Miniature schnauzers are a popular breed of toy dog developed in Germany in the 1800s, when there was demand for small dogs. The schnauzer was already a favoured breed in Germany, but very large. That dog was crossed with affenpinschers and miniature pinschers in order to produce the miniature schnauzer. Miniature schnauzers are prone to certain health problems.
According to "The Veterinarians' Guide to Your Dog's Symptoms" (Michael S. Garvey, DVM, et al, 1999) miniature schnauzers are prone to juvenile cataracts, progressive retinal atrophy and a problem of the eyes not growing to normal size.
According to "ASPCA Complete Guide to Dogs" (Sheldon L. Gerstenfeld, VMD, 1999) miniature schnauzers can be prone to Von Willebrand's Disease (where the blood has trouble clotting), kidney disease and Legg-Perthes disease (where blood circulation to the legs suddenly cuts off).
Sometimes male miniature schnauzers have problems affecting their sexual organs, such as the testicles never decending or being malformed.
Other common problems include seizure disorders, an infection of the hair follicles (called follicular dermatitis), hypothyroidism and pulmonic stenosis, a heart malformation.
According to "The Encyclopedia of Dog Breeds" (2nd Edition) (D. Caroline Colie, PhD, 2005) the most common health problems in miniature schnauzers are progressive renal atrophy and kidney stones.