Sudden Weight Loss in Cats

Weight loss is not a disease in itself, but a sign of an underlying problem. Weight loss can be invisible to the cat’s owner for a long time, as the cat’s fur hides the process.

Your cat’s weight should be checked at least once a year and attention should be paid to the pre-cat weight. Unfortunately, many cat owners attribute weight loss in older and older cats to age, but it is cats of this age that often have health problems. Weight loss is expressed as loss of fluid (usually due to vomiting and/or diarrhea), loss of fat and loss of muscle mass and can be caused by:

  • Eating disorders – poor appetite, low calorie diet.
  • Absorption disorders – impaired food absorption due to a lack of digestive enzymes.
  • Excessive loss of nutrients – vomiting, diarrhea, intestinal parasites.
  • Altered nutritional needs – organ dysfunction, hypertheriosis or pregnancy.

The medical term for “weight loss due to illness” is cachexia (emaciation).

How much does a cat weigh?

The weight of cats depends primarily on the breed, and if a Maine Coon cat is about 15.5 lbs (7 kg) and a Siamese cat is only 6.6 lbs (3 kg), it is normal.

It is not only an experienced veterinarian who can tell if a cat is emaciated. And although the table below is relative, every owner can use it to correlate the physical condition of your cat.

Signs that your cat is underweight:

The obvious signs of the causes of weight loss are the cat’s behavior: the presence of increased appetite or refusal to eat, activity, and the age of the cat.

  • Polyphagia (increased appetite) or anorexia (loss of appetite)
  • Bad breath in the cat’s mouth
  • Increased thirst and urination
  • Changes in feces (watery, greasy, frothy, diarrhea, black and tarry)
  • Vomiting
  • Changes in coat condition
  • Increased or decreased activity
  • Poor wound healing
  • Behavioral changes such as depression, passivity, prolonged sleep.

Causes of sudden weight loss in cats

There are many possible causes of weight loss. These are divided into acute (sudden), chronic (slow and progressive) and other causes for which weight loss is a sign of illness or conditions.

Acute causes of weight loss:

Acute kidney disease.
Result of decreased function of the organ responsible for removing toxins from the body.

Infection.
Bacterial, protozoal and viral infections can lead to acute weight loss due to anorexia and/or vomiting and diarrhea.

Chronic causes of weight loss:

Chronic kidney disease.
Kidney disease leads to decreased function of the organ, which provokes the formation of toxins in the body.

Addison’s disease (hypoadrenocorticism).
An endocrine disorder in which chronic insufficiency of the adrenal cortex leads to a deficiency of hormones, especially cortisol.

Diabetes mellitus.
An endocrine disorder of the pancreas responsible for producing two hormones, insulin and glucagon, which regulate blood glucose (sugar) levels.

Pancreatic exocrine insufficiency.
A disorder caused by the pancreas not producing enough enzymes to digest complex food components such as proteins, triglycerides, and complex carbohydrates, as well as large amounts of bicarbonates, which protect organ mucous membranes from the effects of stomach acid.

Feline immunodeficiency virus.
A viral infection similar to HIV in humans.

Hyperthyroidism.
Hyperthyroidism is almost always caused by a benign thyroid tumor that releases hormones in excess. It is a common cause of weight loss in middle-aged and elderly cats.

Hypertrophic cardiomyopathy.
A thickening of the wall of the left ventricle of the heart. It is a consequence of conditions such as hyperthyroidism or high blood pressure.

Inflammatory bowel disease.

Liver disease.

Other causes of severe weight loss in cats:

Cancer is a malignant tumor.
Cancer is more common in older and older cats and is the leading cause of weight loss.

Dental problems.
Stomatitis, dental abscess, etc., which leads to reluctance to eat food and causes anorexia.

Dietary causes.
Inadequate caloric intake (malnutrition), which can be caused by food quality, insufficient food, a dominant cat that eats most of the food, etc.

Infectious feline anemia (hemobartonellosis).
The disease is caused by an unusual type of bacteria that attaches to the wall of red blood cells, destroying them in the process.

Feline viral leukemia (FeLV).
A disease that is caused by a retrovirus that belongs to the same family as feline immunodeficiency virus. Destroys the immune system and causes cancer.

Stomach ulcers.
Open ulcers develop in the folds of the gastric mucosa due to increased production of stomach acid, certain medications, parasites, stress, infection, and systemic disease.

Glomerulonephritis.
A disease caused by inflammation of the nephrons in the kidneys.

Heartworm.
A parasitic worm infection of the heart and lungs. When a neartworm larva enters a new host, it begins to grow and becomes an adult worm after a few months, dwelling in the blood vessels leading from the heart to the lungs of the cat.

Parasitic worms.
Severe infestation with nematodes, ascarids or tapeworms can lead to weight loss due to loss of nutrients.

Pancreatitis, an inflammation of the pancreas.

Pregnancy and lactation.
If calorie adjustments are not made to the diet during this period of a cat’s life, she will lose weight.

