Low White Blood Count in Dogs

Illness, genetic disorders, cancer and some drug therapies can contribute to low white blood count in dogs. Neutropenia is the medical term for low white blood cell count. The white blood cells (neutrophils) are part of the immune response system. 

Blood cells are manufactured in the bone marrow. The white blood cells (WBC) quickly move through the bloodstream to sites of injury and infection. These cells also travel to sites of the body exposed to toxic substances. 

Bacterial Infection and WBC

Bacterial infections are a common cause of low WBC counts. These infections are usually treated with antibiotics. 

Severe bacterial infections can become so widespread that WBC production in the bone marrow cannot keep up. These infections can cause serious secondary problems and require aggressive forms of therapy. 

Canine Ehrlichiosis

Ehrlichiosis is a particular type of bacterial infection. It is caused by bacteria that are present in the saliva of brown dog ticks. The bacteria enter the blood stream of the dog, where it spreads to other organs. This condition usually presents several symptoms, including low WBC count. The bacteria may attack the nervous system, if left untreated. 

Histoplasmosis and WBC

Histoplasmosis is a fungal infection caused by Histoplasma capsulatum. The fungus breeds in wet, humid regions. Although it found nationwide in the U.S., it is more prevalent in the Mississippi, Missouri and Ohio River Valley areas. 

Infection occurs when the dog is exposed to the infected soil. Healthy, older dogs may not be display any symptoms of infection; however, it can multiply and cause serious localized or systemic infection in young or immunosuppressed canines. 


Parvovirus is a deadly systemic virus that suppressed the immune system. Neutropenia can develop very quickly. The virus invades and destroys cells being produced in the bone marrow, which in turn decreases WBC count in the intestinal tract. 

Immediate treatment is needed, as death may occur in as little as 48 hours after onset. Dehydration is another complication of the disease, which is caused by the profuse vomiting and bloody diarrhea. 

Gray-Colored Collies Disorder

Gray-colored collie disorder is characterized by the color of the nose. Collies with the disorder do not have the black nose, typically in the breed. It is a genetic defect that appears shortly after birth. 

There is a deficiency in the production of WBC, because the stem cells of the bone marrow are impaired. The disease is cyclical, as production of WBC ceases every 10 to 12 days. Unfortunately, there is little treatment. 

Vitamin B12 and Giant Schnauzers

Some young giant schnauzers are genetically unable to absorb sufficient quantities of B12. This leads to anemia and neutropenia. Treatment consists of vitamin B12 therapy. 


Chemotherapy treatment can reduce the WBC count. The therapy can suppress the development of cells in the bone marrow. Symptoms usually appear a few days after beginning treatment and may resolve several weeks after therapy. 

Idiopathic Neutropenia

Idiopathic, means there is no apparent cause for the condition. Young dogs are more at risk of developing idiopathic neutropenia. Treatment is symptomatic. 

Drug Induced Neutropenia

Many medications can cause neutropenia. Phenobarbital, used to treat seizure disorders is a medication known to cause neutropenia. The list of drugs that can reduce WBC count is long.