Trapped Neutrophil Syndrome

(also referred to as Hereditary Neutropenia)

TNS is an inherited fatal immune disorder found in border collies. the Disease was first recognised by veterinarians, Frazer Allen and Boyd Jones in New Zealand, through assistance from breeder Judy Vos (Clan Abby). Although thought to have been around for a long time it is only recently that scientists have started to get a greater understanding of the way it works, it’s affects on the animal and mode of inheritance. The majority of this research has been done by Dr Alan Wilton and his team at the University of New South Wales in Australia.

Neutrophils are the precursors to white blood cells, produced in the bone marrow and, in a normal animal, released into the blood to fight infections. In a TNS affected animal these neutrophils cannot be released from the bone marrow so the animal is unable to mount an effective immune response to infection.

Symptoms can vary greatly, depending on which infections the pup happens to contract; it is because of this that the disease has been difficult to recognise in the past. There are still very few vets in the UK aware of this condition. Symptoms can be seen from as early as 2 weeks old. Affected pups are usually smaller than their siblings with slower growth rates and often appear to have a ‘weedy’ head and poorly conditioned coat. Other symptoms include vomiting and diarrhoea, inappetence, high temperatures/fever, swollen and painful joints and lameness.

Onset of symptoms frequently coincides with first vaccination since this is often the first challenge to a pups’ immune system. Live vaccines are designed to ‘mimic’ certain infections so that the pups’ immune system can produce antibodies against it and recognise it should it encounter the infection again in future. In a TNS affected pup of course this does not happen and the puppy will quickly develop the infection. It is important therefore that if a puppy is suspected of having the disease it does not receive any form of vaccination.

Up until recently diagnosis was difficult and involved invasive techniques. A pup displaying the clinical symptoms described above will usually be blood tested, a low neutrophil count would point to TNS but is not conclusive since other factors such as viral or bacterial infections may also cause this. A bone marrow biopsy is the best way to detect the disease, if the neutrophil levels in the bone marrow are higher than those in the blood it is an indication that these are trapped hence ‘trapped neutrophil syndrome’

Recently Dr Wilton and his team at UNSW announced a chromosome marker test for this disease; this test is able to detect the chromosome ‘carrying’ TNS in affected and carrier animals so it is now possible to obtain a diagnosis without using the invasive bone marrow biopsy technique. Research has shown that the mode of inheritance is recessive, so both parents must carry the gene to produce an affected pup. Initially the marker test was only useful in suspected cases and close relatives of known affected/carrier animals. Recent research and results have shown that the test is also reliable in those dogs that are not related to known affecteds/carriers. While many at first thought the disease might be limited to the Australasian bloodlines, carriers have been identified in all British and ISDS bred dogs too. The test is now available for ALL border collies so we can test all breeding stock and eradicate this disease from the gene pool.

The Border Collie Health Website now also contains a database of test results. This database does of course only contain the results that owners and breeders have chosen to publish and does not include all dogs tested.

If you would like your dog testing please contact Dr Wilton for further information.

**Read Dr Wilton's latest Research Report **

Our experiences...

January 2007 saw the start of a difficult time here at Bryning, one of Lloyd's pups from his 3rd litter, Pip (Kruizcoli Winter Madurai) bred by Louise Rolfe came down with a mystery illness, it was around this time that the work of Dr Wilton and his team was starting to come to light over here with the announcement of the first DNA test results. After talking with other breeders and reading up on the net I realised that little Pip's symptoms sounded like those of TNS. After speaking with Dr Wilton, Louise and I decided to send blood samples for testing and our fears were confirmed, Louise received the news that Pip was indeed affected with TNS and Tia was a carrier of the gene just 5 days after little Pip had been put to sleep to prevent him suffering any further. A couple of days later I received the news I now already knew, that Lloyd was also a carrier. Over the next few months Louise and I and other associated breeders will be testing our related dogs, long term we hope there will be a test available for all border collies so we need never see this disease again.

Read Louise's Account of her experience with Pip...
Update 6th February 2007
Just to let those of you who have kindly offered me advice, wishes and support over the last few days that Pip (Kruizcoli winter madurai), my suspected TNS puppy, went to sleep for the last time at lunchtime today. He was 12 weeks old. He had been through too much over the last 4 weeks and was ready to go. We had done everything we could but he was tired and as I held him in my arms in the sunshine and looked into his handsome little eyes I knew I couldnt put him through any more pain.
Sleep well my handsome son...I'm so sorry.
My heart is broken.
Louise Rolfe

Run fast and free at the bridge little Pip, no more pain and suffering...

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