In dogs affected by TNS, neutrophils become trapped within the bone marrow instead of circulating normally through the bloodstream. As a result, the immune system becomes severely weakened, leaving affected dogs highly vulnerable to recurrent infections and poor overall health.
Neutrophils are one of the body’s first lines of defense against bacteria and other harmful organisms. In healthy dogs, these cells are produced in the bone marrow and released into the blood whenever needed. In dogs with Trapped Neutrophil Syndrome, a genetic mutation disrupts this normal process. Although neutrophils may be produced in adequate numbers, they fail to enter the bloodstream effectively, preventing the immune system from responding properly to infections.
Puppies affected by TNS often begin showing signs at a young age, usually within the first few months of life. Common symptoms include poor growth, frequent infections, fever, lethargy, chronic diarrhea, loss of appetite, weight loss, and delayed development. Affected puppies may appear smaller and weaker than their littermates and may struggle to recover from even mild illnesses. Recurrent respiratory infections, skin infections, and digestive problems are also commonly observed. In severe cases, the condition can become life-threatening due to the body’s inability to fight infection effectively.
Trapped Neutrophil Syndrome is inherited in an autosomal recessive manner. This means a dog must inherit two copies of the defective gene — one from each parent — to develop the disease. Dogs carrying only one copy of the mutation are known as carriers. Carrier dogs usually remain healthy and show no clinical symptoms, but they can still pass the mutation to their offspring. When two carrier dogs are bred together, there is a 25% chance that puppies will be affected, a 50% chance they will be carriers, and a 25% chance they will inherit two normal copies of the gene.
The TNS genetic test is designed to determine whether a dog is genetically clear, a carrier, or affected by the mutation responsible for the disorder. Testing is simple, safe, and usually performed using a cheek swab or blood sample. Laboratory analysis of the dog’s DNA provides accurate results and can identify affected or carrier dogs even before symptoms appear.
Genetic testing plays a vital role in responsible breeding programs. Since carrier dogs appear healthy, breeding without testing may unintentionally spread the mutation within the breed population. By screening breeding dogs before mating, breeders can avoid carrier-to-carrier pairings and significantly reduce the risk of producing affected puppies. This helps improve overall breed health while preserving important genetic diversity.
Currently, there is no cure for Trapped Neutrophil Syndrome. Treatment mainly focuses on supportive care, including antibiotics to manage infections, nutritional support, and close veterinary monitoring. Despite treatment, many severely affected dogs have shortened lifespans due to ongoing immune system complications.
Early diagnosis through genetic testing allows breeders, owners, and veterinarians to make informed decisions regarding health management and breeding practices. Testing for Trapped Neutrophil Syndrome demonstrates a commitment to responsible dog breeding and the long-term welfare of future generations of dogs.
