Boxers like all breeds come with their own genetic problems, that breed clubs, Kennel club and breeders are trying to eradacate. There are a couple of heart conditions that are known in boxers -
    Aortic stenosis - Another genetic heart abnormality. This is when the heart vessels around the aortic valve become narrow (stenosed) a narrowing causes the blood flow to squeeze through the vessels too quickly. The level of narrowing can be detected and graded by a cardiologist vet via stethoscope, a wider vessel will have a slower blood flow which will cause no or mild blood flow disturbances this would be classed as a low grade murmur (no to mild level of aortic stenosis) a grade of 0 - 2 would be completely acceptable and should never cause a dog to have any health problems. A narrow vessel will cause faster blood flow will cause higher level of disturbances heard on stethoscope these murmurs would be graded 3 - 6. A high grade murmur may cause, fainting, exercise intolerance and or sudden young death.

If buying a pup make sure parents (and pref grand-parents) are heart scored and certificate of proof shown. Total score of parents should be 2 or below.

  Cardiomyopathy - This is a very serious condition that can affect a dog of any age even young puppies but symptoms may not develop till adulthood. This condition causes the heart to beat erratically leading to arrythmias (abnormal heart rhythm). Some dogs may not show symptoms of this until later on in life others may have a severe abnormality and this can cause sudden collapse, exercise intolerance and even sudden death. This disease can never be treated but can be in some cases controlled but very often the dog will end up in heart failure due to progressive weakness of heart beat and blood flow.

If thinking about buying a pup make sure you research the breeder a good breeder will happlily discuss the history of their pups pedigree and should be able to reassure that such diseases are not known to be in any of the pedigree.