Hives/ welts

[Luna di Luna]

Hello Boxer World,
We are the very proud owners of Luna, who was graciously welcomed on Boxerworld over the past week. She has adjusted fantastically... except today when Jason came home from work Luna was covered in hives/ welts (dime size to quarter size). We took her to the vet, who suspects Luna ingested something but we don't know what. We live in South San Francisco, CA and Luna had access to the yard and garage while we were at work. We have a few plants in the yard (possibly Oleander, which will be dug up tomorrow); redwood mulch around our rosemary; and we also sprayed bittering agent on some furniture that is being stored in the garage. We would like to avoid allergy testing, if possible, but are very concerned... Any experiences or ideas? By the way, other than scratching, Luna is as happy as can be.
Thank you,
Jason, Jenn & Luna

 

[Just-A-Clown]

Are they bug bites? Beau gets bumps sometimes when he is outside but they go away within a day

 

[Chiefsmom]

Chief had this happen a few weeks back with the large hives and it turned out that there was a spider bite behind his ear. Are there any pinkish unusual lumps that didn't go down with the others? Just wondering if it was a reaction to a bug bite (not specifically to spiders).