DD, it would actually be 12.5 weeks of no wins to blow up that bank, or 225 straight races without winners (horses and dogs).

Benny, probably not the answer your looking for but just go flat stakes to begin with, if you can't break even or make a profit with flat stakes then its unlikely any staking plan or special money management techniques will help.

Is the horses/greyhound races you say you bet is that per day or per week?

i.e. horses 5-6 races per week or 10-12 races per week (5*2 - 6*2)

I'd just take the total races you expect to bet on per week (dogs and horses) and divide 80 by that number, bet that stake per race until you've got maybe 1 cycle of bets under your belt (i.e. 12.5 weeks) and if your above $1,000 use the betting history (POT, SR, Max Drawdown) to look at various staking plans/ideas.

^ I know thats probably not the simple or easy answer you wanted, but thats how i'd approach it if you have the patience.