• There are many potential underlying causes for weight loss in cats.cat image by nutech21 from Fotolia.com
  
  In cats, losing weight is not a disease, but is rather a symptom that something else is going on. If a cat is losing weight, then there is some underlying problem at play that you need to diagnose. There are two basic reasons why a cat may lose weight as a symptom of something else: Stress-caused issues and medical conditions.
  
  

Weight Loss in Older Cats

• In an older feline, the two most common causes of weight loss are diabetes and hyperthyroidism. If your cat is older than 5, these are the first two conditions that a veterinarian should test for. Both of these conditions can be treated through the use of proper diet and medication, and the sooner that a treatment is provided, the sooner the cat will begin to return to its normal weight again.
  
  

Eating-Specific Issues

• There are a number of underlying causes that relate specifically to eating. For example, anorexia is a cat condition that can cause rapid and unhealthy weight loss. Dietary issues such as inadequate quality of food, missing nutrition or an inadequate amount of food can also cause such a weight loss. Dental problems such as gum disease, hurt or missing teeth may also cause weight loss since the cat will have difficulty eating.
  
  

Stress

• When an animal is stressed out, her eating habits may change to the point where she can lose weight at an unhealthy pace. There are a number of things that can stress out a cat, such as moving, bringing a new pet or a new person into the home, boarding, hospitalization or loss of a companion. Typically when the cause of the stress goes away, or the cat becomes accustomed to the change, the weight will return. If the cat does not appear to be stressed out, then a health condition may also be at play.
  
  

Serious Conditions

• There are a variety of health conditions that can cause weight loss in cats. Sometimes the condition itself causes the weight loss, while other times it is the stress associated with the condition that causes the loss of weight. Examples of conditions that can cause weight loss in cats include kidney failure, Addison's disease, leukemia, cancer, feline immunodeficiency virus (FIV), giardia, liver disease, pancreatitis, lymphosarcoma and hyperthyroidism. Because so many conditions can cause weight loss, it is vital that you get a proper diagnosis from a veterinarian to get to the bottom of the underlying causes behind the weight loss.