What causes weight loss in dogs?

Weight Management

There is a wide range of things that can cause a dog to lose weight. The most basic of these is that the dog is not absorbing enough calories from their food to meet their energy requirements. This could be because the food that the dog is offered does not contain the right nutrients for them, or they do not like the taste of it. Some dogs are also quite fussy in what they will like to eat and can be very selective.

Signs and symptoms of weight loss in dogs

If you weigh your dog regularly, the first sign of weight loss is likely to come from the scales.

If your dog is not weighed at frequent intervals, the first thing that you notice may be the physical signs of weight loss, with the dog losing their fat layer, over time hipbones and ribs becoming visible.

Dogs that are malnourished for some time may have dull, brittle coats and have dry, flaky skin making them prone to dandruff. Some dogs may shed hair and can end up with bald patches.

Vomiting and/or diarrhoea can be a sign of an underlying illness or other problem.

Loss of appetite can be a sign that the dog is unwell, or that they dislike the food on offer.

Lethargy can become evident, as the dog is losing weight and does not have the energy to move and play as they would when at a healthy weight and feeling well.

They may be slow-moving, reluctant to go for a walk or become tired and not want to continue after a short distance.

Depression can be a sign of feeling unwell, either from an underlying problem or from having insufficient energy to behave normally.

What causes weight loss in dogs?

Intestinal parasites can divert nutrients from the dog to utilise themselves. Some worms can be present in huge numbers and severely reduce the amount of nutrition left for the dog’s body to use. Large infestations, particularly of parasites that burrow into the gastrointestinal lining, can leave behind damage that will affect the dog’s digestive capability.

A number of medical conditions can cause weight loss, because either they make the dog feel unwell and not want to eat, or because they interfere with the way the body processes and uses the food they eat. These conditions include pancreatitis, gastroenteritis, colitis, cancer, long-standing kidney disease or advanced heart disease. In the case of the last two on the list, weight loss comes after the disease has been present for some time.

Dental pain can be an issue, particularly in dogs fed dry food as attempting to crunch hard kibble with sore gums or abscesses could be extremely painful.

Dogs with sensitive stomachs or those with intolerances and allergies to ingredients in their food can have persistent gastrointestinal problems. Vomiting or diarrhoea, particularly if frequent, means that a lot of the nutritional value of food is wasted as it passes through or is ejected too quickly for the dog to benefit fully.

Other gastric conditions such as Inflammatory Bowel Disease or Irritable Bowel Syndrome can also both lead to dogs having an inability to digest food effectively as damage to the intestinal wall decreases the number of calories they can absorb.

Weight loss combined with vomiting and diarrhoea could indicate that there is a blockage in the gastrointestinal tract, such as a foreign object that has been swallowed.

Ageing can bring on conditions that will result in an old dog losing weight. Weight loss combined with increased drinking and increased appetite could be a sign of diabetes.

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