Response to Two Standardized Exercise Tests in Dogs with Different Cephalic Biotypes.

Area of Science:

• Veterinary Medicine
• Animal Anatomy and Physiology
• Canine Health

Background:

• Dogs are categorized into dolichocephalic, mesocephalic, and brachycephalic biotypes based on cephalic index.
• Brachycephalic conformation, resulting from selective breeding, is linked to conformational defects and medical issues, notably Brachycephalic Obstructive Airway Syndrome (BOAS).
• BOAS presents with clinical signs like respiratory noise, exercise intolerance, syncope, and potentially sudden death.

Purpose of the Study:

• To investigate craniofacial anatomical variations among different cephalic biotypes in dogs.
• To assess the influence of two standardized exercise tolerance tests (6-minute walk and 1000-meter walk) on physiological parameters in dogs.
• To correlate morphometric measurements with BOAS severity and physiological responses to exercise.

Main Methods:

• Eighty dogs of various breeds were classified into dolichocephalic, mesocephalic, and brachycephalic biotypes.
• Morphometric data of the head, body, and limbs were collected.
• Physiological parameters (heart rate, respiratory rate, blood pressure, oxygen saturation, rectal temperature) were measured before and after exercise tests.

Main Results:

• All dogs tolerated the exercise tests; dolichocephalic and mesocephalic dogs demonstrated better exercise tolerance or respiratory adaptation.
• Brachycephalic dogs with higher BOAS grades showed reduced exercise capacity in the 1000m test.
• Specific morphometric features (rostral shortening <38mm, facial foreshortening, neck/chest/nasal fold measurements ≥20mm) indicated higher airway obstruction risk in brachycephalic dogs with BOAS grades 2 and 3.
• Significant physiological alterations (heart rate, respiratory rate, SpO2 <90%, temperature) were observed in brachycephalic dogs post-exercise, not returning to baseline.

Conclusions:

• Extreme brachycephalic conformation negatively impacts respiratory function and thermoregulation, compromising canine health under physical stress.
• Exercise tolerance tests and non-invasive morphometric measurements are valuable tools for early BOAS diagnosis.
• Findings highlight the need for careful management of brachycephalic breeds to mitigate risks associated with their conformation.