Yet again, due to supply problems, the treatment for heartworm disease in dogs is unavailable. The unpredictable cyclical supply issues with melarsamine have been an issue in veterinary medicine for a few years now.
The American Heartworm Society issued an urgent notice a week ago stating that Immiticide (the brand name for melarsamine), the only approved heartworm treatment, would become unavailable for an indeterminate amount of time in the near future. And they meant it when they said near future, because many veterinarians are already running out of the product.
The Society has issued guidelines for the management of heartworm disease until Immiticide comes back on the market. Some of the recommendations include activity restriction, intermittent administration of an antibiotic called doxycycline (which appears to reduce the viability and pathogenicity of the parasites), and use of heartworm preventatives to limit further infestation. Make sure your vet reads the guidelines if your pet tests positive for heartworm.
Heartworm disease is completely preventable. A number of different products with excellent safety profiles are available. Tragically, some studies indicate that a minority of dogs and cats receive the preventatives as they should. Animals in the majority now are at even greater risk.