This guide is part of Vet Direct’s Technical Know-How series, created by our dedicated Technical Team to help you get the most from your equipment.  
 

With a focus on Doppler blood pressure monitoring, this resource has been carefully authored by our Field Based Technical Support RVN, Michelle Richmond DipAVN (Medical), DipAVN (Surgical), CertVN ECC, RVN,  a highly respected RVN with decades of hands-on experience. Michelle’s practical tips and clinical insights make this guide an essential tool for improving diagnostic accuracy and patient outcomes in your practice. 

What Is Doppler BP Monitoring? 

Doppler blood pressure monitoring is a non-invasive technique that uses a piezoelectric crystal to detect blood flow within an artery. The probe, coated with ultrasound gel, is placed over a peripheral artery, commonly on the limb or tail. As the cuff is manually inflated using a sphygmomanometer, blood flow is temporarily halted. During deflation, the return of the audible pulse indicates systolic pressure.  

When to Use Doppler Monitoring 

Doppler is particularly valuable in scenarios where precision is critical or patient size presents challenges: 

• Routine screening for patients over 7 years of age 
• As part of a routine clinical examination / consultation of every patient healthy patient over the age of 7 years 
• Diagnostic screening of patients with conditions associated with hypertension such a feline hyperthyroidism. 
• Monitoring of patients undergoing treatment for hypo and hypertension 
• Prior to patient premedication and post induction of general anaesthesia for patients undergoing surgical procedures 
• During routine procedures when patient have been sedated, such as radiography. 
• During and post-surgery  
• Times of trauma and during intensive care 

Its sensitivity makes it ideal for small patients, including cats and toy breeds, where oscillometric devices may struggle to detect accurate readings. 

Cuff Selection & Placement: Getting It Right 

Accurate readings depend heavily on correct cuff size and placement: 

• Dogs: Cuff width should be ~40% of limb circumference 
• Cats: Cuff width should be ~30% 
• Too small = falsely high readings 
• Too large = falsely low readings 

Placement Tips: 

• Cuff should be positioned above the joint proximal to the probe 
• Ensure the limb or tail is level with the heart to avoid hydrostatic pressure errors 
• The patient must be calm and still—stress and movement can significantly affect results 

Repeat Readings for Reliability 

One-off readings are rarely reliable. Aim to take 3–5 readings, allowing the patient time to settle between measurements. This not only improves accuracy but helps identify trends over time, which are far more clinically valuable than isolated values. 

Common Challenges & Troubleshooting 

Doppler monitoring requires skill and patience. Here are some common issues and how to address them: 

• Locating small arteries: Use slow, lateral movements with light pressure 
• Too much probe pressure: Can occlude the artery—use a gentle touch 
• Movement artefacts: Minimise handling and environmental stressors 
• Peripheral vasoconstriction: Warm the patient or choose alternative sites 

Recommended Equipment from Vet Direct 

Vet Direct offers a range of Doppler systems and accessories to support accurate and repeatable readings: 

• LifeVet Doppler Kit – Compact, reliable, and ideal for small animal practices 
• Sphygmomanometer with Cuffs – Manual inflation for precise control 
• Ultrasonic Doppler Cuffs – Available in multiple sizes for cats, dogs, and exotic species