How long do worming tablets take to have an affect in dogs? Our old Lab is losing weight for no reason that we can see. We thought we would worm him before a visit to the vets.
I would take him to the vets first. Let them diagnose. Our cat lost weight rapidly, it turned out to be treatable kidney problems. I wouldn't self-treat any animal if you are not sure what the problem is.
Just that worms seemed to be the most obvious reason and thought that the vet would prescribe them anyway to rule that out. I don't think worming tablets are self-treating, it is done regularly with horses.
I only worm my cats every six months as per instructions, chrissa - I wouldn't think of it as an immediate reason for losing weight, not in an older animal. I don't know about horses, not my province! My only thought was that worming might get in the way of any other treatment that the vet might prescribe.
Only a day or so, depending on the product. You may not see any worms as they dissolve with some wormers. However, the weight would take a long time to put back on and to be honest dogs can have a heavy worm burden before they will actually lose weight. More likely to be just old age. Try changing his feed to something that will put weight on like tripe or pasta.