Though reliable accounts marking the early origins of the Spanish water dog (SWD) are lost to history, likely ancestors of the SWD (and probably the Portuguese water dog) were described in the Iberian Peninsula around the 12th century. Primarily used as a herding breed, the Spanish water dog has also been trained to perform tasks for fishermen and hunters including towing boats to shore, gathering fishing nets, and retrieving game from waterways. Though still used as working dogs in modern day Spain and other countries, the demand for Spanish water dogs dropped precipitously during the industrial revolution of the late 18th and early 19th centuries when machines took over many tasks historically performed by the SWD and other breeds. This decrease in demand led to a decline in the world Spanish water dog population which still remains relatively small today.
In general, dog breeds with smaller population sizes tend to also have a smaller amount of genetic diversity within the breed. This means that any two individual dogs from a small breed population are more likely to share the exact same genetic information at any given location in their genome, including disease associated genetic mutations. This is ...