Respiratory problems are common in horses, heart problems occur less frequently. It is important to examine both organs as they work so close together. The lungs supply the blood with oxygen and the heart transports it to the organs. Carbon dioxide and metabolic waists go the other way around.   To establish the cause of a respiratory problems can be a real challenge. Small dust particles are a major problem, not only in horses (mould spores, dirt, bacterial endotoxines) but also in man: exhaust from diesel engines etc. The horse seems to be a good indicator for pollution with small dust particles. Spores from moulds and organic material can induce asthma-like problems. If the challenge occurs for a long time heaves may develop. The lung looses its elasticity and the airways get constricted not only by spasm but also by increase in fibrotic tissue. When the condition is irreversible the horse gets emfysema. In summer pasture COPD the lung responds to an allergen when the horse is outside in the pasture. Normally we want to house horses with allergic lung disease outside in the pasture but in summer pasture COPD this will worsen his condition!

 

Viral- and bacterial infections are common causes of respiratory problems but dust is after all these years still underestimated. Heart problems can induce coughing and respiratory distress but a thorough clinical examination will reveal these problems. Exercise, endoscopy, lung function testing, x-rays and laboratory testing can be helpful in making the right diagnosis. In spite of all the often expensive equipment and testing the auscultation of the lungs remains very important for the experienced clinician.

 

In foals infections are the main cause of respiratory problems. Like in infants we see asthma in young foals but it remains uncertain what role infections play in this complex of symptoms. Influenza virus plays an important role as foals are not vaccinated before 5-7 month of age. An unvaccinated mare will not protect her foal with maternal antibodies which makes the foal a target for influenza (and other) virus. Rhodococcus equi can cause abcesses in the lung and in other organs and seems to be increasing in incidence (see topics).

 

Heart problems are often serious and will be examined by function tests, ecg and ultrasound. See also ultrasound.