I know a lot of people who give garlic to dogs in various forms - powdered is what Ann uses, another friend uses capsules from the supermarket, and another crushes cloves and puts them in olive oil and adds some to each meal.
Just found this -
Why the controversy over garlic?
The primary reason AVMA (American Vet association) is against feeding garlic is that it contains thiosulphate, which can cause hemolytic anemia, liver damage and death. However garlic only contains very small traces of thiosulphate and a dog would have to consume a huge quantity for any negative effects. Using Tylenol (acetaminophen) or benzocaine topical ointments to stop itching are far more likely to cause anemia in dogs.
Garlic’s medicinal properties
There are many health benefits to feeding garlic. Here are some things you might not know about this healthy herb:
Garlic is a natural antibiotic and won’t affect the good bacteria in the gut which are needed for digestion and immune health
Garlic is antifungal
Garlic is antiviral
Garlic boosts the immune system
Garlic makes dogs less desirable to fleas
Garlic is antiparasitic