|A typical black and tan Pražský Krysařík|
This tiny breed was bred to be non-utilitarian. Due to this, the name "Prague ratter" is probably not in reference to the dog's abilities in killing rats. It is usually seen in a smooth coated black and tan, but red or other differently colored dogs and dogs with longer fur are sometimes seen. It is rarely seen outside of Prague. They are very delicate with thin leg bones that are prone to being broken. I am unsure of other health problems in the breed, but patellar luxation is mention on the Pražský Krysařík Club of Czech Republic website.
Unfortunately, I was unable to obtain much information on this breed in English. Because of this, my main source for material was Dr. Bruce Fogle's The New Encyclopedia of the Dog. According to this book, the Prague ratter is characterized as follows:
Height: 6-9 inches (16-22 cm)
Weight: 2-6 pounds (1-3 kg)
Here is the standard from the Pražský Krysařík Club of Czech Republic.
Image is from Wikimedia Commons under a creative commons license.