I wouldn't spray the brush compartment with water...remove the brushes and clean them in a bucket of soapy water, but wipe down the brush compartment with a wet rag the best you can without getting it too wet...there is an electric motor and sensors that could be damaged if too much water is used.

If it as my Roomba,.....,with a pair of latex gloves on and outdoors I'd open the bottom compartment and take the two spinning brushes out. Depending on how wet or dry the dog deposit is, with wet I'd put my hose on power spray and hose the two brushes clean, then soak in a bleach solution. If dry, I'd leave them in the sun to further dry and then try getting the dry majority off with a stick or brush. When the majority is off, power spray the brushes and soak them in bleach water solution. Dry brushes ASAP and with a bunch of wet wipes clean out the area around the brushes underneath. If it somehow got into the filter compartment, you've got a lot more difficult a job to clean. You don't want to get water into the motor or fan in the filter compartment. Did you get a spare set of parts, etc. with yours? If so you might just want to toss out and replace with a clean set.