You can say it! Lui lavora come un cane, there are other animal variations as well. For work, best to use as for come:
- Mio padre lavora come postino/My father works as a mailman
- Mia cugina lavora come cuoca/My cousin works as a cook
- Noi lavoriamo come avvocati/We work as lawyers
Using an article in Italian changes the meaning a bit, not always in a positive sense.