Trapped Neutrophil Syndrome (TNS)

Introduction into Trapped Neutrophil Syndrome (TNS)

Trapped Neutrophil Syndrome, better known as TNS, was first recognised in 1996 in New Zealand and Australia, with Australian research is leading the world.

This debilitating disease has only been recognised in the Border Collie breed for the last 8 years and there is no known cure or treatment for affected puppies and dogs.

TNS is usually seen in young puppies before they go to their forever homes, but some puppies do not show signs until up to 7 months old.

There is no treatment for TNS, except to treat the symptoms and keep the pup as comfortable as possible.

Often owners need to make the hard decision to put their young companion to sleep to end its suffering.

Geneticist Alan Alan Wilton of the School of Biotechnology, University of NSW and his staff has developed a DNA test to identify the disease and detect carriers.

Alan Wilton’s laboratory, in Australia, is the only place in the world that DNA tests for TNS.

They have carried out more than 8000 tests on Border Collies from concerned owners and breeders from Australia and across the world.

With responsible breeding, TNS can be eradicated from the Border Collie breed over the coming generations.

What is Trapped Neutrophil Syndrome (TNS)?

Trapped Neutrophil Syndrome was once believed to be rare.

These days it is not so rare but it is believed it went undiagnosed for many years with many veterinarians not knowing what to look for.

Other reasons this disease went undetected for so long include that blood tests do not always show that the white blood (neutrophil) count is lower and it is an autoimmune deficiency.

Puppies can present with a variety of symptoms making it difficult to diagnose.

Many puppies were simply thought to be ’fading’ puppies. Often these puppies were referred to as the runts of the litter.

TNS is autosomal recessive so both parents must be carries to produce puppies with the disease.

Diagnosis is even more difficult because most puppies are sick before leaving the breeder for their new homes.

But there are those that do not develop symptoms of TNS until they are older.

The prognosis is not good with most puppies dying or put to sleep by the time they are 4 months old. It is rare for a puppy with trapped neutrophil syndrome to grow to an adult dog.

Extensive research shows the disease is widespread in the Border Collie breed with positive cases found in Hungary, United States, New Zealand, Australia, and the Netherlands.

While the disease was first diagnosed and recognised in Australia and New Zealand, it was introduced through international lines.

What causes Trapped Neutrophil Syndrome (TNS) in Border Collies?

The first time TNS was diagnosed in Border Collies was in 1996 by Boyd Jones and Frazer Allen.

Since then it has shown up in working and show dogs throughout the world with more than 10 percent test showing up as carriers of TNS.

This could mean TNS goes back to the very origins of the breed and may be found in other collie breeds.

TNS is an autosomal recessive disorder that is inherited and affects the dog’s immune system.

Puppies with the disorder are deficient in nuetrophils (known as neutropenia), which they need to protect them from infections.

In a dog that has TNS, its bone marrow produces the nuetrophils but they are not released into the dog’s system which weakens the immune system.

It depends on the type of infection the dog gets on what symptoms they get. Some TNS puppies are born smaller than usual but others look perfectly normal.

Here are some things to look out for in a Border Collie that can be a sign it has TNS:

TNS carriers are not affected by the disease and will live long, healthy lives.

What breeds of dog are most at risk of developing Trapped Neutrophil Syndrome (TNS)?

While the Border Collie dog seems to be the breed of dog most commonly recognised as being a carrier and inheritor of TNS, there is not enough research available to suggest what other dog breeds it may affect.

These days’ responsible breeders test their breeding dogs before mating them.

If you are interested in buying a Border Collie puppy, ask your breeder for copies of the trapped neutrophil results for both the dog and the bitch used to produce any puppy that interests you.

TNS is an awful disease and there is no cure.

Most dogs affected by the disease are usually put to sleep to stop them from suffering.

By checking that your Border Collie puppy’s parents are TNS clear or TNS carriers, you are assured that your puppy will not be affected by TNS.

Breeders can breed a TNS carrier only to a TNS clear mate, or two Border Collies that are TNS clear.

