Experienced and professional animal trainer provide their insights in answering this question :
A. Those symptoms can be just about anything from a slight infection to something more sinister. You need to have it examined by your vet as soon as possible to establish the cause and start appropriate treatment.

How to Identify Common Pet Problems ?

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

Infections, illnesses, and pain can make your dog tired, listless and uninterested in food. When these symptoms continue for more than 24 hours, they could indicate the presence of a health issue that requires a visit to our veterinary hospital in Diamond Bar.
Surgery, drug reactions, stress, heart disease, and other issues may also cause weight loss in canines. If your dog is refusing to eat, losing weight, or has any other digestive or feeding issues, play it safe and let the veterinarian take a look at your pet.
Bladder infections or urinary tract infections are two major culprits of reduced thirst. It could also be diabetes or kidney disease. If you notice other symptoms like lethargy and lack of appetite, and feel like something might be wrong, it`s important to call your veterinarian and discuss what`s going on.
Lethargic and Not Eating / Drinking – Like lethargy, not eating or drinking well are nonspecific clinical signs that are seen with many cat diseases. Lethargic and Losing Significant Weight – A poor appetite can lead to weight loss, but so can diseases like hyperthyroidism or diabetes, even if your cat is eating well.
A hot, dry nose doesn`t always mean trouble, but it can certainly be a sign of fever, dehydration, or even conditions like dry eye. If your dog`s dry nose is accompanied by other symptoms, like lethargy, vomiting or diarrhea, or changes in activity or appetite, contact your veterinarian for advice.
Some of the signs of parvovirus include lethargy; loss of appetite; abdominal pain and bloating; fever or low body temperature (hypothermia); vomiting; and severe, often bloody, diarrhea. Persistent vomiting and diarrhea can cause rapid dehydration, and damage to the intestines and immune system can cause septic shock.
What are the symptoms of canine distemper? Initially, infected dogs will develop watery to pus-like discharge from their eyes. They then develop fever, nasal discharge, coughing, lethargy, reduced appetite, and vomiting.
Monitor your dog for additional symptoms, such as lack of appetite, abdominal pain, vomiting, diarrhea, lameness, or straining to urinate. If you notice significant alterations in your dog`s behavior or additional symptoms, contact a licensed veterinarian.
Lethargy in dogs can be caused by everything from anxiety and fear to infections, cancer, and other medical issues. If your dog is lethargic, you may also notice symptoms such as slow reactions and a lack of interest in playing.
Cats that are ill will usually show changes in overall appearance, energy level, sociability, coat appearance and/or amount of shedding, appetite, litterbox usage, breathing, or discharges from the eyes or nose. In general, any sudden change should alert you that your cat needs veterinary attention.
Symptoms of Diabetes in Dogs

Obvious weight loss; Loss of appetite; Tiredness; Symptoms of dehydration – panting, repeatedly licking lips, vomiting, diarrhea, very dry gums, and nose.

Pemphigus foliaceus in dogs is a rare autoimmune skin disease that causes blistering in the mouth, nose, and skin. It most commonly affects middle-aged dogs and can appear at any time. Symptoms include pustules on the face, muzzle, ears and feet; ulcers on the nose and lips.
Clinical signs of poisoning in a dog may include: Gastrointestinal signs: vomiting, diarrhea, extreme salivation, loss of appetite, and nausea or dry heaving. Internal bleeding: indicated by pale gums, a racing heart, coughing up or vomiting blood, weakness or lethargy, or a dog`s falling over or collapsing.
Common Signs of Dog Poisoning

The following may be signs of dog poisoning: Diarrhea or blood in the stool (either bright red blood or dark black tarry stools) Vomiting or loss of appetite. Seizures or tremors.