Stress or depression.
A change of residence (a trip), a new family member, the loss of a beloved family member all cause stress and depression, which may be reflected in a cat’s reluctance to eat.

Causes of weight loss in older cats

Weight loss is quite common in older cats and is of great concern to owners.

Weight loss becomes noticeable if the weight of the cat has dropped by more than 10%. Weight loss can progress to emaciation and cachexia. Wasting (weight loss of 20%) is characterized by a protruding skeleton and is caused by severe underfeeding leading to catabolism of body proteins and fats. Cachexia is the final stage of weight loss and is accompanied by weakness, depression and anorexia.

Sudden weight loss in cats over 8 years of age can be caused by a number of reasons. Only a systematic approach to this condition can answer the question of why weight loss has occurred. It is necessary to collect a detailed anamnesis, a thorough physical examination, and appropriate diagnostic studies.

The anamnesis should contain information about the type of diet, whether there was a sudden change of food. It should include information about the cat’s appetite, as well as whether the cat is interested in food but cannot grip or chew it, over what length of time the weight loss has taken place, whether the weight loss has been gradual over several months or whether the weight loss has been sudden and abrupt over a period of several weeks.

If possible, more information should be collected about the presence of vomiting/diarrhoea, polydipsia/polyuria, behavioral changes.

It is also very important to know what medication is used, as many can cause dyspeptic complaints and anorexia.

Since cats, unlike dogs, are less adapted to changes in their environment, it is necessary to find out whether there have been any changes in the home – moving house, repairs, buying new furniture, new family members, new guests, whether there has been a new pet.

After collecting the medical history, a thorough physical examination should be performed. Particular attention should be given to the oral cavity first, as dental disease, stomatitis, gingivitis, and oral neoplasia are quite common in older cats.

Palpation for goiter (enlargement of the thyroid gland) should be standard procedure when examining cats over 6 years of age.

Auscultation of the chest should be performed to detect abnormal heart rate, rhythm, abnormal noises in the heart and lungs.

The abdomen should also be carefully palpated for unusual neoplasms, organomegaly, intestinal thickening, abnormal size and shape of the kidneys. It should not be forgotten that weight loss may be associated with dehydration.Since skin elasticity in cats over 8 years of age is reduced, examination of the skin fold is of no diagnostic value. Therefore, other criteria, such as the condition of visible mucous membranes, are used to determine the degree of dehydration.

Quite often the cause of weight loss in an older cat can be determined by a thorough examination. If this cannot be done, the animal should have screening laboratory tests, which include urinalysis, hematological and biochemical tests. It is also advisable to determine the level of thyroxine in the blood. Testing for viruses, especially feline immunodeficiency virus, is very important. Radiological and ultrasonographic diagnosis of the thoracic and abdominal organs should be performed.

Weight loss can occur against a background of increased or decreased appetite. Weight loss against the background of polyphagia can occur when there is a negative balance of nutrients due to excessive metabolism (occurs in endocrinopathies) or when their absorption or utilization is impaired (caused by GI diseases).

The most common endocrinopathies in cats are hyperthyroidism, diabetes mellitus and hyperadrenocorticism.

Hyperthyroidism is the most common endocrinopathy in cats. Excessive levels of T3 and T4 in the blood result in increased metabolism, clinically manifested by slowly progressive weight loss with increased appetite, hyperactivity, polyuria/polydipsia, intermittent signs of GI lesions.

Diabetes mellitus is the second most common endocrinopathy in cats. Weight loss with normal or increased appetite is the most common clinical manifestation and results from impaired carbohydrate metabolism and increased fat oxidation.

Hyperadrenocorticism is rare in cats. It is manifested by weight loss with polyphagia, muscle weakness, enlarged abdomen, hepatomegaly, and thinning of the skin.

Various gastrointestinal disorders may result in increased appetite and decreased body weight due to poor absorption of nutrients. Worm infestation is traditionally associated with weight loss, but it is rarely severe enough in older cats to cause weight loss and can be easily excluded by laboratory examination. Therefore, inflammatory bowel disease (IBD) and exocrine pancreatic insufficiency (EPPI) are the most commonly included in the differential diagnosis. The history usually includes small intestinal diarrhea, vomiting. On physical examination, a thickened intestine may be propalpated in IBD, and a fat-stained perineum may be observed in the case of ENPJ.

There are many diseases that cause weight loss amid anorexia. These may include infectious, inflammatory diseases, neoplasia, toxic and metabolic disorders. Anorexia and weight loss in an older cat may occur with a sudden change of food, if the cat is not satisfied with the taste characteristics of the food, with a decreased sense of smell, when the cat cannot find the food and assess its condition. This condition may also occur with stress – a change of residence, owners, new family members or a new pet in the house.

Anorexia and weight loss can be caused by a systemic disease. Chronic kidney disease and neoplasia are most common in cats. Older cats with chronic renal failure are usually admitted because of the presence of lethargy, anorexia, and weight loss, not because of noticeable polydipsia/polyuria. Typically, these cats have a history of prolonged selective anorexia, the cat refuses its usual food, but it remains interested in industrial cat food for finicky cats or home food.

