When planned, weight loss can be beneficial to overweight animals that are at risk for endocrine disorders such as hypothyroidism, diabetes, and Cushing’s disease. Planned weight loss can also help slow down the progression of arthritis and joint pain.
However, if you begin to notice your pet is losing weight with no apparent reason, especially over a short period of time, then a warning bell should go off in your head, as this could indicate a serious underlying condition.
Here are the most common conditions associated with weight loss in dogs and cats:
Kidney dysfunction
Your veterinarian can perform a chemistry blood panel and urinalysis that will help to detect kidney dysfunction. An appropriate treatment plan can be recommended by your veterinarian based on the stage of kidney disease.
Gastrointestinal diseases
Intestinal parasites, inflammatory bowel disease and food allergies are some of the most common gastrointestinal diseases that lead to unplanned weight loss in pets.
An animal that is not absorbing proper nutrients and having chronic diarrhea will start to lose weight and muscle mass.
Discuss with your veterinarian evaluating a fecal sample and other diagnostics to rule out any of the above conditions. A food trial is highly recommended for any animal possibly suffering from food allergies, in order to figure out what nutritional components the pet is allergic to, as well as to eliminate adverse side-effects.
Dental disease
If your pet’s mouth is painful as a result of heavy tartar, plaque, tooth root abscesses or even fractured teeth, then eating will become a challenging activity for your pet, which can lead to weight loss.
Monitoring your pet’s food intake will help you determine if dental disease is the underlying cause for their unexplained weight loss. When in doubt, consult with your veterinarian so he or she can examine your pet’s mouth in detail.
Diabetes
Diabetes mellitus is an endocrine disorder caused by either a lack of the hormone insulin or an inadequate response to insulin.
Common clinical signs include fluctuation in weight, increased drinking and urination, weakness in back legs, lethargy, and muscle wasting.
Your veterinarian can make a diagnosis through a detailed medical history, physical examination and often with blood and urine tests. Treatment often involves insulin injections and diet modifications.
Liver disease
Both drastic and gradual weight loss can be associated with liver disease. The liver is a vital organ that removes toxins from the body, provides coagulation factors and aids with digestion.
If the liver stops working properly your dog or cat will become very ill. Ingestion of certain toxins or medications can damage the liver, as well as any conditions associated with the pancreas or bile duct system.
In addition to weight loss, common clinical signs may include vomiting, discoloration of the skin (yellow or jaundiced) and lethargy. Your veterinarian can run blood work to investigate for any changes in liver enzyme values and can perform an ultrasound to further evaluate your pet’s liver.
Hyperthyroidism
This is a common condition in cats, not so much in dogs.
Hyperthyroidism most frequently causes significant weight loss, in addition to vomiting, diarrhea and overactive behaviors. It is caused by a non-cancerous tumor on the thyroid gland, which leads the body to overproducing thyroid hormones.
Your veterinarian can complete blood tests to diagnose this disease. If the results are positive, your pet can be treated with surgery, medical therapy or with a treatment involving radioactive iodine.
Addison’s disease
Addison’s disease, also known as hypoadrenocorticism, is an endocrine disease the can lead to weight loss in your canine pets.
Dogs that experience this condition have a decreased amount of corticosteroid secretion from one of both of their adrenal glands, which in turn alters their body’s ability to regulate certain electrolytes properly and prevents their body from adequately metabolizing specific sugars, fat and protein.
Blood testing can be performed to check for this condition and medical therapy is usually the best treatment option.
Infectious diseases
There are various infectious diseases that can cause weight loss in dogs and cats, along with other symptoms.
Parvovirus and distemper virus are two of the most common infectious diseases among dogs. Both are highly contagious and can cause life-threatening clinical signs, including weight loss, vomiting and diarrhea. Distemper virus can also lead to coughing, difficulty breathing and even seizures. Fortunately, both can be prevented through vaccinations.
Feline Infectious Peritonitis (FIP) is a deadly disease caused by a coronavirus that attacks the walls of the feline’s intestinal tract. FIP is not highly contagious among the majority of cats, especially those in single cat households that have relatively clean environments. However, cats housed in larger populations and those with weak immune systems are at greater risk of infection.
There is no cure for FIP at the present time, and treatment is aimed at providing supportive care, including fluid therapy, antibiotics and steroids.
Cancer
Cancer is another unfortunate condition that causes weight loss in animals. However, keep in mind that not every cancer acts the same way, and clinical signs might vary depending on the animal.
That said, generally speaking any unexplained weight loss in addition to decreased appetite and lethargy should be investigated immediately, as they could be signs of an underlying cancer.
Your veterinarian will often perform x-rays or ultrasound to rule out an internal cancer. If any abnormal lumps or bumps are found, then a biopsy or cytology (evaluation of cells) may be performed.
Stress
Stress and anxiety can disrupt your pet’s normal eating habits, leading to weight loss. A change in environment, a new child or pet in the household, or even a traumatic event can make your pet feel emotionally unbalanced.
If you believe your pet is suffering from stress or anxiety, you should try to eliminate them by providing safe areas in the house, offering lots of positive reinforcement or using pheromone diffusers. If you are unsuccessful, you can consult with an animal behaviorist for further guidance.