Histoplasmosis in Dogs
Histoplasmosis refers to a fungal
infection caused by the Histoplasma capsulatum fungus. Dogs usually ingest the
fungus when they eat or inhale contaminated soil or bird droppings. The fungus
then enters the dog's intestinal tract, where it causes a diseased condition to
develop.
Symptoms:
The most common symptoms for dogs are lack of appetite, weight loss, depression, and diarrhea with straining.
Other potential signs may include:
Coughing
Difficulty breathing (dyspnea), associated with
harsh lung sounds
Unable (or unwilling) to exercise
Enlarged lymph nodes (lymphadenitis)
Lameness
Eye and skin changes
Fever, up to 40 degrees Celsius (104.0 degrees
Fahrenheit)
Pale gums and moist bodily tissues (mucous
membranes)
Yellowish discoloration of the gums and other bodily
tissues (known as jaundice or icterus)
Enlargement of the liver and spleen
(hepatosplenomegaly)
Causes:
The primary cause of this infection is the ingestion of the
Histoplasma capsulatum fungus. The fungus may be inhaled when contaminated soil
is disturbed, such as what happens when dogs scratch or dig in the dirt, or through
contact with contaminated bird droppings, including that from poultry, and bat
droppings.
Other causes for histoplasmosis include:
Diarrhea and anemia — may be a severe hookworm
infection
Enlarged liver, spleen or lymph nodes — consistent
with lymphoma
Respiratory problems — may be distemper, bacterial
pneumonia, or heart disease
Diagnosis:
A chemical blood
profile, complete blood count, and urinalysis will be conducted. While blood
tests may confirm the presence of histoplasmosa antibodies, this only means
that your dog has been exposed to the fungus, and not necessarily that the dog
is in a diseased state as the result of exposure. Further differential testing
will confirm or rule out the actual state of histoplasmosis.
In order to settle on the correct course of
treatment, your veterinarian will want to differentiate the symptoms of
histoplasmosis from the symptoms of other diseased conditions. Severe chronic
diarrhea and weight loss can indicate a variety of conditions for dogs,
including lymphocytic plasmacytic enteritis, eosinophilic enteritis, lymphoma,
chronic parasitism, and exocrine pancreatic insufficiency.
Treatment:
Veterinarians will usually treat this condition with medications on an outpatient basis. If inpatient treatment is recommended, it may be as the result of your dog being unable to absorb nutrients properly (malabsorption) due to the intestinal disorder. If this is the case, your veterinarian will administer drugs, nutrients, and fluids intravenously until the condition has improved.
Living and Management:
After the initial treatment, your dog's activity level should be reduced until it is fully recovered. Cage rest, or restriction to an enclosed environment will limit your dog's movement enough so that it will not stress itself and prolong the recovery period. If the condition does recur, a second course of treatment may be needed.
Prevention:
To prevent the development of histoplasmosis, you will need to try to steer your dog away from areas that are suspected areas of exposure to the histoplasma fungus, such as where birds, poultry or bats might roost, or around soil that is obviously contaminated with bird droppings.