Why do shih tzus have breathing problems

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Last updated: April 8, 2026

Quick Answer: Shih Tzus have breathing problems primarily due to brachycephalic obstructive airway syndrome (BOAS), which affects over 90% of brachycephalic breeds like Shih Tzus. This condition stems from their flat-faced skull structure, with studies showing that 58% of brachycephalic dogs exhibit clinical signs of BOAS. The breed's respiratory issues are exacerbated by their compact nasal passages and elongated soft palate, which can obstruct airflow. These anatomical features have been selectively bred into Shih Tzus since their development in Tibet and China centuries ago.

Key Facts

Shih Tzus are brachycephalic dogs with a skull width-to-length ratio typically exceeding 0.8
Brachycephalic obstructive airway syndrome (BOAS) affects approximately 90% of brachycephalic breeds including Shih Tzus
Clinical studies show 58% of brachycephalic dogs exhibit BOAS symptoms requiring veterinary attention
Shih Tzus have been selectively bred for flat faces since their development in 7th century Tibet
The breed's respiratory issues are compounded by stenotic nares (narrow nostrils) present in 85% of affected dogs

Overview

Shih Tzus, developed in Tibet around the 7th century and refined in China during the Ming Dynasty (1368-1644), were bred as companion dogs for Chinese royalty. Their distinctive flat-faced appearance results from centuries of selective breeding for brachycephalic features, where the skull width-to-length ratio typically exceeds 0.8. This breeding preference created what's now recognized as brachycephalic obstructive airway syndrome (BOAS), a condition affecting over 90% of brachycephalic breeds. The American Kennel Club first recognized Shih Tzus in 1969, and by 2020, they ranked as the 20th most popular breed in the United States with approximately 58,000 annual registrations. Their popularity persists despite growing awareness of their health challenges, with veterinary studies indicating that 58% of brachycephalic dogs show clinical BOAS symptoms requiring medical intervention.

How It Works

Shih Tzus' breathing problems stem from multiple anatomical abnormalities that collectively constitute brachycephalic obstructive airway syndrome. The primary issues include stenotic nares (narrow nostrils present in 85% of affected dogs), an elongated soft palate that obstructs the trachea, and a hypoplastic trachea (narrow windpipe). These structural problems create increased airway resistance, forcing dogs to work harder to breathe. During inhalation, the negative pressure causes the soft tissues to collapse further into the airway, creating a vicious cycle of obstruction. The breed's compact nasal passages, often less than 50% the size of mesocephalic dogs, force them to rely more on mouth breathing. This inefficient respiratory system leads to chronic oxygen deprivation, with studies showing arterial oxygen saturation levels 5-10% lower than in non-brachycephalic breeds during normal activity.

Why It Matters

Shih Tzus' breathing problems have significant welfare implications, with affected dogs experiencing reduced quality of life and increased mortality risk. Veterinary studies indicate that brachycephalic dogs have a 3.4 times higher risk of anesthesia-related death during routine procedures. The condition also limits normal canine behaviors, with 68% of owners reporting their Shih Tzus cannot exercise normally. Financially, BOAS treatment costs average $2,000-$4,000 for surgical correction, creating economic burdens for owners. These health concerns have prompted veterinary organizations like the British Veterinary Association to advocate for breeding reforms since 2016. Understanding these issues helps prospective owners make informed decisions and supports ongoing efforts to improve breed health through responsible breeding practices.