Who says your dog and your toddler shouldn't match?
For a sweater to fit a child of 6 months (18 months, 2, 4, 6, 8, 10 years), you'll need:
375, 465, 595, 825, 985, 1175, 1365) yards of worsted weight yarn.
To fir a dog with a 17 1/2 (19, 21) inch chest, you'll need:
110 (250, 400) yards of worsted weight yarn.