Struvite crystals & stones can be dissolved. Canned food is good bc of the moisture or moisten his kibble w/hot water. Make sure Jonah gets lots of liquids. If he doesn't drink a lot of water, you can make some homemade broth (no seasonings or salt) w/chicken or beef bones (w/all the fat removed). If he's trained to go outdoors only, walk him more often so he can flush out his bladder.
My 2 had struvite crystals b4 & liquefying their diet helped get rid of it.
Canine Kidney Stone and Bladder Stone Prevention - Whole Dog Journal Article 2. Struvite crystals do not require a change in diet. Because struvite crystals do not pose a problem unless the dog has a urinary tract infection, there is no required treatment for crystals, including dietary changes. If the dog does have a urinary tract infection, a prescription dog food will not cure it.