A good client brought her ferret in for an exam. He was a rescued ferret with an unknown background and history. He had been acting a little differently recently and was not eating as well as normal. These clinical signs are nonspecific and can be caused by many disease processes, so a physical exam was performed.
The only abnormal findings for the ferret on the physical exam were an enlarged spleen and a slightly pale color to the gums. An enlarged spleen is a common finding in older ferrets and can be caused by several different diseases. Blood work was done to try to determine what was going on with this little guy. The blood work showed that the ferret had mild anemia. The mild anemia was the reason for the paler gumline. Mild anemia can also cause the spleen to become enlarged, because the spleen can actually make red blood cells when there is anemia.
The ferret was started on an antibiotic as a precaution and on a vitamin/mineral supplement with iron to help treat the anemia. Unfortunately the ferret did not improve. His spleen continued to enlarge, and he became very lethargic. The decision was made to remove the spleen and to check the rest of the organs in the abdomen. The spleen was removed surgically and sent out to a pathologist to find out what was causing it to be so large.
The pathologist found a fungus called histoplasma in the spleen, which caused histoplasmosis. Histoplasmosis is a chronic infection that is not directly contagious to other animals. Animals are typically exposed to histoplasmosis through contact with soil that contains bird or bat feces. It is not known how this ferret was exposed to histoplasmosis. Fungal infections are rare in ferrets, but they are occasionally found in cats and dogs. Fungal infections can produce vague, nonspecific signs and are often diagnosed by cytology or biopsy, as was the case for this ferret. Fungal infection can be treated with either ketoconazole or itraconazole, but severe cases may not improve.