I grew up in Indiana and attended Purdue University for my veterinary degree. We learned about diseases that affected animals all across the country, including fungal diseases. Histoplasmosis was more of a concern in the Midwest than Valley Fever. In fact, a staff member at my first job was tested for histoplasmosis when she gave birth to a child with multiple congenital diseases.
Now, Alan and I spend half the year in Arizona. On a regular basis, the horse and dog groups that I follow on Facebook discuss the perils of Valley Fever in this part of the country. I hike on an almost daily basis in the dusty desert. Three of our four dogs accompany me. We ride the horses in the desert… at least we did last winter when we had two sound horses!
If you have lived in the Southwest for a while, you have undoubtedly been educated, at least to some extent, about this disease. If you are new to living here, or you are one of the thousands of equestrians who migrate south for the winter, you might not know anything about this. I didn’t… Vet school was a long time ago!
A tightness in my chest
About two weeks ago, I started feeling a tightness in my chest. It came after a whirlwind of travel and exposure to many people and places. Alan and I are relatively sequestered in our Arizona home. Although I am current on Covid and flu vaccines, we likely lack immunity to many of the current “bugs” floating around this winter. This symptom started the night before we flew home from Belize.
After 6 days of feeling like I couldn’t easily expand my chest, I took myself to the Emergency Room. I had no other symptoms other than mild upper respiratory symptoms that occurred about a week before the chest tightness began. I also had two negative Covid tests. We hadn’t identified a Primary Care Physician here in Arizona, although we do have established care in Colorado.
When you walk into the ER and tell them that you have tightness in your chest, you get a full workup. I had blood work, survey chest films, an EKG, and a contrast CT scan. I told them that one week prior, we had been scuba diving. It was a shallow dive, but we fought serious currents returning to the boat and I was really, really sucking air. I wasn’t sure if that had something to do with my chest tightness or not… The contrast CT scan was primarily to check for issues related to diving.

I also received a breathing treatment, which was of limited benefit. All of the test results were, for the most part, normal. My blood glucose was 57, so I guess my smoothie didn’t stick with me. Not much sounds good to eat this past couple of weeks.
I was discharged with the diagnosis of “acute bronchitis” and placed on a Prednisone burst of 50 mg for five days. I also was prescribed an Albuterol inhaler. Although the pred gave me a horrible headache, I do think it helped my breathing somewhat, especially by the end of the five days. The inhaler maybe helped a little?
I saw a physician a week later and established care. High on his differential is an atypical viral infection, something he has apparently seen quite a bit of this winter. However, one of the rule-outs is Valley Fever. I am at the 2-week mark of chest tightness as I am currently writing this. I am also suffering from fatigue (hard to get excited about doing much when you have to work so hard to breath) and a limited appetite.
He started me on another Pred burst, although not as high a dose. I return in a few days for more testing. He will repeat tests designed to assess my heart function, as well as evaluate me for possible pulmonary hypertension. Blood work will assess several things, including a test for Valley Fever.
What is Valley Fever?
As I alluded to in the first paragraph, Valley Fever is a fungal disease. The technical name for it is Coccidioidomycosis, although most physicians simply call it Cocci. It’s named for the San Joaquin Valley in California where it was first identified. The fungus is found in the southwestern United States, most commonly Southern California, Arizona, Utah, Nevada, New Mexico, Texas, and areas of Mexico. Arizona has the most cases, followed by California.

