Most people these days worry about weight gain more than loss, but if your dog is suddenly losing weight for no apparent reason, it can be a cause for concern. You may not notice weight loss until it’s pretty significant, especially if your dog has long or thick fur. Weighing your dog monthly throughout their life is a great habit to get into so you can spot trends in either direction quickly.
Body weight is a simple balance of calories in versus calories out, so if your dog loses weight, something has gone wrong with this balance. It could be that they are taking in fewer calories, the body is suddenly burning more calories, or the nutrients from food are not getting where they need to be. The reasons for this can be very varied. Let’s look at some of the common causes of sudden weight loss in dogs that’s unexplained or unexpected.
Causes of reduced calorie intake
- Lack of appetite, also called anorexia, may be due to many things. Your dog may become less interested in food because they feel unwell or nauseous due to illness such as liver or kidney disease or stress and anxiety, such as a new baby or big changes in the home.
- Pain. If your dog is in pain, they may be depressed or simply not want to move to actually go and eat. This may be particularly true if they have mouth or dental pain or pain in their neck.
Tasty Tips
Causes of increased calories burned
Increased exercise. This may sound silly, but if you suddenly have more time to walk your dog, they’ve met a new friend to play with, or someone else is walking your dog more, then they may simply be exercising more and need more food. Talk to your vet about whether the food they are on is adequate.
Pregnancy and lactation take lots of energy. If your dog is pregnant or feeding puppies, she will need ad lib puppy food to keep her energy balance right.
Certain diseases, such as cancer and diabetes, may result in your dog eating normally or even more than usual but still losing weight.
Nutrients not getting where they are needed
- Almost any gastrointestinal disease can cause weight loss. The food your dog eats may pass through the gut too quickly to be properly absorbed, such as in cases of diarrhoea. A deficiency in certain enzymes may mean they can’t digest fat or one particular component of their food, leading to malnutrition and weight loss.
- Parasites, such as worms living in the intestines, can ‘steal’ a significant amount of your dog’s food. Always make sure your preventative healthcare is up to date and suitable for your dog’s lifestyle.
Should you be concerned?
Unless you’ve made a conscious effort to get some weight off your dog, any unexplained weight loss should be investigated. Try to be an observant owner. Has your dog’s appetite increased or decreased? Are they drinking more than usual? Have you noticed any diarrhoea or changes in colour or frequency of their stools? Could they be pregnant? Has something drastic happened at home, like a new arrival?
The more information you can give your vet, the better. They will almost certainly want to do blood and urine tests as well as the normal physical exam. If you can take a stool sample, that will help too.
As we said at the beginning, weight loss may be a very early sign of disease, so regular weight checks are essential for spotting things as soon as possible so you can get help. As always, if you are ever concerned or unsure, talk to your vet. It’s always better to be safe than sorry.
Reviewed by Dr. Hein Meyer, DVM, PhD, Dipl-ECVIM-CA
Related products
Sensitive Stomach & Skin Dog Food
Hill's Science Plan Sensitive Stomach & Skin Adult Wet Dog Food with Chicken is a complete premium dog food for adult dogs from 1 year. This savoury tinned loaf is enriched with ingredients that support digestive health & skin care.
Sensitive Stomach & Skin Small & Mini Adult Dog Food
Hill's Science Plan Sensitive Stomach and Skin Small & Mini Adult Dog Food with Turkey is a complete premium pet food for small breed adult dogs aged 1–6 years. This deliciously soft mousse is enriched with ingredients that support digestive health & skin care.
Perfect Digestion Small & Mini Adult Dog Food
Hill's Science Plan Perfect Digestion Small & Mini Adult Dog Food with Turkey is a complete premium pet food for small breed adult dogs aged 1–6 years. This deliciously smooth mousse is precisely balanced to deliver the appropriate amount of energy and to support digestive health in adult, small breed dogs.
Perfect Weight Small & Mini Adult Dog Food
Hill's Science Plan Adult Small & Mini Dog Food with Turkey is a complete premium pet food for adult small dogs from 1 year old that are prone to weight gain or slightly overweight. This deliciously smooth mousse is formulated to deliver the appropriate amount of energy to support weight maintenance in adult dogs.
Related articles
Kidney Disease in Dogs: Causes, Signs & Treatments
Discover the causes, signs, and treatments of kidney disease in dogs and find methods of supporting your dog's kidney health. Learn more at Hill's Pet UK.
What should I do about my overweight dog?
Dog obesity is a significant problem - learn more about helping your dog become trimmer and healthier through improved nutrition.
Vet's Advice About A Dog Diet
Just like every other pet owner, vets are responsible for giving their pets the best possible nutrition, exercise and care needed to keep them healthy and happy.
Excessive Dog Itching: Potential Causes
Understand the potential causes of excessive dog itching and how to address them. Seek relief for your dog with expert advice from Hill's Pet UK.
Put your dog on a diet without them knowing
Our low calorie formula helps you control your dog's weight. It's packed with high-quality protein for building lean muscles, and made with purposeful ingredients for a flavourful, nutritious meal. Clinically proven antioxidants, Vitamin C+E, help promote a healthy immune system.
Put your dog on a diet without them knowing
Our low calorie formula helps you control your dog's weight. It's packed with high-quality protein for building lean muscles, and made with purposeful ingredients for a flavourful, nutritious meal. Clinically proven antioxidants, Vitamin C+E, help promote a healthy immune system.