Valley Fever in Dogs

What is Valley Fever in Dogs?

Valley fever is caused by a pathogenic fungus called Coccidiodes immitis that lives in the soil and thrives in particular desert climates. Valley Fever, also known as coccidioidomycosis, is a fungal infection that primarily affects humans and animals living in arid regions, particularly in the US Coccidiodes immitis can be found in the low desert regions of New Mexico, Texas, California, and most especially in Arizona.
While it is prevalent among humans, it can also impact our furry companions, such as dogs. Valley Fever in dogs can cause a range of symptoms and discomfort, but with early detection and appropriate treatment, most dogs can recover fully. It is estimated that for about every 50 dogs with Valley Fever our Tucson vets will see 1 case in cats.

Related: Valley Fever in Cats

In this article, we will delve into the details of Valley Fever in dogs, including its causes, symptoms, diagnosis, and treatment options.

How Do Dogs Get Valley Fever?

Valley Fever is caused by the inhalation of fungal spores called Coccidioides immitis or Coccidioides posadasii, which are found in the soil of a specific geographic area. These spores can become airborne when the soil is disturbed, such as during construction, storms, or other activities. 

Valley Fever occurs when dogs inhale the spores, and when the spores are inhaled by your dog, they can grow into small balls in your pet's lungs. In dogs and cats with strong and healthy immune systems, the body is usually able to "quarantine" the pellets and prevent symptoms. About 70% of dogs that inhale Valley Fever spores are able to control the disease quickly. These dogs are asymptomatic and may later develop immunity to the disease. This is very similar to what happens in humans.

However, if your pet is old or has a compromised immune system, the spherules undergo replication by division, producing numerous endospores. As the spherules rupture, the released endospores can infect nearby lung tissues, leading to the spread of the infection within the lungs.

The Life Cycle of Coccidioides

Coccidioides is found in the environment as a saprophytic fungus, mainly found in arid or semi-arid alkaline soil areas. The fungus survives in the soil as mycelium, forming a network of branching filaments. These mycelia produce specialized structures called arthrospores. These arthrospores are small, barrel-shaped spores that contain infectious particles. They are very fragile and when the soil is disturbed by digging, walking, construction, and high winds, these threads split into tiny individual spores that form airborne particles that can be inhaled by humans and animals, including dogs, who can inhale these infectious particles when breathing in dust.

Once inhaled, the spores grow into small balls and continue to expand until they rupture, releasing hundreds of endospores.

Each endospore can grow into a new blob that spreads the infection to the lungs until the dog's immune system surrounds and destroys it. Valley Fever occurs when the immune system does not kill the glomerules and endospores quickly enough and they continue to spread in the lungs and sometimes throughout the animal's body.

What are The Signs of Valley Fever in Dogs？

The symptoms of Valley Fever in dogs can vary widely, ranging from mild to severe. 

The Early Signs of Valley Fever in Dogs

• Lethargy: Dogs with Valley Fever may appear more tired or sluggish than usual.
• Coughing: A persistent cough is a common early sign of Valley Fever in dogs.
• Fever: Dogs may develop a fever, which is often accompanied by a loss of appetite.
• Decreased appetite: Dogs infected with Valley Fever may lose interest in eating or have a reduced appetite.
• Weight loss: Unintentional weight loss can occur in dogs with Valley Fever.
• Lameness: Some dogs may experience lameness or stiffness, which can be mistaken for joint problems.
• Respiratory problems: Dogs may exhibit difficulty breathing or have rapid or shallow breathing.
• Swollen lymph nodes: Enlarged lymph nodes can be a sign of Valley Fever.
• Eye problems: Dogs with Valley Fever may develop eye inflammation, redness, or discharge.

Symptoms of Advanced Valley Fever in Dogs

• Persistent cough: The cough may worsen and become more severe.
• Difficulty breathing: Dogs may experience severe respiratory distress, such as rapid breathing, panting, or wheezing.
• Bone and joint pain: Valley Fever can affect the bones and joints, leading to swelling, lameness, or even fractures.
• Skin lesions: Dogs may develop skin lesions or sores, which can be painful or prone to infection.
• Neurological signs: In rare cases, Valley Fever can affect the central nervous system, leading to seizures, coordination problems, or paralysis.
• Organ involvement: In advanced cases, the infection can spread to other organs, such as the liver, spleen, or heart, causing additional symptoms.

