Grass Awn Migration (Foxtails) in Dogs

Key Takeaways

Foxtails and other grass awns, are a common form of seed dispersal for many types of grass. 

• Awns have numerous bristles that allow the seed head to embed in the skin and orifices of animals and their shape makes them difficult to remove

• Dogs commonly acquire grass awns while running through long grass, particularly affecting their lower limbs, nose, mouth, and ears

• Awn migration causes significant irritation and commonly results in bacterial infection and abscess formation

• Symptoms include non-healing wounds, excessive licking or rubbing of an area, and wounds that ooze pus

• Ultrasound is commonly used to diagnose grass awns that aren’t readily visible

• Treatment involves removing the awn, which may require anesthesia and surgery

• Antibiotics are indicated if infection is present

• Prognosis depends on where the awn is located and the extent of damage caused by infection

A Closer Look: What is Grass Awn Migration in Dogs?

Grass awn migration causes similar symptoms to other migrating foreign bodies, including porcupine quills. Grass awn migration is a seasonal problem in regions where dogs are exposed to grass species that produce this type of seed. This condition is not common in areas where the primary type of grass in the environment is a mowed lawn. Any dog who runs through long grass that has gone to seed can be affected. 

The outcome for embedded grass awns depends on their location, the path of travel, and the extent of infection. Grass awns embedded in the skin generally cause mild irritation that resolves once the awn is removed. Grass awns embedded in the nose, mouth, ears, or tissues around the eyes are more difficult to remove and indicate a need for more urgent veterinary care to expedite relief and prevent complications. In rare cases, grass awns migrate into the thoracic cavity and cause serious, life-threatening infection.

Risk Factors

Most grass awns lodge in the skin, and cause significant irritation as they migrate through tissue. This irritation leads to symptoms of dermatitis such as excessively rubbing or licking an area and redness or crusting of the skin.

Grass awns that enter the skin through the bottom of a dog’s foot often migrate upwards towards the top of the foot.  These commonly form a soft, hairless, dark pink blister on top of the foot as the awn migrates out. 

Dogs that run with their mouths open are at risk of grass awns becoming embedded in their oral tissues. Grass awns can also be inhaled through the nose or mouth. Once in the airways, the awns cause significant inflammation and tissue damage. Grass awns in the airways are at risk of migrating into the thoracic cavity, causing a serious bacterial infection called pyothorax.  Other common locations for grass awns are the tissues around the eyes and within the ears. The irritation caused by the awns results in keratoconjunctivitis and otitis, respectively.

Grass awn migration commonly results in bacterial infection of the migration tract, particularly by the bacteria Actinomyces. Symptoms of infected grass awn tracts include:

• Non-healing wounds • Wounds draining pus • Swelling, heat, and pain at the wound site • Lethargy

These infections often progress to abscesses that require veterinary attention and antibiotic treatment.

Possible Causes

Many types of grasses and other plants produce awns, and all of them are potentially dangerous to dogs. The specific type of grass that the awn comes from does not affect the outcome for dogs.  Grass awns typically lodge themselves into the skin when dogs are running through long grass. Hunting and working dogs have the highest risk of exposure for this reason. In some cases, awns become lodged in the mouth, nose, or ears as the dog runs.  

Grasses are found on every continent, and most locations have at least one awn-producing grass species. Most cases of grass awn migration occur during the summer, when dogs are outdoors and the grass is fully grown. In warmer climates, awns are seen year-round.

Main Symptoms

Symptoms of oral grass awns include:

Coughing • Gagging • Swelling of the neck or face • Swollen, painful lumps in the mouth • Difficulty chewing

Excessive drooling

Symptoms of grass awns in the nose, mouth, or upper airway include:

CoughingSneezingDifficulty breathing • Increased respiratory rate

Grasses are found on every continent, and most locations have at least one awn-producing grass species. Most cases of grass awn migration occur during the summer, when dogs are outdoors and the grass is fully grown. In warmer climates, awns are seen year-round.

Testing and Diagnosis

Grass awns in the skin, ears, and mouth are often readily visible, especially if they haven’t been present for long. They migrate forward towards the front of the seed relentlessly, every time the tissue around the awn moves.  As time passes, they often go deeper and become harder to see. Diagnosis of grass awns embedded deep in tissue typically involves diagnostic imaging, such as ultrasound. Through imaging, the location of the awn and any associated infection is identified.

Steps to Recovery

Due to their shape, grass awns typically migrate deeper into tissues until removal. The only definitive treatment is removal of the awn, which may require sedation or general anesthesia and surgery. In many cases, antibiotics are required to treat any infections at the site of injury. Infected wound sites also require thorough cleaning and removal of damaged tissue to allow proper healing. 

Due to the propensity of grass awns to continue migrating deeper into tissues, prompt removal is important. Most cases of grass awn migration affecting the skin, nose, mouth, and ears have an excellent prognosis with appropriate treatment. Grass awns embedded in the tissues around the eyes occasionally cause corneal ulcers on the eye’s surface, which have a good prognosis. The rare cases of grass awns migrating into the thorax have a fair prognosis, as the resulting infection can be life-threatening and the required treatment is extensive.

Prevention

Preventing access to long grass is the best method of preventing grass awn migration. Watching dogs closely during outdoor activities is also important, as these grasses commonly grow in backyards, parks, and along roads. Monitoring at risk dogs regularly for evidence of embedded awns to ensure prompt treatment when required helps prevent complications.

Is Grass Awn Migration Common in Dogs?

Grass awn migration is common in dogs, particularly in areas where awn-producing grasses grow.

Typical Treatment

• Removal • Surgery • Antibiotics

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