Foxtails and Cheatgrass: Colorado's Grass-Awn Season
Every summer, Front Range veterinarians pull barbed grass seeds out of dogs' ears, noses, eyes, paws and worse. Foxtail and cheatgrass awns are built to drill forward and never back out, and Colorado's dry grassland trails are full of them from early summer until the snow flattens them. This is what to look for, where the risk is highest, and what prevention actually works. There is no vaccine and no home fix; a seed that has gone in needs a vet.
What a grass awn is
Foxtail is the common name for the bristled seed heads of several wild grasses; cheatgrass (downy brome) is the invasive annual that carpets disturbed ground across the Front Range and turns from green to tawny by June. Both produce awns, seed heads with backward-pointing barbs. The barbs catch in fur, work toward the skin with every step, and once through the skin can only move one way. Veterinarians describe awns migrating from a paw into a leg, from the nose into the airway, and from the skin into the chest or abdomen.
Season and where
Colorado's season runs from late spring through fall, once the grasses dry, roughly June through October and longer in a dry year. The highest-risk terrain is tall, dry, unmowed grass, which describes most of the foothills and plains trails near Denver:
- Green Mountain in Lakewood: grass from top to bottom, no shade.
- Marshall Mesa south of Boulder: open grassland benches.
- North Table Mountain and South Table Mountain in Golden: mesa-top grass.
- Two Brands Trail at Hildebrand Ranch in Littleton: exposed grass and shrub.
- Creek and greenway corridors with rank grass on the verges, such as the Sand Creek Greenway.
- Unmowed dog parks and the edges of ball fields in any city.
Awns also ride home. They work into car seats, dog beds and the fur of a second dog, so a seed picked up on Saturday can go into an ear on Tuesday. Shake out bedding and vacuum the car during the season.
The common thread is a dog leaving the tread. A dog that stays on a packed-dirt trail collects far fewer awns than one that noses through the grass beside it, which is one more argument for the leash rules those parks already have.
Signs a seed has gone in
The Denver and Wheat Ridge veterinarians whose guidance we read describe the same pattern: a sudden change in one body part after time in dry grass.
| Where | What you see |
|---|---|
| Nose | Sudden violent sneezing fits, pawing at the nose, sometimes a nosebleed |
| Ear | Head shaking, head tilt, scratching one ear, crying when the ear is touched |
| Eye | One eye red, swollen, squinting or held shut, discharge |
| Paw | Limping, constant licking of one toe or the web between toes, a small swelling that may drain |
| Skin (armpit, groin, under the tail) | A fast-growing, painful lump; a draining tract |
| Mouth or throat | Gagging, repeated swallowing, coughing after eating grass |
Any of these after a grass hike is a same-day veterinary visit. Awns do not work their way out, antibiotics alone do not remove them, and the longer one travels the harder it is to find. Do not dig at a paw lump with tweezers; the seed is usually deeper than it looks and breaks apart.
The two most urgent cases. An awn in the eye can scratch the cornea within hours, and an awn inhaled into the nose can continue into the lungs. A dog sneezing uncontrollably or holding an eye shut after a grass walk should see a vet today, not tomorrow.
Prevention that works
- Avoid dry tall grass. From June onward, pick trails with packed tread and keep the dog on it. Shaded creek trails such as Lair o' the Bear have less seeding grass than open mesas.
- Trim the fur. Awns catch in long hair first. Keep the fur between the pads and around the toes short, trim feathering on the legs and ears on spaniels, setters and doodles, and consider a summer clip on heavy coats. A groomer will do it if you cannot; request grooming quotes in Denver or browse dog groomers by city.
- Do a full-body check after every outing. Pads and between every toe, armpits, groin, under the collar, inside the ear flaps, around the eyes and nose, under the tail. Brush the coat against the grain. Thirty seconds at the trailhead saves a surgical bill.
- Consider a field vest or boots for dogs that work through brush. Neither is complete protection, and a boot can trap an awn against the skin, so the check still matters.
- Pull cheatgrass in your own yard before it seeds. Most backyard awn cases come from the fence line, not the trail.
- Teach a settle at the trailhead. The check is only useful if the dog stands still for it; a minute of practice at home each evening pays off at the car.
What there is not
There is no vaccine, no repellent and no preventive medication for grass awns. Prevention is route choice, grooming and the check. Treatment, when it is needed, is a veterinarian locating and removing the seed, sometimes under sedation, sometimes with imaging; we are not going to pretend otherwise or suggest anything you can do at home beyond looking carefully and going in early.
Awn season overlaps with the hottest and snakiest months on the same trails. Read cooling vests for Front Range summers and rattlesnake avoidance training for the rest of the summer checklist, and dog boots for Colorado trails for the surfaces that justify a boot.