Grass-Seed Darts and Potential Risks

Grass-seed darts are a potential danger to pets during the summer and autumn. There are many species of grass around the world that can present a threat, but two common problem species in the UK are Wall Barley and Barren Brome. Here we explain what to look for and the risks associated with contact.

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Hordeum murinum (above) is commonly known as wall barley or false barley. It is a species of grass with a single un-branched seed head which can reach 10 cm long.

Bromus sterilis (above) is commonly known as barren brome, poverty brome, and sterile brome. It is a species of grass with drooping, branched seed heads (or spikelets), each containing 4-10 seeds.

Grasses with grass-seed darts have an ability to work their way into the soil and ability to attach to a dog’s or cat’s fur. Once attached, the darts can then work through the animal’s coat and ultimately can penetrate skin and enter deeper tissues.

Three features of the seeds that enable them to penetrate skin are:

  1. Long, stiff tails or ‘awns’ which are projections of the ‘seed-case’ or lemma. These orient the spikelet so the point always leads, like the quill on an arrow.
  2. A pointed, hardened tip at the head of the spikelet that is called a callus. This enables the point to penetrate earth.
  3. The awn, the seed-case, and the tip are all covered with tiny barbs called retrorse barbs. These help the spikelet to catch in an animals’ fur.

Retrose barbs shown on a seed case:

Retrorse barbs face backwards from the tip, so any movement tends to drive grass-seed darts forward into the soil or deeper into an animal’s coat or orifice. Once the spikelet tip reaches the skin it can be driven through the skin and onward into the deeper tissues by the barbs acting as a ratchet. The presence of foreign material penetrating the skin causes a local immune reaction. The grass-seed dart is accompanied by microorganisms which can cause infection too.

Dogs suffer more than cats

Dogs suffer with grass-seed darts penetrating their skin and orifices far more than cats. This may be because cats are much more accomplished at grooming them out of their coats by themselves. Any area of a dog’s body can be penetrated by a grass-seed dart, but there are orifices and areas which are penetrated most often.

- Ears - Eyes - Groin
- Paws - Tonsils - Penis
- Arm pits (axilla) - Nostrils - Vulva

What to do if grass-seed darts enter your dog’s ears

Ears are the most common orifice that grass-seed darts enter. They move down the external ear canal and can penetrate the ear drum entering the middle ear. It is possible for them to continue their journey deeper into the body and they may even enter the brain.

If on a walk your dog suddenly starts to shake its head violently and grass-seed darts are present, you have to be concerned that one may have entered his ear. Unless it is at the very entrance to the ear it will require a vet with an auroscope and alligator forceps to remove it, with your dog possibly under sedation or general anaesthesia.

What to do if grass-seed darts enter your dog’s paws

Paws are the area of the body where grass-seed darts most commonly penetrate the skin. They most often burrow under the skin on the top of the foot at the end of the web between digits. Here they cause a cyst-like swelling, due to foreign body reaction and infection, and a discharging fistula, which the dog licks frequently.

If you can see the tail of the grass-seed poking out it may be worth trying to pull it out, but if there is a swelling and a hole discharging pus it will require veterinary attention for removal.

What to do if grass-seed darts get in your dog’s arm pits

Arm pits are a less common site of penetration of grass-seeds; however, the seeds can quickly enter deeper tissue because the skin is very thin here and the dog cannot reach to groom itself. Grass-seeds that penetrate at this point can sometimes enter the chest of a dog with serious consequences.

Grass-seed darts can be very challenging foreign objects for vets to retrieve – they are small and do not show up on x-ray. Often vets resort to complex surgical operations under general anaesthesia to manage these foreign bodies. They will force dye into the discharging hole and then follow the dye, dissecting out the tract, the tissue reaction, and the grass-seed dart. The body can then start to heal.

Prevention is better than cure when dealing with grass-seed darts.

  • This is a summer and autumn problem and is another good reason, in addition to the heat, to have your dog’s coat stripped or cut short. Particularly around the toes, ears, and undercarriage, including the arm pits and groin.
  • Owners should avoid walking their dogs in areas where there is dart grass growing.
  • After each walk owners should check their dogs for darts:
    • Between the toes and pads;
    • In and around the ears;
    • In and round the mouth;
    • The arm pits;
    • Groin areas

David Chamberlain BVetMed., MRCVS.
Veterinary Consultant to PetSafe®

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