reduction in airway diameter, this can be performed either on a treadmill or in some institutes ridden endoscopic examination can be performed.

How is RLN treated?

The only method of treatment available for RLN is surgery. It is important to understand that not all cases of RLN require treatment. Treatment is only indicated if the condition is severe and/or affects the horse's performance, ie the horse has reduced exercise tolerance.

Many horses used for general purpose riding, dressage and showjumping suffer from RLN with no ill-effect as they do not need to exercise at maximal intensity. In contrast, RLN can severely affect those horses used for racing or endurance riding.

Surgery can involve a hobday (ventriculectomy) and/or a laryngeal tie-back procedure depending on the type and severity of laryngeal paralysis. Recently, some institutions have started to perform standing laser surgery of the larynx which avoids the risks associated with general anaesthesia.