There are other factors besides the landing page that go into your ad quality score, and I can’t speak to them without seeing the ads, keyword selection, etc.
That being said, there are some things I noticed that should improve the conversation rate of your page, which should help bump up your score.
First, on mobile, some of the elements are overlapping/cut off. That’s something you should definitely investigate and correct.
Perhaps the biggest issue is that you have two offers competing with each other. People fear making the wrong choice and are just as likely to not chose either at all to all to avoid this. Stick to just one and have it match what’s on your ad.
I like that you have options, but they aren’t differentiated enough on the page. Why should someone choose one over another? Also, if I request a sample, will it be the one shown? Is the the right one for my dog breed?
I know you attempt to offer some info with the link to your products, but I would remove that because it just takes people away from your offer. Keep them on the page and direct them to your goal.
I like the icon for vet recommended, but it would be better if there was some sort of stat or supporting context. Does it have an official approval from a vet association, a report that documents the vet recommended claim or anything like that?
Finally, I think you can refine the copy a bit. It feels a bit stilted in places and seems like your trying to stuff the keyword dry dog food in there.
I hope that helps.
Best of luck!