Samples collected from McNabs across the United States were evaluated for their genetic signature and found to support the creation of a unique breed signature for the McNab. Additionally, the tested dogs were also evaluated for certain physical traits and over 100 disease-causing mutations to help establish a baseline for these in the McNab population. They have a keen sense of territory and seldom wander away from home. They are also more likely to defend their territory and family members than many of the more sensitive herding breeds. . McNab dogs may carry the MDR1 mutant gene and can be very sensitive to Ivermectin, which is a common ingredient in heartworm prevention medications. This drug and others can cause serious health problems or even death. A DNA test that demonstrates whether a dog has the mutation is available through the Washington State University College of Veterinary Medicine. The test can be completed by sending them a cheek swab through the mail.