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Let us know if you have any questions for Merck Animal Health. We are here to help you when you need it!

To report an adverse reaction, product-related problem, or human exposure, please call Merck Animal Health Technical Services:

1-800-224-5318

For after-hours emergencies, please call the number shown above. A recorded message will provide the telephone numbers for emergency support services if immediate assistance is needed.

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SENTINEL Brand Products require a prescription from a veterinarian.
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Important Safety Information

SENTINEL^® SPECTRUM^® Chews (milbemycin oxime/lufenuron/praziquantel). Dogs should be tested for heartworm prior to use. Mild hypersensitivity reactions have been noted in some dogs carrying a high number of circulating microfilariae. Treatment with fewer than 6 monthly doses after the last exposure to mosquitoes may not provide complete heartworm prevention. For complete product information refer to the product insert.

SENTINEL^® FLAVOR TABS® (milbemycin oxime/lufenuron). Dogs should be tested for heartworm prior to use. In a small percentage of treated dogs, digestive, neurologic, and skin side effects may occur. For complete product information refer to the product insert.