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What is Valley Fever?

Valley Fever is a disease caused by a fungus, found in the Phoenix area (and other southwest cities and states), known as Coccidiodes immitis.  It has two completely different forms, depending on whether it is in the environment or has entered a host animal.  When it is in the environment, it exists as a mold. During dry spells, the mold goes dormant in the soil, and can remain dormant for prolonged periods of time.  Once the rains come and especially during the monsoon season, the fungus grows and produces long filaments of mold that contain infectious spores.  The tiny spores readily become airborne when the soil is disturbed by winds or by construction, farming, or digging.  If the spores are inhaled, they transform into a yeast-like organism that infects the lungs.  Remember, dogs generally use their noses to sniff the environment and can readily inhale spores in the dust accumulated inside and outside of our homes.

Valley Fever can take two main forms of disease in the dog, the Primary Disease and the Disseminated Disease.  The Primary Disease is limited to the lungs.  Symptoms of Primary Valley Fever include a harsh dry cough, a fever, a lack of appetite, and/or lethargy or depression.  These symptoms usually occur about 3 weeks after infection.

In the Disseminated Disease the fungus has disseminated or spread to other parts of the body.  The bones and joints are most commonly infected, and lameness is the most common symptom.  The joints may become swollen and painful.  Other symptoms are non-specific and may include lack of appetite, lethargy or depression, a persistent fever, and/or weight loss.  In rare cases, the fungus invades the brain, resulting in seizure activity or paralysis.

A ‘titer test’ can be used to determine whether your dog has Valley Fever antibodies.  Depending on your dog’s symptoms and the severity of illness, your veterinarian may also recommend additional blood tests and diagnostic x-rays of the chest and any affected legs.  The fungus can also be detected by microscopic examination of samples of fluids or infected tissue.


What is the treatment for Valley Fever?

At the present time, dogs that develop Valley Fever require lengthy treatment with anti-fungal medications.  The duration of treatment will depend on the severity of infection. In many cases, treatment will be required for 6-12 months.  And in other cases, if the fungus has specifically invaded the nervous system or is isolated in a specific joint, the dog may require anti-fungal medication for life.  Sometimes, additional medication is also needed to help control symptoms, depending on which area of the body is affected.

There are a number of anti-fungal medications for treatment of Valley Fever.  Although the treatment is prolonged, the dog usually begins to feel better within 1-2 weeks after the treatment begins.


For more information, please visit or call us at 623.298.4200 to schedule an appointment.

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14445 W. McDowell Rd
Suite A-106
Goodyear, Arizona

Phone: 623-298-4200
Fax: 623-935-6026

Hours of Operation

Monday 7:30am - 5:30pm
Tuesday 7:30am - 5:30pm
Wednesday 7:30am - 5:30pm
Thursday 7:30am - 5:30pm
Friday 7:30am - 5:30pm
Saturday 8:00am - 1:00pm
Sunday Closed


For after hours please contact the VetMed at (602) 697-4694.