If you ask most people about dogs eating garlic they may well suck in their breath and tell you that it's poisonous to our canine friends and that they shouldn't eat it. To a certain extent this is true, garlic can cause anaemia but one study that came to this conclusion fed garlic at the equivalent of 60 cloves per day to a dog the size of a golden retriever (K W Lee et al if anyone feels like a scintillating read)! It was at this level that anaemia resulted, that's a shed load of garlic. Below this level no ill effects resulted. Now I'm not saying that you should feed anywhere near this eye watering amount but for most dogs a little garlic can be hugely beneficial. It contains a whole host of vitamins and minerals, helps detoxify the body, it's an anti fungal, antibiotic and is a fabulous natural anti parasitic amongst other things. A safe dosage of fresh crushed garlic (not Chinese due to high arsenic content) would be a sixth of a teaspoon per day per 5lbs body weight, so for example a 30lb dog would have a teaspoon (although I feed less than that, about half a clove every other day to my hounds and as yet we have had no fleas or ticks at all this parasite season). As with all new foods, start low and build up, if there's an adverse reaction stop feeding it.
Important bits: as garlic is so pungent do not give to a dog that is on any medication, is pregnant or lactating or a puppy under 6 months of age. Make sure your dogs digestive system is fit and healthy before introducing in to the diet.