When dogs suddenly lose weight, it can be due to malabsorption, problems eating, and loss of appetite. Under certain circumstances, stomach and intestinal parasites, kidney problems, diabetes, Addison's disease and cancer can also be behind it.
There is usually only reason to worry if there are other pathological symptoms. In some cases, weight loss is just an early symptom.
Below you will learn about the 10 most common causes, how you can recognize them and what to do in specific cases.
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#1 Malabsorption
Malabsorption occurs when the dog eats enough but cannot absorb enough nutrients from the food. Typical triggers for this are:
- Chronic inflammatory bowel disease
The exact cause is still unknown here. However, existing allergies, chronic stress and a bacterial imbalance are considered the biggest risk factors.
It can usually be recognized by chronic vomiting, constant diarrhea and abdominal pain. Affected dogs also usually become increasingly thinner. [1]
- Exocrine pancreatic insufficiency
Exocrine pancreatic insufficiency is a disease of the pancreas. The result is that not enough digestive secretions are produced for hormonal reasons.
Digestive problems are almost inevitable here. Affected dogs often get constant diarrhea, eat enough but still lose weight. [2]
According to studies, around 2% of all dogs are allergic to certain foods. It becomes a problem when allergens are found in everyday food.
This can usually be recognized by redness and swelling on the face immediately after eating. Nausea and vomiting are also typical here.
Dogs with malabsorption get enough energy from their diet, but can only absorb a small amount of the nutrients it contains. As a result, they continue to lose weight despite eating enough.
#2 Loss of appetite
Loss of appetite can either be learned or due to illness. Doctors also speak of “anorexia”. The most common triggers include:
- Feed change
- Hormonal disorders
- Toothache
- Side effect of medication
- Problems with the heart
- Severe stress
- Autoimmune diseases
- Bacterial infections [3]
In simple cases, it could simply be because the dog is spoiled or doesn't like his current food. The aim here is to encourage the dog to eat.
However, if the dog becomes thinner and loses weight, there are probably illnesses behind it. It can also manifest itself in different ways:
If the cause is harmless, the problem usually resolves itself within 24 hours. However, if it becomes permanent, then I recommend seeking medical help immediately.
When dogs struggle with a loss of appetite, it is usually due to the food or the pampering of the four-legged friend. Under certain circumstances it can also indicate illnesses. Here, too little food leads to dogs losing weight.
#3 Diabetes
Diabetes can have two different causes. Type 1 occurs primarily in dogs, while type 2 is more common in humans. The differences?
- Type 1: The dog can no longer regulate blood sugar levels properly because too little insulin is produced in the body.
- Type 2: Blood sugar spikes occur more often because the dog no longer responds adequately to insulin. [5]
Both types result in blood sugar levels being too high or too low more often. This is not only harmful, but can also have devastating consequences.
In most cases, diabetes can be recognized by the dog being very thirsty and losing weight even though he is eating enough. Other typical symptoms are:
- Constant urge to urinate
- Strong hunger
- Lethargic behavior
- Dog is not gaining weight
- Nausea and vomiting
- Decreased coat quality
- Dog seems weak [6]
Unfortunately, there is currently no cure for diabetes. Nevertheless, the symptoms can be easily treated with a change in diet and medication.
Dogs with diabetes can no longer regulate their blood sugar levels adequately. As a result, affected four-legged friends usually eat and drink more, but still lose more and more weight. Unfortunately there is no cure here.
#4 Kidney problems
The primary task of the kidneys is to excrete any toxins and metabolic products through the urine. The kidneys are also essential for water balance.
Depending on the cause, kidney problems can be rapid or slow, as well as acute or chronic. The most common triggers include:
- Severe dehydration
- Heat stroke
- Food poisoning
- Bite of a snake
- Bacterial inflammation
- Congenital hereditary disease
- Old age [7]
Visible symptoms usually only appear when around ⅔ of the kidneys have failed. Unexplained weight loss is also typical here. Other symptoms of this are:
- Listless behavior
- Blood in urine
- Pale colored gums
- Dog urine stinks
- Strong bad breath
- Changed drinking behavior
- Coordination problems [8]
Since the symptoms of kidney disease only appear very late, you should not waste any time and seek professional help immediately.
