Excessive thinness in a dog isn't just a cosmetic problem – it can signal health complications, metabolic disorders, unsuitable nutrition or psychological strain. Identifying the cause early and a professional approach are key to increasing a dog's body weight safely and effectively.

How can you tell if a dog is too thin?

Before you start changing the daily portion, it's important to assess the dog's actual body condition. This is what the so-called BCS (Body Condition Score) is for – a scale for assessing a dog's nutritional condition from 1 (severely underweight) to 9 (obese).

Typical signs of being underweight:

• clearly visible ribs, spine and hip bones
• poorly developed muscle mass (especially on the legs)
• a pronounced “waist” when viewed from above
• reduced vitality, tiredness or reluctance to move

TIP: If you're not sure, it's best to consult a vet or a pet nutritionist.

Possible causes of low body weight

Health reasons:

• Internal parasites – roundworms, tapeworms 
• Digestive system disorders 
• Metabolic disorders – diabetes, hyperthyroidism.
• Chronic systemic disease – liver, kidneys, cancer.
• Inflammatory or infectious diseases – for example after a viral infection.

Dietary and routine-related causes:

• Insufficient calorie intake – the daily portion is too small.
• Low-quality food – unsuitable composition, low fat or protein content.
• High physical activity – working and sporting breeds have higher energy needs.

Psychological and behavioural factors:

• Stress, a change of environment or routine
• Anxiety, separation problems
• Social stress (competition at the bowl, dominance)

How to gain weight healthily and safely: recommended approach

Step 1: Diagnosis and ruling out health causes

Especially in the case of sudden or significant weight loss, it's essential to have:

• a clinical examination at the vet
• basic laboratory tests (blood count, biochemistry, stool tests)
• possibly an abdominal ultrasound or EPI tests

Step 2: Optimising nutrition

Increasing the energy value of the food:

• Choose food with a higher content of fat and good-quality animal protein.
• Target values: min. 22–28 % protein, 14–20 % fat.
• Make sure it's highly digestible – recipes with fresh meat are a good choice.

Increase the daily calorie intake:

• Increase the food portion by 10–20 % compared with the manufacturer's recommendation.
• Split the food into 2–3 smaller meals a day.
• Increase the portion gradually, monitoring digestive tolerance (stools, bloating).

Energy supplements:

• Salmon oil, coconut oil – a concentrated source of calories.
• Nutritional pastes for weight gain – suitable during recovery or loss of appetite.
• Eggs, cooked meat, wet food (canned food) – occasionally as an addition, while keeping the diet balanced.

Supporting appetite and digestion

Some dogs lose weight because of poor appetite or malabsorption. These can help:

• Brewer's yeast – supports digestion, appetite and immunity.
• Prebiotics and probiotics – important for intestinal problems or after antibiotics.

Routine and psychological measures

In sensitive dogs, stress is a common factor behind loss of appetite. These can help:

• a stable daily routine (feeding at the same time, in the same place).
• a calm, undisturbed environment while eating.
• positive reinforcement – rewards for eating, patience.

When to seek expert help?

• Your dog doesn't gain weight over the long term despite a larger daily portion.
• There is loss of appetite, diarrhoea, vomiting or changes in behaviour.
• You suspect a chronic disease or a metabolic disorder.
• You need an individual nutrition plan for a sporting, convalescent or older dog.

TIP: A good choice is a veterinary nutrition specialist or a clinic specialising in internal medicine.

Summary: How to help your dog gain weight the right way

✅ Assess body condition using the BCS scale.
✅ Check their health – rule out parasites and chronic diseases.
✅ Increase the calorie value of the diet – ideally through a combination of food and supplements.
✅ Provide a calm, comfortable environment at mealtimes.
✅ Monitor your dog – weight, appetite, stools, activity.
✅ Don't hesitate to turn to an expert if you don't see results.