Experienced and professional animal trainer provide their insights in answering this question :
A. You should see a vet to check what is it ( tumor, cyst, absces, sth else) Loss of appetite is a very unspecific sign connected with many different diseases.

How to Identify Common Pet Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced pet care professionals :

Fatty tumors, also known as lipomas, happen most often in middle-aged or older dogs, especially around the ribs, although they can show up anywhere. They`re considered a natural part of aging. Any breed can have them, but larger dogs and those who are overweight are more prone to them.
If you spot any abnormal lump or bump on your cat, you should contact your veterinarian. While lipomas are not life-threatening, other causes of bumps can have more serious side effects. There is nothing you can do to prevent your pet from getting lipomas.
Chondrosarcoma in dogs most commonly affects the flat bones of the body, such as the ribs, skull, nasal cavity, and pelvis. Clinical signs may include localized swelling (which may be painful), decreased appetite, pain, and dehydration. Additional clinical signs may depend on the location of the tumor.
Lipomas – These are among the most common types of lumps on dogs, and are fortunately a growth that owners don`t need to worry about. These lumps are fatty benign tumors that may vary in size and can appear across a dog`s body, becoming more frequent as they age.
A lump on the left side rib cage can be caused by underlying skin conditions like boils, warts, skin abscess, or cysts. Other rare causes for painful lump on the rib cage on the left side includes colonic neoplasm.
In dogs, the spleen lives in the abdominal cavity, snuggled up under the rib cage on the left side of the abdomen alongside the stomach.
Fatty tumors, called lipomas, may show up anywhere on a cat`s body. They aren`t cancerous and don`t need to be removed unless they keep your cat from getting around well. They`re seen more often in older or overweight cats. To check a lump for cancer, your vet will use a needle to get a sample.
If your cat has soft, round lumps under their skin, they might have lipomas (noncancerous fatty tumors). Although lipomas in cats are usually benign, they require proper diagnosis by a veterinarian.
The most common reason for a lump forming on the ribs is something known as a lipoma, which is a collection of fatty tissue. This type of lump can lie beneath the surface of the skin covering a rib. They are usually painless, freely mobile under your fingers and stay the same over time.
Rib tumors are uncommon in dogs. The most common reason for presentation is a palpable mass, although occasionally dogs will present with either lameness or respiratory difficulties. The two most common rib tumors are osteosarcoma and chondrosarcoma. Rib osteosarcoma is an aggressive tumor with a high metastatic rate.
In dogs, the most common type of malignant skin cancer is a mast cell tumor. These tumors are superficial lumps that can be painful. They often swell, frequently bleed and then scab over, only to bleed again a few days later. They should not be squeezed by the owner, as squeezing can make them swell even more.
Some common causes include fat, tumors (benign and malignantVery virulent or infectious.), cysts, infection (abscess), allergic reactions and swelling from injury or hernia. A hernia occurs when one tissue or organ protrudes through another into an abnormal place on the body, often causing a lump or bump.
The spleen is a fist-sized organ found in the upper left side of your abdomen, next to your stomach and behind your left ribs. It`s an important part of your immune system but you can survive without it.
The xiphoid process, also referred to as the metasternum, is a small, bony extension of the sternum at its lower end. When this part is damaged, it gets inflamed. The resultant swelling may form a lump on the abdomen.
The chest wall includes the spine, sternum, and ribs. Many types of tumors can grow in this structure. Some are primary tumors, which originate in the chest wall; these can be either benign or malignant. Others are secondary tumors, which spread (metastasize) to the chest wall from another site in the body.
Life expectancy

When a splenic mass is benign, your pet may live for many more years following the surgery. If the tumour has already spread, then your pet may live quite comfortably for an additional three to six months, before the spread of the cancer causes other issues such as bleeding or breathing difficulties.

