Cyclic Neutropenia (Gray Collie Syndrome)



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Cyclic Neutropenia (Gray Collie Syndrome)


Cyclic Neutropenia (CN) is a fatal recessive stem cell disorder that affects both smooth and rough collies. Also known as Cyclic Hematopoiesis or "Gray Collie Syndrome," dogs affected by Cyclic Neutropenia appear visibly lighter than non-affected littermates - even from puppies with the Merle coloration.


Cyclic Neutropenia is a disease that affects the neutrophils of a dog. Neutrophils are a type of white blood cell, and are an integral part of the dog's immune system. Every 10-12 days, the dog will experience a dramatic drop in the number of neutrophils circulating through their blood stream, leaving them extremely susceptible to infections. The dog will often experience diarrhea, fever, joint pain, or other symptoms associated with eye, respiratory, or skin infections. Bleeding episodes can also occur. Unfortunately, most affected dogs will die as puppies. Even with the best care, most dogs will not likely live past 2-3 years of age.


Gray Collie Syndrome is an autosomal recessive mutation, meaning that a dog must have two copies of the mutation in order to display the symptoms associated with this disorder. A dog with one copy of this mutation is known as a carrier and does not exhibit any symptoms. A dog that carries the mutation can pass on either the normal or mutant allele to any offspring. If two carriers are bred with one another, there is a 25% chance per puppy born that they will develop symptoms of CN, and a 50% chance per puppy born that they will be carriers of CN.

Sample Type:

Animal Genetics accepts buccal swab, blood, and dewclaw samples for testing. Sample collection kits are available and can be ordered at test now.

Test Is Relevant To the Following Breeds:

  • Rough Collie
  • Smooth Collie


Animal Genetics offers DNA testing for Cyclic Neutropenia (CN). The genetic test verifies the presence of the recessive CN Gene and presents results as one of the following:

GCS/GCS Affected The dog carries two copies of the mutant gene and is homozygous for Canine Cyclic Neutropenia. The dog will appear gray in color (Gray Collie Syndrome) and will experience symptoms associated with the disorder. The dog will always pass a copy of the mutation to its offspring.
GCS/n Carrier Both the normal and mutant copies of the gene detected. Dog is a carrier for the Cyclic Neutropenia mutation and can pass on a copy of the defective gene to its offspring 50% 0f the time.
n/n Clear Dog tested negative for the Canine Cyclic Neutropenia and will not pass on the defective gene to its offspring.