GET a benchmark body weight for your animal and re-weigh regularly - at least every 6 months. This is particularly important once your animal is entering old age as major organ system diseases can be present but show no other signs for a long time before you notice something is wrong.

ALWAYS - try to keep your animals body weight within the normal published range for it's type. Your veterinarian will advise you of the correct weight.

SEEK the advice of your veterinarian as soon as you notice significant weight loss.


Weight loss is one of the most important cardinal signs of disease processes in all animals. For this reason owners should record their animal's body weight and check it regularly. Small changes in body weight from the usual weight for an animal (+/- 4-5%) can be regarded as being normal. Changes in body weight associated with known major changes in life-style - such as increased exercise, or reduced intake of food may also not be significant.

However, weight loss in excess of 10% is likely to be significant and chronic gradual weight loss over a long period OR very rapid weight loss can be extremely important.


Weight loss can be going on for a considerable time before an owner is aware that there is a problem. This is particularly true in two situations :

    1. When the animal has long hair coat which masks visualisation of the body outline
    2. When the weight loss is very slow and protracted over a long period of time (such as is seen in chronic renal failure and other chronic diseases)

During weight loss body fat reserves are usually lost first, followed by lean body muscle mass (protein). In some disorders loss of body water is also a significant cause of body weight loss - leading to dehydration.

Visibly, weight loss can be recognised by :

    1. sunken eyes
    2. ribs are obvious and protrude from the body
    3. the dorsal spinous processes on top of the back bone are obvious and protrude
    4. the animal seems unusually light for its size when picked up
    5. muscle mass may be lost - from the limbs, temporal muscles above the eye.


There are several basics causes of weight loss

  • Inadequate calorie intake to meet maintenance requirements
  • The animal eats enough calories in it's food intake, but it is unable to digest, absorb or assimilate (utilise) the calorie-producing nutrients (ie fats, carbohydrates and proteins) in the food.

Exocrine pancreatic insufficiency 


Malabsorption syndrome 

Bile acid deficiency 

Diabetes mellitus 

  • The animal has a disease that causes large energy wastage

    Malignant cancer 

  • The animal has a catabolic disease that increases it's base metabolic rate
  • Major body organ disease or failure  liver, heart, lungs, kidney

Hyperthyroidism (especially middle-aged and older cats)



Increase calorie intake

Correct underlying disorder/disease


Updated October 2013