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Dietary Reactions in Dogs

Gastrointestinal Food Reactions in Dogs

Gastrointestinal food reactions in dogs encompass abnormal clinical symptoms triggered by a specific diet. Dogs experiencing such reactions struggle to digest, absorb, and/or utilize certain foodstuffs.

It’s important to distinguish gastrointestinal food reactions from food allergies, which involve an immune response to specific dietary components. Despite this distinction, both conditions share similar symptoms, causes, diagnostics, and treatments, posing a challenge for attending veterinarians to differentiate between them.

The causes of reactions to a particular diet often remain unknown but may be linked to specific dietary ingredients, additives, or compounds. Dogs may also react to the toxic effects of food contaminants like Salmonella or spoiled foodstuffs such as mold/fungus.

Gastrointestinal food reactions can affect dogs of any age, breed, or gender. For instance, gluten sensitivity has been observed in Irish setters, while lactose intolerance is frequently found in adult dogs.

Symptoms and Types

Signs may manifest after introducing a new food item or source into your dog’s diet. Clinical indications might diminish during fasting under medical supervision or within days of a dietary alteration. Typical symptoms of a dietary reaction comprise:

  • Diarrhea
  • Vomiting
  • Flatulence/abdominal gas
  • Reduced appetite
  • Weight loss
  • Inadequate weight gain
  • Abdominal pain and discomfort
  • Excessive itching/scratching
  • Poor body condition


Typically, adverse dietary reactions are associated with a sudden change in diet. Additionally, dogs may react to food additives, coloring, spices, or substances like propylene glycol. Other contributing factors include an inability to process specific components in food and toxicity from contaminated or spoiled foods.


Your veterinarian will conduct a thorough and detailed history-taking session, particularly focusing on the dog’s dietary habits. Diagnosing food reactions can be challenging due to the possibility of other health issues presenting similar symptoms. Furthermore, there are additional disorders that might coincide with dietary intolerances, making the diagnosis more complex.

Initial laboratory tests may include a complete blood count, biochemistry profile, and urinalysis. However, these results may appear normal if there are no other underlying diseases present. Further testing might be necessary to rule out other conditions that could cause similar symptoms in dogs.

The most commonly used diagnostic approach involves modifying the dog’s diet to identify the specific trigger. Initially, home-cooked diets or specialized plans with minimal ingredients or additives are implemented. This helps pinpoint the problematic dietary component in the individual dog. Typically, clinical symptoms begin to improve within a few days of starting the new diet. Once an improvement is observed, your veterinarian will attempt to identify the particular dietary ingredient using various food components.

Endoscopy, a procedure involving a small camera attached to a flexible tube, may also be employed by your veterinarian. This allows for a close examination of the internal structure of the intestines and enables the collection of tissue samples for laboratory analysis. Abdominal X-rays can also aid in ruling out other conditions that may manifest similar clinical symptoms.


Dogs experiencing severe vomiting, diarrhea, or other clinical symptoms may necessitate hospitalization for intravenous fluid administration, antibiotics, and supportive care. However, in most instances, hospitalization is not required.

The key to an effective treatment regimen lies in identifying the problematic dietary component and eliminating it from the dog’s diet. If the offending component cannot be pinpointed, your veterinarian will propose and assist in devising a nutritionally complete exclusion diet. In cases where a definitive diagnosis cannot be attained, a trial-and-error approach may be adopted. Your veterinarian will create a plan to either include or exclude specific dietary components and closely monitor the dog’s response.

Living and Management

The prognosis for most patients is highly favorable, particularly if the problematic dietary component has been identified. The primary objective of therapy is to avoid the triggering dietary component altogether.

For dogs diagnosed with food sensitivities, it’s crucial to refrain from feeding them food scraps or introducing new food items without consulting your veterinarian first. If your veterinarian has recommended a specific diet, strict adherence to the prescribed regimen is essential.

Poor response to treatment often stems from reduced owner compliance, such as giving the dog “treats.” It’s important to ensure that children or visitors do not feed the dog without prior permission. Maintaining good owner compliance is key to achieving long-term improvement in clinical symptoms.

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