I have found that a $5 bottle of B12 supplement from WalMart is my trick to the afternoon slump.
The item I love besides the price tag is it has no caffeine. B12 is something our body needs and it is water soluble so our body naturally flushes it so it is not possible to overdo it.
Combine this vitamin supplement with exercise and you have a new lifestyle.
BTW - the highly advertised 5 hour energy is excellent but pricey and it has the equivalent of one cup of coffee. It has multiple vitamin Bs including my favorite B12 for energy.
Here's a summary of the the content for the vitamins from 5 hour energy:
Vitamin B3 (as Niacinamide)* 150%
Vitamin B6 (as Pyridoxine Hydrochloride) 2000%
Folic acid (vitamin B9) 100%
Vitamin B12 (as Cyanocobalamin) 8333%
and something called: "Energy Blend" 1870 mg Daily value not established
So you can see if 5 hour energy relies heavily on B12, the $5 bottle of over 30 pills is a great value.
Hope this helps - love dogs with a special fondness for labradors. Best of luck with Kassy!