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Grass Awns Can Cause Significant Medical Problems to Animals

By : Time McDermott, DVM, OSU Extension Educator, Franklin County (originally published in Farm and Dairy)


Because foxtail awn are shaped similar to a lawn dart, they can become lodged somewhere in a grazing animal and medical or surgical care may be required in order to remove it safely.

It seems like foxtail grass has taken over every pasture and hay field in Ohio in 2019. My good friend and Extension colleague, Clif Martin, wrote an excellent article detailing “How to Fight Foxtail in Forages” in the October 3rd, 2019 All About Grazing column in Farm and Dairy. I highly recommend you review this article to learn strategies to manage this weed. If his article is not enough to get you motivated, then hopefully this article will.

Foxtail is not only a weed competitor and invader of your hay and pasture fields, but it also can cause some significant medical problems for grazing livestock, horses and companion animals. Take a close look at the picture of a foxtail awn. It is very tiny as you can see in comparison to the dime placed for reference. Note that its shape is similar to a lawn dart, which means that it can only travel in one direction, point first. Depending on what species variety of foxtail grass present, this places the seed heads with grass awns very close to the feet, mouth, ears, eyes and nostrils of grazing animals, livestock guard dogs, and horses as they move through fields either walking, running or grazing. That puts these species of animals at risk for a medical condition called a foreign body which means that the awn has lodged somewhere and may need medical or surgical care in order to remove it safely and positively impact the health of the animal.

A foreign body is a serious medical problem, if the awn is lodged in the foot, either in the pad of a canine or inter-digitally (between the toes) of any species, it can fester and cause infection. Compound this problem from mud and feces and this can worsen the infection. A grazer than cannot walk or a dog that cannot run is a problem for the producer. Grass awns can become ocular foreign bodies as well. The grass awn can become lodged in the tear ducts, under the main eyelids or behind the third eyelid. This can cause discharge, swelling, increased tear production, conjunctivitis and corneal ulceration. The signs are usually unilateral but both eyes can become infected at the same time. This presentation of ocular signs may resemble pinkeye to producers. Grass awns can also become lodged in the nares(nostrils) of each of these listed species. Presentation signs may include discharge, facial swelling, and sneezing.

If hay is made off a field that is contaminated with foxtail grass, it increases the chance that the animal may contact the grass awn at any point that the hay is fed. An oral grass awn foreign body can lodge and cause mouth ulcers or hay blisters in multiple species. If the infection becomes severe, it can cause decreased feed intake that will negatively impact the growth of the animal. Some signs of a problem may include drooling, decreased appetite, bad smell and discharge.

Grass awns can also become lodged in fleece of small ruminants as they move through a field and if enough contamination is present, can decrease the value of the fleece.

So check your fields and your hay carefully to make sure you are not setting yourself for a problem down the road. If you suspect that your grazing animal, horse or livestock guard dog may have a grass awn foreign body, contact your veterinarian as soon as possible. The earlier that a problem can be diagnosed, the earlier that treatment can be attempted and the greater the chance of a successful outcome.

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