Hello Shirley, I'm Dr. Deb.
I recently came online and see that your question about Sid hasn't been answered. I'm so sorry that you've had to wait for a response but if you still need assistance, I'd like to help if I can.
The behavior you're describing is actually fairly common for many dogs but it is nonetheless distressing for all of them and their owners.
We have fairly limited options when it comes to Sundown Syndrome which is usually secondary to dementia... which may be mild or severe...but we do have quite a few supplements which appear to help a large number of dogs with this condition. Of course, they don't appear to help every dog, unfortunately, but would be worth a try. Most all of them are available on the internet.
The only drug licensed for use in dogs for this disorder is Selegiline but I've been quite disappointed in the results thus far.
1. Cognitive supplements such as Neutricks, SAMe (Novifit) and Senilife may be useful for some dogs.
2. Combinations of antioxidants such as Golden Years (Sogeval *) or Cell Advance 440 (VetriScience)
3. High dose fish oils; Welactin or 3V Capsules are specifically formulated for dogs which is why I mention specific name brands.
4. Combination of Acetyl-l-cystine and alpha lipoic acid (200mg/400mg)
5. Many dogs will benfefit from Melatonin which can help them relax and to sleep better at night; it's also a potent anti-oxidant. The dose would be 6 mg which I'd probably give to Sid around 4 pm. Nature's Bounty is a good manufacturer.
6. Diets such as B/D (which is a prescription diet from your vet) or the Purina senior diet with MCT oil may improve cognition and reduce anxiety for many dogs.
I also encourage owners to actively engage and play with their dogs to help with mental stimulation. Regular exercise is also a good thing to keep the blood flowing to the brain.
I hope this helps and that you see improvement with his behavior. Again, my apologies for the delayed response. Deb