Valley Fever (Coccidioidomycosis)

What is Valley Fever?

Valley Fever is caused by a fungus that lives in the desert soil. Dogs contract Valley Fever by inhaling these fungal spores in the dust raised by disturbances such as, but not limited to, digging, wind and construction. The dog may inhale only a few spores or many hundreds. Once inhaled, the spores grow and mature and produce new cells, spreading the infection.  The sickness Valley Fever occurs when the immune system does not kill the cells quickly and they continue to spread in the lungs and sometimes throughout the animal's body. Only about 30% of dogs that inhale spores become sick.


The most common symptoms for pulmonary (of the lung) infection are: coughing, fever, weight loss, lack of appetite and lack of energy. A dog may have one or a number of these symptoms. When the infection spreads outside of the longs it disseminates (spreads) the disease. The most common symptom of disseminated disease is lameness, but after the infection has disseminated it can affect any organ. Other symptoms that may occur are but are not limited to: seizures, swollen lymph nodes, eye inflammation, pain or weakness, soft abscess like swelling under skin, and non-healing ulcerated skin lesions.


In order to do a complete work-up and depending on the symptoms, x-rays and bloodwork are warranted. Sometimes biopsies will be done in order to determine skin lesions. There is a specific lab test for Valley Fever and though highly reliable it can show false negatives. Please consult your veterinarian for the best choices of diagnostics regarding your pet.


Valley Fever is treated with an anti-fungal. The most commonly used is Fluconazole, but occasionally Itraconazole or Ketaconazole have been used. There are other drugs on the market that can be used and are best discussed with your veterinarian to determine if they are acceptable. Possible side effects of medications are: GI upset, liver or kidney elevations (these organs help to process the medication), lethargy or loss of appetite. There are numerous side effects that are less likely and, like people, each patient will respond differently.

While the length of treatment will vary depending on symptoms and response to medications, it is usually a lengthy process. Minimum treatment is six months to a year. However, disseminated disease may require lifelong treatment. Occasional liver support is recommended to help prevent damage of the liver with long term medications.


Is Valley Fever contagious to me or my other animals?

No. Valley Fever is inhaled. It is possible for only one dog in a multi-dog house to get Valley Fever. It all depends on the dog’s immune support.

Will my dog recover from Valley Fever?

Depending on your dog’s health and response to treatment, Valley Fever can go into remission. Occasionally lifelong treatment is needed depending on response to treatment or symptoms of disease. Occasionally very sick and immune-compromised dogs have a hard to time responding to treatment and euthanasia is warranted for quality of life.

Can Valley Fever relapse? Yes Valley Fever has known to relapse in dogs, especially with disseminated disease. If relapse occurs, occasionally patients will not respond to the same anti-fungal or occasional lifelong treatment is warranted.

Is Valley Fever preventable?

At this time there is no guaranteed way to prevent Valley Fever except to completely avoid any areas where it is found. However there are studies being done to make a vaccine to either prevent Valley Fever or lessen the effects of the disease.

We always recommend having your dog examined by your veterinarian, to come up with a specific health plan that caters to your pet’s health needs. If you are considering adopting or have adopted one of our Valley Fever dogs and do not have a veterinarian, we have a list of veterinarians that do first exams free. If you are looking for further information please check out the following website: