My Dog will not eat Dog food!
As a dog owner myself, I often get worried when my dog will not eat. Assuming there are no underlying health problems, dogs sometimes refuse to eat their own food simply because they are spoiled rotten. Dogs are spoiled by us humans due to table feeding and feeding when ever they beg for what we snack on. This behavior causes the dog to develop a taste for human foods over time and they prefer human foods rather than dog foods. I had my Mastiff go a day with out his own food when i refused to mix any human food into it. This is how you know you’ve got a spoiled dog, they are expecting you to mix human foods into their food and they know you will do it eventually if they refuse their dog food. There is nothing wrong with mixing human foods into the dogs meal as long as it is done right but the issue is that some days you might not be able to do this and the dog will have no choice but to eat their own food.
Mixing human foods into the dogs food is not an issue for most of us but we can’t always do this, there will be days where the dog will have to eat their own food. If you can do it everyday it is not a problem other than having a spoiled dog and if it makes you happy. For those who can’t, there are 
some easier alternatives to getting them to eat their own food by mixing with easy low cost items. I have tried my many ways to get them to eat their food with a minimum amount of mixing with human foods. Remember you can treat your dog to raw foods on weekends or every now and then, raw meats are great for dogs and it is really what they should be eating. I will share what worked for me and what did not work here.
You have to remember our canines are very smart beings especially the Cane Corso’s like mine. A trick once worked may not work again. For example, I used to mix yogurt with my dogs meals and he used to eat it right up and then some of my family members decided to spoil the dog by feeding tastier foods and now she won’t even touch the yogurt. There are somethings however they will always like such as cheese, peanut butter, chicken etc.
An easy dog not eating solution!
The easiest way to solve the “dog will not eat” problem is to take a slice of cheese and melt it a little bit then add it to their dry food, they will eat this right up. This is the quickest and easiest way for you to get your dog to eat their food. A pack of cheese won’t cost you much and you can do it in a jiffy. This should always work for you and solve your dog not eating problem. If you wish to permanently stop the dog not eating dog food problem, you have to permanently cut out all table feeding, mixing human foods etc. They may refuse to eat their food and whine for a day or two but eventually they will have no choice and will eat their own food but you will have to keep up with this new behavior change on your part.
Puppy not Eating ..
New puppies (puppies separated from their mothers after 8 weeks) may not eat due to a sudden a change in surroundings, but this should change by the end of the day. If your puppy continues to not eat, take them to a veterinarian immediately. There may be underlying diseases that can cause a puppy to not eat such as Parvo which is fatal. When a puppy is eating and still not gaining any weight it could be due to underlying diseases or worms. It is important to check the stools of a puppy for any signs of blood stains and their consistency as loose stools may be caused by worms. A fecal exam will prove the type of worms your puppy has so remember to a sample stool if you are visiting your veterinarian for the first time. You can introduce boiled chicken blended into some white rice for the first 8 hours to get their stools back to normal after Deworming.
Below are link to many diseases which can cause your dog or puppy to not eat, please have a look.
https://pets.webmd.com/dogs/my-dog-weak-lethargic
When it comes to eating issues, check your dog food first. Most of the time it is the reason why they refuse to eat. I have two french bull dogs and they refused to eat their dog food. They would only eat food that I offer them by my hand. Then a friend of mine advised me to cook dog food for them and it was really effective. They recovered their appetite and went back to their normal weight. They became even healthier than before and they seem to be more active than the time I am feeding them commercialized dog food. I did not realize before that I am feeding my dogs poison because of the chemicals and preservatives. These elements will not do any good to our dogs. Shall we continue to feed them (poison them)?