Sitefinity's licens agreement can be found online here: http://www.sitefinity.com/purchase/license-agreement
The section on Community Edition reads "1.2 Community Edition. The Software may be used only for your internal purposes that do not generate profit; you may not use the Software to create a website that generates or supports the generation of profits for a for-profit organization, and you may not use the Software in a load-balancing environment. You may engage an independent contractor to use the Software to build and maintain a website for you, and you may pay the independent contractor for their services; however, the resulting website may not be used for the purpose of generating profit.
So a veterinary clinic that generates profit would not qualify to use the community edition. We do have a small buisness edition that might be able to meet you needs.
I hope this helps.