Microfilaria

Ag or Ab Test

Thoracic radiography

Echocardiography

Adults

Microfilariae

Dog

****

***** (Ag)

***

MPA, PA, RHE, PTE, PIE

**

Respiratory, weight loss, exercise intolerance, heart failure

Ivermectin, milbemycin, selamectin, or moxidectin

Melarsomine, doxycycline, supportive treatment

Moxidectin,^a ivermectin, milbemycin, or selamectin + doxycycline,

Cat

*

** (Ag)

**** (Ab)^#

**

PA, PIE

****

Respiratory, vomiting, sudden death, heart failure

Ivermectin, milbemycin, selamectin, moxidectin, or eprinomectin

Supportive treatment;, doxycycline + melarsomine, heartworm extraction

NA

Ferret

*

*** (Ag)

*

RH

***

Heart failure, respiratory, sudden death, heart failure

Ivermectin, milbemycin, selamectin, or moxidectin

Supportive treatment (including corticosteroids)

NA

^aImidacloprid-moxidectin is the only approved microfilaricide.

* = rarely useful; ** = somewhat useful; *** = moderately useful; **** = often useful; ***** = excellent test; Ag = antigen; Ab = antibody; # = Ab-positive does not prove mature infection, only exposure/abbreviated infection; MPA = main pulmonary artery enlargement; PA = pulmonary artery enlargement; PTE = pulmonary thrombus/thromboembolus; PIE = pulmonary infiltrate with eosinophils; ML = macrocyclic lactone (macrolide); RH = right heart enlargement; NA = not applicable

Adapted from McCall, JW. Clin Tech Small Anim Pract. 1998;13(2):112.