One study demonstrated negative changes in blood parameters when dogs were given 5 grams of garlic per kg of body weight.2 This translates to eight cloves for a 12 - pound dog! (puppyup.org)
The data gathered in this study have now been used for a further study to investigate whether specific blood parameters can be used in the opposite way to predict future changes in fitness. (sciencedaily.com)
It also resulted in lower stress hormones and improved blood parameters suggesting it was dealing with some of the underlying mechanisms (18). (novaholisticjournal.com)