Trapped Neutrophil Syndrome in Dogs

Although most puppies with TNS show signs of the condition in the first few weeks, some do not have symptoms until they are more than six months old. Some are discovered when they are given their immunizations at three months because the puppy will have a bad reaction to that. With really mild cases, there may be no signs of disease at all until the dog gets ill and never seems to recover completely. Once your dog has an infection or other illness, his health gets worse until he is no longer able to function and the major organs shut down. It is best to euthanize your puppy before this happens if possible because of the amount of suffering he will have to go through.

Trapped neutrophil syndrome (TNS) is a common fatal genetic autosomal disorder that has only been found in Border Collies. With this condition, the bone marrow produces the neutrophils normally but they are not transferred to the blood where they are needed to fight illnesses. In other words, the neutrophils are trapped, which is where it got its name. With such a low immune system, the puppy usually does not make it through his first year of life.

In fact, most puppies become sick and die by the time they are about four or five months old. The first sign of TNS you may notice is that the puppy’s head and legs are longer and he is smaller than the other puppies in the litter. Soon, inflammation of the joints and lameness should be evident, and increased body temperature may also be noticed if your puppy has an infection, which is likely because of the weak immune system.

This is a hereditary disorder that is usually evident at birth, but may not be noticed for a few weeks when the other puppies grow larger than the ones that are affected. However, sometimes the signs are mild enough that you may not notice it at all until the puppy gets his first illness. Unfortunately, without a good immune system, your puppy will be sick most of his life until he dies or is euthanized.

• Abnormally long head and legs
• Smaller than other puppies
• Inability to nurse properly
• Failure to thrive (does not gain weight or grow normally)
• Weakness
• Lack of interest in surroundings
• Depression
• Swollen joints
• Leg pain
• Lameness
• Frequent illnesses and infections
• Higher than normal body temperature

• The cause of TNS is a mutation of the VPS13B gene, which is only found in Border Collies
• Most puppies become sick and die by the time they are about four or five months old
• it is a common fatal genetic autosomal disorder
• The bone marrow produces the neutrophils normally but they are not transferred to the blood
• The neutrophils are trapped

After going over your dog’s medical history, the veterinarian will do a complete physical examination. Auscultation and palpation will usually test normal although the joints may be swollen. Your dog’s body temperature may be elevated if infection is present. Reflexes are usually normal but your dog may be unable or unwilling to stand on his own for any length of time. A complete blood count (CBC) is important because it will show decreased neutrophils (the most likely sign), leukocytes, lymphocytes, eosinophils, creatinine, potassium, nitrogen, and chloride. Your dog may also be slightly anemic. Also, alkaline phosphatase will be notably elevated. A PCR-based assay is a definitive test, although most veterinarians will have to send it to a laboratory for the results since they do not have the equipment to process the sample.

A bone marrow biopsy is the most effective way to get a diagnosis right away. This procedure is done by inserting a large needle into your dog’s hip and extracting the bone marrow to be microscopically evaluated. If your dog has TNS, a low neutrophil count will be found. Your dog will be sedated or under general anesthesia for this procedure. Radiographs (x-rays) will likely show fractures in the limbs and a reduced bone density.

Although TNS is not curable and is almost always considered fatal, some dogs with mild cases can be treated with medication to prolong their life expectancy and increase their quality of life.

Medication

Some of the medications that your veterinarian may prescribe include metronidazole (Flagyl) for infection, glucocorticoids for swelling and pain, and azathioprine, ciclosporin, or another immunomodulatory drug to help boost the immune system. Tramadol, carprofen, or NSAIDs may be given for pain.

Therapy

There are some experimental treatments that may help with pain and some veterinary professionals suggest a diet high in antioxidants. Others have suggested vitamin supplements and vegetarian diets. However, these are unproven and experimental.

Unfortunately, this condition is almost always fatal within the first year of life. To spare your dog from suffering, euthanasia may be best if he is having frequent infections and pain.