Trapped Neutrophil Syndrome is an inherited disease affecting Border Collies. This disease affects the immune system and its ability to fight infection. Affected dogs most commonly present between the ages of 6-12 weeks with signs of immune dysfunction. Symptoms of the disease are dependent on the specific infection that the dog is fighting and may include failure to thrive, poor growth, weight loss, lethargy, diarrhea, and vomiting. Affected dogs may also present with active respiratory, skin, eye or ear infections. Affected puppies are often smaller than normal littermates and can have a narrow, elongated, ferret-like head. Occasionally affected dogs can be mildly affected and not show signs of disease until 1 to 2 years of age, but typically affected dogs die from an infection by four months of age.