Foxtail grass is a common annual weed found across the globe, recognized by its distinctive, brush-like seed head that gives the plant its name. As a summer annual, it emerges in late spring and grows throughout the warmer months, often flourishing in disturbed habitats like roadsides, fields, and neglected lawns. This grass reproduces solely through seed, which develops into a spike-like cluster at the top of the stem.
Identifying the Common Foxtail Varieties
The term “foxtail” refers to several species, with the genus Setaria containing some of the most common weedy varieties, including Giant, Yellow, and Green foxtail. These grasses are visually identified by their cylindrical, bristly seed heads, which are composed of numerous spikelets surrounded by fine, hair-like structures called bristles or awns. These bristles give the plant a fuzzy, fox-tail appearance.
Distinguishing between the Setaria species often requires a closer look at the leaf and seed head structure. Giant foxtail (Setaria faberi) is the largest, growing up to four feet tall, and is characterized by a distinctive nodding or arching seed head. Yellow foxtail (Setaria pumila) typically has long, sparse hairs located near the base of its leaf blade, where it meets the stem. Green foxtail (Setaria viridis) is generally shorter, with hairless leaves, and possesses an upright seed head that sometimes has a purple tint to its bristles. While Setaria species are widespread, other grasses like Foxtail Barley (Hordeum murinum) and certain brome grasses also produce dangerous, barbed seed heads that are commonly referred to as foxtails.
Why Foxtail Grass Poses a Threat to Pets
The danger of foxtail grass lies entirely within its mature seed heads, which break apart into individual seeds or awns designed for soil penetration. These awns are sharp and equipped with microscopic, backward-pointing barbs, which act like a one-way mechanism. Once a seed attaches to a pet’s fur, the barbs prevent it from backing out; any movement only serves to propel the awn forward, turning the seed into a migrating foreign body in an animal’s tissue.
Common entry points for these seeds include the paws, especially burrowing between the toes and causing painful abscesses and swelling. Awns can also enter the ear canal, causing the pet to shake its head violently, and may migrate deeper to cause severe infection or even rupture the eardrum. The most concerning exposures occur when the seeds are inhaled into the nasal passages during sniffing, triggering intense, chronic sneezing and nasal discharge. From the nose, the awn can travel into the respiratory tract, potentially leading to a serious lung infection like pyothorax (an accumulation of pus in the chest cavity).
Foxtail awns do not dissolve inside the body and carry bacteria with them as they travel through soft tissue. If they penetrate the skin, eyes, or other openings, they can cause abscess formation and may require surgical removal to prevent further internal migration toward vital organs. Pet owners should watch for persistent licking, limping, head shaking, or any unexplained swelling, as these are common signs of an embedded foxtail.
Eradication and Prevention Strategies
Controlling foxtail grass on a property requires a combined strategy of mechanical, cultural, and chemical methods to prevent the production and spread of the dangerous seeds.
Mechanical Control
The most effective mechanical control is to pull or mow the weeds before the seed heads fully mature and dry out, which typically occurs in late spring or early summer. Hand-pulling is feasible for small infestations, but it is necessary to remove the entire plant, including the roots.
Cultural Control
Cultural control focuses on improving the health and density of the turf to outcompete the opportunistic weed. Maintaining a thick, lush lawn through proper watering, fertilization, and appropriate mowing heights helps to deny the foxtail seeds the sunlight and space they need to germinate and establish.
Chemical Control and Pet Prevention
Pre-emergent herbicides prevent the weed seeds from sprouting if applied in early spring before the foxtail begins to emerge. For existing, established plants, a post-emergent herbicide designed to selectively target grassy weeds can be used, though this is most effective while the plants are still small. Pet owners must avoid walking animals in areas with tall, dry, or overgrown grass. After any outdoor activity, a thorough inspection of the pet’s fur, ears, eyes, and especially the paws and between the toes, is necessary to remove any seeds before they can embed.