The less common form is the cardiac form, which attacks the heart muscles of very young puppies, often leading to death. The majority of cases are seen in puppies that are between six weeks and six months old.

Please remove spaces between words.
Thelesscommonformisthecardiacform,whichattackstheheartmusclesofveryyoungpuppies,oftenleadingtodeath.Themajorityofcasesareseeninpuppiesthatarebetweensixweeksandsixmonthsold.