The other day I was walking my pet on a bike trail here in California. At this time of year it is very dry and all the weeds and grass has dried up.
After we got home I washed my pets feet (because of insecticide) as I always do. Later I noticed that my pet was worrying one foot. I tried to look at it but he had all this hair around his foot and between the pads of his feet. I could not see anything so I waited a day to see if he would stop. He did not stop so I looked in my dog book and read that I should examine the area with a magnifying glass.
I still could not see anything with all that hair in the way so I carefully clipped the hair from his paw and between his pads with a rounded nose scissors. I noted that while I was cutting the hair out I found some tar that hat made the hair mat together and was very hard. That alone was enough to bother him and make it hard to walk for any long distances. It was fine in the house where he could walk on nice soft carpet but when he walked on hard pavement it would surely make his paw tender.
After I had cut out all the mats and grass I finally found it! It was a tiny splinter that had gotten under the skin and like any splinter was bothering him. I took a tweezers and took it out. He was so grateful and I gave him a pet cookie for being so patient with me while I poked around his feet, which he hates as most pet do.