By Christie Long
I’ve written about heartworm disease before, but it always comes to mind as spring approaches and with it the return of mosquitoes, which transmit heartworm disease to pets when biting them.
In Colorado, we enjoy a relatively low incidence of heartworm disease in our pets. The American Heartworm Society recorded between one and five cases per clinic along the Front Range in 2010. Compare that to clinics in the east and the Gulf Coast region, which can record more than 100 cases per clinic per year and you can see that we are spared the worst of this awful disease.
Last year at our clinic, we treated two dogs that were positive for the disease. Even though we talk to every dog owner (and many cat owners) about the importance of year-round prevention against this disease, some still don’t choose to purchase the preventative medications for their pets.
I’ve tried to understand why pet owners are willing to take their chances against this disease. Untreated, it can be fatal. Before it’s fatal, it causes coughing, exercise intolerance, nosebleeds, pneumonia and heart failure. Treatment can be extremely painful and requires long periods of cage rest and inactivity.
Since last summer, a new development in the pharmaceutical industry has made it even more difficult to treat this disease. The only drug that will kill the adult heartworm in dogs is called melarsomine. It is a compound derived from arsenic. Last summer, the main U.S. supplier of the drug stopped manufacturing it. At this point, the veterinary community is unsure when, if ever, this drug will be available on the U.S. market again.
Luckily in Colorado there are lots of veterinarians who have melarsomine on the shelf that we don’t use very often. But drugs lose their potency and expire in time, so this supply won’t last forever.
We have been fortunate to obtain some supply from European markets. It’s likely that geographical regions that have many cases of heartworm-positive dogs will use the majority of these supplies.
Veterinary researchers are trying to determine if there are other drug protocols that might effectively treat the disease, but this research is not complete. Currently, melarsomine is the only reliable treatment option.
For an average-sized dog, a six-month supply of heartworm prevention is about $5 and $7 per month, depending on the brand of prevention selected. Given that heartworm disease treatment may not even be possible at some point in the future, your best bet is on prevention.
Christie Long is a veterinarian at the VCA Animal Hospital in Fort Collins, CO. Long left her job in software sales in 2000 to travel for 13 months. Along the way, she was touched by the plight of the animals she saw and somewhere in the Nepalese Himalayas she vowed to return to school to become a veterinarian. While she often finds end-of-life situations heart-wrenching, she considers herself blessed to be called upon as a trusted advisor to families during difficult times. Dr. Long’s family includes her husband and travel partner, Wiley, their 5-year-old son, Wiley IV, their dogs Pancake and Gizmo and cats Sneaky and Sidh.