The ANKC now has the following requirements to have Border Collie dogs and their progeny registered as suitable breeding stock:

How can Trapped Neutrophil Syndrome (TNS) in Dogs be prevented? What Can I Do to keep my Dog from Developing Trapped Neutrophil Syndrome (TNS)?

There is little you can do to prevent your dog from developing TNS, unless you are the breeder.

Either a puppy is born with the disease, is a carrier or is born without it. Symptoms are first seen in puppies as young as 2 weeks old and up to 7 months old.

You can avoid buying a Border Collie that is affected by TNS by buying your puppy from a reputable breeder who tests their breeding stock to ensure they are not breeding from TNS affected animals and carriers.

When buying your new Border Collie puppy check with the breeder about TNS and whether they have tested their dogs for the disease.

If they have, talk to them about the results and ask for a copy so you understand what you are being told.

A Border Collie that is a TNS carrier will have an absolutely normal life and is not at risk of developing the disease.

However, breeding with TNS carriers should be avoided to ensure the disease is eventually bred out of the Border Collie breed.

It takes two carriers bred together to produce TNS affected dogs. Breeding a Border Collie TNS carrier to a clear dog to breed pups can result in puppies that are also TNS carriers.

Breeders can then test these puppies so any carriers are desexed before going to pet homes and the clear puppies can be kept for breeding.

By selectively breeding, breeders do not lose generations of excellent lines but can desex any puppies affected by trapped neutrophil syndrome to ensure they are not bred from once they leave their homes.

Over the years this will effectively stamp the disease out completely from the Border Collie breed.

How do I know if my dog has Trapped Neutrophil Syndrome (TNS)? What are the signs and symptoms?

Many affected Border Collie puppies appear ‘ferret like’ in the head and are often smaller than normal, with abnormally slow growth rates. Many also have poor hair growth on their coat.

Other puppies appear normal until they get sick and symptoms include:

How is Trapped Neutrophil Syndrome (TNS) Diagnosed?

TNS is not difficult to diagnose but it may take a three prong approach to get an accurate diagnosis.

Your vet will take a blood sample and test the neutrophil count. Blood tests do not always show up low neutrophil levels and, if they do, these can be caused by other illnesses such as viral and bacterial infections.

X-raying the Border Collie puppy’s limbs may show fractures in the metaphyses, thin cortices and reduced bone density with sclerotic bone close by to any fractures which can help in a TNS diagnosis.

The most accurate diagnosis is a bone marrow biopsy as puppies with TNS have an increased ‘myeloid to erythroid ratio’ meaning they have more white blood cells than they should.

This is how the name Trapped Neutrophil Syndrome came about as the neutrophils (white blood cells) is trapped in the bone marrow.

In 2007, a genetic mutation test (DNA) became available with only a blood sample or cheek swab required.

The results of this test categorise animals as either clear, a TNS carrier or as affected by TNS. Now that this relatively simple test is available it means there is the opportunity to breed the disease out of Border Collies altogether as testing is now relatively simple.

No longer is there any excuse to breed with Border Collies affected by TNS.

What kind of vet do I see if I suspect I have Trapped Neutrophil Syndrome (TNS) in my Border Collie?

If you suspect your Border Collie puppy has TNS take it to your regular vet and let them know what you think.

Your vet will check your puppy over and check it for any other problems that may cause its symptoms.

If your vet thinks there is a chance it is TNS they will organise DNA testing for the disease.

What is DNA Testing for Trapped Neutrophil Syndrome (TNS)?

It was early in 2007, that Jeremy Shearman identified the defect behind trapped neutrophil syndrome.

Working in Dr Alan Wilton’s laboratory, he developed a DNA test to identify dogs that are TNS carriers.

The simple test uses DNA from a blood test or a swab from inside the dog’s mouth.

Since the development of this test (18 months between January 2007 and September 2008) many dogs from across the world have been tested and it has been found that from:

Overall, from 2627 Border Collies tested in this 18 month period from around the world, 531 tested as carriers giving an overall 20.2 percent of dogs tested as carriers, and seven dogs tested positive to trapped neutrophil syndrome.

When looking at these results, you need to put it into perspective as the dogs tested mostly came from lines suspected to have the genetic mutation in them.

