Hi Michelle,
Thanks for your question.
I think you are doing the right thing using the Dawn soap. There are not a lot of options here for ‘treatment’. I think the plan would be prevention and I see 2 ways you can deal with this that are pretty straightforward.
Restricting access to the area under the tree would be ideal and you could do this with fencing. Restricting access to the entire backyard could be considered as well and replace it with more walks out the front door.
The other idea is a little more adventurous. You could consider shaving your dog’s hair significantly so that washing the sap off is really easy. You could have a groomer perform a ‘lion’s cut’ which many animals really like having done in the summertime. I would do this with my cats so that we didn’t have hair in the house and on the furniture. I quite liked it but I’m sure it wouldn’t be too many people’s taste.
I hope this helps.
Dr. Clayton Greenway
Disclaimer: healthcareforpets.