This handsome fellow is Bronson, a Bullmastiff. The breed was created by crossing mastiffs and bulldogs. They are a solid, stocky breed with a fun personality. Because of their size and guarding ability, it is important to socialize them at an early age. Females weight between 100 and 120 pounds. The males are even larger. The ones I see often weigh about 140 pounds. Bronson is one of the most well-behaved dogs I have ever met. He is a great ambassador for his breed.
Unfortunately, Bullmastiffs are susceptible to a medical problem which eventually causes blindness. Name the disease. There is extra credit available if you know the mode of inheritance.
DIAGNOSIS: PROGRESSIVE RETINAL ATROPHY (PRA)
Progressive retinal atrophy is a condition which causes blindness. In dogs that suffer from the disease, the retina degenerates. Usually night vision is lost first. People tell me their pet seems confused in the dark or does not want to go outside at night. As the condition progresses, all vision is lost. Blindness may occur at any age. Unfortunately, there is no treatment for this condition.
In Bullmastiffs, the disease is caused by an autosomal dominant gene. That means all individuals with this gene will eventually suffer vision problems. A company called Optigen (Ithaca, New York) developed a test for this condition. I recommend testing all Bullmastiffs before purchase and/or breeding. Further information on testing is available at www.optigen.com.