Experienced and professional animal trainer provide their insights in answering this question :
A. Weight loss is always a worrying sign. You should take him to your vets for blood test and examination. There is a long list of possible causes like liver or kidney problems, hormonal imbalances, diabetes or even a tumour.

How to Identify Common Pet Problems ?

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

A dog who loses weight but still seems to be eating and drinking as much as before might need a visit to the veterinarian, too. “They`re not taking in enough calories to support themselves,” says Shawn Finch, DVM, with Gentle Doctor Animal Hospitals in Omaha, Neb.
In a pet with weight loss, the most common screening tests would include complete blood count (CBC), serum biochemistry profile, urinalysis, and parasite testing. Based on the results of these screening tests, additional specific tests may be recommended.
If your dog drops over 10% of his or her total body weight in a short period and with no discernable outside factors, then you should be concerned. Just like with human beings, you need to keep tabs on your dog`s weight since it is so often an indicator of health, like any other bodily change.
Weight loss is the number-one dog cancer symptom Dr. Zaidel says he sees. It`s often the sign of a gastrointestinal tumor. “I`ve had a lot of dogs stop eating because of gastrointestinal tumors, so they lose weight very rapidly,” he says.
In extreme cases of tapeworm infection, your dog may lose weight despite eating normally. This is due to the tapeworm feeding on the nutrients in your dog`s intestines.
As a guideline, dogs can safely lose 2 to 4 percent of their body weight per week until they are at their desired weight. During the diet period, your dog`s weight should be checked every two to four weeks. This can usually be done at your family veterinarian.
As a rule of thumb, losing more than 5% of your weight over 6 to 12 months may indicate a problem. If you`re an older adult with other medical conditions and health issues, even a smaller amount of weight loss may be significant.
According to the American Cancer Society, unexplained weight loss is often the first noticeable symptom of cancers of the esophagus, pancreas, stomach, and lung. Other cancers, such as ovarian cancer, are more likely to cause weight loss when a tumor grows large enough to press on the stomach.
Increased water intake and weight loss are definitely cause for concern, and should prompt a visit to your veterinarian for an exam and blood tests. The two leading causes of these signs together would be kidney failure and diabetes mellitus.
Cancer, pulmonary conditions, abdominal diseases, and other illnesses can cause a dog to have trouble keeping weight on. If your dog is taking certain medications, side-effects from the medications can cause him to lose weight and have trouble gaining it back.
Signs of heartworm disease may include a mild persistent cough, reluctance to exercise, fatigue after moderate activity, decreased appetite, and weight loss. As heartworm disease progresses, pets may develop heart failure and the appearance of a swollen belly due to excess fluid in the abdomen.
A sudden change in a dog`s appetite may mean he is infected with roundworms. Food may lose its appeal, or he may suddenly be more hungry because worms are stealing nutrients from his food.
Kristen: Yes, you can lose weight if you have a tapeworm. That`s one of the symptoms of having a tapeworm.
Intestinal worms can be a serious problem in young puppies. Hookworms can cause anemia and roundworms can lead to poor growth and development. In adult dogs, however, intestinal parasites are only occasionally life-threatening.
By treating a slight infestation of intestinal parasites, a quick recovery can be assured. If the infestation becomes severe, it will take your dog longer to recover once treatments have begun. Follow your veterinarian`s treatment plan and always use medications as directed.
Visible worms in the stool or vomit—roundworms resemble spaghetti, while tapeworm segments look like cucumber seeds or rice.
We discuss different types of worms and symptoms further down, but the easiest way to tell if your dog has them is by looking at their poop. Most worms are visible in their stool, and come in a variety of sizes. Other common symptoms are weight loss, increase in appetite, bloating tummy, diarrhea, and vomiting.
Your veterinarian will take a stool sample to test for the presence of microscopic eggs laid by adult worms. The veterinarian will then mix the sample with a solution that makes the eggs more visible underneath the microscope. In some cases, a routine stool sample test may be insufficient to diagnose a parasite.
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 …
Unintentional weight loss has many different causes. It might be caused by a stressful event like a divorce, losing a job, or the death of a loved one. It can also be caused by malnutrition, a health condition or a combination of things.
Losing weight without trying may indicate an underlying condition. Conditions that cause unexplained weight loss include overactive thyroid, inflammatory bowel disease, and depression. A good rule of thumb is to see your doctor if you`ve lost a significant amount — more than 5% of your weight — within 6 to 12 months.
Protein is a priority

“If the dog is losing lean body mass then a diet higher in protein may be necessary,” says Wakshlag. Protein is necessary to build and maintain muscles, and as dogs age, they often stop synthesizing as much protein on their own — increasing the need for it in their diet.

