Dogs suffering from heartworm disease will have to make their case in order to get treatment, at least temporarily.

Merial announced recently that supplies of Immiticide (melarsomine dihydrochloride) will be limited through the first quarter of 2010. Immiticide is the only licensed, FDA-approved product available for the treatment of canine heartworm disease.

A letter signed by Zack Mills, DVM, Merial’s vice president of sales, was sent to veterinarians at the beginning of December. The letter said the shortage was due to “unforeseen technical difficulties.”

“The difficulties are connected to meeting certain regulatory requirements at an independently owned facility that manufactures the active ingredient of Immiticide (melarsomine dihydrochloride),” said Merial spokeswoman Natasha Joseph.

There is also a temporary shortage in the supply of Merial’s Heartgard (ivermectin) Tablets (non-beef, hard tablets only), with plans to return to full supply in 2011. However, Joseph stressed that the shortage does NOT include Heartgard Chewables and Heartgard Plus (ivermectin/pyrantel) Chewables.

The Immiticide letter also asks veterinarians to “only order Immiticide as necessary to provide immediate adulticidal therapy in dogs diagnosed with heartworm disease.” It also says that orders for the drug will only be taken from Merial Customer Care, so veterinarians must make a case for each patient in order to obtain the drug.

“Each request for Immiticide is discussed on a case-by-case basis, nbsp;veterinarian-to-veterinarian, to evaluate the overall health of the dog, disease classification, absence or presence of clinical signs, and other criteria,” Joseph said.

It was not clear exactly when the supply would be back to normal, but Merial said it is trying hard to rectify the situation.

“We are working diligently to return to full supply as soon as possible,” Joseph said.

Veterinarians with questions about heartworm disease can call a Merial Technical Solutions veterinarian at (888) 637-4251, Option 1.