Answer: The dog urine would possibly damage some of the foliage where it contacted the plant but it would be unusual for that to cause discoloration over a more extensive area. In future, rinse the fresh urine off with plain water right away to dilute it and that should help avoid problems.
Yellowing can be a sign of over or underwatering, a sign of root damage, a sign of damage to the main central trunk or stem, or a sign of pest or disease or even a sign of accidental chemical or herbicide exposure or overfertilizing. Without seeing the plant it is very difficult to make a diagnosis.
I would suggest you consult with your local Penn State cooperative extension and see if they can determine what is causing the problem. Based on knowing that, you can work to treat it. If a chemical control is needed, they will have the most up to date information on what to use and how/when is best to apply it for maximum results.
Good luck with your topiary!
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