Application of Ultrasound in Detecting and Removing Migrating Grass Awns in Dogs and Cats: A Systematic Review

Abstract

Migrating grass awns are an important cause of disease in dogs and cats. Plant awns can migrate into several body tissues and cavities because of their fusiform shape and backward-pointing barbs. Their migration causes inflammatory tissue reaction and clinical signs depend upon their localization. Ultrasound has been described as a useful, noninvasive, and readily available tool to identify and guide vegetal foreign bodies removal in animals. The aim of this systematic review was to summarize current knowledge on the application of ultrasonography in the identification and removal of grass awns from various anatomic locations in dogs and cats. We selected and analyzed 46 papers on the application of ultrasonography in dogs and cats affected by migrating grass awns. The ultrasonographic appearance of grass awns is characteristic, although their size and location can influence the visualization and the attempt of removal. In some cases, migrating grass awns are not directly visualized by ultrasonography, but the lesions caused by their migration can be easily seen. Ultrasonography can be considered a useful diagnostic tool to localize and remove migrating grass awns; however, when the migration occurs in less accessible locations or discrete foreign bodies are present, this diagnostic tool should be considered as a part of a multidisciplinary approach with advanced diagnostic imaging modalities.

Keywords: canine; feline; foreign body; grass awn; ultrasonography.

Figure 1

Grass awns removed from various anatomic locations with characteristic fusiform shape.

Figure 2

Modified Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram with the review search strategy and study selection.

Figure 3

Transthoracic ultrasonographic image of a spindle-shaped hyperechoic foreign body consistent with a migrating grass awn (red arrow) in the pleural space of a dog. White arrow indicates a rib.

Figure 4

Transabdominal ultrasonographic image of a spindle-shaped hyperechoic foreign body consistent with a migrating grass awn (red arrow) in the left iliopsoas muscle of a dog.

Figure 5

Ultrasonographic image of a spindle-shaped hyperechoic foreign body consistent with a migrating grass awn (red arrow) within the preputium of a dog. White arrow indicates the os penis.

Figure 6

Ultrasonographic image of a spindle-shaped hyperechoic foreign body consistent with a migrating grass awn (red arrow) located in the subcutaneous space of a dog.