How to Test for Valley Fever in Dogs?

If you live in an area where this disease is prevalent and your dog is showing signs that are consistent with valley fever, your veterinarian will recommend diagnostic testing to determine whether your dog has this infection. This testing will most certainly include a titer test to determine whether your dog has valley fever antibodies (evidence of exposure to the fungus). 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. 

Blood tests are commonly used to detect antibodies against the fungus Coccidioides in a dog's bloodstream. The two primary blood tests used are the enzyme-linked immunosorbent assay (ELISA) and the complement fixation (CF) test. These tests can help determine if your dog has been exposed to the fungus and has developed an immune response.

In some cases, if a specific area of concern, such as a skin lesion or swollen lymph node, is present, your veterinarian may perform an aspiration or biopsy. This involves taking a small sample of tissue or fluid from the affected area and examining it under a microscope to look for evidence of the fungal infection.

What Is the Treatment for Valley Fever in Dogs?

Antifungal treatment for Valley Fever is not immediately effective. Your dog's course of antifungal treatment is expected to last 6 to 12 months or longer. Dogs with severe infections and weakened immune systems may need to be on the medication indefinitely. Thankfully, the survival rate for affected dogs is high.

Fluconazole, ketoconazole and itraconazole are the antifungal medications your veterinarian will choose. They are effective in targeting the fungus and stopping the growth in your dog's body.

Regular monitoring through blood tests and follow-up visits is vital.

Cost of Valley Fever Medication for Dogs

Typically, The cost of medication for Valley Fever in dogs can range from a few hundred dollars to several thousand dollars. the treatment for Valley Fever in dogs involves long-term antifungal medications such as fluconazole or itraconazole. These medications are often required for several months to a year or more. 

Natural Remedies for Valley Fever in Dogs

While there is no definitive treatment for valley fever in dogs and medication is often required, there are natural remedies and supportive care measures that can be used in conjunction with veterinary treatment.

• For example, giving your dog nutritional supplements such as vitamin C, vitamin E (multivitamin) and omega-3 fatty acids may help to improve your dog's immune response to the infection.
• Probiotics can help maintain a healthy gut microbiome and support immune function. They may also aid in digestion and nutrient absorption.
• Providing a balanced and nutritious diet can help support your dog's overall health and immune system. 

How to Prevent Valley Fever in Dogs?

• Avoid areas with a high prevalence of Valley Fever, especially during windy conditions or construction activities.
• If you reside in an endemic region, keep your dog indoors during dust storms or when the wind is strong.
• A vaccine is in development.

A vaccine may be available in the future to prevent Valley Fever or make it only a very mild disease in dogs. Valley Fever vaccination is useful for animals traveling to places like southern Arizona and southern California and for dogs living in those places.

Can Valley Fever Be Cured in Dogs?

Yes, while there is no definitive cure for Valley fever in dogs, it is important to note that many cases of the infection resolve on their own with supportive care and time.

Can Humans Get Valley Fever from Dogs?

Yes, humans can contract Valley fever from dogs. Valley fever is a zoonotic disease, meaning it can be transmitted between animals and humans. The same fungal organisms (Coccidioides immitis or Coccidioides posadasii) that cause Valley fever in dogs can also infect humans.

If a dog is infected with Valley fever, the fungus can be present in their respiratory secretions, including their nasal discharge. Direct contact with these secretions, such as through sneezing or coughing, can potentially expose humans to the fungal spores. 

Can Valley Fever Go Away on Its Own?

Yes, in many cases, Valley fever can go away on its own without specific treatment. When dogs are infected with the fungus that causes Valley fever (Coccidioides immitis or Coccidioides posadasii), their immune system typically mounts a response to fight off the infection. Over time, the immune system is often able to control the fungal growth and eliminate the infection.