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Ask Dr. Michael Salkin Your Own Question
Dr. Michael Salkin
Dr. Michael Salkin, Veterinarian
Category: Cat Veterinary
Satisfied Customers: 28486
Experience:  University of California at Davis graduate veterinarian with 45 years of experience.
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A couple of months ago, we accidentally gave our 10 yr old 6

Customer Question

A couple of months ago, we accidentally gave our 10 yr old 6 lb Persian cat the 9+ lb dose (instead of the 5-9 lb) of Advantage II for cats.
No adverse reaction (to be seen) at the time. Perfectly normal. We didn't take him to the vet.
The other day, at the annual exam, our vet discovered a large bone swelling on his lower jaw on his right side as well as a heart murmur. When his bloodwork came back, his heart enzymes--I believe that was the terminology--was 185 when it should be max 100, ideally 50ish.
The vet also recommended at biopsy of the bone swelling to test for cancer...which is put on hold until he gets a cardiac ultrasound.
Could the heart murmur and sudden onset (potential) cancer growth have been caused by giving him the wrong dose of Advantage II? What consequences could this accident have caused?
Thank you for your time.
Submitted: 1 year ago.
Category: Cat Veterinary
Expert:  Dr. Michael Salkin replied 1 year ago.

No, Jennifer, there's no mechanism for either imidocloprid or pyriproxyfen (the ingredients in Advantage II) to cause such pathology nor has such pathology been seen in long-term studies of these drugs. By the prinicple of Occam's Razor, Milo's murmur is due to age-related cardiomyopathy (heart muscle disease) and the bony swelling represents an age-related cancer. You mustn't blame yourself for that accidental overdose which in retrospect was quite small in any event.

Please respond with further questions or concerns if you wish.