Travel in South America by car with dog.

You will need different proof of vaccination for each country.
You should know going West all roads are dicy!
When are you going?
Argentina said yesterday their borders will not open until the first of the year at the earliest!  So that is out.
Chile is in the same boat.
You are looking at very long drives with little refreshment stops.
I tried driving to SP many years ago and said never again.
Just driving from Foz across the river into Puerto Iguazu then to Salto, we turned back due to roads.

Thank you for your reply.  I did not know that Argentinian borders will be closed through this year.  Where do you get reliable and updated information from?  I could not find this info. when I looked.  We were hoping to go in November.  I know it's a lot of driving and I know the roads are often terrible. 
We have flown to Argentina and Chili before but it just seems like an adventure to actually see this trip from a car.  We'll keep researching and thanks so much for your help.

https://www.h2foz.com.br/fronteira/arge … im-do-ano/
I live on the border and 60% of hotels have closed, as well as many businesses.
Many reports of pirates robbing on the roads.

Paraguay has been demanding the opening of AR border, but PY is so overwhelmed by Covid as is AR.
Argentinians are and have been stuck in PY since Jan 2020. They even sued AR, but Supreme Court denied it.
BR President opened BR/PY bridge, but Foz has set up health checks and turning many PY away due to their need for vaccines and flooded Foz's hospitals.

Remember BR land borders are closed.

Thanks for that link.  When you say BR land borders are closed you are talking about for tourists, right?  Just asking because I am flying to US for a week in 3 weeks and sure hope I can get back in with my valid RNM card?

Land borders....You can return via air with no problem. Be sure to read entry into US if you have been to BR within 14 days of entry.
Daughter had to quarantine in Mex for 15 days before entering. (She is Brazilian and only school visa)

Well, Texanbrazil, you taught me a few things today, Thank you!  I am a US citizen and I have had two Covid vaccinations so hopefully all will be well but I will double check.

Well, you should be fine. Many BR people going into PY and flying into Miami to have the vaccine. They are supposed to quanitine in PY, but for $100 you can a Neg test and hotel bill saying you stayed in PY,