Sudden changes in dog behaviour are often early indicators of underlying health issues, making them an important signal for pet owners to pay attention to. Excessive lethargy, unusual aggression, sudden nervousness, and sometimes even frequent zoomies are usually due to potential health issues that may have many causes - most of which invariably come down to their diet. In fact, recent studies in veterinary immunology have revealed that 70-80% of a dog’s immune system resides in the gut. When the gut is inflamed by an insufficient or poor diet, it releases inflammatory cytokines that can cross the blood-brain barrier. This explains why a dog might sometimes seem strangely moody, lethargic, or excessively excited with frequent zoomies. They are not being naughty or acting up; they may instead be experiencing digestive and health issues that could need immediate medical attention and care.
The Gut-Brain Nexus: How Food Affects Dog Behaviour
According to veterinary science and food safety specialist Dr. Davide Stephanutti, “there is increasing evidence today that what you feed your dog influences not just their health but also how they behave. This is largely due to the deep impact that certain nutrients have on maintaining normal physiological and biochemical functioning within the body.”
A dog’s digestive tract is often considered to be their "second brain" as it affects everything from heart rate and digestion to emotional responses and overall wellbeing. And the health of a dog’s digestive tract depends on its microbiome, which consists of trillions of microorganisms that live in a dog's gut. These microorganisms actively influence brain chemistry, neural development, and behaviour. A balanced microbiome supports emotional stability, while disruption (called dysbiosis) triggers stress, anxiety, and inflammation that affects mood and temperament. That is why it is important to stay alert about unusual or post-meal behaviour shifts. Such changes often reflect physiological responses to internal issues, and recognizing them provides insights into how diet affects a dog’s gut health.
Foods That Can Cause Behavioural Problems in Dogs
Studies have clearly shown that certain ingredients have a negative impact on dog gut health and behaviour. Processed foods and fillers like refined grains and corn create rapid spikes in blood sugar levels, leading to inflammation, hyperactivity, inattention, and behavioural unpredictability in dogs. Similarly, common additives, artificial preservatives, synthetic colours, and flavour enhancers trigger allergic responses and digestive issues in sensitive dogs. Research indicates that approximately 10 - 15% of dogs experience behavioural changes from these additives alone.
Then there is the overload of omega-6 fatty acids in meals that contain only kibble. Unfortunately, dogs on a kibble-only diet end up consuming a disproportionately higher amount of omega-6 fatty acids with little trace of omega-3 fats. While omega-6 fatty acids create digestive imbalances, omega-3 fatty acids are known to calm gut irritation and support brain health. The ideal omega-6 to omega-3 ratio for dogs is approximately 5:1, and that can be achieved by feeding dogs a mix of hand-made and freshly cooked, protein-rich meals and kibble while limiting their carbohydrate content.
Nutrients That Support Healthy Dog Behaviour
Most vets agree that a minimally processed diet made using fresh and natural ingredients like those available from Brunswick Fur Food supports dog gut health, leading to:
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An improved and diverse gut microbiome
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Better emotional stability
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Reduced stress hormone levels (cortisol)
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Fewer compulsive or hyperactive behaviours such as excessive lethargy, anxiety, spinning, pacing, and frequent zoomies
Therefore, it is important to ensure optimal levels of protein, carbohydrates, and healthy fats in your pup’s diet. Include foods like cooked salmon, sardines, and mackerel that are naturally rich in omega-3 fats. Additionally, when feeding your pup, do try to add foods that contain compounds called phytonutrients or phytochemicals. These are components of plants that promote optimum cellular health, resulting in overall wellbeing, improved quality of life, and increased longevity.
Meal Timing and Portion Size
Dogs fed one large meal daily often display more extreme behavioural swings than those on a twice-daily schedule. That is why the Australian Veterinary Association recommends splitting the daily food allowance into two meals for most adult dogs. This approach:
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Reduces the digestive workload at any single sitting
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Maintains steadier blood sugar throughout the day
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Decreases bloat risk in susceptible breeds
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Minimizes extreme post-meal behaviour changes
For working breeds or highly active breeds like Border Collies, veterinarians recommend three smaller meals to maintain consistent energy for activity.
Vet recommendations for Dealing with Sudden Changes in Dogs' Behaviour
To avoid potential imbalances in dog gut health, vets recommend the following:
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Switch to high-quality, fresh-cooked meals with whole proteins, healthy fats, and complex carbs.
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Keep a food diary to help record and eliminate foods causing digestive issues and allergies.
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Check the first five ingredients on your dog food label. If you see corn, wheat, by-products, or vague terms like "meat meal," consider changing.
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Add vet-approved probiotics to restore microbiome balance.
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Feed smaller, more frequent meals to stabilise blood sugar.
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Channel energy with gentle post-meal walks.
Dr. Davide Stephanutti suggests watching for specific patterns like frequent dog zoomies after eating, or lethargic, shivering dogs. Red flags include gas and soft stools, persistent lethargy over 24 hours, sudden aggression, or vomiting. These warrant immediate vet checks to rule out toxicities and other possible health concerns.
FAQs-
Can dog food affect behaviour and mood?
Yes, dog food plays a major role in behaviour and mood. Poor-quality or highly processed foods can cause gut inflammation, blood sugar spikes, and nutrient deficiencies, leading to hyperactivity, lethargy, anxiety, and aggression. A balanced, fresh diet supports emotional stability and consistent energy levels.
2. Why does my dog get zoomies after eating?
Post-meal zoomies are often caused by sudden blood sugar changes, digestive discomfort, or poor nutrient absorption. Foods high in refined carbohydrates and additives can overstimulate the nervous system, triggering bursts of energy. Switching to high-quality, easily digestible meals can help reduce this behaviour.
3. What is the link between gut health and dog behaviour?
Gut health directly affects brain function through the gut-brain axis. An unhealthy gut microbiome releases inflammatory chemicals that impact mood and stress levels. When gut bacteria are balanced, dogs show better emotional control, reduced anxiety, and improved focus.
4. What is the best diet for improving dog behaviour?
The best diet for behavioural balance includes fresh, minimally processed proteins, healthy fats (especially omega-3), complex carbohydrates, and natural fibre. Foods like salmon, sardines, vegetables, and fresh-cooked meals help support digestion, brain health, and steady energy.
5. When should I see a vet for sudden behaviour changes in my dog?
You should consult a vet if your dog shows persistent lethargy, aggression, vomiting, diarrhoea, gas, trembling, or behavioural changes lasting more than 24 hours. These symptoms may indicate digestive disorders, allergies, or underlying medical conditions that need professional care.
