Introduction
As a pet science blog author, I’ve always been fascinated by the myriad of health issues our furry friends can encounter. One such issue is histoplasmosis, a fungal infection that not only affects our pets but can also impact humans. In this article, I’ll share with you everything you need to know about this intriguing disease, from its causes to its symptoms and treatment options.
What is Histoplasmosis?
Histoplasmosis is a fungal infection caused by the Histoplasma capsulatum, which is found in the soil and enters the body through the lungs. It can infect dogs, cats, and even humans, causing a variety of respiratory and intestinal symptoms. Some animals recover from the infection without any therapy, while others require treatment with antifungal medication, which is usually successful.
Where is Histoplasma Found?
Histoplasma prefers areas that are moist and humid and grows best in soils that contain nitrogen-rich organic matter, such as bird or bat droppings. It has been identified in the soil of 31 states in the U.S., with most infections occurring in the region of the Ohio, Missouri, and Mississippi rivers.
Who Gets Histoplasmosis?
Dogs and cats can both be infected with histoplasmosis. Infections are more common in outdoor pets, particularly in hunting dogs. Animals of any age can get histoplasmosis, but most infections occur in animals under four years of age.
How Do Pets Get Infected?
Pets get infected by inhaling the spore-like particles of the fungus that inhabit the soil. These tiny particles are small enough to reach the lower respiratory tract (lungs). A few cases of infection in strictly indoor animals have been reported, and it is suspected that potting soil or dirt brought in from outside may be the source of infection in these animals.
Symptoms of Histoplasmosis
The symptoms of histoplasmosis are varied and depend on the severity of the infection. Infections start in the lungs, and as the fungal organisms replicate, the animal can develop a respiratory form of the disease. Many healthy animals will recover from milder respiratory infections on their own. However, in animals with a poor or deficient immune system, the respiratory infection may become more severe or spread to other parts of the body.
The most common symptoms in dogs or cats are weight loss, fever, loss of appetite, and depression. Labored breathing with increased lung sounds is present, and many animals may also have a cough. In dogs with the gastrointestinal form, diarrhea and blood in the stool are often common symptoms. In addition to these symptoms, both cats and dogs may be anemic and have pale gums.
Diagnosis of Histoplasmosis
Diagnosis of histoplasmosis is often made from information obtained from the pet’s history, symptoms, x-rays of the chest and abdomen, and by finding the organisms in the infected tissue. A needle aspirate or biopsy of the infected tissue can often yield some of the small budding fungal organisms.
Treatment of Histoplasmosis
In many simple cases of the respiratory form of histoplasmosis, treatment may not be necessary because the animal will clear the infection on its own. However, because of the risk of the infection spreading or becoming more severe, treatment is often initiated as soon as a positive diagnosis is made.
The treatment of choice is an oral antifungal drug. The most commonly used ones are itraconazole or fluconazole. Ketoconazole is sometimes used when cost is a consideration, though it may not be as effective and can be more toxic than itraconazole. The treatment usually lasts several months or longer. The success in treating histoplasmosis is very good if the correct treatment is used and instituted before the animal becomes too debilitated.
Preventing Histoplasmosis in Pets
There is no vaccine to protect against histoplasmosis. The best prevention is to avoid areas where histoplasmosis is known to be a problem, such as areas where large numbers of birds or bats roost. In