Canine cyclic hematopoiesis

What is ... ?: 

 This disorder of the immune system occurs in gray collies. Puppies are usually smaller and weaker than their littermates and by 8 to 12 weeks of age they develop clinical signs such as fever, diarrhea or joint pain, or other signs associated with eye, respiratory, or skin infections.

The disorder is caused by an abnormality of the stem cells in the bone marrow, from which all blood cells develop. The result is a cyclic fluctuation in blood cell numbers, primarily neutrophils, which are very important in fighting infections. Every 10 to 12 days, the number of neutrophils drops dramatically, and then rebounds. There is increased susceptibility to infection corresponding to the dip in neutrophil numbers. As well, the normal activity of the neutrophils is impaired. These dogs are also prone to bleeding episodes due to the drop in platelet numbers.
 

How is ... inherited?: 

The mode of inheritance is autosomal recessive. Both parents must carry the abnormal gene for the offspring to be affected.

What does ... mean to your dog & you?: 

 This is a very serious disorder. These dogs are subject to severe recurring bacterial infections, primarily of the respiratory or gastrointestinal tract. Even with the best of care, affected dogs rarely live beyond 2 or 3 years of age.

How is ... diagnosed?: 

 Affected dogs have a light silver gray, possibly mixed with light beige, hair coat and a characteristic light coloured nose. Pups usually experience clinical illness by 8 to 12 weeks of age and are brought to the veterinarian at that time, if the breeder does not recognize the defect before then.

The disorder is diagnosed based on the cyclic fluctuation in blood cell numbers, as well as the characteristic coat coloration.
 
For the veterinarian:
Cyclic neutropenia occurs every 10 to 12 days, persists 2 to 4 days, and is followed by a rebound neutrophilia (during which infections resolve). Other hematologic abnormalities include non-regenerative anemia, and cyclic reticulocytosis, monocytosis, and thrombocytosis. Even with optimal care, affected animals usually die before 2 to 3 years of age due to chronic recurring infections and/or hepatic or renal failure associated with amyloidosis.
 

How is ... treated?: 

The only practical treatment is supportive care and antibiotics during neutropenic episodes. Without supportive care, pups usually die before 6 months of age. Even with the best of care, including very close monitoring and antibiotics to counteract the variety of infections, these dogs usually die before 2  or 3 years of age.
Bone marrow transplant and gene therapy have been attempted on an experimental basis.
FOR MORE INFORMATION ABOUT THIS DISORDER, PLEASE SEE YOUR VETERINARIAN.

Breeding advice: 

As a rule, parents and littermates of affected dogs should not be used for breeding, to avoid perpetuating this lethal defect.
HealthGene Laboratory offers a DNA-based test for canine cyclic hematopoiesis that identifies normals, carriers (heterozygous), and affected dogs, which will assist with judicious breeding.

Resources: 

Raskin R. Hematologic disorders – cyclic hematopoiesis. In: Schaer M, ed. Clinical Medicine of the Dog and Cat. London, UK: Manson, 2010:261. 
Sargan DR.  Cyclic hematopoiesis in IDID - Inherited diseases in dogs:web-based information for canine inherited disease genetics. Mamm Genome. 2004 Jun;15(6):503-6.


What breeds are affected by ... ?
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