Ultrasonographic Features of Grass Awn Migration in the Dog

Abstract

The aim of this study was to describe the ultrasonographic features of grass awns in soft tissue. A 10 MHz linear transducer was used. Ultrasound images from 25 dogs (27 awns) were collected and compared with the results from water bath studies using wild oat seeds (Avena spp.) collected in the field. Wild oat seeds were the most common grass awn found in soft tissue of dogs. Ultrasonographically grass awns appeared as a double/triple spindle-shaped echogenic interface within soft tissue. The same appearance was observed in water bath studies. In four dogs, the grass awn was removed surgically with a clamp introduced into a fistulous tract, using sonographic guidance. The grass awn was not found surgically in only three dogs, suggesting more attention during surgery. Ultrasonography is a useful diagnostic imaging technique to identify grass awns within soft tissue.

Penetrating palpebral grass awn in a dog

“…FBs in subcutaneous and underlying soft tissue structures in animals are a common problem, especially in pets [3,4,6,10,14] and represent a diagnostic challenge [1,2,17,22,23].…”

“…Wood and plant material are not inert and usually harbor bacteria and/or fungi that evoke a septic FB reaction, giving rise to a chronic infection [2,22]. Hunting and working dog breeds are more exposed to this disease because of increased contact with grass awn, and longer coats probably play a role of predisposition to grass awn retention [2].…”

“…The clinical syndromes produced by grass awn migration are varied as evidenced by the numerous locations in which the awn may lodge and the resultant clinical manifestation produced [2]. Within the eye, grass awns usually lodge in the conjunctiva or nictitating membrane [2,21], while more, in general, grass awns usually lodge in the external ear canal, causing, in some cases, the rupture of the tympanic membrane, or in interdigital spaces, causing draining tracts; grass awns could also be frequently found in the respiratory and also in the thoracic cavity [17][18][19][21][22][23][24].…”

“…Ultrasonography provides a useful diagnostic tool for identification of both radiopaque and non-radiopaque FBs in soft tissues and can be used successfully in multiple areas of the body, including the eye [21,22]. Furthermore, FBs are frequently encapsulated and there is exudate surrounding them that helps in identifying them [22].…”

“…Furthermore, FBs are frequently encapsulated and there is exudate surrounding them that helps in identifying them [22].…”