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Dangers of Grass Seeds for Dogs

Grass-seed season: medical problems caused by grass seeds peak in spring and summer ... 

Amongst the Australian veterinary community, spring and summer are known as grass-seed season. This is when many dogs seek veterinary care for medical problems caused by grass seeds.

It’s hard to imagine that a simple grass seed can cause issues but they are a big problem for dogs in many areas of Australia. In one recent study from south west rural NSW, 2% of the dogs seen at veterinary clinics during spring and summer came in because of grass seeds. Medical issues ranged from mild swelling to life-threatening illness.

What grass seeds are causing the problem and how?

In Eastern Australia, the grasses that cause the most issues are Spear Grass, Barley Grass, and Wild Oats
In Western Australia, Brome Grass also causes problems. All share the characteristic of having sharp pointy seed heads

The part of the grass that causes the problem is the awn. This is a hard case that surrounds the seed. They have a sharp spikey head and an arrow shape with bristles that point backwards. The shape helps the grass self-propagate. 

The sharp point enables it to bury into soil whilst the arrow head bristles prevent it from coming out again. Moisture in the soil also causes the awn to swell to keep it in the soil. 

The problem is, when the awns get caught in the fur of dogs, the seeds easily penetrate the skin surface. As in the soil, their shape means they travel forwards but not backwards

A dog’s body is a lot less dense than soil, so once the seed enters the body it can keep travelling large distances, ending up in the bladder, lungs, spinal cord, and even the brain. 

Symptoms depend on where the awn enters the body, what path it takes, and where it ends up.

Why do grass seeds cause problems?

The body recognizes the grass seed as foreign and tries to wall it off and remove it. The grass seeds also naturally carry bacteria, which cause infection. This creates a strong inflammatory reaction, with pain, swelling, and pus. Technically, this inflammatory reaction is called an abscess

The inflammation caused by the body as it tries to remove the grass seed and fight the infection causes damage to nearby structures. This inflammation can be disastrous in certain locations, such as within the lung, spinal cord, or brain. 
It is not uncommon for dogs to have multiple grass seeds embedded under the skin. A common site is the paw. This shows up as a red, painful swelling on the foot, sometimes oozing pus. It will usually be quite painful and the dog will lick it a lot. 

Another common site on the skin is around the head and neck. As well as piercing the skin, grass seeds can enter the body via the ears, eyes, nose, throat, vagina, and intestines. 

Dogs are always sniffing with their noses to the ground. Grass seeds frequently get snorted up the nose or inhaled down the windpipe. Once inside the body, the seeds migrate. The seeds will take the path of least resistance. 


For example, grass seeds that are inhaled go down to the lungs. There they cause pneumonia. From the lungs, the grass seeds tend to travel into the chest space (outside the lungs), then follow the diaphragm (the muscle between the chest and the abdomen) towards the spine, and travel up into the spinal cord. Such dogs will have symptoms of spinal cord disease and may have trouble walking. Grass seeds that enter the vagina frequently end up in the bladder and cause a bladder infection. [1-5] 

Ears are another very common site for grass seeds. The study from rural NSW actually found that 47% of dogs with grass seeds coming to see a general vet, actually had the grass seed stuck in their ear. The grass seed not only causes irritation and infection but it can pierce the ear drum and cause infection inside the ear. 

Risk factors 

Contrary to what you might think, dogs with medium-length coats are actually at highest risk compared to dogs with short-haired or long-haired coats. They are three times more likely than other dogs to have problems. It is not the length of coat that matters but the density. Medium-length coats have a higher density undercoat, which traps the grass awns and is more likely to hold them closely against the skin. 


Working dogs, who spend much time amongst the fields, are at particular risk. Any dog that has access to farmland is twice as likely to be affected. 
Breeds reported to be at higher risk include:
The grasses that cause problems flower from October to December, mainly in response to rain. So, more dogs are seen with grass seed issues following lots of rain in spring and summer.

Symptoms

The symptoms of grass seeds depend on where they enter the body, where they travel in the body, and where they end up. 


Grass seeds in the following sites, may cause these symptoms:


#1. Skin
  • Pain 
  • Swelling 
  • Licking the area constantly 
  • Oozing a bloody discharge 
  • Lameness 
#2. Ears
  • Itchy, irritated ears 
  • Pus in the ear 
  • Head tilted to one side 
  • Shaking the head constantly 
#3. Nose
  • Sneezing
  • Discharge from the nose 
  • Blood from the nose 
  • Shaking the head 
  • Pawing or rubbing at the muzzle 
#4. Eyes
  • Sore, red eye 
  • Swollen eyelids 
  • Mucky eye gunk 
#5. Inhaled into the windpipe
  • Coughing 
  • Fever 
  • Tiredness 
  • Breathing quicker and harder 
  • Not eating 
  • Large glands in the neck 

#6. Spinal cord 

  • Trouble walking 
  • Decreased appetite 
  • Tiredness 
  • Trouble weeing 
  • (often follows pneumonia) 

Diagnosis


Diagnosis is usually confirmed by retrieving the grass seed from the site, usually under anaesthetic. Most vets will assume that any painful swelling on a dog during spring and summer, particularly one that is oozing pus, could be caused by a grass seed. This is especially so if the swelling is on the foot or if the coat has grass seeds attached.

For eyes and ears, grass seeds are very painful. The ear or eye will need to be examined under some form of sedation to find the seed. Endoscopy (using a tube with a camera attached) may be needed if a grass seed is suspected up the nose or down the throat.

