Valley Fever: What is it?

Valley Fever (or Coccidioidomycosis)
Valley Fever is a fungal infection and is caused by the fungus Coccidioides immitis, which lives in the soil.  The highest incidence of this disease occurs in the desert areas of the Southwest: Arizona, New Mexico, parts of California and Texas.
The disease occurs in most species of domestic animals, many exotic animals, and in man.  Boxers and Doberman Pinschers seem to be more susceptible and difficult to treat.  Boxers are more susceptible because their immune system is not as strong as other dogs.  Dobermans have a higher incidence of hypothyroidism and Von Willebrands disease.  Older dogs (> 8 years) can have underlying medical problems that complicate the treatment.  
The most frequent means of entry, in Dogs, is through the respiratory system.  Dogs catch the disease when some of the reproductive elements or spores (which are the size of tiny dust particles) of the fungus enter the body.  The spores may also infect the body through an open wound.  Once inside the body, the fungus begins to grow.   Signs of the illness depend upon which part is involved.  IT IS NOT CONTAGIOUS.   In dogs with the respiratory form they often cough, a deep gagging cough.  With bone infections they often limp.  Usually they have a fever and are losing weight with a poor appetite.  
In the majority of cases, the body’s own defense system (immune system) will squelch the disease before it gains a serious foothold  Sometimes the immune system can be weakened by other diseases, like Tick Fever, Von Willebrands disease, hypothyroidism or cancer which will allow the Valley Fever to take hold in the body.  A very large percentage, possibly greater than 90% of dogs in the Southwest, has or has had Valley Fever.  If, however, the immune system fails to control the attack, clinical illness follows.
Possible Signs of Valley Fever:

• Elevated temperature of 104-105 degrees
• Listlessness
• Anorexia or loss of appetite
• A pronounced dry, harsh cough
• Swelling of joints
• Skin abscesses
• Limping
• Incoordination
• Seizures

Diagnosis and treatment
There are lots of causes for coughing and limping.  The Veterinarian will use history, physical exam, and sometimes x-rays and lab tests to make the diagnosis.  There is a Valley Fever blood test that measures antibodies.  Antibodies are proteins that the body makes to fight infections.  Test results are not always clear cut and must be evaluated in light of other findings (history, exam, x-rays, etc.)
Treatment of Valley Fever in dogs is not a simple matter.  It involves long-term therapy with close monitoring.  Antifungal medicines are used to treat Valley Fever.  The two most commonly used are Fluconazole or Itraconazole.   We usually treat respiratory infections 4-6 months and bone infections at least 12 months, sometimes longer.  
Valley Fever respiratory infections normally carry a good prognosis.
A few dogs can’t be cured and instead go into remission.  In these patients once you discontinue the medication signs reappear weeks to even years later.  Age, response to treatment, and presence of other medical problems determine the prognosis.
There is no vaccine to prevent the acquiring of Valley Fever, so at this point prevention relies on general good health measures.  The best chance for a successful treatment is early detection, elimination of Ticks and Fleas from their environment and annual vaccinations for other harmful diseases.  Consult your veterinarian for further information on the diagnosis and treatment of Valley Fever.  Your veterinarian is the most qualified person to advise you on your pet’s health and welfare.