How does infection with Valley Fever occur?
The simple explanation is that the spores are present in the dust. A horse, dog, or human inhales the spores. The environment in the lungs signals the fungus to move to the next stages of its lifecycle.
An article written by the National Institute of Health (NIH) states that most people will not even know they have been infected. A minority will experience flu-like symptoms 1-3 weeks after exposure. These symptoms include: headache, fever, cough, fatigue, muscle and joint aches, night sweats, and/or a skin rash. I have had fatigue, a minimal cough, and the chest tightness. Of course, as of this writing I don’t have a diagnosis of Valley Fever!
What are the chances that I will get Valley Fever?
The NIH article answers this question in a rather disturbing manner…
If you live or vacation in the desert regions where the fungus resides, you are very likely to get valley fever. However, once you have had valley fever, unless your immune system changes drastically, you will have developed a lifelong immunity to the fungus.
Another article states that people over the age of 60 are at greater risk (that’s me!) as well as immune-compromised individuals, diabetics, pregnant women in their 3rd trimester, and Blacks and Filipinos. Approximately 20,000 cases are diagnosed each year, most in California and Arizona.
Valley Fever in horses
Horses are less likely to be infected than other animals. However, if they show clinical signs, it is usually too late for treatment. Most of the time, the horses are euthanized. However, in recent years, better and more affordable anti-fungal medications have made treatment a possibility. One reference suggested that symptoms can show up years after exposure, but I had difficulty confirming that. There is not much detail in the literature about the active disease in horses.
There are three forms of Cocci in horses. To be sure, they essentially mimic what Valley Fever can do in humans.
The respiratory infection presents as one would expect… nasal discharge, rapid or difficult breathing, coughing, and if the problem is long-standing, weight loss. The infection creates a generalized pneumonia, a granulomatous pneumonia (nodules of infection), or pleuropneumonia (infection that spreads to the pleural space between the lungs and the chest wall.) Pleuropneumonia starts with pneumonia.
Systemic infection means that the spores escape the confines of the lungs and spread throughout the rest of the body. This can happen in people as well. Granulomatous lesions can be found in various organs and locations within the body. Clinical signs can be extremely varied depending on what organs or body cavities are affected.
A localized subcutaneous infection is the least common form of Valley Fever in horses.
Valley Fever in dogs
The symptom list for dogs described in this article closely approximates what I have been feeling! Coughing, fever, weight loss, lack of appetite, and lack of energy are seen in dogs affected by Valley Fever. Again, in my case, I have no fever and minimal coughing, but no appetite and no energy are spot on.

Dogs are possibly at an even higher risk than people or horses. Our Aussie/BC “Great White Hunter” Finn has his nose in the dust for the majority of our time in the desert. He loves to chase the jackrabbits and he is always burrowing after the voles. It would be impossible to prevent my dog from acting like a dog. There is also the quality of life to consider! He LOVES his desert runs.
Just as with people and horses, Valley Fever can be a localized disease, or spread throughout the body. The previously linked article mentioned these symptoms that might indicated systemic disease:
- lameness or swelling of limbs
- back or neck pain, with or without weakness/paralysis
- seizures and other manifestations of brain swelling
- soft abscess-like swelling under the skin
- swollen lymph nodes under the chin, in front of the shoulder blades, or behind the stifles
- non-healing skin ulcerations or draining tracts that ooze fluid
- eye inflammation with pain or cloudiness
- unexpected heart failure in a young dog
- swollen testicles
Again, much like people and horses, dogs that are treated promptly and who have infection restricted to their lungs have the best prognosis and the quickest recovery. Hospitalization and occasionally surgery might be required. Severe cases may be fatal.
What is the important take-away from this post?
I don’t know as I am writing this in real-time whether or not I have Valley Fever. However, I DO know that I live in an area where I most certainly could have Valley Fever. If you live here, full or part-time, or travel here, you need to know about this disease. You need to know to tell your physician or your veterinarian that you traveled to Arizona. A vet or a physician in Minnesota isn’t going to think to ask you if you have recently visited the Southwest!
Keep this in the back of your mind if you or one of your animals becomes ill and you have visited this beautiful, sunny part of the country!
Update at the last minute
The day before this posted, I underwent several tests to rule in or rule out what has plagued me this past week. One of those tests was for Valley Fever. My doctor sent a write-up of my history and symptoms to two pulmonologists and a cardiologist. All three believe that I am suffering from an atypical virus. The past few days, I have felt much better. I’m not sure if it is because of the oral steroids I am taking, or if what ailed me has run its course. I’m just glad to be feeling better. I am still glad we are testing for more serious issues.
A few days before this posted, this article about a canine vaccine for Valley Fever hit my inbox. Apparently, there are some promising advancements made in developing a vaccine that works for dogs. The plan is to eventually extrapolate that to humans, but it is expected to take many years and a whole lot of money. It is hoped that the canine vaccine will be available for distribution to veterinarians sometime this year! Stay tuned… I will keep watching for information. I would love to be able to vaccinate my dogs. I encourage you to read the article, it has some interesting additional information.
See you next week… I’m not sure if it will be another slaughter installment or if my need (and yours) for a break from that topic will prevail.
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