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. At this moment in time the marker test is only useful in suspected cases and close relatives of known affected/carrier animals. The research is ongoing to develop a full DNA test that can be used on ALL border collies so we can test all breeding stock and eradicate this disease from the gene pool.

If you think you may have an affected pup and would like to have it tested, please contact Dr Alan Wilton, he needs as many cases studies as possible to further his research.

The Border Collie Health Website ( ) now also contains a database of test results so far, as well as pedigrees of known affecteds. If your dog is related to any of these known carriers/affecteds you may be able to have it tested, please contact Dr Wilton for further information.

I also urge all those that have had dogs tested to PLEASE publish your results, good or bad; it’s only by sharing this information with each other that we can minimise the risks when planning matings and move towards eradicating this disease.


This text is from Natalie Holtappel’s website ( ). Thank you!