I'm not sure we can assume she's overfeeding Jag - especially since he already looks pretty lean. Dodger is one of those dogs that survives on very little but plenty of working/performance dogs need at least 4%.
I am not sure about worms but definately for giardia - you need to do at least 3 fecal exams, over a week because depending on the cycle, you can get a false negative result!
Does he get any grains? Dodger's only source of grains is training treats but plenty of dogs need something to bind it all together... Have you tried feeding tripe? A friend of mine swears that finding tripe to her dog "cures" everything