Why Small Dogs Develop Pyloric Stenosis and Pylorospasm

In dogs, the pylorus is a muscular valve located between the stomach and the small intestine. Under normal circumstances, this valve remains closed while the stomach fills with food, then opens to allow partially digested food to pass into the small intestine for further digestion.

Small dogs can develop two related conditions affecting this area: pyloric stenosis and pylorospasm. Pyloric stenosis is a narrowing of the pylorus, while pylorospasm is an abnormal spasm of the pyloric muscle, both impairing the passage of food out of the stomach and causing vomiting.

Understanding the Role of the Pylorus in Digestion

The stomach’s primary function is to store large amounts of food and break it down with acids and enzymes. After digestion in the stomach, food passes through the pyloric sphincter to the duodenum (the first part of the small intestine). This process typically takes about 12 hours.

In cases of pyloric stenosis, the opening becomes abnormally narrow, while pylorospasm causes intermittent muscle contractions that reduce the opening’s size temporarily. These conditions make it difficult for food to leave the stomach properly, leading to symptoms.

Why Do Small Dogs Develop These Conditions?

There are several reasons small dogs, particularly certain breeds, are more prone to pyloric stenosis and pylorospasm:

• Congenital Causes: Some small or brachycephalic breeds such as Lhasa Apsos, Shih Tzus, Pekingese, and Malteses can be born with thickened pyloric muscles causing a narrowing from birth. Symptoms are often noticed between four and twelve months, usually after weaning when solid food is introduced.
• Acquired Causes: Chronic inflammation of the stomach lining (gastritis), infections, ulcers, tumours, or stress can cause progressive thickening or spasms of the pyloric muscles later in life.

Recognising the Symptoms to Protect Your Dog

Common signs of pyloric stenosis or pylorospasm include:

• Intermittent vomiting, usually around an hour after eating
• Vomiting of undigested or partially digested food
• Weight loss due to malnutrition if the condition is severe
• Occasionally only partial vomiting, as some food may pass through the narrowed opening

Feeding watery or finely ground food can help ease passage, while bulky or dry foods may exacerbate symptoms.

Diagnostic Journey and Treatment Options

Diagnosing these conditions requires a thorough veterinary history and sometimes imaging like X-rays to assess the pyloric opening size and stomach condition.

Treatment depends on severity:

• Management: For pylorospasm, managing diet, medications to control spasms, and sometimes tranquillisers can help dogs live comfortably with symptoms.
• Surgery: For pyloric stenosis, surgery to widen the pyloric opening (pyloromyotomy or pyloroplasty) has a high success rate and allows dogs to return to normal digestion and a happy life.

Living With and Supporting Your Dog

Small dogs with pyloric conditions often lead happy lives post-treatment or with careful management. Regular veterinary check-ups are essential to monitor weight and digestion. Responsible pet ownership includes recognising early symptoms and seeking vet advice promptly.

Conclusion

Pyloric stenosis and pylorospasm primarily affect small and brachycephalic breeds due to congenital muscular changes or acquired inflammation. With accurate diagnosis, appropriate treatment, and ongoing care, affected dogs can recover well and live full, healthy lives. If your small dog vomits frequently or loses weight, consult your vet to explore if pyloric conditions might be the cause and discuss the best path to recovery.