If dogs don't gain weight, it's usually due to a worm infestation or an unsuitable diet. However, under certain circumstances it can also indicate chronic stress, constant diarrhea, diabetes or pancreatic weakness.
There is usually only cause for concern if the dog is currently too thin or underweight. Then it could be a symptom of an underlying disease.
Below you will learn about the 9 most common causes, their symptoms and what you should do in specific cases.
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#1 Worm infestation
Worms are so common in dogs that doctors recommend a preventive worm treatment every 3 months. However, these parasites are rarely really dangerous.
They can only become a problem in dogs with existing illnesses or very young puppies. The 6 most common types of worms in dogs are:
- Roundworms
- Heartworms
- Hookworms
- Whipworms
- Lungworms
- Tapeworms [1]
The problem? When there is a severe infestation, these “blackheads” in the stomach and intestines often prevent dogs from gaining weight or losing weight. Other symptoms include:
- Worms in the stool
- Chronic diarrhea
- Swollen stomach
- Dog vomits worms
- Loss of appetite
- Occasional cough
- Dog seems weak [2]
Here, a worm treatment is usually carried out as treatment. For prevention, I also recommend that your doctor give you an individual plan for preventive deworming.
When dogs are infected with worms, they often do not gain weight despite eating more. In most cases, it can be recognized by the presence of worms in the stool or vomit. A normal worm treatment is enough to solve the problem.
#2 Pancreatic weakness
The pancreas is a small V-shaped gland. It is primarily responsible for the formation of hormones and the production of digestive juices.
If too few digestive juices are produced, doctors speak of “exocrine pancreatic insufficiency” – a weakness of the pancreas. Typical causes are:
- Genetically determined
- Inflammation of the pancreas
- Internal injuries
- Congenital hypofunction [3]
This disease means that the nutrients eaten cannot be absorbed properly. It is very difficult to gain weight here. Other symptoms include:
- Strong hunger
- Occasional vomiting
- Continuous weight loss
- Constant diarrhea
- Severe flatulence [4]
This hypofunction can rarely be cured. The symptoms can be treated very well by supplementing with appropriate enzymes.
Dogs with exocrine weakness of the pancreas have trouble absorbing nutrients. This can usually be recognized by the fact that the dog is losing weight, has constant diarrhea and does not want to gain weight despite increasing the amount of food.
#3 Inappropriate diet
An unsuitable diet is always considered when it does not meet all of the dog's needs or leads to chronic problems.
In particular, advocates of “Biologically Appropriate Raw Feeding” (BARF) often struggle with this because they decide everything themselves. Typical errors here are:
- Too much low-fat protein: Compared to fats and carbohydrates, protein makes you feel significantly more full and prevents dogs from eating a lot.
- Too high a water content: Dogs are now omnivores, but the proportion of fruit and vegetables in their food should not be too high.
- Too few fats: Compared to proteins and carbohydrates, fats have more than 2 times more calories at 9.3 kcal per gram.
- Too much fiber: Too much healthy fiber makes you extremely full and often leads to stomach aches, which means dogs don't eat enough. [5]
In most cases, it is a combination of the above factors why the dog is not gaining weight. The solution is to motivate the dog to eat:
- Mix raw eggs or rice into the food
- Use high-fat treats like liver sausage or peanut butter
- Increase the amount of food and add bone broth
For individual food recommendations, I can recommend this food check. Completely free of charge and afterwards you will even receive up to 20 free food samples.
If a dog's diet has too much fiber, too little fat, too much protein and a high water content, then it's no wonder the dog doesn't gain weight. This diet is ideal for a diet, but not recommended if you are underweight.
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#4 Changed calorie needs
Whether a dog gains or loses weight primarily depends on the calorie balance. If you consume fewer calories than you burn every day, you will lose weight.
And vice versa. Even if you increase the calories you consume, your calorie needs may also increase. Typical causes for this are:
- pregnancy
- Increased physical activity
- Hyperthyroidism
- Dog serves as a hunting companion
- Side effect of medication
- Cushing's syndrome
- Cold temperatures
- Milk production
Dogs need more energy, especially in winter and during pregnancy. Even if you have an overactive thyroid, you often don't gain weight. Typical signs of this are:
- Strong thirst
- Constant diarrhea
- Nervous behavior
- Rapid breathing
- Hyperactivity
- Unexplained weight loss
- Strong appetite
Treatment here depends on the underlying cause. In most cases, however, the symptoms can be alleviated with the help of medication.