Neoplasias develop in cats over 5 years of age, most often malignant. The most common neoplasias occur in the skin and subcutaneous tissue, digestive organs, mammary glands, and respiratory tract. Weight loss and anorexia are relatively common non-specific clinical signs.

Weight loss can also occur with normal appetite. The cat has an interest in food, but the animal cannot eat it. In this situation it is necessary to rule out a foreign body, diseases of the mouth, pharynx, esophagus – stomatitis, gingivitis, neoplasia of the mouth, esophagus, thorax (thymoma).

Diagnosis

The veterinarian should do a complete physical examination of the animal and listen to your history of life – what food she gets, if there are multiple animals – how their relationship works, how often the cat nurses and feeds kittens, what medications she gets, and other symptoms, if any. Hyperthyroidism and diabetes are common causes in older and older cats and can be checked first.

Certain tests will need to be performed to make a diagnosis, including:

A biochemical profile, a complete blood count and urinalysis to assess the cat’s overall health and organs.
These tests can reveal infection, kidney function, liver function, anemia, calcium and magnesium levels. All of this data helps paint an overall picture of health.

Bile Acids Test.
To assess the condition and function of the liver.

X-ray or ultrasound of the abdomen.
For evaluating organs, looking for tumors or aneurysms.

Blood tests to determine T3 and T4 hormone levels.
Some cats with hyperthyroidism may have normal levels of these hormones in their blood tests. If so, a T3 suppression test (7 oral doses of T3 thyroid hormone and a blood test after the hormone has been given) may be performed. In a healthy cat, T4 levels will drop; in a cat with hyperthyroidism, T4 levels will remain unchanged or increase slightly.

Fecal testing.
To look for helminths (parasite worms).

Treatment of Weight Loss in Cats

Treatment should address the underlying cause of the disorder (if any) as well as nutritional support, which may include appetite stimulants or a feeding tube for a cat with anorexia and addressing other possible causes.

Systemic diseases

Renal failure – low-protein diet, phosphorus binders, saline solution to treat dehydration.

Addison’s disease – lifelong replacement of missing adrenal hormones.

Hyperthyroidism – radioactive iodine to stop tumor growth or surgery (tumor removal).

Hypertrophic cardiomyopathy – treatment aims to relieve symptoms, including beta-blockers to help with heart muscle contraction, blood viscosity and activity limitation.

Diabetes – switch to a low-protein diet. If dietary management cannot control the condition, treatment with insulin injections is required.

Pancreatitis – maintenance therapy, antitumor drugs, use of antibiotics for infection.

Pancreatic exocrine insufficiency – pancreatic enzyme extract, high-protein diet. Antibiotics are sometimes prescribed to treat bacterial infection in the small intestine.

Liver disease in cats – diet and nutritional support, herbal decoctions, anti-nausea remedies, in some cases corticosteroids.

Inflammatory bowel disease – strict diet for good digestion, corticosteroids to reduce inflammation, immunosuppressants, sometimes prescribed antibiotics.

Glomerulonephritis – diuretics to remove excess fluid, high-protein diet, drugs to treat high blood pressure, steroids to reduce inflammation.

Cat cancer – Treatment will depend on the type of cancer and metastases. The radical method of treatment is surgery (removal of the tumor). Chemotherapy or radiation therapy are also used.

Infections and parasites

Infections
Antibiotics are used to treat a bacterial infection. Supportive care is also needed to treat dehydration as well as to support nutrition. Helminths are treated with medications and safety precautions for maintenance and infestation are recommended.

Feline viral leukemia (FIV and FeLV)
Incurable, support is offered which consists of maintaining the cat’s stress-free living conditions. Antibiotics are used to treat infections that are likely to occur with this diagnosis. A high quality diet, good conditions and regular check-ups with the veterinarian can prolong the cat’s life.

Parasitic worms.
Medications are used to treat helminths and safety precautions for keeping and infesting are recommended.

Heartworms.
Heartworms are difficult to treat. In mild cases, it is possible to use an adult to kill heartworms, but this method of treatment has a high risk.

Other treatments

Pregnancy and lactation
Pregnant and lactating cats need to increase their diet.

Diet
In order to satisfy the nutritional needs of a cat it is necessary to provide it with a balanced diet of good quality food. If more than one animal is present, if necessary ( e.g. when one individual is dominant), feed from separate bowls and/or in different places

Stress
Determine the cause of stress and reduce it. If there is more than one animal, give each one a private place to eat and rest. Eliminate and manage conflicts between them, give them time and play.

Reyus Mammadli/ author of the article

I have had pets since childhood: cats, guinea pigs, rabbits, geese, chickens, ducks, parrots, aquarium fish and dogs (in the yard). Of course, I constantly encountered diseases of pets and treated them. Glad to be able to share my skills and experience, as well as advice on caring for and adapting these critters and birds.

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