In Australia, the mutation comes from a single recessive gene resulting from a common ancestor in the lines.

Alan Wilton’s staff has said more research needs to be done to see if this is the case in the English Border Collie lines or if it is a mutation in a different gene or a different mutation in the same gene.

These days’ breeders can test for TNS so they can avoid mating two TNS carriers together and reduce the risk of breeding puppies that are carriers or have the disease. Carriers mated to TNS clear Border Collies will, on average, produce litters of puppies that have half that are TNS carriers and half that are clear of the disease.

At only a few weeks old, puppies can be tested very easily and without stress by taking a mouth swab (buccal samples) or using a spot of blood on an FTA card.

Where is the DNA Testing Carried out?

Currently the only testing facility is in Australia at A/Prof Peter Williamson laboratory in New South Wales.

Anyone in the world can send a sample in for testing.

The preferred option is blood samples in EDTA form. EDTA stops blood samples from clotting on the FTA card. Use only a small amount of blood and send the sample directly to Peter Williamson laboratory.

Peter Williamson
Room 551/552, RMC Gunn Building B19,
Faculty of Veterinary Science
The University of Sydney, NSW 2006,

If you cannot get to a vet, contact the laboratory and a collection kit can be sent out to you.

Buccal samples are much easier to get from puppies than blood sample; they are not always as reliable as the blood analysis.

You must get enough cells in the sample you take from inside your dog’s mouth and other issues can give a poor reading.

While blood samples can also cause problems if you flood the card with too much blood, this is the most reliable method.

Here are some useful links to help you if you want to have your Border Collie tested for TNS:

How curable is Trapped Neutrophil Syndrome (TNS) in Border Collies?

Trapped Neutrophil Syndrome is not curable in Border Collies. Once a puppy or dog is diagnosed with TNS, it is likely to be put down to end its suffering.

How your dog is treated and how long this takes varies from case to case as it depends on the symptoms an individual dog suffers from. Steroid and antibiotic treatment can help an affected dog lead a normal life but TNS is almost always fatal.

Your Border Collie puppy is likely to suffer from persistent gastrointestinal and bone infections because the bone marrow becomes clogged with the neutrophils.

Before buying your beloved Border Collie, make sure you check its parent’s health history with the breeder before making a decision.

Border Collies tested for Trapped Neutrophil Syndrome (TNS)?

If you are thinking of getting a Border Collie puppy, make sure you do all the health checks.

The following link is an incomplete, public list of Border Collie pedigrees that have tested positive to either having trapped neutrophil syndrome, being carriers or producing puppies with this debilitating disease.

If you would like to know more at any stage, please feel free to contact A/Prof Peter Williamson (tel 02 9351 3653, email p.williamson at This information sheet is for you to keep.
Any person with concerns or complaints about the conduct of a research study can contact the Animal Welfare Manager, University of Sydney on (02) 8627 8175 (Telephone); (02) 8627 8180 (Facsimile) or will.miekle at (Email)

At the time of writing this the cost of the test is $110 (incl GST) so contact Peter Williamson at the University of Sydney for the lastest fees.


TNS is an insidious genetic disease that responsible breeders from around the world are trying to eradicate with the help of Alan Wilton in Australia and his staff.

With the development of DNA testing there is no reason to breed from two TNS affected Border Collies.

In Australia, the Australian National Kennel Council requires all Border Collie litters registered with them to have TNS results for all puppies before they can be registered with the organisation.

This is great news for the Border Collie breed in Australia, for responsible breeders, and all puppy buyers.

If you want a Border Collie that is trapped neutrophil syndrome free, make sure you buy puppies that come from DNA tested parents. Avoid buying from non-ANKC breeders that do not test their animals, as there is a higher than normal likelihood of the disease being present in their Border Collie puppies.

Trapped Neutrophil Syndrome is now a preventable genetic disease that is debilitating for the puppy and heartbreaking for the owner.

With the combination of breeding and testing. Breeders can firstly genitic test to get a marker status of their dogs, carrier or non-carrier, if they do not know the genetic health of their dogs. Then a responsible breeder can now breed out this disease with genetically tested parents and progeny.