Hello and welcome to the AADF forum. Sorry to hear that you are having a few dietary problems with your Whippet. Regarding life stage foods, there are conflicting opinions but as your dog is still lively I think you are probably right in not going down the route of selecting a senior food. With reference to your dog's increased appetite, is this a new thing or as he always been a hungry dog? Have you had him to the vet for a blood screen? I was just wondering if there might be a problem with his liver or kidneys that might be causing this. Having said that, many dogs (including my own) would probably eat forever if they were allowed to.
I've just looked at Arden Grange Sensitive is grain free and the formula is as follows:
Analytical Constituents: Crude Protein 25%, Fat Content 14%, Crude Ash 9%, Crude Fibres 3%, Calcium 2.3%, Phosphorous 1. 5%, Omega-3 2.2%, Omega-6 1.72%.
Composition: Potato 50%, ocean white fish meal 26%, refined chicken oil, beet pulp, whole linseed, chicken digest, whole dried egg, yeast, krill, minerals, prebiotic FOS, prebiotic MOS, yucca extract, glucosamine, MSM, chondroitin, cranberries, nucleotides.
Additives (per kg)
Vitamins: Vitamin A 18,000 IU, Vitamin D3 1,350 IU, Vitamin E 240 IU.
Trace Elements: Zinc chelate of amino acid hydrate 500mg, Copper chelate of amino acid hydrate 100mg, Manganese chelate of amino acid hydrate 67mg, Calcium iodate anhydrous 2.4mg, Selenised Yeast (inactivated) 65mg, Antioxidant (rosemary extract)
On their website they give some very sensible information about feeding quantity. I am wondering if you are perhaps feeding too much? It is tempting when one has a hungry dog but I understand that it can cause loose or soft poo.
You ask about Canagan. I gave this to mine quite a while ago when it was fairly new to the market. They put weight on very easily and for them the higher fat level was not suitable, despite my giving a smaller quantity than RDA. However, had it not been for that, I might have kept them on it because I like the formula; the carbohydrate source is sweet potato, which is well regarded. You know that your dog is OK with this because you already feed it as a supplement. Also the protein is more moderate than some of the better quality foods. That might be a good thing for your older Whippet. Perhaps you could give the company help line a call and have a chat with them? Here is the telephone number: 0800 068 0608.
If you do decide to give it a try, please could you update this thread? You never know if it might be helpful to someone else.