Ferrets & Heartworm

Heartworm is spread by mosquitoes, the early lifestages of the parasite occur within the mosquito, larvae enter the bloodstream when biting a ferret. Adult heartworms form in the ferret, living and reproducing in the heart and adjacent blood vessels. This produces microfilariae, which circulate in the blood supply, and are re-ingested by mosquitoes. Heartworm can cause inflammation and obstruction of affected vessels.

Clinical signs

Ferrets affected by heartworm can display – Sneezing, coughing, anorexia, lethargy, dyspnea.  With most serious obstructions, this disruption of heart function and blood flow can cause vascular abnormalities and death.


Diagnostic tests include imaging;
Radiographs – enlarged heart, pleural effusion.
and tests to detect the presence of
Blood samples sent for detection of microfilariae in specific stains
Antigen/ELISA testing – larvae must have been present for 6 months for a positive result


Ivermectin once monthly until clinical signs resolve and microfilaemia are absent. Like with dogs, you can add in other medications to assist with treatment. The main aim is destroying the adult worms with ivermectin, and preventing further reproduction.


If you live in an area endemic with heartworm, you should use heartworm preventative treatment

  • Ivermectin – oral or injectable monthly
  • Selamectin – Revolution monthly
  • Moxidectin – Advocate monthly
  • Proheart annual injection

You can also reduce exposure to mosquitoes by limiting play outdoor activities at dawn and dusk when mosquitoes are most active.


Once infected – prognosis is guarded to poor.


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