Evaluation of the canine pregnancy using ultrasound

Ultrasonography is the ideal modality for evaluating the canine pregnancy for many reasons. You can assess the following easily with most ultrasound machines:

  • Foetal Heart Rate (FHR)
  • Foetal Movement

Ultrasound has many advantages, including the fact that there is no ionizing radiation exposure to the developing foetuses. The ultrasound procedure is also quick & non-invasive, with sedation of the patient not necessary.

Note that for estimation of foetal numbers, radiography is more reliable than ultrasound. Radiography can only be used from day 55 of gestation (once skeletal mineralization has occurred). Ultrasound is inaccurate because only a small portion of the uterus can be imaged in one view, and some foetuses may be double counted and others not counted at all.


Canine Foetal Heart Rates: What’s Normal & Abnormal?

  • The normal foetal heart rate should be >220bpm
  • If foetal heart rate is <180 bpm or excessive foetal movement is detected, this is an indicator of foetal distress and hypoxia.
  • If foetal heart rate is <160 bpm, immediate surgical intervention is indicated to prevent foetal death!

Measurement of FHR using M-Mode on the Mindray M6Vet with the C11-3s probe.

How do you calculate FHR on your ultrasound machine?

Download our PDF Guide here

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