What Makes a Dog or Cat Lose Weight?

How to Know if Your Pet is Underweight--and What to Do About It

By October 16 | See Comments

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What Makes a Dog or Cat Lose Weight?

There are several ways to tell if your pet is underweight, and the problem should be addressed right away. See what can cause a dog or cat to be under their ideal weight.

Is your pet underweight? There’s a lot of attention given to the problem of obesity, but it’s flipside, overly skinny pets, is of equal concern.

When cats and dogs are underweight it can indicate a more serious health problem, or can reveal that your pet is feeling anxious and stressed out. Weight loss can lead to a decreased quality of life for cats and dogs--they feel cold faster, can become lethargic, and may experience damage to their internal organs. Shelter pets are frequently underweight. Regardless of the cause, weight loss should be taken seriously: it’s tough on a pet’s body, and even if the cause is just a matter of your pet being finicky about food, the underlying issue should still be tackled and resolved.


Many illnesses--including diabetes, cancer, and heart diseases--can have weight loss or a loss of appetite as a symptom. Parasites can inhibit a pet’s ability to absorb nutrients, and dental problems can make eating painful, resulting in a reluctance to eat. Finally, don’t discount the power of your pet’s feelings; changes large and small can affect your pet’s appetite, and depression may be a factor.


To some extent, the symptoms of underweight pets are precisely what you’d expect: a loss in weight compared to your cat or dog’s standard. You may also notice your pet acting lethargic, lacking the usual nicely groomed coat, and experiencing stomach issues from vomit to diarrhea. As well as seeing the difference in your pet’s weight and appearance, your sense of touch can also help to reveal weight loss. Feel along your dog or cat’s side--while you should be able to feel the rib cage, you should not be able to see any bones.


If your pet’s weight loss is the result of an illness, parasites, or another condition, tackling the underlying cause may help restore your pet’s appetite and ability to maintain a healthy weight. Some basic tactics to get your pet’s eating habits back on track are to provide several meals each day and to tempt animals with homemade or warmed up food. If necessary, you can feed pets through a syringe, and provide higher calorie food to help make every bite that your cat or dog eats count toward helping restore a normal weight.

When you notice that your pet has lost weight, or no longer seems interested in eating, a visit to the vet is likely in order. If simple at-home techniques do not restore your pet’s appetite and ability to keep on weight, the veterinarian will perform a physical, ask some basic questions, and potentially do some tests to determine what’s causing your cat or dog’s eating problems. The vet may take blood samples to check for certain diseases, check your pet’s stools for signs of parasites, or perform X-rays. To catch any problems early, watch for any changes in eating patterns, and take them seriously.

This information is for informational purposes only and is not meant as a substitute for the professional advice of, or diagnosis or treatment by, your veterinarian with respect to your pet. It has, however, been verified by a licensed veterinarian for accuracy.

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