Garlic, feed in small amounts with food approx 3 times a week, adjust quantity to size of your dog. For example for a medium sized dog 1 small clove 3 times a week should be adequate, don't overdo it.
Probiotics can sometimes be necessary, here we would recommend your make own Kefir and if to solve a specific problem, feed in small amounts daily, as general good gut maintenance maybe 2-3 times a week. Alternatively buy a good quality probiotic from your health food shop.
Making your own Kefir is in our opinion the best probiotic you can get, it also the cheapest, because if you look after your Kefir culture, you have an everlasting supply.
Generally though, if you feed a raw diet, there is very little likely hood of your dog needing probiotics on a regular basis, as your dogs gut bacteria should thrive from the food you feed.
Treats : Avoid probably 90 % of what is currently sold as dog treats, most contain grain and more grain, some even claim to be pure meat, they might be but even then the preservatives in these products may cause severe short and long term digestive upsets.Read the labels, -- even if it seems these days you need a magnifying glass the size of dinner plate to decipher the ingredients in most food stuff. Good quality white fish skin treats, with or without kelp added, is a good bet, but avoid salmon for the reasons already given. You could also opt to make your own jerky either in the oven or in a dehydrator. A much cheaper option than most of the truly additive free meat treats on the market.
The good news is, none of the above is rocket science. There is no need to over guild the lily and make raw feeding complicated or expensive.
The above is as close as you are likely to get to provide the diet your dog have evolved to thrive on. That diet is essentially the diet of their ancestor, the wolf. If you follow these recommendations, you will get close to that.
You may see your super cute Shih tzu, but he or she is-- bar a small part of DNA ---- a wolf.
The other bit of good news is: it is not hard work and it is not expensive, just relax use your common sense and select and prepare your dog's food yourself. The payback for making this change is a happy healthy dog and that in itself is --priceless.
Disclaimer :The above represents our opinions formed from 2 decades of feeding a raw food diet and liaising with our customers about the same. It should not be taken to represent veterinary/medical advise.