Lower airway disease may be limited to the respiratory tract or may involve the “whole horse” with systemic signs such as elevated temperature and loss of appetite. The most common finding is upper airway mucus seen with an endoscopic exam. This finding can be observed with several differing syndromes (inflammatory airway disease, infectious bronchitis, pleuropneumonia, etc.) so a specifiic diagnosis is required for proper treatment. Lower airway disease also can be caused by environmental allergens and irritants. These airway diseases can be responsible for a significant cause of decreased racing and training as well as increased costs to the owner for diagnosis and treatment.
Exercise-Induced Pulmonary Hemorrhage: EIPH is a very common problem in racehores and, depending on its severity, can be responsible for increased veterinary costs to the owner as well as lost days training and racing. This syndrome, which occurs in nearly all horses over their racing career, is characterized by blood found in the horse’s airway post-exercise that originates from the lungs.
Upper Respiratory Tract Dysfunction: Normal mechanical function of the upper airway is critical to the racehorse. Diagnosis is primarily made by an endoscopic examination. Surgery is available to treat some of the conditions with outcomes dependent on the individual case. The most common problems include:
**Displaced soft palate – common in young horses and often related to conformation. May resolve with maturity, management, equipment changes or surgical intervention.
**Laryngeal paralysis (roarer) – decreased function of the ability to abduct an arytenoid – can vary from mild to severe with corresponding impact on performance as airway size decreases. Surgery is available for most cases.
**Entrapped epiglottis – epiglottis becomes enveloped in aryepiglotic tissue (membranes that are normally under epiglottis). This condition usually has a good prognosis with surgery.
**Collapsing pharynx – the entire pharynx decreases in airway size during exercise. This is only visible during dynamic videoendoscopy. It has a poor prognosis for racing success.
Colic – The leading cause of death in horses, colic refers to abdominal pain which can have many causes. The discomfort can be caused by a simple obstruction, usually in the large colon; a strangulation, usually a twist or torsion in the small or large intestine that shuts off the food passageway and blocks the blood supply; abnormalities of the intestinal blood supply (vasculature), usually caused by parasites (i.e., strongyle larvae in the blood vessels); and other disorders that include gastric ulcers.
Tying Up Syndrome - Exertional rhabdomyolysis, also called “tying up,” refers to an exercise-related muscle condition that typically presents with a shortened, stiff stride, anxiety, pain and sometimes results in the horse being unable to move forward. In severe cases the muscle damage can result in permanent muscle atrophy and in rare cases renal collapse. Management and early diagnosis play a significant role in managing this syndrome in racehorses.
EPM (Equine protozoal myeloencephalitis) is a common neurological disease of horses. Horses with EPM most commonly have abnormalities of gait but also may present with signs of brain disease. The disease ranges in severity from mild lameness to sudden recumbency and clinical signs are usually progressive. Two causative protozoa agents have been identified: Sarcocystis neurona and Neospora hughesi. Diagnosis is based on clinical signs and antibody tests on either blood or spinal fluid. Treatments are aimed at inhibiting the protozoa metabolism and improvement related to treatment may be noted over an extended period of time.
Infectious disease is any disease process that is capable of spreading rapidly to others by aerosol or direct contact. Examples are equine herpes virus, equine influenza, etc. Race training facilities carry risk of infectious disease by the very nature of their operations with frequent introduction of new horses, confined stabling area, and travel between racing locales. Specific vaccine requirements are mandatory at most racetracks and care is given to management of the entire backside as well as the individuals to minimize this risk.