EQUINE ENDOSCOPY
An endoscope is a piece of equipment which can be used to look inside some parts of the body of the horse in order to
identify abnormalities. Fibreoptic endoscopes transmit images from the subject, through long thin glass fibres into a
magnifying eyepiece. Videoendoscopes display the images on a television screen, making it easier for several people to
view the procedure. Flexible endoscopes have controls to enable the veterinary surgeon to turn the end to obtain the required views. This article discusses some of the uses and applications of endoscopy in the horse.
Respiratory endoscopy
One of the most common reasons for ‘scoping’ a horse is to investigate poor performance or abnormal respiratory noise.
The endoscope is passed up one of the horses nostrils, often with the aid of a twitch or mild sedative and into the pharynx
(throat region). The larynx of the horse is the opening to the trachea (windpipe). There is a condition known as recurrent
laryngeal neuropathy seen in larger breeds of horse in which the left side of the larynx becomes paralysed such that the
opening to the windpipe is compromised during exercise. This results in an inspiratory ‘roaring’ noise at a canter and can
limit airflow to the lungs and severely affect performance. It is a common problem in racehorses, but can be significant
in all types of performance horse from hunters to dressage horses. Endoscopy is used to assess the severity of this prob-
Picture of a horse’s larynx showing left
sided laryngeal paralysis (the horse’s left
is to the right of the image.
Picture of the same horse’s larynx following tie-back surgery.
lem and guide treatment which in severe cases is ‘tie-back’ surgery, in which the defective left side of the larynx
is surgically fixed in the ‘open’ position. Some horses have more complicated problems causing partial obstruction of the airway during exercise. These can be investigated by performing endoscopy on a treadmill, or using
one of the newer overground systems in which the endoscopic equipment is mounted on the horse or jockey during exercise and the images relayed telemetrically to the veterinary surgeon.
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N.de P. 2011
An endoscope can be passed through the larynx into the
trachea, in order to look for any discharge from the lungs.
This may be blood in the cases of horses with exercise
induced pulmonary haemorrhage (EIPH), pus in horses
with pneumonia, or excessive amounts of mucus in horses
with recurrent airway obstruction (RAO, also known as
heaves, COPD or equine asthma). Sterile fluid can be
flushed into the airway in order to assist in the collection
of a sample of the discharge. This technique is known as
tracheal lavage and is very helpful in the diagnosis of
pneumonia and allergic lung disease.
Other disorders can also be investigated by endoscopy of
the respiratory tract. Ethmoid haematomas are abnormal
masses found at the back of the nasal passages, which can
cause intermittent nosebleeds. These may be visible on
Videoendoscopic image of the lower
end of a horse’s trachea (windpipe)
where the airway divides to each lung.
endoscopic examination. Treatment can involve
formalin injections via the endoscope or transendoscopic laser surgery. Sinus disease which can cause
nasal discharge can be investigated by the passage of
an endoscope up the nostril to view the drainage
from the sinus into the nose, and also by trephining a
hole directly into the sinus and inserting the endoscope, a technique known as sinuscopy.
View of the nasal passages of a normal
horse.
The guttural pouches are outpouchings either side of
the horse’s pharynx which are connected via slit like
openings to the throat. A small endoscope can be
guided under the flap which guards the opening to
the guttural pouch. The guttural pouches are potential sites of fungal infection which can cause severe
Pus
Endoscopic view inside a normal guttural pouch
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Videoscopic image showing pus discharging from the guttural pouch opening.
[email protected]
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life threatening haemorrhage, a condition known as guttural pouch mycosis. They are also the most common site for horses
to harbour streptococcus equi (strangles) bacteria either as frank pus (known as guttural pouch empyaema) or in lower
numbers in apparently normal horses following recovery from strangles infection. Guttural pouch washes can be taken using the endoscope to identify these silent strangles carriers, and treatment with penicillin can be directed via the endoscope
into infected pouches.
Gastroscopy
An endoscope can also be passed down the oesophagus (gullet)
of the horse into its stomach, in a technique known as gastroscopy. In adult horses, this requires an extra-long endoscope measuring 3.5 metres in length. This technique, which is performed in
the standing sedated horse, is most commonly used to look for
gastric ulcers. Gastric ulcers are extremely common in horses
and often go unrecognised as signs can be surprisingly vague and
mild. Although it is often thought of as a problem associated
with racehorses, all types of horse and pony can be affected.
Signs can include poor performance, reduced appetite, weight
loss, irritability, poor hair coat and more rarely intermittent colic.
In a recent survey, over 60% of horses in were found to have
gastric ulcers. Gastroscopy is used to identify the ulcers and
grade their severity, and then to monitor the success of treatment,
which includes drug therapy, management and dietary changes.
Image of a gastric ulcer
Naomi de Pennington performing videogastroscopy.
Other uses
An endoscope can also be used to examine the urinary tract, in the identification of bladder or urethral stones, tumours or
infections. Endoscopes can also be very valuable in examining the oral cavity, in the investigation of dental disease.
Avonvale Veterinary Practice Ltd
01295 670501
[email protected]
N.de P. 2011