Histoplasmosis in dogs is a non-contagious infection which is caused by the fungi, Histoplasma capsulatum. The organism thrives in the soil particularly in moist and humid conditions. It abounds in organic matter such as bat and bird droppings which are rich in nitrogen.

There are several predisposing factors which have been associated with increased incidence of Histoplasmosis in dogs. Young dogs are at higher risks of acquiring the disease. Dog breeds which are prone to developing Histoplasmosis include brittanys, pointers, and weimaraners.

Histoplasmosis is acquired by inhalation of airborne spores. The organism localizes in the lungs to multiply and spread to other organs of the body via the circulatory system. Aside from dogs, the infection can also affect cats and humans. Just like dogs, cats and humans acquire infection via inhalation of spores and not through direct contact of infected animals.

Most dogs with Histoplasmosis suffer from the subclinical form of the disease thus they fail to show any clinical manifestation. In severe cases, the symptoms which are manifested will depend on the organ system/s which has been affected. Histoplasmosis in dogs often affects the respiratory and digestive tracts. In some cases, it may cause a systemic infection when the causative agent is widely distributed throughout the dog's body systems.

The most common clinical manifestations include-general malaise accompanied by a lack of appetite and weight loss. Straining and diarrhea are also common. Histoplasma infection in the lungs is manifested by coughing and abnormal lung sounds which indicates problems in respiration. A dog's lymph nodes may be enlarged and the mucus membranes of the mouth and other parts of the body appear pale. There may also be lameness and fever. If the infection has reached the liver, there may be jaundice wherein the body tissues appear to have a yellowish tinge. The spleen and liver may also appear enlarged.

Together with clinical signs, a correct diagnosis is achieved by conducting several diagnostic tests to detect the presence of Histoplasma capsulatum and assess the effect of the infection on the body. Your vet may recommend any of the following tests to support the initial diagnosis -complete blood count, biochemistry profile, urinalysis, x-rays, fine needle aspiration, eye exam, biopsy, serologic tests, and fungal culture.

The treatment of choice for Histoplasmosis in dogs includes the long term use of oral antifungal drugs itraconazole or fluconazole. Some respiratory infections associated with Histoplasmosis may not require treatment because the animal is able to get rid of the infection on its own. Treatment is often successful if the diagnosis has been made in the early phases of the disease before the dog has developed serious complications.

There is no vaccine that can protect your dog against Histoplasmosis. The best way to protect your dog is to prevent it from roaming in areas where the fungus is known to be present. Places where populations of birds, poultry or bats are present should also be avoided.

Being able to diagnose the early signs and symptoms that your dog will develop before that a minor health issue become a major one is a skill that every dog owner should learn.