Symptoms of Cancer in Cats

Lack of energy. Change of personality. Stiffness. Rapid weight change (gain or loss)

Tumors can be benign or malignant (cancerous). Benign tumors are not invasive, do not spread to other areas of the body, and are easy to remove surgically. Malignant tumors can spread and cause harm to the animal. Malignant tumors can invade surrounding tissue and spread to distant organs.
Some, however, warrant more immediate attention. Give us a call if your pet`s bump meets any of the following criteria: The area is painful to the touch or when your pet moves, especially any bumps located in the groin or armpit. The bump is noticeably growing or changing over the course of a month or less.
Trauma: If a cat bumps a part of their body, lumps or firm bruises can form in these areas. These types of bumps usually go away in less than a week.
A lump or bump may appear due to mild trauma, which should heal on its own, but it could get infected, so keep an eye on it. If an infection causes an abscess, a pus-filled swollen spot on the skin, we may need to drain and treat the abscess, and may need to prescribe antibiotics to help your kitty heal.
The signs of stomach tumors develop gradually over weeks to months. They include chronic intermittent vomiting, lack of appetite, lethargy, and weight loss. Vomit may be blood-tinged or have a “coffee grounds” appearance. This is related to tumor ulceration (opening) causing bleeding.
There are numerous reasons as to why your cat`s abdomen could start filling up with fluid, thus resulting in a swollen, hardened stomach. Hemorrhaging, inflammation, ruptured bladder; any one of these has the potential to cause your cat a lot of pain or distress, and should be seen by a vet as soon as possible.
Osteochondroma is a common bone tumor but a rare tumor in the rib. It is often asymptomatic and observed incidentally. The tumors typically begin to grow before puberty and continue until bone maturation is reached.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Q. Why does my dog eat grass?
ANSWER : A. As another user mentioned, dogs can eat grass when they want to vomit. Sometimes, when a dog has an upset tummy, they will eat grass. If you notice your dog eating grass frantically, you can assume vomiting will shortly follow. Grass does not digest and pass normally. If your dog eats too much grass, it can cause serious issues with pooping. Your dogs poop can end up all tangled inside of her, and it can need veterinary assistance to remove it. The same goes for celery, so avoid feeding celery to your dog.

The other day my boyfriend accidentally left the laundry room door open where we were keeping the trash that was filled with cooked chicken bones. She ate one of the chicken bones lightning fast. We had to induce vomiting by feeding her some hydrogen peroxide. After we had fed her the peroxide, she immediately began frantically eating grass because her tummy was upset.

If there is something lacking in your dogs diet, it could be that your dog is eating grass to make up for it. I am sure that my dogs diet is extremely well balanced (I do not only feed her an air-dried raw food-type diet (Ziwipeak), but a wide variety of safe, healthy foods), so when she eats grass, I know that it is because she has an upset tummy.

That is why I think it is important making sure your dog has a very well balanced diet. If your dog is on a low quality kibble, your dog may be trying to let you know by eating grass (or eating poop).

Q. Small lump on my dog’s throat, what should I do?
ANSWER : A. Lumps and bumps on the throat or neck can be caused by a wide range of things. Depending on the lumps size, if it is under the skin or appears on the skin itself, and its location on the throat can all indicate different things.

There are a large number of structures in the neck there ranging from thyroid glands, nerves, salivary glands and even lymph nodes. Illness, disease or irritation can all cause swelling or issues there. You may also see additional symptoms such as trouble swallowing, drooling, lethargy or changes in weight and appetite to help narrow down the cause of the lump. Testing via blood work or an X-ray may help to determine the cause and proper treatment.

Lumps and bumps on the skin can also be caused by allergies such as an allergic reaction or sting, or even an abscess under the skin. Allergies are usually treated with an allergy medication to help stop the response and any itching or redness. Abscesses (cuts or scrapes that get infected and swell with fluid) are usually hot or painful to the touch and may ooze debris. These are usually drained at a vet, and then treated with antibiotics.

If the cause of the lump is not known, your vet may also recommend taking a sample of the lump to send to a Lab. This can help to determine what exactly is causing the lump and how to treat it.

Q. My dog hasnt eaten snce I left 4 days ago. I won’t be home for 6 more days. How can the caretaker get her to eat?
ANSWER : A. If your dog is feeling a bit sad while you are away and is refusing to eat, your pet sitter may try some things such as adding in boiled chicken or turkey to meals to encourage eating. A pet-safe gravy may also entice your dog to eat as well while you are gone. Your pet sitter may also want to offer smaller meals more often throughout the day to give your dog more chances to try and eat when she is feeling more comfortable and a little less sad. A game of fetch or playing together may also get your dog’s appetite going and help her to feel more comfortable eating around your pet sitter.

