Ultrasound scans late in pregnancy can offer much more than a headcount. They can show us how puppies are developing, whether structures appear normal, and in some cases, even give clues about when labor might begin.

In this video, a late-term pregnant Cocker Spaniel is scanned using the Vinno D10, first with a microconvex probe, then with a linear probe. Both deliver great results—but you’ll immediately see a jump in clarity when the linear probe is applied:

Did You Know You Can See Puppy Intestinal Movement on Ultrasound?

In dogs, fetal intestines start moving around 13 to 9 days before whelping. (In humans, similar movement occurs around 22 to 20 weeks before delivery.) With the right equipment, you can see this on ultrasound.

Watch the video again and focus on the pup’s abdomen—you’ll spot the intestines forming clearly, something that’s only possible with a high-resolution linear probe. Being able to detect these kinds of details could help narrow down the timing for delivery, giving breeders and vets an extra tool to guide care decisions.

Microconvex Probes: Versatile and Practical

The microconvex probe is a favorite for small animal ultrasound. It’s compact, provides a wide view, and reaches deep enough to get all the information you usually need in pregnancy scans. It’s especially helpful when scanning medium to small dog breeds where maneuverability matters.

This is why many ultrasound training programs and paraprofessional courses recommend a high-quality microconvex as the go-to starting probe.

The Linear Advantage: Detail You Can’t Miss

Linear probes operate at higher frequencies, which means better resolution, especially when looking at structures close to the surface. In the second half of the scan video, you’ll notice sharper edges, finer anatomical detail, and an overall increase in image clarity.

That’s because linear probes are designed to excel in the near field—the part of the scan window closest to the probe. When puppies are situated near the abdominal wall, as they often are in late-stage pregnancy, a linear probe gives you a clear edge.

When to Use a Linear Probe

If you’re scanning cats or dogs under 15–20 kg, a microconvex will usually be all you need. It’s the best all-rounder. But if you’re a veterinarian, experienced tech, or working in a clinical setting, adding a linear probe can enhance your diagnostic accuracy—especially for late-term scans or follow-up imaging.

So while not essential for every scanner, linear probes can bring significant value for those with advanced machines or in veterinary practices looking to elevate their imaging standards.