Affected dogs show signs 30 minutes to 4 hours after ingesting the poison. Initially affected dogs become anxious and have an elevated body temperature. Panting is usually seen. Progressively they become worse and staggery.
Parvo smell has a unique very bad-smelling poop that is not easy to forget. The smell has been described as metallic, with hints of blood stench since the virus affects the intestinal walls, and a seemingly sweet scent.
The scent generally associated with parvo is caused by blood in the stool. Dogs with bloody stools because of hookworms have precisely the same smell. MORE IMPORTANTLY, if a puppy is diagnosed with Parvo BEFORE there is blood in the stool, the antivirals` effectiveness is MUCH GREATER.
Some of the earliest signs of kidney disease in dogs may include subtle weight loss, urinating/peeing more often and drinking a lot more water.
Signs that a dog has liver disease can vary and include loss of appetite, vomiting, stomach ulceration, diarrhea, seizures or other neurologic problems, fever, blood clotting problems, jaundice (a yellow tinge noticeable in the skin, mucous membranes, and eyes), fluid collection in the abdomen, excessive urination and …
Leptospirosis is a bacterial disease of dogs and other mammals that primarily affects the liver or kidneys. The bacteria (Leptospira) that cause leptospirosis, commonly called leptospires, thrive in water and have a helical or spiral shape with a characteristic hook on one or both ends.
Initial symptoms of canine distemper include an elevated body temperature (above 103.5°F or 39.7°C), reddened eyes and a watery discharge from the nose and eyes. More developed symptoms include lethargy, tiredness and eventually anorexia. At this stage, coughing, vomiting and diarrhea may also occur.
Lethargy is a common sign of illness. When your dog doesn`t feel well, he may have a decreased energy level. Any behavior that is unusual for your dog, such as hiding, listlessness or pacing, difficulty breathing, or trouble walking, merits a call to your veterinarian.
If your dog seems sad, it might mean he or she is not feeling well either emotionally or physically. In any case, do not ignore it! Like humans, a sad dog could be an indication of depression or it could be a symptom of a physical injury.
If you see your dog being sick and it is accompanied by lethargy, depression, diarrhoea or loss of appetite, it could indicate an underlying problem so speak to your vet as soon as possible.

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. My cats nose is stopped up on antibiotics. She has a loss of appetite, acting normal though. Is 3 ounces of can food enough in 24h? 9 pound cat
ANSWER : A. Cats with stopped up noses tend to eat much less, as you’ve noted, because they can’t smell their food as well. And the smell of food is pretty important to a cat’s appetite. You can start by warming up the food in a microwave – not too hot, test it yourself by putting your finger right in the center, as the temperature of microwave food can vary – as this will intensify the smell and hopefully make your cat more interested.

Saline nose drops, like those that are used on little kids, are safe to use on a cat to clean the discharge that is dried around and in the nose. There’s a brand called Little Noses that’s available in the U.S. That I like. You can put it on a q-tip and try to remove the debris. Humidifying the air with a humidifier can help as well, or you can put the cat in the bathroom and run the shower enough to generate steam. Don’t use “real” nose drops like Neo-synephrine or anything else like that – cats quickly build up resistance to them.

A 3 oz can of food is an OK amount in 24 hours, but do try the techniques above to help your cat get more interested in food. You might also try some baby food – no garlic or onions in the ingredients – as cats usually really like the taste of it.

Q. My 2 months old rottweiler puppy isn’t eating properly. Shes only eating shredded or minced chicken but adding any thing means she won’t eat.
ANSWER : A. This is not a nutritionally adequate diet for your puppy. She needs to be eating a good quality puppy food. Put the proper amount in her bowl and put it down without any fuss. Leave it for fifteen minutes. After that, if she has not eaten, pick it up–again without fuss–and do not give her anything else to eat until her next scheduled mealtime, not even treats. When she is due to eat again, repeat the process. This may take quite a few days to resolve, as she will try to hold out for the chicken. Do not give in! Remember that you are not starving her. The food is there, but she is choosing not to eat. When she realizes that this is all she is going to get, she will begin to eat and your problem will be solved.

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. My dog doesn’t eat, what should I do?
ANSWER : A. If this is a puppy, see a veterinarian immediately. Puppies should want to eat. Common causes for anorexia in puppies include viruses (parvo is a big one), parasitism, and foreign bodies. They need immediate care – go to an emergency vet if yours isn’t open. Puppies can get low blood sugar and dehydration very quickly.

If this is an adult dog and you observe other concerning signs, such as diarrhea or decreased energy, you should see a veterinarian.

If the dog seems otherwise bright and stable, try offering different types of food: wet food, canned tripe, or cooked chicken and rice. Some dogs will go for canned baby food: chicken, turkey, or beef as the main ingredient. Make sure there are no garlic or onions in the ingredients!

Causes of anorexia in adult dogs can range from less serious to severe. Younger dogs are more likely to get into trouble- they tend to eat things they shouldn’t, and can get foreign bodies from eating things like socks, or stomach upset from getting in the trash. Any dog may stop eating due to stress, or just being a picky eater. Middle aged dogs can stop eating when they’re stressed and also have Addison’s disease, which can be fatal. Older dogs tend to stop eating when they develop cancer or renal disease.

