Intestinal intussusception in dogs: target sign on ultrasound
4-month-old German Shepherd puppy recovering from parvovirus that starts vomiting again, with tenesmus and bloody, mucoid faeces. A tubular mass is palpable in the mid-abdomen.
What ultrasound image would you expect on the transverse section of the lesion?
chevron_right Show answer and explanation
A. A hyperechoic linear structure in the lumen with intestinal plication
This is the image of a linear foreign body. It can be associated with intussusception, but it is not the sign of intussusception itself.
B. A dilated, fluid-filled loop with clean acoustic shadowing in the lumen
This suggests obstruction by a solid shadowing foreign body, not intussusception.
C. Multiple concentric alternating hyper- and hypoechoic rings (target sign)
Correct. In transverse section, the layers of the intussusceptum inside the intussuscipiens and the entrapped mesenteric fat form concentric rings; in longitudinal section parallel layers are seen. Ileocolic intussusception is most common in puppies with previous enteritis.
D. A segment with a thin wall and loss of layering, with free peritoneal gas
This suggests intestinal necrosis or perforation with pneumoperitoneum, a possible complication but not the characteristic image of intussusception.
lightbulb Key takeaway
In worsening enteritis or chronic diarrhoea in puppies, examine the ileocolic junction looking for the target sign. Absent Doppler flow in the invaginated segment suggests vascular compromise. After reduction or resection, consider enteroplication to reduce recurrence and look for a cause (parasites, enteritis, a mass in adults).
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.