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Valley Fever (Coccidioidomycosis) in Dogs

Posted May 15, 2014 in Dog Diseases & Conditions A-Z

Valley fever is a fungal infection most commonly seen in the desert regions of the southwestern United States. The fungus lives in the soil where it dries into delicate strands. When the soil is disturbed — even just by walking on it or by strong winds — those strands break up into smaller spores which are then inhaled into the lungs where the infection begins. According to the Valley Fever Center for Excellence at the University of Arizona, “About 70% of dogs who inhale valley fever spores control the infection and never become sick.” In those that do, the effects of the disease can range from mild to severe and can occasionally be fatal.

Both people and animals can get valley fever but they do not transmit the infection between one another. Valley fever is considered non-contagious. If multiple animals or humans are affected in a household, each infection was acquired independently by inhaling spores from the same environment.

How common is valley fever in dogs?
A study, run by the Valley Fever Center for Excellence, sampled 60 dogs in Arizona and estimated that about “4% of dogs will become sick with valley fever on an annual basis.” They expect that dogs in the low desert regions of Arizona, New Mexico, southwestern Texas and the central deserts of California are at greater risk.  

What are the symptoms of valley fever in dogs?
If your dog does get sick with valley fever, the symptoms can be pretty nonspecific.Dog in desert cave If the infection is only in the lungs, you may see:

  • Lack of appetite
  • Lethargy
  • Fever
  • Coughing

If the infection spreads beyond the lungs it has a particular affinity for infecting the bones resulting in:

  • Pain
  • Swelling
  • Seizures
  • Abscesses
  • Eye problems
  • Heart failure

How is valley fever diagnosed?
Your veterinarian will undoubtedly be running certain tests based on your dog’s clinical symptoms, including but not limited to:

  • Chest or bone X-rays
  • Routine blood tests
  • Cultures
  • Biopsies

In addition, there is a specific blood test that does not identify the organism itself but does test for antibodies against the valley fever fungus; a positive result indicates that your dog was infected with the organism.

If you live in an area where valley fever exists, or even if you and your dog have travelled to such an area recently, your veterinarian will likely recommend this test anytime your dog exhibits symptoms consistent

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Mike has more than 35 years of experience in companion animal veterinary practice and is a valued member of IDEXX’s Pet Health Network team since 2013.