Only one of these can be true, but not both. Cleaning dog kennels can be disgusting but at the end of the day you've improved the dog's living conditions. Sounds to me like you need to go 'big picture' and that you have a dream job. Further, BE GRATEFUL YOU HAVE A JOB.
One of my jobs was busing tables and cleaning the kitchen at the end of the day, I made sure everything was clean. I enjoyed that and came home dirty but always feeling an accomplishment from good hard work.
I am extremely grateful I have a job, sense I am willing to go on the road I have many job opportunities, but this job this job is what I want to be doing, where I want to be for my family and where I want to retire. So to have the working conditions so poor, it is just very frustrating.