Trifexis overdose.

Dr. Marie replied:

Trifexis is a good medication for flea and heartworm prevention, but it can possibly cause problems if a dog eats too much of it.

We can see toxic effects if a dog ingests more than 400mg/kg of spinosad (one of the ingredients in Trifexis). So, let's assume your chihuahua is 5 lbs. This is the equivalent of 5/2.2 = 2.3kg. This means that if he ingested more than 2.3x400mg = 909mg of Trifexis then I would be worried.

The chihuahua size of Trifexis contains 140mg of spinosad. So, 4 tablets would be 4x140=560mg.

As 560mg is less than the toxic dose for your dog of 909mg, Snarles really should be ok.

There have been some reported cases though of dogs being extra sensitive to Trifexis and having lethargy and reluctance to eat after even a single dose. In severe cases dogs can have seizures. Fortunately these occurrences are rare.

Most of the time, if a dog eats too much Trifexis, they will vomit. Because they have vomited up the medication, it is much less likely that they will keep enough drug in the body to produce side effects.

It sounds like your dog will be ok. However, if he continues to be lethargic or if he has repeated vomiting or tremors/seizures then I would have a vet take a look.

Dr. Marie.

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