Hi there --

Welcome to Just Answer.

There are differing opinions on the toxicity of avocado fruit, leaves, bark, etc. So it can be very confusing. Some veterinary sources will list them as non-toxic and others will mention that they can be toxic to dogs. It appears that mild exposures of smaller amounts, limited amounts of vomiting and diarrhea may occur. This is typically mild and self correcting.

With very large amounts there are reports of heart issues developing. These reports are in question. This level of toxicity should not be a problem with the level of exposure you are describing in this size dog.

SO you may expect to see vomiting within 6 hours after ingestion if there had been enough eaten.

http://www.aspca.org/pet-care/poison-control/people-foods.aspx

This is a link to the ASPCA poison control center information -- for verification of the information provided.

If you need further information -- I will be happy to assist you.