Iverhart Plus Recall
Dogs weighing 75 pounds or more may not be fully protected
News item written by Mary Straus, published in the Whole Dog Journal, October 2009
Update July 2014: Iverhart Plus reintroduced after potency and shelf life issues led to the product being withdrawn. See Virbac relaunches Iverhart Plus heartworm preventive
Update September 2013: More Iverhart lots recalled. See Virbac expands Iverhart Plus recall to 34 lots
Update August 2013: More Iverhart products recalled. See Iverhart Plus Expanded Recall
Update April 2013: Another recall for the same problem, affecting products of all sizes. Again, dogs at the top end of the weight range for the product may not be protected. See Virbac Recalls Six Lots of Iverhart Plus Flavored Chewables for more information.
On August 13th, 2009, Virbac Animal Health, Inc. announced that it was recalling certain lots of Iverhart Plus® Flavored Chewable Tablets, a heartworm preventative. Routine stability testing found these lots no longer contained enough ivermectin to be effective for dogs weighing more than 75 pounds.
Lot numbers 090093 and 090095 of Iverhart Plus Large (51-100 pounds) were recalled. A third lot for small dogs (up to 25 pounds), 090073, was also recalled because it was found to be nearing the potency limit. These lots were sold to distributors starting March 20th, 2009, so any product purchased earlier would not be affected.
The recalled product is not harmful, but may leave larger dogs unprotected from heartworm infection. Virbac recommends that dogs who weigh more than 75 pounds who were given the recalled product be tested five to six months after the last dose was given (I advise waiting the full six months to test your dog, since it can take that long for heartworm larvae to mature into adults that can be detected by heartworm tests).
Virbac will reimburse veterinarians for heartworm tests performed on 75-plus-pound dogs who were given the defective product. Their standard product guarantee will also cover heartworm treatment for any dog taking Iverhart Plus who is found to be infected with heartworms.
If you purchased the recalled product, you should return any unused portion to your place of purchase for replacement from a different lot number. The lot number is listed on the bottom lid/flap of the box in a white text field and on the blister foil of the individual doses. Note that even though dogs who weigh less than 75 pounds are fully protected now, the product may lose further potency over time, so it’s important to replace it rather than continue to use it even if your dog is under the weight limit. That also applies to the single lot for smaller dogs that was recalled.
Virbac has notified its distributors and are asking them to notify the veterinary clinics who purchased the recalled lots. Only those who received the recalled lots will be contacted, so your veterinarian may not be aware of this recall.
Testing has confirmed that all other lots of Iverhart Plus Flavored Chewable Tablets remain potent. Only the three lots identified are affected by this recall.
Virbac Technical Services, 800-338-3659 ext. 3052
You can contact me if you have any comments, but I regret to say that I can no longer respond to questions about individual dogs. See my Contact page for more information. My name is Mary Straus and you can email me at either or