Don't forget the expenses
You can expect your net income to be down if your total income is lower, but remember that net can dwindle even when total income booms. If your income has increased, your expenses most likely have too. So always count expenses when calculating net, including your salary and rent—even if these were paid to you. And pay close attention to the two expense categories that you can actually control: inventory and support staff costs.
You want to look at these as percentages of gross income, not gross numbers. For example, inventory costs to gross in a small animal hospital normally run 14 to 16 percent. Support staff costs (salary and taxes for all team members other than doctors and groomers) run 22 to 23 percent. Again, these are industry benchmarks, so use them as that. Be more concerned with your percentages staying relatively the same whether your income rises or falls.