Infections are a common cause and may reflect stress or be an expression of management error. They vary from highly contagious types, some of which are notifiable and all of which require veterinary attention, to more low grade organisms that are often a consequence of reduced resistance and usually difficult to recognise. They may result, for example, in loss of condition, abnormal discharges, enlarged lymph glands and discoloured membranes in the eye, mouth and nostril. They generally don't disadvantage the sedentary animal, but are the bane of commercial yards and likely to impede any animal expected to perform at the highest level.

They commonly affect the respiratory system, because this system is so essential and likely to be tested in exercise. They may also affect other body systems and are particularly troublesome when they affect the liver.

Non-infectious respiratory conditions are capable of specific differentiation and can generally be helped. They are sometimes allergic; abnormal blowing after exercise could also be due to anaemia or dehydration; or might reflect a nutritional problem.

Dehydration, caused by electrolyte loss, has an adverse influence on cardiac efficiency; while anaemia, due to causes as varied as worm burdens and cold stabling, impedes oxygen transport.

You may submit a full history and details of any investigations conducted. These would ideally include laboratory test results and reports, particularly of deficiencies, abnormal blood levels, bacterial or viral organisms identified.

It may then be possible to help, or to advise on steps to take, both managementally and with your vet, in order to achieve a solution.