If dogs need more calories due to their everyday life or due to illness, but the diet only covers their daily requirement, then they will not gain weight. The solution here is to identify the underlying cause and take a proactive approach.
#5 Inflammatory bowel disease
While the stomach is primarily responsible for breaking up the food, the intestines are responsible for the actual digestion and absorption of nutrients.
The problem? If the intestines are chronically inflamed, the dog often cannot fully absorb nutrients. Typical risk factors are:
- Worm infestation
- Disturbed intestinal flora
- Weakened immune system
- Allergies and intolerances
- Severe or chronic stress
- genetics [6]
The problem? Even an increased amount of food only helps to a limited extent because the dog simply cannot absorb enough nutrients. Other symptoms are here:
- Nausea and vomiting
- Dog is not gaining weight
- Intermittent digestive problems
- Dog refuses food
- The dog's belly gurgles
- Dog constantly licks his lips
- Constant flatulence
- Frequent belching [7]
Such chronic inflammations cannot always be cured. However, they can usually be treated well with medication and a change in diet.
If the dog's intestines are chronically inflamed, digestion also suffers. This can usually be recognized by the fact that dogs do not gain weight despite a higher amount of food, often vomit, constantly get flatulent and often burp.
#6 Diabetes
Diabetes not only affects people, but also dogs. In addition, a distinction is made between the two different types of four-legged friends.
- Type 1: The body produces too little of the hormone “insulin” to regulate blood sugar levels.
- Type 2: The body no longer responds strongly enough to insulin to manage blood sugar. [8]
The problem? If the blood sugar level is constantly too high, it damages the vessel walls and causes deposits in the blood vessels.
In most cases, diabetes can be recognized when the dog becomes very hungry and thirsty but does not gain weight. Other symptoms are here:
- Increasing visual impairment
- Unusually frequent urge to urinate
- Unexplained weight loss
- Feeling of weakness
- Decreasing coat quality
- Cloudy eyes [9]
Unfortunately, diabetes is still considered incurable in both humans and dogs. The symptoms can be treated very well with diet and medication.
Dogs with diabetes usually become unusually hungry, drink a lot and still don't gain weight – on the contrary. Many affected dogs even struggle with being underweight, feeling weak and getting cloudy eyes.
#7 Chronic stress
Compared to most mammals, dogs are so empathetic and sensitive that stress can get to them. Common triggers for this are:
- presence of strangers
- Loud noises
- Unusual loneliness
- Lack of socialization
- Regular vet visits
- Violent upbringing [10]
In most cases, stress can be recognized when affected dogs walk around restlessly, pant constantly or even start to shake. Other typical symptoms are:
- Profuse salivation
- Dog is not gaining weight
- Yelling and whining
- Dog avoids social contacts
- Ears laid flat
- Dog refuses food
- Retracted tail [11]
Sensitive breeds are most often affected here. In order to reduce stress, it is important to identify and eliminate the cause. Alternatively, you can get him used to it.
Severe or chronic stress can cause dogs to lose their appetite and not gain weight. What is typical here is that affected dogs have their tails tucked in, their ears are flat back and some are constantly panting and shaking.
#8 Not hungry
If dogs struggle with a loss of appetite, it may be due to illness or training. Typical causes of so-called “anorexia” are:
- Chronic stress
- Dog doesn't like his food
- Pain when chewing
- Unintentional parenting mistakes
- Taking medication
- Hormonal problems
- Pain when swallowing
- Autoimmune diseases [12]
If the dog doesn't eat any food but eats treats, that's usually a good sign. If he avoids any food, it may be due to illness.
It's no surprise that dogs don't gain weight. In addition, the following symptoms in particular can help with the diagnosis:
- Dog regurgitates what he has eaten
- Dog has problems chewing and swallowing
- Dog only eats wet food
- Dog gets diarrhea immediately after eating [13]
If the problem doesn't resolve itself within a day, I recommend visiting the vet. Even earlier if you drink an abnormally small amount.
If dogs are not hungry and therefore eat less or nothing at all, this can indicate existing illnesses. Affected four-legged friends do not gain weight even if the food portion is increased. It is important to seek medical help here.
#9 Diarrhea and vomiting
Diarrhea causes…