What are Coccidoidmycosis?
Coccidioidomycosis is a dust borne infection that is seen in areas with alkaline soil, extremely high temperatures, minimal rainfall and low elevation (the Southwestern United States and Mexico, for example). Common in dogs, the disease is not contagious. Typically, infection will be due to inhaling spores from the fungus, which may be transported through the air on dust particles. Should your dog be infected with coccidioidomycosis, he will experience some degree of respiratory disease.
Also known as Valley Fever, coccidioidomycosis is a fungal infection caused by the fungus Coccidioides immitis, which leads to a varied degree of respiratory illness in dogs.
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Symptoms of Coccidoidmycosis in Dogs
Coccidioidomycosis may be a mild illness in some dogs while in others it can be disseminated and severe. It can produce a variety of symptoms (depending on whether the organs are involved and how severe the infection is) in your dog, to include:
- Cough and symptoms similar to those of pneumonia
- Loss of appetite and weight loss
In the disseminated form of the disease (when it has spread), many tissues may be impacted. Additional symptoms can include:
- Swollen lymph nodes
- Skin lesions, often over the bones that are infected with the fungus
- Chronic cough
- Swollen joints
- Ongoing diarrhea
- Eye inflammation
About 20% of dogs that are infected with coccidioidomycosis have the disseminated form.
Coccidioidomycosis infection may be so mild as to produce no symptoms, or the infection can be in the disseminated form, meaning that it has spread throughout your dog’s body. In some cases, the disease will be self-limiting and the infection will be resolved on its own. In other cases, the infection will be chronic.
Causes of Coccidoidmycosis in Dogs
Coccidioidomycosis is caused by the fungus Coccidioides immitis, which live in the soil. Coccidioides requires certain conditions in order to survive and reproduce, including high temperatures and minimal rain. In areas where these fungi are prevalent, it is thought that most people or animals become infected, but most infections cause either no or minimal symptoms.
Dogs will typically become infected with Coccidioides immitis through the inhalation of spores, which may be carried on dust particles. This is the only known form of infection. The infection will typically happen between one and three weeks from exposure. Should your dog have a suppressed immune system, his chances of acquiring the more severe form are higher. Epidemics are possible after a drought follows a time of significant rain, as the conditions become suited for a dust storm.
Diagnosis of Coccidoidmycosis in Dogs
Your veterinarian will conduct a physical examination of your dog, and ask you for information regarding your dog’s symptoms, as well as how long he has been experiencing them. In addition, your veterinarian may conduct x-rays of your dog’s lungs along with a blood test (to see if antibodies are present to coccidioides). Should your dog have a lesion that is draining, the veterinarian may take a small sample and view it under a microscope in order to determine the type of fungus that is causing the infection.
Treatment of Coccidoidmycosis in Dogs
Should your dog’s infection not be self-limiting, antifungal medications will likely be prescribed for your dog. The most common is Fluconazole (2.5-10 mg/kg/day) and while the treatment length is varied, it can be as long as one year, particularly if your dog has the more severe disseminated form of the disease. Ketoconazole (10-30 mg/kg/day) and Itraconazole (10 mg/kg/day) are also regularly used, typically offering fewer side effects, however, they do cost more. The most effective antifungal medication may be Amphotericin B, though the drug is very nephrotoxic, meaning it is harmful to your dog’s liver. Should your dog’s infection not be resolved with the other antifungals, or they be unable to tolerate the medication, your veterinarian may recommend trying Amphotericin B. The treatment of mild cases of coccidioides is typically successful. Those with the disseminated form have a more difficult time recovering.
Recovery of Coccidoidmycosis in Dogs
Your veterinarian will recommend appropriate follow up depending on the severity of your dog’s infection. You will want to make sure to administer medication as recommended so that your dog has the best chance of recovery and attend recommended follow up appointments.
The prognosis for dogs with the mild form of coccidioidomycosis is very good. In the case of dogs with the disseminated form of the disease, their prognosis will be more guarded.
Should your dog be struggling with the disseminated form of the disease, upon completing treatment, the infection may reappear and require additional attention. Your veterinarian can provide you with information regarding the next step to take should this be the case.