Show respect to your elders — that includes your dog, who at 13 to 15, has officially entered old age. Even if your dog is moving a bit more slowly these days, there are lots of things the two of you can still enjoy together. And there are many things you can do to help ensure she remains in the best health possible.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Q. How do I determine how much my overweight pet should weigh?
ANSWER : A. There are many tools to determine overweight and obesity levels in pets. A new tool, morphometric measurements and body fat index, are available to accurately determine a pet’s ideal weight; this will allow an accurate determination of the amount of food a pet should receive to achieve weight loss. Feeding the correct amount will lead to greater weight loss success.

There are many weight loss food options to help pets reach their ideal weight. Your veterinarian can help make a ideal weight recommendation. Here are some tips to help your dog lose weight in a healthy and safe way:

1. Diet: Providing a healthy and well balanced diet is essential to your pet’s overall health. Finding the right food for your dog can be a challenging process. For those overweight animals many commercial dog companies offer weight loss diets, but it is important to evaluate food labels for adequate nutritional content.

You want to ensure you are not missing other essential vitamin or mineral content. Volume of food is also important and the amount of food that works for one breed of dog may not be the same for another breed of dog. Portion control as opposed to free-choice feeding can help your dog to drop a few unnecessary pounds.

There are also prescription weight loss foods designed by veterinary nutritionists, such as Hill’s r/d (http://bit.ly/1AoENSd). Some pet owners find that home cooking is the best option for helping to provide a well-balanced and realistic diet plan. There are websites such as balanceit.com that offers recipes to fit your dog’s specific needs. Consulting with your veterinarian or a veterinary nutritionist to find the appropriate diet is a great way to help your dog be as healthy as possible.

2. Exercise: Another great tactic for weight loss for your dog is exercise. Whether this is through running, walking or playing with a favorite toy all of these are wonderful types of exercise to help keep your dog at a lean and healthy weight.

For those pet owners with busy schedules utilizing professional dog walking services or playtime through dog daycare services is another option. It has been shown that those pet owners that exercise regularly with their pets generally live a healthier lifestyle.

3. Physical therapy: As animals age pet owners offer encounter their favorite canine having more difficulty walking and have a dwindling desire to play with toys. Physical therapy, specifically hydrotherapy is a wonderful way to help older and arthritic animals gain more mobility and lose weight. Hydrotherapy has been proven to have several therapeutic effects on the body including, muscle strengthening, relief of swelling, decreased joint pain, less stiffness in limbs, improved circulation, weight loss, and increased tissue healing to name a few. For more information on the benefits of hydrotherapy:
http://bit.ly/1w1qqoy

4. Veterinary visit and blood work: Weight gain can also be related to underlying health concerns such as hypothyroidism or other endocrine disorders. Scheduling a veterinary evaluation and routine blood work can be another important component in increasing the longevity of your dog’s life. Conditions such as hypothyroidism that predispose dogs to gain weight can be treated with a daily medication to improve hormonal balance. If feel that your dog is unnecessarily overweight there can be an underlying health condition that needs to be addressed.

5. Healthy treats: Pet owners love the chance to reward their favorite canine companion with treats and most dogs jump at the chance to consume these delicious products. The problem is many treats, which can include commercial dog treats or table scrapes can add many unnecessary calories to your dog’s daily intake. Reading labels and making note of the calories in these treats is an important component of understanding your dog’s overall health. Treats should not exceed more than 10 percent of your pet’s daily calories. There are healthier treats that can be offered to your pet to keep calories lower yet provide a fuller sensation. A pet owner can add steamed or pureed vegetables, such as carrots, green beans or sweet potato to add more fiber and thus a fuller feeling for your dog.

