In 1991, a family of Boxers with dilated cardiomyopathy (historically known as Type III Boxer cardiomyopathy) was
identified as having a myocardial L-carnitine deficiency. Affected dogs demonstrated some reversal of disease with
L-carnitine supplementation. However, affected dogs eventually died from their heart disease, even while on
supplementation. L-carnitine deficiency does not appear to be the cause of DCM in the majority of Boxers, or in other
breeds. However, it is still considered a potential etiology for Boxers with DCM and supplementation should be considered
for these rare cases.