Meats & Animal Products
Animal Fat 
Animal fats are a mixture of fats rendered from different animals. The source of these are varied and include restaurant grease and factory by-products. The mixture of different animals makes it hard to avoid particular ingredients if your dog has an allergy or intolerance. You can never be sure which animal fats are present and also they can vary batch to batch so that even if your dog does tolerate it, it might not in a later batch of dog food.
Animal fats tend to become rancid when exposed to air so they need to be preserved either with artificial preservatives such as BHT, BHA or Ethoxyquin or more natural preservatives such as tocopherols. You should avoid artificial preservatives where possible.
Always look for a product with a named fat source i.e. Chicken fat or lamb fat
Beef
Although a good source of protein, beef is known to cause intolerances in some pets. It is also less digestible than chicken, turkey and lamb.
Fresh Chicken 
Chicken meat is a good protein source with a balanced amino acid mix. "Fresh" is the term used when the % given is for the meat quantity before processing when it is weighed in its wet form. This can be misleading as you are perceiving the % of wet quantity, yet 2/3 of the water is lost during processing leaving you with a much smaller meat content in the final product.
Dried Chicken or Chicken Meal
Chicken meat and meal is an good protein source with a balanced amino acid mix. This is the same as fresh chicken but with the water removed which means that it gives a better guide to the actual quantity in the final product. Can be described as "The dried, clean rendered flesh of the animal with the water and fat removed".
Chicken Fat
Chicken fat is a good quality fat source that is highly palatable.
Duck
Duck meat is a good source of high quality protein. It is easy for dogs to digest and also scores well in taste tests. Duck meat is also a good source of vitamin A and B3 as well as several minerals.
Egg
Egg is the most digestible source of protein as well as providing vitamins and minerals.
Fish
Fish is an excellent quality protein source that is also highly palatable. It also contains good levels of omega 6 and omega 3 which consist of polyunsaturated fatty acids DHA and EPA. DHA is known to help brain function.
Fish Oil
Fish oil contains good levels of omega 3 which consist of polyunsaturated fatty acids DHA and EPA. DHA is known to help brain function.
Lamb
Lamb is a good protein source. It is rich in calcium and a good source of zinc. Lamb meal is used in many hypo-allergenic dog foods.
Meat & Animal Derivatives
"Meat and animal derivatives" is a generic term that covers all animals and parts such as heads, feet, guts, lungs, hair, feathers and wool! This term can be used to hide undesirable ingredients and allows the manufacturer to change the meat source from batch to batch to whatever is the cheapest available at the time of manufacture. Meat and animal derivatives are used in many successful pet foods because most consumers don't know any better.
Go for named meat sources wherever possible.
Poultry Byproducts
Clean parts of slaughtered poultry, such as heart, lungs, liver, kidneys, feet, abdomen, intestines and heads. Can be a good food source but would be better if the actual source was specified, ie chicken.
Grains, Vegetables, Supplements & Additives
Cereals
"Cereals" is a term used to cover many different grains used in pet foods. When you see this as an ingredient, it means that you cannot be certain what is actually in your dog food because they are not using a "named" ingredient. This allows manufacturers to use the cheapest grain available at the time of manufacture and this can change batch to batch.
Corn
Corn is a frequently used pet food ingredient, however it can be difficult for dogs to digest. Used as a carbohydrate source, it is cheap and could be described as a filler. Some dogs are sensitive to corn.
Derivatives of Vegetable Origin
"Derivatives of vegetable origin" is a generic term used to describe by-products of vegetable origin. This is yet another term that is commonly used in pet foods that covers many different ingredients so that pet food manufacturers can use the cheapest available.
EC Permitted Additives
The term "EC permitted additives" covers a large range of different chemicals, allowing a pet food manufacturer to use any of them without having to individually name any of them. This includes artificial colours and flavourings which are known to cause hyperactivity. More worryingly, pet foods using this term can contain preservatives such as BHA, BHT and Ethyoxquin which have been shown to cause cancer.
Oats
Oats are a versatile ingredient used as a fibre source, also providing a good source of energy.
Pea Flour
Pea Flour is a powder milled from roasted peas. It is good in small amounts as it is rich in iron and calcium as well as being high in protein and fibre. Some foods use it in larger quantities as a protein source but meat protein is more easily digestible.
Potato
Potato is a high quality carbohydrate. It is often used as an alternative to rice and therefore a good ingredient for dogs with rice intolerances but its starchiness may not make it a suitable ingredient for diabetics.
Propylene Glycol
Propylene Glycol is a preservative that is used in pet foods. It is best avoided as it is known to cause problems such as hair loss, dull coat, diarrhoea etc. Also used in antifreeze.
Rice
Rice is the most digestible of all grains and is known to be low in allergy risk and so is found in many "hypo-allergenic" pet foods. Rice is rich in unsaturated fatty acids and B Vitamins.
Rosemary
Rosemary is used in pet foods as a preservative as it is a natural antioxidant.
Seaweed
Seaweed is a great source of iodine and minerals.
Soy
Soybeans are widely used in dog foods as a protein source. However, soy is commonly known as a cause of food allergies in dogs.
Sugar Beet Pulp
Beet pulp is a good source of insoluble and soluble fibres but it is largely a filler.
Tocopherols
Tocopherols (Vitamin E) are a naturally occuring antioxidant which is used to preserve pet foods. Tocopherols are often made from edible vegetable oils. The use of Tocopherols is often a good indication of a better dog food.
Wheat
Wheat is a grain used as a carbohydrate source in dog foods, however it is associated with causing allergies in many dogs and is usually the first ingredient to be looked at when dietary intolerance is suspected.
