This site is really angering me today, it just deleted my post completely.
Most of that article is laughable, simply because it is drawing conclusions that are not neccessarily based on anything, or may be based on 1 study (which is not proof, studies need to be replicated before conclusions can be drawn) or it is drawn on anecdotal evidence. For instance splenic hemangiosarcoma and osteosarcoma have not been proven to be effected by altering, it is a hypothesis that has not had enough studies to corroberate that claim, both cancers are more common in certain breeds and could possibly have other links to causation (such as inadequate nutrition...). Pyometra, effects approx. 25% of intact females, if you read down that article, the risk of dying from it jumps from 1% in the overview to 4%. Not sure how they are getting their numbers if they cannot keep it consistent in 1 article. Yes, altering an animal has repurcussions, but at what point is it worth risking or not risking? Considering the fact that humans have created breeds with so many health issues and genetic problems, and the majority of people who breed dogs give little or no thought to the health and well being of the animal, Id say altering a dog is a smaller risk to take compared to the neglect and ignorance of dogs health overall from most owners.
In any case, anyone who calls a dogs heat a "period" (no offense OP, they are fundamentally different) is not knowledged enough to keep an intact animal, I dont trust the general public to be able to keep an intact animal without accidently producing litters.