Even though my two redbones do go to dog parks, field trials, etc., they rarely have fleas. If I notice them scratching, or I get a flea bite myself, the first thing I do is go over them with a flea comb. These are fine-toothed combs available at any pet supply store for a few bucks. Some are plastic, some metal.
Fleas are most likely to congregate around the anus and genitals, under the collar, in folds of skin, and on the belly. Check the entire dog for fleas by running the comb through the fur. Disturbed fleas are apt to hop — sometimes several feet, so do this outside or in a confined area, like the bathroom. If you can handle the comb with a thumb free to trap the flea against the comb’s teeth, it is less likely to get away. Fleas have hard shells which make them difficult to kill. I crush them against a hard surface with the flat side of a fingernail or cut them with a knife against a hard surface. Some people just toss them into a bucket of sudsy water, then flush them down the toilet. Check the dog several days in a row, then check again two weeks later—flea eggs take about two weeks to hatch out. In addition to live fleas, the comb is apt to scrape loose flea droppings and flakes of dry dog skin. Flea droppings are brown or black, about the size of pepper flakes. There may be flea eggs mixed in with these, so makes sure you clean these off the floor and comb when done.
Ingested flea meds and poor quality food can also cause skin irritations. The most common food allergy in dogs is corn, which is used as a filler in most of the cheaper brands of dog food. All dog food sold in the U.S. is labeled with the ingredients in order of importance. If corn is among the first few ingredients listed, you may be better off switching to a different brand. The first few ingredients listed should all be animal-based — meat and meat by-products. Often times there are locally produced brands that are fairly cheap and use minimal corn and other grains.
Disclaimer: The publisher is not a veterinarian, and these are based on her own experiences