Trapped Neutrophil Syndrome, Hereditary Neutropenia

Trapped Neutrophil Syndrome (TNS) or Hereditary Neutropenia is a rare blood disease of Border Collie affecting puppies between 2 weeks and 7 months of age. The disease was originally described in the Australian and New Zealand population of Border collies and is characterised by a deficiency of segmented neutrophils in the blood and hyperplasia of myeloid cells in the bone marrow. The widespread nature of the disease indicates that the mutation of the gene responsible for this condition was either already present in the founder dogs used to establish the breed or originated very early in the breed.³ TNS onset has also been associated with previous drug therapy, particularly with anti-seizure medications and sulfa drugs.¹

Trapped Neutrophil Syndrome is an autosomal recessive disease that presents as a neutropenia (low neutrophil cell count) due to failure to release neutrophils from the bone marrow.

Signs

Severely affected pups show abnormal craniofacial development with a narrowed elongated skull shape described by breeders as ferret-like. Affected pups are often smaller than their litter mates and suffer from chronic infections and failure to thrive resulting from a compromised immune system.³ Signs include fever, lameness, joint swelling, loss of appetite and diarrhea.

Treatment

There is usually a good response to long-term corticosteroid treatment. However, care is required to avoid adverse effects associated with corticosteroid use. It is also imperative that medications are not withdrawn abruptly as a second remission may not always be achievable.²

References

1. Mordecai Siegal. UC Davis Book of Dogs: The Complete Medical Reference Guide for Dogs and Puppies
2. Perkins MC, Canfield P, Churcher RK, Malik R. Immune-mediated neutropenia suspected in five dogs. In: Aust Vet J. 2004 Jan-Feb;82(1-2):52-7.
3. Jeremy R Shearman1, and Alan N Wilton. A canine model of Cohen syndrome: Trapped Neutrophil Syndrome