How to Assess Fetal Viability in Cattle: What Matters and When to Act

By Dr Duncan Houston

Pregnancy loss in cattle is more common than most producers realise, and in many cases it happens quietly between checks. The challenge is not just detecting pregnancy. It is determining whether that pregnancy is still viable and likely to result in a live calf.

The key question is not “is she pregnant?”
It is “is this fetus developing normally and likely to survive?”

The earlier you identify problems, the more options you have to manage risk and reduce loss.

Quick Answer

Fetal viability in cattle is assessed using ultrasound, fetal heart rate, and tools such as pregnancy-associated glycoprotein testing. A viable fetus shows normal growth, movement, and an appropriate heart rate for its stage of gestation. Abnormal findings or declining markers increase the risk of pregnancy loss and require closer monitoring or intervention.

Why does fetal viability matter?

Pregnancy loss affects both productivity and profitability.

Typical patterns:

• Losses occur in early and mid-gestation

• Dairy herds tend to have higher loss rates than beef herds

• Risk increases with stress, illness, and reproductive technologies

What this leads to:

• Reduced calving rates

• Increased costs

• Disrupted breeding programs

Clinical insight

The biggest losses are often the ones you do not detect until much later.

What does “fetal viability” actually mean?

Fetal viability is about two things:

• Is the fetus developing normally in the uterus?

• Is it likely to survive to term and after birth?

What matters most

A confirmed pregnancy does not guarantee a live calf.

How do vets assess fetal viability?

Transrectal examination

What it shows:

• Pregnancy presence

• Approximate stage of gestation

• Fetal position

Limitations:

• Does not assess fetal health directly

• Limited information on viability

Ultrasound examination

This is the most useful tool in practice.

What it allows:

• Visualization of fetal movement

• Measurement of fetal size

• Assessment of fluid and placental structures

• Detection of a heartbeat

Clinical insight

Ultrasound moves you from guessing to actually seeing what is happening.

Fetal heart rate

Heart rate is a key indicator of viability.

Typical ranges:

• Around 200 beats per minute early in pregnancy

• Gradually decreasing toward about 100 near term

What matters:

• Consistency with gestational age

• Presence of a strong, regular heartbeat

Decision checkpoint

A heart rate that is lower than expected or irregular can indicate distress.

PAG testing

Pregnancy-associated glycoproteins reflect placental function.

What it shows:

• Strength of pregnancy

• Placental health

What to look for:

• Stable or increasing levels suggest a viable pregnancy

• Declining levels may indicate risk

Clinical insight

PAG trends over time are more useful than a single measurement.

How serious are viability concerns?

Mild

• Slight variation in measurements

• No obvious abnormalities

Action: Monitor

Moderate

• Slower growth or borderline findings

Action: Recheck and monitor closely

Severe

• Abnormal heart rate

• Poor movement

• Placental concerns

Action: Increased monitoring and intervention

Critical

• No heartbeat

• Clear signs of fetal compromise

Action: Pregnancy loss likely

What increases the risk of fetal loss?

Common risk factors:

• Transport or environmental stress

• Systemic illness in the cow

• Poor nutrition

• Assisted reproductive techniques such as IVF or embryo transfer

Clinical insight

Higher-value pregnancies are often the most vulnerable.

When should you be concerned?

• Changes in behaviour or condition of the cow

• Abnormal ultrasound findings

• Declining PAG levels

• History of previous losses

Decision checkpoint

If something does not fit the expected pattern, it is worth rechecking sooner rather than later.

What should you do right now?

Step 1

Review breeding and pregnancy records

Step 2

Schedule appropriate pregnancy checks

Step 3

Monitor high-risk animals more closely

Step 4

Reduce stress and environmental challenges

Step 5

Reassess if abnormalities are detected

Time-based guidance

• Initial check around 30 to 45 days

• Follow-up around 60 to 90 days

• Additional checks based on risk

What happens if problems are detected?

Possible responses:

• Increased monitoring

• Addressing underlying disease

• Adjusting nutrition

• Veterinary intervention where appropriate

What matters most

Early detection gives you more options to manage risk.

Common mistakes that lead to losses

• Only checking for pregnancy once

• Ignoring mid-gestation losses

• Not monitoring high-risk cows

• Delaying follow-up checks

• Assuming all pregnancies will progress normally

How do you improve outcomes long-term?

• Use structured monitoring schedules

• Track pregnancy outcomes

• Identify patterns of loss

• Adjust management based on data

Clinical insight

The best herds treat pregnancy as a process to monitor, not a single event.

FAQ

How early can fetal viability be assessed?
Around 30 days with ultrasound, with more detail available as pregnancy progresses.

What is the most reliable indicator?
A normal fetal heartbeat combined with appropriate development.

Can pregnancies fail after early confirmation?
Yes, mid-gestation loss is common.

What does a low heart rate mean?
It may indicate fetal distress or compromised viability.

Is PAG testing always necessary?
Not always, but it is useful in higher-risk or valuable pregnancies.

Final Thoughts

Fetal viability is not a single check. It is something that needs to be monitored over time.

The most important shift is moving from confirming pregnancy to actively assessing whether that pregnancy is progressing normally.

If you detect problems early, you can adjust management and reduce losses. If you only check once, you miss the opportunity to intervene.

If you want help setting up a monitoring schedule or interpreting fetal viability findings, ASK A VET™ can guide you through assessment, risk management, and improving pregnancy outcomes across your herd.