Dogs lose weight for a range of reasons. If you’ve noticed your dog is unexpectedly losing weight, here are some possible reasons why.

Sometimes, you might actively be trying to get your dog to lose weight if they’re a bit heavy. However, if your dog is losing weight unexpectedly, it’s good to get to the bottom of why this might be happening.

In some cases, the fix could be simple – like giving them a bit more food – but in other situations, unexpected weight loss could be a sign of a more serious cause that requires attention.

Here are some reasons why your dog might be losing weight:

1. Gastrointestinal problems

If your dog is suffering from gastrointestinal problems, a side effect could be weight loss. Gastrointestinal problems can be caused by anything from parasites to inflammation or cancer, or even an obstruction. If a gastrointestinal issue is the cause, your dog may also display other symptoms like diarrhoea, vomiting, lethargy, and a lack of appetite.

2. Kidney failure

Kidney, or renal, failure could also be a reason your dog is losing weight, although this condition doesn’t always cause weight loss. Weight loss in a dog with renal failure is often due to nausea, a reduced appetite, or changes in hormonal and metabolic factors due to the build-up of waste products in their blood.

3. Inability to digest/absorb food

This could be due to exocrine pancreatic insufficiency (EPI) or Megaesophagus. If your dog has EPI, their pancreas isn’t producing enough of the right digestive enzymes. With Megaesophagus, the dog’s oesophagus swells and stops working properly, meaning the food doesn’t even make it to the stomach.

4. Diabetes

Diabetes might cause your dog’s rapid weight loss due to its inability to convert the nutrients from food into energy. You might also find that they lose their appetite, meaning they’re not getting any nutrients at all.

5. Reduced appetite

Another reason your dog may be losing weight is that they’re not eating due to a reduced appetite. This could be due to discomfort caused by a condition like a toothache, for example, or because they’re generally feeling ill. It could also be because they don’t like the food you’re giving them, or they’re feeling anxious or stressed about something and simply don’t feel like eating.

6. Unsuitable diet

If your dog is otherwise healthy and gulps down their food with gusto, a possible reason for unexpected weight loss might be unsuitable, or not enough, food. If you’ve just upped their activity level, for example, by taking them along on runs, but haven’t increased their food, this could be why they’re losing weight.

Of course, this list isn’t exhaustive, and there may be another reason why your dog is losing weight. If the above suggestions haven’t helped, and your dog continues to lose weight, it’s recommended you visit your vet to find the underlying cause and get them on the right treatment as soon as possible.