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.
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
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
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.
text is from Natalie Holtappel’s website (