Start him on a start-up protocol, you do not want to make him more stressed out, with diarrhea and throwing up. Try a half drop of activated, you cannot measure a half drop from an eyedropper. So it is one drop of activated in a glass, fill it up to 1/2 cup of water. Throw out 1/4 of the cup, then top it back up to 1/2 a cup. Place that in his water dish and see what happens. The chlorine dioxide molecules are gone, in 1 to 1 1/2 hours leaving traces of salt and the undrunk water. So it has to be replenished, watch him and his drinking habits carefully; put on your lab coat and make observations. If 1/2 a drop of activated is too much, do it again throw a 1/4 cup out again, then top it off to 1/2 cup. Then you are down to 1/4 a drop of activated.
If your dog does not want to drink the chlorine dioxide water, place it up on your countertop, wait, for 30 minutes then place it on the floor and observe what your dog does. The chlorine dioxide will be at a reduced state, and your dog might finally agree to drink it.
If you do not already have Jim Humbles book "MMS Health and Recovery Guidebook" it can be bought for around ten bucks on Amazon; it has protocols for animals. I have read a lot of anecdotes about animals, and they say that they have a natural attraction to small amounts of chlorine dioxide in their water. Dogs rather drink out of a toilet than out of a dish of water that has been sitting around for two days. Once a toilet has been flushed, it aerates the water, oxidizing it. Dogs with their keen sense of smell, can sniff out quality water, because it is aerated or oxidized.
After 1 day on 1/2 drop, make your way up to 1 drop the next day, then 2 on day 3. If your dog has diarrhea and throwing up bring it back down to 1 drop, and stay there for a week, then try 2 drops again. Some people on this forum cannot tolerate more than 3/4 's of a drop. Many pig and poultry farms run a constant supply line of chlorine dioxide into the drinking water, albeit small amounts. It saves them the cost of antibiotics, and also chlorine dioxide does not seem to affect us or the microbiome of animals. The animals are more healthy and there are far less dead animals.