what could be causing sudden appetite loss in a dog?

my 2 year old pitbull is completely healthy and super active but lately he has really lost his appetite. he used to eat his food voraciously but recently i have had to put gravy in it just to make him interested, and lately that isnt even working. switching the food upsets his stomach and he is sick of his current food. he rather not eat than eat his food, which is purina large breed formula. is there a better food for dogs with sensitive stomachs??

maybe he's sick check with vet

Why Isn't My Dog Eating?Causes for a Pet's Refusal to Eat© Mia Schamp-CarterJun 15, 2008 Illnesses and injury can cause a pet to lose his appetite and understanding why this occurs can help owners take the necessary measures to ensure a quick recovery.A dog may lose his appetite due to a vast array of illnesses, and even discomfort from an injury can cause a refusal to eat, but understanding why this occurs and what actions to take will help pet owners steer their pet toward recovery.“A loss of appetite and lethargy are the two most common generalized symptoms of illness in pets. These are usually the first symptoms to arise in a sick pet, and the two symptoms can often be interlinked,” explained Dr. Michael Levine, DVM, who added, “When a pet stops eating, I recommend a prompt visit to the vet’s because it’s much easier to deal with the situation early on.”The Causes for Not EatingThe causes for a lack of appetite are many and varied. In many pets, even slight discomfort due to an injury, upset stomach or illness will result in a complete refusal to eat, while other pets will only stop eating when seriously ill.In many cases, it’s minor digestive system upset that causes a pet to stop eating. This can result from eating an unfamiliar food, a non-food item or from a chronic problem, like a stomach ulcer or intestinal parasites. In these cases, the dog will exhibit other signs of digestive problems such as vomiting, diarrhea, excess flatulence, burping, and gurgling sounds in the stomach.“In cases where a minor case of upset stomach is to blame, it’s often best to allow the system to rest for 18 to 24 hours by withholding food. After that period, small amounts of bland food (like cottage cheese or plain white rice with boiled hamburger or boiled skinless chicken) should be offered – start out with just a bite or two and slowly increase the meal size every four hours. This is often all it takes to get the animal back on track,” explained Dr. Levine.In other cases, particularly when there is no sign of digestive upset, the refusal to eat is often the result of an illness or injury. The following are among the most common causes:InfectionVirusesPancreatitisTooth decay/injury and gum diseaseDisease affecting major organ systems, like the kidneys or liverPain from trauma and injuryDiscomfort from chronic pain, such as arthritis or hip dysplasiaDiscomfort due to hot weatherAnxiety or emotional distressBloat or Gastric Dilitation VolvulusIntestinal obstructionThe Effects of Not EatingA decrease in appetite is often the first sign of illness, followed by a complete loss of appetite and a refusal to eat. Often, the pet will also stop drinking, which is a very urgent situation, as dehydration can lead to organ failure in a matter of hours.Lethargy is also a common early sign of illness, as failure to eat leads to hypoglycemia, also known as low blood sugar, which can result in lethargy, weakness and trembling.“One of the simplest ways to combat lethargy is to boost blood sugar with honey or maple syrup, given every four to six hours. I recommend this for any pet who has stopped eating,” explained Dr. Levine, who added that rubbing the syrup or honey on the gums can help in instances where the pet will not lick it voluntarily.The sugar contained in the honey or maple syrup will help reverse the effects of hypoglycemia, and in many cases this will trigger the pet to resume eating and drinking. One large spoonful is sufficient for every 20 pounds of body weight, given every four to six hours, depending on the animal’s activity level (more activity requires more sugar).Failure to eat can also lead to a circular problem, as when the stomach is empty for an extended period of time, the organ’s lining can become inflamed and irritated by the bile and excess stomach acids that accumulate. This can lead to nausea, vomiting of a clear yellow liquid and a continued refusal to eat due to an upset stomach.“If your pet has not resumed eating within 24 hours, or if he’s showing any other signs of illness, it’s important to get him to the vet as soon as possible because a failure to eat weakens the body, and this allows illness to get a better foothold,” Dr. Levine explained.MaY GOD Bless and Keep You

That's odd. Same thing here. My 9 month old female has started refusing her dry food but she is playing like crazy. I put gravy and she ate it . Then refused again after a while, added canned and is eating again. She is healthy and saw vet ran bloodwork /did physical said she may just be tired of her food? I hate switching food as she is on one of the best (eagle pack). I am wondering if with the heat dogs get less appetite as one of my friend's dog is doing the same. Now I am tired of adding canned to dry as I am afraid I am spoiling her. She must be ok as she still accepts treats or canned added to food . So I guess she is trying to manipulate me to give good food? Only way to make her eat now is having my kitten watch her as she gets defensive. I hate to do that but I am at my wits end!I am so tired of this and I hope she goes back to eating normally. I am just tired of seeing her lay down in front of the food and turn her head away like if it disgusting!I would recommend a vet visit as I did,and only once declared healthy, then you can try to stay away from gravies and canned foods as they seem to make things worse. He will not starve to death, dogs can stay without food for a good 3-4 days try leaving it out with him in a crate all night. Eventually he should get really hungry and eat.