There is no one-size-fits-all recipe to know when the right time is to take your dog to the vet. The moral of this story is, if it’s not getting better, your pup feels bad, or you’re worried – go see the vet!

Read Full Q/A … : My Dog Won’t Eat

Q. Why does my dog eat grass? He throws up afterwards!
ANSWER : A. There is much debate over why dogs eat grass and then vomit afterwards. One theory is that the dog may have an upset stomach, and so eats the grass blades which then irritate the digestive system and causing vomiting to happen. Another theory is that the dogs are eating grass to mimic a “lost nutrient” of their ancestors found usually by hunting and then eating the contents of the stomachs of herbivores. A third theory is that dogs just do it because to them, it’s fun and they can.

If your dog has been vomiting a lot recently, either related to or unrelated to eating grass, then it is always a good idea to schedule a wellness exam with your vet to make sure there are not any issues causing illness. Grass, especially in areas where livestock may graze can also be a host for parasite eggs, which can in turn infect your dog with an internal parasite (and thus cause vomiting and diarrhea).

If your dog is not eating at all, this is more concerning and points further to some digestive upset causing his or her symptoms. Making an appointment with your vet as well as bringing in a sample of his or her stool is best for helping your pet feel better.

Q. My 20 month Cavalier doesn’t eat unless I let him eat from my finger, then he eats. Sometimes he will only eat once a day and leave his food.
ANSWER : A. It is possible that your dog is just not satisfied with his current food, or may be a picky eater. There are several things you can try to encourage your dog to eat.

The first step is to remove any additional treats or people food that may be more enticing to your dog than his own meal. If you feel you must give him some form of treat, be sure to place them directly in his food bowl and mixed with his regular diet. This allows him to get some snacks while also “forcing” him to try out his current meal to get the reward.

Enticing your dog to try his food by adding a pet-safe gravy or even a few treats of plain boiled chicken mixed in can help. Be sure to mix the foods thoroughly so he must explore his own food before getting the treat.

Some small breed dogs may also have a hard time with certain bowls and their collars. If there is a metal name tag on the collar and a metal bowl, the clinking sound can sometimes scare off dogs and make them not want to eat from their bowl. Using a bowl of a different material, or removing the collar prior to a meal may help with this issue.

Your dog may also just not be into his current food and may like another variety better. You can try a new variety by gradually switching over a period of 7-9 days, slowly adding in more new food and removing old until it is switched. This change may encourage him to try out meals again, and the slow changeover will allow his body to adjust to the new diet without digestive upset.

Q. Why do dogs eat grass?
ANSWER : A. Some pet parents get concerned when they see their favorite canine nibbling on grass in the yard. They wonder whether it is because hunger, boredom or an indication of an underlying illness. Often the consumption of grass will result in vomiting because it irritates the stomach and gastrointestinal tract. This is an extremely common problem for dog parents. There is no one reason for why dogs exhibit these behaviors and it is very much dependent on each dog. Here are some of the reasons why our dogs choose to eat grass:

1. Nutritional Issues

Historically speaking, dogs are considered omnivores, which mean they consume a variety of both meat and plant-based food. There is some indication that dogs with a low fiber diet may choose to scavenge in the grass to fulfill this nutritional deficiency. These dogs may also find that grass has an appealing flavor and consistency. If you feel that this may be the reason for your beloved canine consuming grass then consider discussing with your veterinarian on how to incorporate more fiber into your dog’s diet.

2. Boredom

Many dogs who are not receiving adequate exercise will be become bored and search out activities to occupy their time, including eating grass. Evaluate how much exercise your dog is getting on a daily basis and consider more walks or other fun activities, such as playing fetch or tug of war.

3. Upset Stomach

There is a belief that dogs with an upset or gassy stomach will self-medicate by consuming grass. Vomiting often follows this grass eating activity eliminating the contents of the stomach or changing the gas distension within the gastrointestinal tract. However, there is not much scientific evidence to back up this theory. If you are concerned about too much gastric acid in your dog’s stomach or any other underlying medical issue that could be the reason for their grass eating, consult with your veterinarian.

Overall, grass eating is usually not toxic to your dogs unless your lawn contains chemicals, including pesticides or herbicides. Monitor your dog’s behavior along with his diet and exercise to determine if there is a reason for the inappropriate grass snacking.