Nasal discharge The snotty nose!


Joe Ivey BVSc MRCVS, Rosevean Veterinary Practice

If you have been around horses for any period of time you will have seen a horse with nasal discharge at some time. Nasal discharge can result from inflammation or bleeding in any part of the respiratory tract.
The respiratory tract involves:

  • the nose and nasal cavity with the air-filled bony cavities in the skull called the sinuses which communicate with the nasal cavity;
  • the throat (pharynx) and the air filled guttural pouches which sit on either side of the throat;
  • the larynx which forms the junction between the windpipe (trachea) and the pharynx;
  • the windpipe and the lungs which comprise of dividing airways (bronchioles) like the branches of a tree and the air sacs (alveoli).

The nasal cavity and airways are lined with cells that produce mucus and have tiny hairs that together trap particles and transport them upwards to help protect the delicate air sacs. If the airways become infected or inflamed for any reason then an increased amount of mucus is produced this can appear at the nose as a thick discharge. The commonest causes of respiratory tract inflammation are viral, bacterial and allergic respiratory disease all of which can present with nasal discharge among other symptoms. There are many other less common causes which may present with either a unilateral (one-sided) or bilateral (both sides) discharge. If the nasal discharge is unilateral it generally means the source of the problem is in front of the pharynx where both sides of the nasal passages communicate. However, a bilateral nasal discharge can come from any part of the respiratory tract.

Some common causes of nasal discharge:

Sinusitis (infection/inflammation of the sinuses) Viral or bacterial respiratory infection
Tooth root infection/abscess Allergic respiratory disease e.g. recurrent airway obstruction (RAO)
Guttural pouch infections EIPH (Exercise induced pulmonary haemorrhage)
Strangles Pnemonia
Guttural pouch infections


In order for us to work out what is causing the discharge we need to consider the age of the horse, the breed and use of the horse, the history of the problem and perform a physical examination.
Age: Certain conditions will only be relevant in very young or new born foals such as a cleft palate. Otherwise age can give an indication as to the likelihood of a condition but it is not set in stone. For example, viral and bacterial respiratory infections are more common in young horses whereas nasal tumours are more common in older horses.

Breed and use: A thoroughbred race horse is more likely to get exercise induced pulmonary haemorrhage (EIPH) post racing; a condition in which the horse bleeds into the lungs during galloping. In general competition horses are more likely to come into contact with viral infections.

Other signs: The presence of other signs will also assist with localising the source of the discharge, for example with infections the horse will often also have a raised temperature and be unwell whereas a horse with an allergic condition will be physically well. Conditions involving the sinuses often result in facial swelling. A full physical examination will examine the respiratory tract and the mouth to identify abnormalities.

Type of discharge: The appearance of the discharge can often give clues to the cause. A clear mucus-like discharge is often seen with a viral infection or in allergic respiratory disease. A yellow or green discharge suggests a bacterial infection which could originate from any site in the respiratory tract or be secondary to another cause of inflammation e.g. viral infection. A one-sided discharge that is very smelly often suggests a tooth root infection. A bloody discharge can be associated with EIPH, trauma or a tumour of the ethmoid bones at the back of the nasal cavity. Swallowing disorders can result in a nasal discharge containing food material.

In some cases further diagnostic procedures are required:

  • X-rays – fluid lines present in the sinuses or guttural pouch, changes around a tooth root, or masses in the nasal chambers may help indicate where or what the problem is.
  • Respiratory tract endoscopy – by passing a small camera up the horse’s nose we can visualise the nasal chambers, guttural pouches, pharynx, larynx and upper airways and we can also use this to take samples from these structures if required.
  • Bacteriology – this involves taking swabs and or washes from potentially infected areas and culturing the bacteria that may be present.
  • Blood sample – haematology and biochemistry can show us what the white and red blood cells are doing which may indicate a certain type of infection, blood loss, or associated systemic disease.
  • Cytology – involves looking at cells from samples collected from the lungs or windpipe, by washing sterile saline into the airway then drawing it back. The resultant fluid can be analysed to see what sort of cells are present and therefore what sort of problem may be present.
  • CT imaging of the skull – gives a three dimensional x-ray image of the skull which can help diagnose more unusual condition


The treatment for nasal discharge will depend on the cause. Viral conditions may simply require rest and anti-inflammatories, bacterial infections will often additionally benefit from antibiotic treatment and some sinus conditions may require surgery and flushing using an indwelling catheter.

  • Most conditions will benefit from some management changes to assist the resolution of the nasal discharge:
  • feed from the floor to assist natural drainage of the respiratory tract and sinuses;
    turn out as much as possible;
  • stop ridden work;
  • if the horse is unwell keep it in isolation to prevent the spread of infectious disease;
  • use dust-free management to reduce the irritants to the respiratory tract.

Please remember that in the majority of cases nasal discharge is not a serious problem. In most cases it is likely to be a mild respiratory infection but if you do see some of the more serious symptoms such as a unilateral, purulent, bloody, smelly discharge or any other signs of disease then it may warrant earlier intervention by your XLEquine veterinary surgeon.

Author: The Editor

Share This Post On