It can be worrying, watching your dog shed kilos without knowing why. Whether it's a change in diet, stress, or something more serious, there are numerous factors that could be at play. In this guide, we cover the top 8 reasons why your dog might be losing weight — arming you with the knowledge to better care for your pup.

If your dog's weight loss has you concerned, don't wait. Reach out to your veterinarian today for advice tailored to your dog's unique needs.

8 reasons for dogs losing weight 

1. Poor digestion or malabsorption

If your dog is eating their food as normal but still losing weight, it’s possible they’re struggling to digest or absorb nutrients.

Exocrine Pancreatic Insufficiency (EPI) is the body’s inability to produce digestive enzymes. This can affect your dog’s ability to digest proteins, fats, and carbohydrates, leading to weight loss and in some instances, an increase in appetite — as the dog tries to compensate for their digestive difficulties and lack of vital nutrient absorption.

Small Intestine Bacterial Overgrowth (SIBO) is another condition affecting your dog’s level of nutrient absorption. SIBO affects the surface of intestines absorbing nutrients, sometimes leading to weight loss and chronic diarrhoea.

In other cases, diet is the cause. Low-quality ingredients, artificial additives, preservatives, and excessive fibre content can trigger digestive issues including diarrhoea and bloating: these conditions further limit your dog’s absorption of nutrients, leading to weight loss.

Next steps for dogs losing weight from poor digestion or malabsorption

Look for highly digestible diets containing quality ingredients like human-grade protein to maximise your dog’s nutrient absorption.

2. Oral health

Loss of appetite (inappetence) may be caused by a dental issue like a painful tooth, swollen gums, or even an abscess, making it difficult to eat.

Next steps for weight loss from oral health issues

If your dog has lost their appetite and is struggling to eat their food, make an appointment with your vet for a thorough oral health examination.

If your dog has a history of dental interventions or reactive behaviour, don’t try to resolve dental issues at home — veterinarians can support you in solving this issue without risk to you or your dog’s safety.

🐶 Read more: Protecting dental health: how to clean your dog's teeth →

3. Age

Weight loss can happen at both ends of the age spectrum: in both cases, it’s worth investigating to ensure your dog’s health and wellbeing.

Puppies are constantly curious and playful, always on the move. These small bundles of fur need more calories to support their physical and mental development. But if your puppy is underweight and missing growth milestones, they might not be receiving enough calories to keep up with this demand.

As dogs reach their senior years, they can lose weight due to changes in metabolism, appetite, digestive function, or age-related illnesses.

Next steps for age-related weight loss in dogs

If you’ve noticed weight loss in your puppy or senior dog, ask your veterinarian to screen for any underlying health issues that might be affecting them. They can also advise you on the best diet and nutrition to fit their age.

Lyka has tailored diets customised to your dog's breed, weight, age, and activity level that updates as they grow, so you never have to worry about them getting the nutrients they need to thrive. Our biologically-appropriate formulations contain targeted ingredients to support your dog’s weight management needs, wherever they are in life.

🐶 Read more: How to care for your senior dog: expert tips to improve quality of life →

4. Medical conditions

Weight loss can be caused by diseases that affect the metabolism or curb your dog’s appetite. These may include diabetes, hyperthyroidism, heart disease, cancer, inflammatory bowel disorder, or infections in the gastrointestinal tract.

Next steps for weight loss relating to medical conditions

If you’re concerned about your dog’s health and the possibility of an underlying health condition, seek advice from your vet as soon as possible.

5. Parasites

Parasites such as roundworms can be a common cause of weight loss because they live in the dog’s intestines and feast on their nutrients. These worms can multiply fast if left untreated and can create the appearance of a pot belly.

Next steps for weight loss due to parasites

If your vet confirms that your dog has picked up a parasite, they can provide a quality dewormer that should clear the problem up. Dogs can pick up parasites easily from their environment and other dogs, so prevention through regular worming tablets is key.

6. Stress or anxiety

Both humans and dogs can lose their appetite when they feel stressed because their body is in a heightened state of fight or flight responsiveness.

Next steps for weight loss from stress or anxiety

If your dog struggles to relax and seems anxious for long periods, their focus is probably on their immediate surroundings, not their mealtimes. Help them learn how to relax through training and try to find quiet, safe spots that they can retreat to, away from any stimulus that might be causing stress.

7. Activity

If your underweight dog is very energetic or a working dog, they may be burning off more calories than they’re consuming.

Next steps for weight loss due to activity

If your pup enjoys a complete and balanced diet, consider increasing their portion sizes under the guidance of your veterinarian. Monitor their weight and their body condition until they reach the ideal size for their breed and age.

8. Diet and nutrition

Poor quality dog food is often formulated with low quality ingredients, which lack the essential nutrients and energy necessary for a dog’s daily needs, leading to malnutrition and subsequent weight loss.

Insufficient protein in a dog’s diet leads to decreased muscle mass and energy levels, causing weight loss.

Next steps for diet-related weight loss

Check that your dog’s diet is complete and balanced so they’re not missing out on any nutrients that may be contributing to their weight loss. This is especially important if they eat home-cooked meals or a raw diet.

Lyka: nourishing real food portions to support healthy weight gain

If your dog seems to be shedding a few too many kilos, it's crucial to figure out why.

At Lyka, we tailor portion sizes to your dog’s unique needs. If your dog needs to gain a little weight, we’re here to help you find the perfect serving size for steady, healthy weight gain.

Let’s work together to get your dog back to feeling their best.