The most common complaints for horses admitted for internal medicine problems are: respiratory diseases, poor performance, chronic weight loss, neurologic problems and gastrointestinal diseases. Less frequently, horses are admitted for ocular, urinary and skin problems.

Respiratory diseases include a wide range of conditions, the most severe being pneumonia or pleuro-pneumonia. In cases of pleuritis, horses need immediate assistance, focused therapy including drainage of fluid and aggregates from the pleural cavities. Upper airway diseases are frequent, and therapy may involve both medical and surgical management, like in the case of guttural pouch empyema and sinusitis.

Poor performance may have several causes, including orthopedic problems. Horses must be examined from the musculoskeletal apparatus to respiratory system, where conditions of the upper tract (laryngeal hemiplegia, dorsal displacement of the soft palate, entrapped epiglottis being the most common cases) can be diagnosed using video-endoscopy. Lower respiratory tract may be investigated using both endoscopy and ultrasonography of the chest. In these cases, blood tests represent one more diagnostic tool.

Chronic weight loss and gastrointestinal diseases require a complete set of exams: physical examination, blood tests, rectal examination and biopsy, glucose absorption test, gastroscopy and abdominal ultrasonography.

The neurologic patient is frequently a challenge and blood tests associated with diagnostic imaging (radiography, ultrasonography and sometimes scintigraphy) represent the best tools.