is a parasite you will not hear much about since it rarely causes significant disease. Its importance lies in the fact that its immature form (slender larvae called microfilariae) can be easily confused with those of Dirofilaria immitis (heartworm)
. D. reconditum
lives in the body cavity and subcutaneous (just below the skin) tissues
of dogs and is found throughout the United States.
The life cycle of D. reconditum includes an intermediate host like that of heartworm. Only in this case the intermediate host is a flea, tick, or louse instead of the mosquito.
The adult worms which are ½ to 1-inch long may be found on necropsy or as an incidental finding during surgery for some other reason. The microfilaria can be found in the bloodstream. Based on their size and shape, your veterinarian should be able to distinguish them from heartworm microfilariae under the microscope. The presence of a D. reconditum infection should not affect the common serologic test used to diagnose heartworm.
Usually no treatment of a D. reconditum infestation is required, however, a single treatment of ivermectin (0.11 mg/lb) will eliminate the microfilaria. It is unknown if any antihelmintics will kill the adult worms. Since it is not considered a pathogen, few efforts have been made toward its prevention or control. Controlling the flea, tick, and lice populations would be beneficial.