Primary Lens Luxation: A hereditary defect that destroys the fibers holding the lens of the eye in place. The lens shifts out of place, causing sudden and painful blindness. The genetic mutation responsible for the condition has been identified. PLL Clear dogs will not develop the condition. PLL Carrier dogs have an extremely low risk of it and may pass the mutation on to their offspring. PLL Affected dogs are likely to develop PLL and definitely will pass the mutation to their puppies. All MBTCA-member breeders are required to test their breeding dogs for the defect. 
 

          Heart Problems: Mini Bulls may have defective heart valves that make it difficult for blood to flow through the heart properly. Undiagnosed and untreated heart valve problems can lead to congestive heart failure, atrial fibrillation, and early death. All MBTCA-member breeders are required to have their breeding dogs screened by a board-certified veterinary cardiologist; the screening must include a cardiac ultrasound (echocardiogram) with color Doppler to check the valve flow accurately.
 

          Kidney Problems: Hereditary nephritis (HN) and polycystic kidney disease (PKD) are often called “silent killers” because dogs may exhibit no symptoms until their kidneys have failed. HN is tested with a urine screening; PKD requires a kidney ultrasound. All MBTCA-member breeders are required to test their breeding dogs for HN. 
 

          Deafness: Although usually associated with white dogs, colored Mini Bulls have been known to be deaf as well. A noninvasive hearing exam called a Brainstem Auditory Provoked Response, performed by a specialist, verifies a dog’s hearing ability. All MBTCA-member breeders are required to have BAER tests performed on their breeding dogs.
 

          Patella Luxation: The patella, or kneecap, can slip out of place, causing the dog pain while walking. In some cases, surgery may be required