hello, constipation is a huge problem with some dogs. the previous respondent is correct on all counts. this business of giving a dog oil is not efficient although it may be effective. if something is indeed blocking elimination or if there is an obstruction otherwise, this oil may allow some material to pass. This makes the owner think that all is well with the dog when in fact all that happened was that the obstruction moved a little to the side, allowing fecal material to pass. whatever is causing the obstruction is still there so a week or so goes by with the dog in horrible discomfort.
IF THE PROBLEM IS FIBRE: the fibre content can be increased by the addition of a 15ml serving of cooked oatmeal per 5kg bodyweight to his meals. it could also be that your pet food is of poor quality.
EXPRESSION OF THE ANAL GLANDS: it doesn't take a rocket scientist to do this yet it does get messy. most vets will do it for a minimal fee if they charge anything at all. it does involves the insertion of a finger into the dogs anus so the dog does express some surprize at the intrusion. if the material comes out like a strip of dried glue then it is indeed an anal gland problem. it may be only part of the problem so don't stop there.
OBSTRUCTION: GET an Xray. bones will show up clearly and the vet will make the correct diagnosis. Dogs have been eating bones for millennia and dogs have been dying a painful slow death from their eating of these bones for just as long. if they would only stick to bones that don't splinter but they don't. Dogs also eat socks, slippers, dog toys like those red rubber cones into which you insert peanut butter etc. and other items so look around to see if you are missing anything