For seeds inside the body, it can be very difficult to work out that a grass seed is causing the problem. Such dogs may come in with a range of symptoms, such as a fever from pneumonia or trouble walking if the seed is in the spinal cord. Many such cases end up being referred to veterinary specialists, sometimes weeks after the grass seed has entered the body. 

An x-ray of the chest can identify pneumonia or pus in the chest but it won’t be obvious that a grass seed is the cause. To identify a grass seed as the problem, it may be necessary to use other tests. A CT (computed tomography) scan is frequently used. It mainly helps identify exactly where in the body the abscess is. 

Only in about 20% of cases is the grass seed obvious. Magnetic Resonance Imaging (MRI) may be used as well. Surgery is ultimately required to find and treat the abscess and remove the seed. This confirms the diagnosis.
An ultrasound can sometimes help find the grass seed in swellings that keep recurring under the skin.

Treatment

Very occasionally, a grass seed will continue to travel until it comes out the other side of the leg or body. In most instances, however, the seed needs to be surgically removed. Abscesses need to be opened and drained to remove the pus and find the grass seed. It can be quite difficult to find the grass seed because it can disintegrate with the moisture. If it can’t be found, the abscess is usually cleaned thoroughly with saline in the hope that that flushes the material out. 


If the grass seed isn’t found and is still in there, the chance of the abscess reforming is higher. Sometimes, all we can do is wait to see if an abscess will reform there or elsewhere and do repeat surgery to try and find the seed again. Antibiotics are also often given to help fight the infection as well as pain relief and an anti-inflammatory.

Prevention

The best thing you can do to prevent grass seeds embedding in your dog’s skin is to groom (brush) your dog weekly. In one study, clipping the fur and searching for grass seeds was found to be ineffective. However, weekly grooming made a big difference. This is not related to grooming the seeds out. Rather, it is because grooming reduces the density of the undercoat. It also reduces the number of cross-hairs. This decreases the chance of grass seeds sticking within the coat. 


Avoid long grasses carrying awns during walks!
Breeds with long coats have a less dense undercoat. So, despite the long hair, the grass seeds don’t tend to stick and don’t cause as many problems. 

Similarly, with long-haired cats, frequent grooming by the cats themselves reduces the cross-hairs and makes grass seeds less likely to stick. In fact, cats have the most problems with grass seeds going up their nose!

Clipping the fur can make weekly grooming much easier but clipping should not be substituted for weekly grooming.

If you do have a dog with dense hair around the bottom of their paws, such as Cocker Spaniels, I do recommend that you clip the hair around the paws very shortIt won’t necessarily stop grass seeds from getting in there but it makes it much easier to find them and identify problems.

For working dogs that wear muzzles, putting some coarse mesh over the top may help to prevent grass seeds from being inhaled.

Mow your lawns after rain, before grass seeds form. If you can, try not to allow your dog to walk through seeded grasses at this time of year. And if you do, check their paws for seeds and groom them thoroughly afterwards.

References:

1. Agut A, Carrillo JD, Anson A, Belda E, Soler M. Imaging Diagnosis-Urethrovaginal Fistula Caused by a Migrating Grass Awn in the Vagina. Vet Radiol Ultrasound. 2016;57(3):E30-33.
2. Hicks A, Golland D, Heller J, Malik R, Combs M. Epidemiological investigation of grass seed foreign body-related disease in dogs of the Riverina District of rural Australia. Aust Vet J. 2016;94(3):67-75.
3. Linon E, Geissbuhler U, Karli P, Forterre F. Atlantoaxial epidural abscess secondary to grass awn migration in a dog. Vet Comp Orthop Traumatol. 2014;27(2):155-158.
4. Vansteenkiste DP, Lee KC, Lamb CR. Computed tomographic findings in 44 dogs and 10 cats with grass seed foreign bodies. J Small Anim Pract. 2014;55(11):579-584.
5. Whitty CC, Milner Hr Fau - Oram B, Oram B. Use of magnetic resonance imaging in the diagnosis of spinal empyema caused by a migrating grass awn in a dog. N. Z. Vet J. 2013;62(2):115-118. 

written by Meredith Crowhurst, November 2018 for Australian Dog Lover (all rights reserved).

About the Writer

Dr Meredith Crowhurst is a Melbourne-based veterinarian from national mobile vet app-based booking service Pawssum.

A Melbourne University graduate with more than a decade of experience, she has extensive consultation and surgical experience and has worked with dogs, cats, rabbits, guinea pigs, rats, mice, birds, and various other animals.
Meredith understands the importance of the human-animal bond. Her aim is to treat pets and their owners with empathy and compassion, delivering the best standard of care.

Previously, Meredith completed a Bachelor of Arts/Bachelor of Science degree and completed her PhD in the biomedical sciences. As well as treating animals, Meredith’s aim is to educate and make medical science knowledge accessible for all.



About Pawssum

Pawssum’s on-demand vets can help with 80% of a pet’s health checks at home. They cover urgent medical check-ups, vaccinations, dental, heart, eye and ear checks, taking blood and lump samples, in-clinic follow up or dog training and behaviourist. There’s even an at-home euthanasia service offering increased comfort and privacy. The Pawssum app also keeps a pet’s complete health records accessible by the pet owner or physician at any time, for continuity of service.

Pawssum vets offer visits out of normal business hours, 7 days a week in all major Australian capital cities. For more information, please visit www.pawssum.com.au or call 1300 34 35 80
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