Fungal Infection (Coccidioidomycosis) in Dogs

Coccidioidomycosis is a common fungal infection in the southwestern United States, such as southern California, Arizona, and southwestern Texas. The sandy and alkaline soil in these areas make these areas the perfect breeding grounds for Coccidioidomycosis to survive and reproduce. In fact, Coccidioidomycosis is also called Valley Fever because of the amount of those infected coming from the valleys of southwestern California. It only takes about a dozen tiny spores of Coccidioides immitis to infect your dog just by breathing in the dust in these areas. This fungal infection can be mild to severe, with the severe form being life threatening. Dogs who are very young, old, or have a weakened immune system are more susceptible to the severe symptoms.

Fungal infection (Coccidioidomycosis), which is also known as Valley Fever, is usually caused by a dimorphic fungus (Coccidioides immitis) in the dog’s environment, such as the soil. This fungal infection can cause serious breathing issues, respiratory infections, swelling of the lymph nodes, and painful sores or ulcers. The areas of southwestern United States, Central America, Mexico, and South America all have been known to harbor this fungus in the soil.

The warning signs of Coccidioidomycosis can vary depending on whether your dog has a mild or severe infection. The more Coccidioides immitis spores that your dog has inhaled, the more severe the infection and the worse the symptoms will be. The age and health of your dog are also factors in how serious the infection will be. There are dogs that do not get any signs of infection at all besides sleepiness and loss of appetite, some that have just a mild infection similar to the flu, and then some dogs may get pneumonia. If your dog is going to have any symptoms at all, you will notice them approximately 7 to 21 days after he is exposed to Coccidioides immitis spores. While the most common sign of Coccidioidomycosis fungal infection is a dry cough, there are many more symptoms if the infection spreads (disseminates) into the rest of your dog’s body and bones. The signs that the fungal infection has spread are:

• High body temperature
• Hacking or gagging when eating
• Loss of weight
• Appetite loss
• Extreme tiredness
• Weakness
• Limping
• Lymph node swelling under the mouth, shoulder, or knees
• Pneumonia
• Lesions with seepage
• Abscesses over infected areas of bones
• Swelling of legs
• Obvious pain in back or neck
• Paralysis
• Seizures
• Swelling of the eyes
• Swollen testes

 Types

• Mild infection includes a slight cough and maybe some fever
• Severe infection (Disseminated) can include many issues such as high fever, swelling of the legs, eyes, and testes, pneumonia, paralysis, seizures, and even heart failure

The cause of Coccidioidomycosis is exposure to Coccidioides immitis spores. Since the spores are a fungus that lives outside in southwestern areas of the United States, Mexico, South, and Central America it is important that you do not let your dog spend a lot of time outside around these areas, especially where there is dust. The best way to prevent this is to provide ground cover (i.e. mulch, grass, gravel) in the areas where your dog may go to prevent dust. Here are some other tips:

• Find out if there are any outbreaks of Coccidioidomycosis in the area
• Keep your dog inside most of the time
• Discourage your dog from digging and sniffing the ground
• Avoid taking your dog outside if it is hot right after it rains

Your veterinarian will need to give your dog a thorough physical examination including heart rate, blood pressure, and body temperature. The veterinarian will also need to know when the symptoms started, your dog’s medical history, and any changes in appetite, activity, or behavior. A number of tests will need to be completed to determine if your dog has Coccidioidomycosis.

• Complete blood count (CBC)
• Blood chemistry panel
• Urinalysis
• Stool sample
• Digital radiographs (x-rays) of the chest, bones, and joints
• Cocci test  (also called cocci serology, cocci titers, or Valley Fever test)

If tests are negative, but your veterinarian still suspects Coccidioidomycosis, these tests will need to be repeated in one month. The veterinarian may also decide to run some more tests to help with diagnosis such as fungal swab from tissue samples, biopsy of cells, fluids, or tissues to look for fungus and CT scan or MRI.

If you catch the illness early and get your dog treated right away, there is a good chance of recovery with one of the three most common oral antifungal medications:

• Ketoconazole (Nizoral)
• Itraconazole (Sporanox)
• Fluconazole (Diflucan)

Some dogs are able to recover within a few weeks of treatment, but the medication should be continued for the full amount of time your veterinarian directs, which is usually about 6 to 12 months. If your dog has a severe case of disseminated Coccidioidomycosis, the treatment will likely be much longer. In fact, some dogs will require a lifetime treatment of the medicine.

There are some side effects of each of these medications, which are:

• Fluconazole (Diflucan) is the most common medication used for Coccidioidomycosis because it is easier on the liver and it is able to treat the brain and eye tissues that are sometimes infected. The side effects of this drug are dry coat, hair loss, dandruff, excessive drinking, excessive urination, and a negative effect on the kidneys. If your dog has had any kidney problems, your veterinarian will likely keep the dose as low as possible to prevent damage to the kidneys.
• Ketoconazole (Nizoral) was the first drug used on Coccidioidomycosis and is still used, although it has to be used in conjunction with vitamin C to be absorbed. It also has been known to cause high liver enzymes, lack of appetite, nausea, vomiting, diarrhea, lightening of the coat, and infertility.
• Itraconazole (Sporanox) is the strongest drug for Coccidioidomycosis and may be used in severe cases. This drug has the highest risk of stomach upset, increased liver enzymes, skin reactions (i.e. ulcers, abscesses, dermatitis, hair loss), and it has to be administered with food, which is difficult if your dog has no appetite. Your dog may need to be hospitalized so the veterinarian can watch for bad reactions for the first 24 to 48 hours. 

Your veterinarian may also prescribe cough medicine to relieve your dog’s coughing, pain medication, anti-inflammatories, and a special diet.

Most dogs (over 90%) that get treatment early will recover within a few weeks, and will continue to get better with continued long-term medication. If your dog has severe disseminated Coccidioidomycosis, the chances of recovery are guarded due to the damage to the lungs or brain. If that is the case, your dog may need surgery to remove the damaged tissue and be on medication for life. Approximately 80% of dogs with disseminated Coccidioidomycosis recover if treated early with one of the oral antifungal medications.

The best chance of recovery for any type of Coccidioidomycosis is to be sure to follow the instructions given to you and continue to follow up with your veterinarian.