Q. Whenever I take my dog on walks he always barks at people and others dogs in my neighborhood. What should I do to resolve the problem
ANSWER : A. The very first thing to do is to make sure your dog is getting sufficient physical and mental exercise every day. A tired dog is a good, happy dog and one who is less likely to bark from boredom or frustration. Depending on his breed, age, and health, your dog may require several long walks as well as a good game of chasing the ball and playing with some interactive toys.

Figure out what he gets out of barking and remove it. Don’t give your dog the opportunity to continue the barking behavior.

Ignore your dog’s barking for as long as it takes him to stop. That means don’t give him attention at all while he’s barking. Your attention only rewards him for being noisy. Don’t talk to, don’t touch, or even look at him. When he finally quiets, even to take a breath, reward him with a treat. To be successful with this method, you must wait as long as it takes for him to stop barking. Yelling at him is the equivalent of barking with him.

Get your dog accustomed to whatever causes him to bark. Start with whatever makes him bark at a distance. It must be far enough away that he doesn’t bark when he sees it. Feed him lots of good treats. Move the stimulus a little closer (perhaps as little as a few inches or a few feet to start) and feed treats. If the stimulus moves out of sight, stop giving your dog treats. You want your dog to learn that the appearance of the stimulus leads to good things.

Teach your dog the ‘quiet’ command. Oddly, the first step is to teach your dog to bark on command. Give your dog the command to “speak,” wait for him to bark two or three times, and then stick a tasty treat in front of his nose. When he stops barking to sniff the treat, praise him and give him the treat. Repeat until he starts barking as soon as you say “speak.” Once your dog can reliably bark on command, teach him the “quiet” command. In a calm environment with no distractions, tell him to “speak.” When he starts barking, say “quiet” and stick a treat in front of his nose. Praise him for being quiet and give him the treat.

As in all training, always end training on a good note, even if it is just for obeying something very simple, like the ‘sit’ command. If you dog regresses in training, go back to the last thing he did successfully and reinforce that before moving on again. Keep sessions short, 15-20 minutes max, and do this several times a day.

Q. Rescued a dog almost two weeks ago, and now that her kennel cough is gone her personality shines!! No previous training, how should I start?
ANSWER : A. POST FOUR:

After your dog is familiar with the behavior you lured from scratch, and taught to your dog, you can start to use the “no-reward marker” I talked about. What you do is ask the dog to perform the behavior, and if the dog does not perform the behavior, you simply say your no-reward marker (choose one: eh-eh, hey, uh-oh, oops) show them the treat, put it behind your back, and BRIEFLY ignore your dog. Just turn your back for a second or two, before turning back to your dog and saying, “let’s try that again.” When you’re ready to start over with your dog, make sure you move around. If you are repeating the same cue while in the same position, while your dog is in the same position, you are likely to receive the same results. The more you move around, and start fresh, the better your chances are of having your dog listen to your cue the second time around. BIG rewards when they dog it successfully! Lots of praise and treats.

My no-reward marker is “hey.” When my dog does something wrong I say, “hey” and she immediately understands that she needs to offer a different behavior. This is clear to her. I don’t have to say it in a mean way, I simply say, “hey” in a normal tone of voice and she understands what the word means.

Once you’ve built up that connection and communication with your new dog, you can work on all kinds of fun behaviors! I personally enjoy the more zen-like behaviors: https://www.youtube.com/watch?v=ruy9UMcuGh8

I like to teach my dog fun tricks that offer her a “job” to do of sorts like object retrieval: https://www.youtube.com/watch?v=I4iertZSva8

(object retrieval training completed; what it looks like: https://www.youtube.com/watch?v=jx0Dml28FGY)

Scent-games are fun too! Very confidence building. Hide a REALLY smelly treat in a box, and place that box in a line of boxes. Let your dog go in the room while saying something like “search!” or “find it!” and watch them hunt for that smelly treat! Lots of rewards when they find it!

