Most people are either unfamiliar with the term "shunt" or are used to its application as a treatment to drain excess fluid from the brain following a stroke.
There is another type, however, that can occur in animals, including dogs. Specifically, a portosystemic shunt is an abnormal connection between the hepatic portal vein and the rest of the circulatory system. This vein connects the gastrointestinal tract to the liver. This abnormal connection in turn causes blood from the gastrointestinal tract to bypass the liver, depriving it of oxygen and vital nutrients. When this occurs, the liver is unable to completely perform its own vital functions, including assisting with the body's metabolism and eliminating toxins from the system. The final effect is to expose the affected animal's body to toxic byproducts from its own digestive system. [...]
The Havanese breed seems to suffer from a wide variety of health problems, though none of these health problems seems to appear with a high frequency. This is most likely due to the fact that Havanese breeders and enthusiasts have dedicated a great amount of time, effort and research into keeping the gene pool healthy and minimizing the risk of disease development. Indeed, the breed is thought to be relatively healthy and the average lifespan for one of these dogs can be anywhere from 12 to 15 years of age. Heath problems do pop up in the breed, though, some more often than others and some more serious than others. One of the health problems seen occasionally in the Havanese is the liver shunt. [...]