What's Valley Fever?
Valley Fever (VF), or Coccidioidomycosis, is reaching epidemic proportions in Arizona, affecting both people and dogs. Dogs, in fact, are even more susceptible than humans, by virtue of their closer proximity to the ground where Valley Fever spores live.
VF is a fungal infection contracted by inhaling soil-dwelling spores. When soils containing the fungus are disturbed and dust is raised, spores may be inhaled with the dust. Soil is disturbed by things like construction, digging (by dogs or humans), and wind. Dogs, known to dig and to stick their noses right into the dirt, have potential to breathe in many, many spores at a time. The microscopically small spores are found in the arid soils of the low desert regions of the southwestern U.S. In recent years, we've seen explosive population growth in Arizona and an associated increase in new home construction and extreme disturbance of the soil. The increase in the number of cases of VF seems to closely correspond to the increase in population. VF infections are more likely to occur during certain seasons. In Arizona, the highest prevalence of infections occurs June through July and from October through November.
Many dogs in this part of the country become infected with VF, but do not become visibly ill. In most cases, only a mild respiratory inflammation occurs as the dogs’ defense mechanisms wall off the organisms. However, very young puppies, older dogs, or dogs with weakened immune systems are at much higher risk to develop a more serious case of VF. In severe cases, the disease can spread throughout the lungs and invade other organs with the fungal infection. Once the spore has been breathed into the lungs, the spore transforms itself into a larger, multi-cellular structure called a spherule. The spherule grows and will eventually burst, releasing lots of small endospores. These develop into new spherules, and the cycle repeats again and again. This is how the fungus can be spread from the lungs through the bloodstream to other organs.
Valley Fever is not contagious to other pets or family members!
A person with VF cannot infect another person or a dog;
a dog with VF cannot infect another dog or a person!
VF is classified as either Primary or Disseminated disease. Primary disease, or the initial infection, is limited to the lungs and may go away on its own, or the dog may become sick enough to require medication. Early symptoms often seen in the initial stages of Valley Fever are dry, harsh cough, fever (anything over 102 is considered a fever), depression, and lack of appetite. Symptoms typically occur about 3 weeks after infection. In dogs, VF commonly spreads to other parts of the body. When this happens, the dog has what is referred to as Disseminated disease, which means that there are fungus cocci throughout the body. These dogs will almost certainly die without treatment. In disseminated disease in dogs, the bones and joints are the most frequent targets and lameness is the most common symptom. Other symptoms of disseminated disease include lack of appetite, lethargy, persistent fever, and weight loss. Occasionally, the fungal infection may reach the brain, and seizures can result.
The diagnosis of Canine Valley Fever is made by the history you give your vet, the symptoms the dog is having, and results of blood tests which measure the levels of VF antibodies produced by the dog’s immune system. Other diagnostic testing may be required, including but not limited to other blood tests, x-rays of the chest and/or any painful or swollen bones or joints, repeat antibody testing, etc.
What Can Be Done?
In most cases, dogs that develop symptomatic VF will require treatment with an anti-fungal medication. It’s a lengthy treatment, depending on the severity of the infection, but usually lasts 6-12 months, and sometimes longer. Dogs with infection that’s invaded the brain or spine may require medication for life to keep symptoms from returning. Anti-fungal medications are very expensive, but are the only way to treat the cause of this disease.
One of the most commonly prescribed antifungal medicines is ketoconazole (Nizoral) and is the least expensive of the group. It’s given orally, with food, and our most recent experiences (2/2005) are that cost of treatment with this medicine is running $30/month. A typical dose is 1 pill, twice a day. The common side effects to Nizoral include loss of appetite and vomiting, and rarely liver problems can develop. Newer antifungal drugs are itraconazole (Sporanox) and fluconazole (Diflucan). Both drugs are reported to have fewer side effects, but they can cost significantly more. Sometimes, if a dog is experiencing uncomfortable side effects on ketoconazole, the veterinarian will prescribe one of these newer drugs. Many people travel to Mexico to obtain these drugs at a lower cost.
(In the Phoenix area, there are a few Veterinary Pharmacies that offer these medications at a significant discount. While DLRR does not endorse or recommend private businesses, we have been told that a local possible source for these medications is Pet Health Pharmacy, 12012 N. 111th Ave, Youngtown, AZ 85363, 1-800-742-0516. They have quoted prices over the phone. Consult with your veterinarian.)
The good news is that most dogs, with the appropriate medication and treatment, do recover from this disease. In fact, most dogs are acting normally, and have a very good quality of life after the first week or so of treatment with the medication. Antibody tests, also called serologies or titers, will be repeated periodically, and the results will determine the point at which the medication can be stopped.
Once a dog has been diagnosed with and treated for VF, they are probably immune for the rest of their lives from a new infection. A small percentage of dogs will die of Valley Fever, despite aggressive anti-fungal medications. These are usually dogs with severe, disseminated disease.
Because of the very regional nature of this organism, funding for research related to VF is limited. Drug companies don’t foresee enough profit in investigating or developing treatments for a disease contained within such a limited region. However, Assemblyman Roy Ashburn (R-Bakersfield) introduced new legislation in February, 2002 to provide additional funding from the state of California for scientific research towards the development of a vaccine against VF. The bill would secure $1 million to continue the Valley Fever Research Project.
If you have a dog with VF, or have further questions about VF, please consult with a veterinarian. The information contained here is for general informational purposes only and is not a substitute for professional veterinary advice or a veterinary exam. Should you have any questions about your pet's health, please call or see your veterinarian immediately.
If you have more general questions about Labs, please visit the Labrador FAQ site, a very comprehensive site with all kinds of information about Labs.