Respiratory pathologies of viral, bacterial, inflammatory, and fungal origin

Respiratory symptoms in horses can be similar (coughing, sputum, increased effort and/or respiratory rate), but the causes of these symptoms can be different. Viral infections are common.

Viruses are common, particularly the herpesvirus responsible for the notorious rhinopneumonia. Unfortunately, no specific treatment for these viruses exists.

Bacteria can also invade the respiratory tract, particularly strangles, which is highly contagious. Antibiotics may sometimes be necessary.

Sometimes, it is simply an allergic reaction to hay, as in equine asthma; in this case, corticosteroids or bronchodilators will be helpful.

Finally, fungal infections are quite rare. To make a diagnosis, the respiratory system will be observed using a camera (endoscope). This will allow samples to be taken from more or less deep within the airways, which will be sent to the laboratory for analysis.

Upper Respiratory Tract Pathology

Laryngeal hemiplegia

Laryngeal hemiplegia means that a cartilage (arytenoid cartilage) in the horse's larynx presents a degree of paralysis, varying in severity, causing a characteristic noise during exercise (horning). The paralysis of this cartilage causes a reduction in the diameter of the tracheal inlet, reducing, particularly during exercise, the flow of air to the deep airways. This can cause exercise intolerance, varying in severity depending on the intensity of the exercise required of the horse.

The diagnosis of this pathology can most often be made via endoscopy (examination with a camera) of the upper airways at rest.

Dynamic endoscopy (the camera is held in place at the larynx while the horse is working) allows visualization of this region during exercise, thus providing additional information to optimally target the type of treatment.

In most cases, and depending on the degree of paralysis, treatment consists of inserting a prosthesis into the paralyzed cartilage to fix it in a more open position or reinnervating the paralyzed cartilage so that it gradually recovers normal function.

Dorsal displacement of the soft palate

This involves a displacement of the soft palate above the epiglottis. This reduces airflow through the deep airways and causes a snoring sound during exercise as well as exercise intolerance. A dynamic endoscopy (placement of a camera in the horse's throat while it is working) is necessary to diagnose this type of displacement, which, in the majority of cases, is not present at rest.

Ethmoid Hematoma

An ethmoid hematoma is a mass that develops in the nasal cavities. It can sometimes cause intermittent bleeding and respiratory noises. Treatment is sometimes necessary.

Guttural Pouch Infection or Fungal Infection

Guttural pouches are air-filled cavities located bilaterally to the throat. Bacterial or fungal infections can occur there. It is important to have them examined by endoscopy if suspected, as large vessels and nerves pass through this area, which can lead to serious consequences if affected.

Sinus Diseases

Sinus diseases are common in horses. Most of the time they are associated with the presence of dental anomalies and in this case we often notice a unilateral purulent and nauseating discharge. Surgical treatment to drain the contents and dental care are sometimes necessary.

Resting Endoscopy

Endoscopy involves inserting a camera into the horse's airways through the nasal cavities. This examination allows visualization of the various structures of the upper respiratory tract, visualizing the amount of mucus, and assessing the presence of thickening or other abnormalities in the deep airways. In addition, samples can be taken through the endoscope to diagnose bacterial, viral, or inflammatory airway pathologies.

Dynamic Endoscopy During Exercise

Dynamic endoscopy involves placing a camera at the horse's throat while it is exercising. This examination allows for the assessment of the upper airway during certain types of work or a certain positioning of the horse's head and neck. Dynamic endoscopy is very useful in cases of respiratory sounds during exercise or to diagnose certain upper airway pathologies not visible with resting endoscopy (e.g., displacement of the soft palate).

Tracheal Lavage

Tracheal lavage involves injecting sterile fluid into the trachea and then collecting it for macroscopic observation with the naked eye. It is then sent to the laboratory for bacteriological analysis, for the detection of viruses or fungal elements, and for cytological analysis (analysis of the cells in the fluid).

Bronchoalveolar Lavage

Bronchoalveolar lavage involves injecting sterile fluid into the bronchi and then collecting it. The fluid is visually examined and then sent to the laboratory to assess the presence of inflammatory cells, blood, etc.

Arterial Blood Gas Measurement

This involves taking blood from an artery and measuring oxygen, carbon dioxide, and pH to obtain an idea of the quality of gas exchange, the horse's oxygenation, etc.