Lethargic after Trifexis.

Dr. Marie replied:

Thanks for your question. I am getting a lot of questions about Trifexis lately!

First I'd like to re-do the math just to see what kind of dosage of Spinosad your dog has had.

So, Daisy weighs 25 lbs which is 11.4 kg.

She ate a 20-40lb Trifexis which contains 560mg of Spinosad and also a 60-120 lb tablet which contains 1620mg of Spinosad. That makes a total of 2180mg.

This translates to a dosage of 2180/11.4 = 191mg/kg.

We start to see toxic effects that we get really worried about at 500mg/kg.

What that means is that there really shouldn't be any life threatening things happening here.

The Trifexis label does indicate that some dogs can have some minor side effects such as stomach upset and lethargy. And then, there are some unusual cases where we have seen very odd side effects of stupor, lethargy and even seizures. (These don't seem to be connected to dose at all however as dogs can get them randomly even with a proper dose.)

From what you have described, I think you are ok to wait things out for a while. Here are some things that would make me want to go to the vet:

-If you are seeing tremors or seizures.
-If the lack of appetite lasts for more than 48 hours.
-If there is vomiting that just isn't stopping (i.e. more than 12 hours).
-If your gut is just telling you that something is really wrong.

In the meantime, be sure not to offer Daisy any extra treats outside of her regular dog food. We don't want to give her anything that would cause even more stomach upset. Keep her as quiet as possible and if you feel that things are getting worse then, yes, I would see the vet.

Hope she is ok!

Dr. Marie.


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Dr. Marie replied:

Tremors would be something you would be seeing when she is awake. Dogs will often have little episodes that look almost like seizures when they are sleeping but these are likely just dreams. If, however, when she is awake, you are seeing her legs or body shaking then I would call this a tremor.

Tremors themselves are not life threatening, but tremors can progress to seizures. Most seizures are not life threatening but they are not pleasant. If seizures are lasting a long time they can be damaging to the brain.

Hope that helps.

Dr. Marie.