When dogs develop problems with their kidneys, this can usually be recognized by their urinating and drinking behavior. It is also typical for affected dogs to become thinner and lose weight despite eating an appropriate amount.
#5 Problems eating
In some cases, dogs want to eat but can't. The most common causes for this include:
Teeth pain caused by dental caries, holes in the tooth, a broken tooth or inflammation can make eating very painful.
This can often be recognized by the fact that the dog refuses dry food but eats wet food. Redness and swelling in the mouth are also typical here.
Tonsillitis doesn't make chewing painful, but it does make swallowing painful. In most cases this is caused by bacteria.
It is typical for affected dogs to breathe loudly, gag frequently and produce a lot of saliva. If the inflammation lasts for a long time, affected four-legged friends often lose weight. [9]
If the esophagus widens due to genes or illness, then doctors speak of “megaesophagus”. Weight loss is also typical here.
In addition, affected dogs vomit very often, have louder breathing and also cough more often. This can be identified relatively easily with the help of an ultrasound scan.
Toothache, tonsillitis and esophageal dilatation can cause dogs to want to eat but not be able to. Depending on the severity, this can lead to dogs losing more and more weight within just a few days.
#6 Increased calorie needs
Weight loss is usually the result of a caloric deficit. In addition to the amount eaten, other circumstances can also increase the calorie requirement:
- Hyperthyroidism
If the dog's thyroid produces too many thyroid hormones, it stimulates the entire organism. In other words: all organs are running at full speed.
In most cases, it can be recognized by affected dogs breathing rapidly, having an increased heart rate, having diarrhea and drinking unusually much.
Calorie requirements are increased during pregnancy. If the dog doesn't get a larger portion to eat, he will lose weight.
After birth, the calorie requirement is also slightly increased because milk production costs energy. Here, too, you should slightly increase the amount of food.
- Changed lifestyle habits
When dogs suddenly have a play partner such as a second pet or a large garden, they often become significantly more active. The same applies to children.
Your calorie needs also increase in winter because heat production requires a lot of resources. In summer, however, you can reduce the daily food ration. [10]
Hyperthyroidism, pregnancy and changes in habits can increase dogs' calorie needs. When dogs stop eating, they become increasingly thin and lose weight.
#7 Chronic vomiting
When vomiting, the contents of the esophagus and stomach are emptied through the mouth in a gush. Typical causes of chronic vomiting are:
- Inflamed pancreas
- Liver and kidney failure
- Addison's disease
- Allergies or intolerances
- Tumor in the pancreas
- Inflammation of the stomach lining
- Viral infection [11]
Doctors also differentiate between vomiting and regurgitation. When you vomit, the stomach contents come up; when you regurgitate, only the esophagus is emptied.
In both cases, however, it results in the nutrients from the food not being fully absorbed and the dog losing weight. Other typical symptoms are:
- Mucus in vomit
- Food is only half digested
- Dog keeps choking
- Blood in the vomit
- Dog also has diarrhea [12]
If even a change in food doesn't bring any improvement, then I recommend visiting the vet. Medication can often greatly reduce the symptoms.
If dogs chronically vomit or have constant diarrhea, this can lead to weight loss despite sufficient amounts of food. In most cases this has to do with infections or diseases of the stomach. Medical help makes sense here.
#8 Stomach and intestinal parasites
When most people think of parasites, they first think of lice, fleas or ticks. Parasites inside the body, the so-called “endoparasites”, are just as common.
Infestations occur so frequently, not only in strays, but also in domestic dogs, that a worming treatment is recommended every 3 months. The typical suspects here are:
- Roundworms and tapeworms
- Whipworms and hookworms [13]
These worms usually only show visible symptoms once they have spread widely. The most common signs include:
- Dog loses weight
- Chronic diarrhea
- Worms in the stool
- Dog tires quickly
- Bloody stool
- Unexplained flatulence
- Severe itching
- Occasional cough [14]
The solution? A wormer. In the past, tablets were primarily used for this purpose. Nowadays, drops are a much more pleasant option that is just as effective.
If dogs are infected with stomach and intestinal parasites, this can also affect digestion and body weight…