If your dog is showing any other signs of illness in addition to the refusal to eat (beyond normal missing an owner), then it is always a good idea to keep an eye out and contact a veterinarian as needed.

Read Full Q/A … : ufdc.ufl.edu

Q. A large lump behind the last rib left side, not eating?
ANSWER : A. You should see a vet to check what is it ( tumor, cyst, absces, sth else) Loss of appetite is a very unspecific sign connected with many different diseases.

Q. My cat is one year old. He has diarrhea, not eating last for one day. This problem is too with my other 2 cats and one is died.
ANSWER : A. His not eating is the most concerning for me. They cannot go more than a few days without eating or they risk liver damage. Your cat needs to be seen by your vet for an exam and bloodwork to determine the cause for your cat’s loss of appetite. Based on the findings, your vet will be able to give you a clearer picture of what is going on with your cat and be able to offer you treatment options.

Try enticing your pet to eat with beef or chicken baby food that does not contain onion or garlic powder. Onion and garlic causes anemia. Warm it in the microwave for a few seconds. Stir it with your finger first to make sure there are no hot spots and that it isn’t too hot. This makes it more aromatic and appealing to your pet. Wetting dry food or mixing wet food with low sodium chicken broth, also warmed, might entice your pet to eat. Some cats like to be petted while they eat, some want to be left alone. You’ll know your cat’s habits and be able to act accordingly.

Q. My 9 month old Maltese-Shih eats his own feces. Is there anything i can give him to get him to stop?
ANSWER : A. Coprophagia (or eating stool) is very common in young dogs. Luckily, most dogs will outgrow this behavior as they age. There are several theories as to why dogs do this which range from mimicking the mother dog’s behavior of cleaning the den, nutrient deficiency, boredom or just plain enjoyment of it.

If your dog is eating his own, removing the feces as soon as he deposits them is best in preventing them from being eaten. Keeping your dog on a leash while he potties can also help to catch any stool before he finds it. If he is eating other stool as well, sweeping the area prior to letting him out to go potty can help you identify and remove any left-behind stool.

There is also a product called For-bid that is available to make stool distasteful to pets. This product is sprinkled over every meal for a period of a week. When your dog attempts to eat the stool formed from this product, it becomes distasteful and discourages him from doing so. Most dogs will stop after a week of use, but some may need a few reminders from time to time to completely stop the behavior.

Q. My spayed,indoor cat is 5 years old.She weighs 10.3 and eats a measured 210 calories of UR food daily. Does she sound over weight to you?
ANSWER : A. 10.3 sounds very large for a domestic cat, unless she is specifically a giant breed such as a maine coone etc. There are some very good body condition score guides which help us assess weight issues in our patients (Royal Canin and Hills food companies both publish online resources for such). Main points of focus are a large abdominal fat pad hanging loose under a cats belly, whether the ribs can be felt easily, fat pockets either side of the tail and loss of an hourglass figure or ‘waist’ behind the ribs. Many veterinary clinics run free weight management checks and clinics. It may be that you can reduce her food intake or you may have to change to a lower calorie version, active playtime with treatballs, chasing food around the house or lazer pointer games can all help to increase activity levels. Excess weight risks complication similar to people with joint, diabetes, increased risk of tumors and cardiac/respiratory issues all being more common in overweight cats

Q. My dog recently stopped eating after he was overfed by mistake, he seems fine, he is still drinking but refuses to eat. Its been nearly 48 hours now.
ANSWER : A. Overeating may have caused some digestive upset, which is causing him to not eat, however overeating may also cause a serious condition called bloat. Bloat symptoms include a large bloated abdomen that may be painful to the touch, labored breathing or panting, attempting to vomit or defecate without success, refusal to eat, and pale or blue tongue and gums. If you see these signs, then immediate veterinary care is needed. If your dog seems otherwise fine except for not eating, you can try to entice him to eat and settle minor upset stomachs with a meal of boiled rice and chicken, however if he has not eaten in over 48 hours it is best to seek veterinary care as a more serious problem could be underlying.

Read Full Q/A … : When to put a dog to sleep