Pyloric Stenosis in Dogs: Acquired and Congenital Guide

Pyloric stenosis is a condition where the passage between a dog's stomach and small intestine—the pyloric canal—becomes narrowed, making it difficult for food to pass through normally. This can have a significant impact on your dog's health and nutrition, especially when it causes frequent vomiting and weight loss.

Also known as chronic hypertrophic pyloric gastropathy, pyloric stenosis occurs when the muscles around the pyloric canal thicken excessively or when the canal itself is naturally too narrow. This leads to a blockage that prevents partially digested food from moving efficiently into the intestine.

Regular vomiting following meals is a common sign, which can weaken your dog overall and may contribute to dental problems due to acid exposure from stomach contents. Although not very common, some breeds have a higher risk of developing this condition, so it’s useful for owners to be aware of the symptoms and treatment options.

In this guide, we'll explore both acquired and congenital pyloric stenosis in dogs, discuss which breeds are most susceptible, explain causes, symptoms, diagnosis, and share current treatment methods recommended by veterinary experts.

Understanding Acquired and Congenital Pyloric Stenosis

Pyloric stenosis in dogs manifests in two main forms: congenital and acquired.

Congenital Pyloric Stenosis

Dogs born with the congenital form often develop symptoms between 4 to 12 months of age, typically after weaning when they begin eating solid foods. It's caused by an abnormal thickening of the smooth muscles surrounding the pylorus, narrowing the channel from birth.

This form is more common in brachycephalic (flat-faced) breeds, and symptoms include persistent or projectile vomiting, failure to gain weight properly, and dehydration.

Acquired Pyloric Stenosis

The acquired form develops later in life, often in middle-aged or older dogs, and results from gradual thickening of the pyloric muscle or mucosa over time. It may be linked to chronic gastritis, increased stress, ulcers, or other health conditions.

Small breeds such as the poodle, Pekingese, Shih Tzu, and Lhasa Apso are most at risk for the acquired form, with clinical signs often including chronic intermittent vomiting, mild to moderate weight loss, and abdominal distension.

Breeds Most at Risk

While any dog can develop pyloric stenosis, certain breeds exhibit a higher susceptibility, particularly when considering the form of the condition:

• Congenital form: Brachycephalic breeds such as the English Bulldog, Boston Terrier, and Boxer are most commonly affected.
• Acquired form: More common in small breeds including the Poodle (all sizes), Pekingese, Shih Tzu, and Lhasa Apso.

Causes and Risk Factors

The root cause of pyloric stenosis varies depending on the form. Congenital cases are related to genetic and conformational factors that produce a thickened pyloric muscle from birth.

Acquired stenosis may arise from chronic irritation or inflammation of the stomach lining, hormone imbalances, stress, or secondary complications from gastric ulcers or tumours. These factors can lead to progressive narrowing of the pyloric canal over time.

Recognising the Symptoms

The most common and consistent symptom across both types is vomiting, frequently occurring within a few hours after eating. In congenital cases, vomiting may be more severe and persistent, whereas acquired cases may show intermittent episodes.

Other signs include:

• Weight loss and poor body condition
• Decreased appetite or reluctance to eat
• Signs of dehydration due to fluid loss
• Dental issues related to frequent vomiting
• In acquired cases, possible abdominal swelling

Diagnosing pyloric stenosis can be challenging due to symptom overlap with other digestive conditions, so a vet will perform comprehensive examinations and diagnostic tests.

Diagnosis: How Vets Confirm Pyloric Stenosis

Your veterinarian will take a detailed history and conduct a physical examination. Diagnostic steps often include:

• Blood and biochemical tests to assess general health
• X-rays and barium contrast studies to visualize stomach emptying
• Ultrasound imaging to inspect pyloric muscle and canal thickness
• Fluoroscopy and endoscopy to provide real-time and inside views
• Exploratory surgery and biopsy in uncertain or acquired cases

Treatment and Management Options

Surgical intervention is typically the most effective treatment for pyloric stenosis, aiming to enlarge the pyloric canal and restore proper food passage.

Following surgery, your vet will recommend a carefully managed diet that is highly digestible and low in fat to ease digestion.

Supportive care including fluid therapy may be necessary to treat dehydration or electrolyte imbalances.

Recurrence is rare but can occur, sometimes requiring additional surgery.

Preventing Pyloric Stenosis and Supporting Your Dog

While congenital pyloric stenosis is largely preventable through responsible breeding practices—avoiding breeding affected dogs—owners of breeds at risk should remain vigilant for early symptoms.

Managing stress, ensuring good digestive health, and timely treatment of stomach irritations may help reduce the risk of acquired pyloric stenosis.

Conclusion: Ensuring a Healthy Digestive Life for Your Dog

Pyloric stenosis, whether congenital or acquired, poses challenges for affected dogs but with timely veterinary care and appropriate surgery, most dogs go on to enjoy good quality lives.

If you notice frequent vomiting or other signs of digestive distress, particularly in high-risk breeds, seek veterinary advice promptly. Early diagnosis and treatment are key to successful outcomes.