Amanda Kelly’s family received their first Toy Manchester Terrier (TMT) as a gift from her grandparents back in 1985. They fell in love with the uncommon breed and the rest is history. 

In the decades that followed, Amanda and her late mother, Wendy, worked in partnership breeding TMTs, a small breed that is black and tan in color and known for its athleticism, intelligence, and people-pleasing nature.

“They live and breathe every day for their people,” Kelly says. “They love with their whole bodies.”

The breeding community for TMTs is close-knit and concentrated mostly in North America, so when a small number of dogs started to develop urinary stones at a young age, Kelly and others wanted to know why and what they could do to prevent it. 

Kelly credits fellow breeder, Janna Morgan, with making the connection to the University of Minnesota Urolith Center (MUC), where researchers began collaborating with breeders to investigate and pinpoint the cause of the stones. Dr. Eva Furrow, MUC co-director and associate professor of small animal internal medicine and genetics at the UMN College of Veterinary Medicine, was among those looking into the disease, known as hereditary xanthinuria.  

“Working with breeders, we did genetic testing on the dogs and discovered a mutation that was causing the xanthinuria,” Furrow says.  

Hereditary xanthinuria is an autosomal recessive genetic disorder that results in excessive xanthine (a metabolic byproduct) in the urine. This increases the risk for the formation of xanthine bladder or kidney stones and can cause significant kidney disease. 

Once diagnosed, xanthine stones can be treated surgically or with other removal techniques, but the disease tends to recur without additional intervention. To help prevent future stone formation, high fluid intake is recommended, along with a low purine diet. 

With the mutation discovered in 2015, MUC researchers were able to develop a genetic test for hereditary xanthinuria and allow breeders to take a preventive approach to curtail the disease. 

“We were able to start offering a genetic test. Genetic testing of breeding dogs makes it possible for breeders to easily avoid matings that would produce affected puppies,” Furrow says. 

The discovery was embraced by the TMT community, with breeders like Kelly integrating genetic testing into their operations. As the breed is rare, the number of puppies born each year is much smaller than more popular dog breeds and the number of dogs diagnosed with xanthinuria smaller yet. 

“The number of affected puppies that we had was relatively low, but it doesn't make it less important,” Kelly says. “The test for xanthinuria allowed us to catch the problem before it became an issue that was affecting a wide swath of dogs. And that's really important because it's much better to catch a problem when it's affecting a very small number of dogs than to wait until you have a larger number of dogs suffering.”  

In the time since genetic testing became available, the number of xanthinuria cases in TMTs dwindled. Furrow says she hasn’t seen a xanthine stone submitted to MUC from a TMT in years. The development of hereditary xanthinuria testing also opened the door for other types of genetic screening for TMTs. 

“I can't emphasize enough how important the support that our breed has received from the University of Minnesota has been,” Kelly says. “We spent decades trying to figure out how to stop diseases like xanthinuria. I will always be grateful that there are organizations like the University who are willing to support small breeds.”