Q. My 4 year old Chihuahua mix began having a series shaking/panting episodes (last 15m- 1hr) out of the blue. Vet’s tests say its not physical.
ANSWER : A. There are many causes for shaking/panting. The shaking and panting are both signs of stress, and your dog may be dealing with anxiety, or stress, related to an event that happened, or is happening. I realize you cannot answer questions on this, however, I will ask some questions that you can ask yourself. Have you recently moved? Have you ever hit or yelled at your dog? Has the weather been bad lately (storms)? Have you had any new guests stay over recently? Have you had any dogs come to your home recently? Have you had any dogs or cats in your yard recently? Was your dog frightened by something initially (a falling pot/pan; a loud bang from the washing machine; a gunshot; a backfiring car/truck; someone screaming in your home/a fight)?

If you answered yes to any of those questions, it could definitely be that. Dogs don’t typically hang on to something for very long, but if it really frightened your pup, then she/he could be feeling serious anxiety related to that specific event, and relating other events to that one.

Do not yell, or hit your dog. I’m not assuming you do, but if you do, please stop doing that right away. It could be that your dog is afraid of you specifically, and you notice the shaking/panting when you are near, because that is the only time your dog is doing it.

If you’d like to purchase a consultation with me (I know, it’s a lot to ask, but I really feel like I could help) I’d be more than happy to ask you many questions, and together we can figure out what the heck is going on here. It’s important that your dog is comfortable, and if your pup is always feeling anxious/uneasy, then his/her quality of life is in jeopardy.

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 Beagle listens to me, but cries & whines when I’m gone & doesn’t listen to my parents. I adopted him just a couple days ago. Any tips for my folks?
ANSWER : A. I really highly doubt that your Beagle listens to you and has formed a connection with you in just a couple of days. It takes months to build up any kind of serious connection with your dog. You need to work on communication with your dog through training them to understand different cues. For instance the Leave-It cue: https://www.youtube.com/watch?v=R1TS5nA7z5Q

You have to work on bonding with your dog through mental stimulation. Training is very important. Luring each new behavior from scratch, and training using treats is how you form a strong bond with your new dog. No scolding is ever necessary… work on being calm, and positive, all the time.

If your dog is crying/whining when you leave, this may be separation anxiety. You’re going to have to separation train this dog from scratch. This dog needs to learn that separation can be a good thing! Tell your “folks” to NOT scold the dog when he is crying/whining after you leave, because that will make your dog MORE anxious when you leave next time. Your dog will be dwelling on the negative if your parents fuel your dogs negative feelings towards you leaving. FUN things should happen when you leave. Your parents should pull out the treats and start doing some basic obedience training with your dog. Your parents should stuff a Kong filled with awesome treats (peanut butter) and give it to him so he feels happy when you leave.

I have some excellent separation anxiety exercises you can work on. If you’d like, you can purchase a consultation with me, and I will go over how to separation train from scratch. It will make your dog comfortable being alone, guaranteed.

Read Full Q/A … : I Don't Like My Mother

Q. My 4 yr old male Catahoula Leopard Dog mix is a rescue. He’s become very possessive of me around larger dogs. How can I correct this behavior?
ANSWER : A. Sudden behavior changes can sometimes indicate an underlying health issue, so scheduling a checkup with your regular vet is always the first step. Once any health issues have been addressed, then you can address the behavioral ones. It is very common for dogs to become “possessive” of people or objects when around other dogs or people, and is called location guarding. Possession of objects or places can be a little easier to manage, however possession around other dogs can be treated as well. Working from a distance in a technique called BAT or Behavioral Adjustment Training may help. This technique involves your dog and another calm dog. Start off at a far distance and then move in until your dog becomes reactive or wary of the other dog. Move back a small amount and wait for your dog to become calm. If he shows calm behavior, reward with lots of praise, treats and love! If he becomes agitated or possessive, move back until he is calm, or stop the session completely and try again later. While this may take some time, it can help dogs learn that other dogs are not a threat to them or their people. Reading more information about BAT training or contacting a local trainer in your area can help with further advice and techniques!

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.