Because I am of the old school of dog breeder and possibly because I have a range of ages in my dogs, I wouldn't use a carriage of any sort. If they are too ill to use their own legs they just exercise in the garden(Freckles has a cruciate ligament injury and is on cage rest, so only gets out to do ws and ps, then back in her cage, hopefully it's only temprary then she will be with Allez and Belle), if they are old or young they don't need as much exercise, so they have shorter walks (Bobby is 4 months, Hester is 13 years and has arthritis, so tehy walk half a mile on lead twice a day - its enough, Bobby ill be with the big dogs one day), fit healthy guys have much longer (Allez and Belle have their hour free running plus half an hour road walking) Makes for a busy day, but it's my choice to have them and I put the time in. Sorry, but puppies get exercised separately from adults in my book. JMHO