Defensive industries, like healthcare, are more attractive to income investors. That's because companies in this sector are less likely to suffer significant business disruptions in times of economic trouble, meaning they are also less likely to cut their payouts. Medical needs, unlike many technological products or services, aren't optional. Sure enough, the healthcare industry is home to many excellent dividend stocks. Let's consider two that could reward their shareholders for a lifetime (or more): Merck (NYSE: MRK) and Medtronic (NYSE: MDT).

Merck isn't having a good year: The company's shares are down by 4%. One reason behind the drugmaker's poor performance is that investors are worried about potential competition for Keytruda, Merck's famous cancer drug, which is by far its biggest growth driver. Summit Therapeutics, a clinical-stage biotech, has a medicine in development called ivonescimab that could rival Keytruda in non-small cell lung cancer (NSCLC), one of its key markets.

Start Your Mornings Smarter! Wake up with Breakfast news in your inbox every market day. Sign Up For Free "

Furthermore, Keytruda will lose patent exclusivity in the U.S. in 2028 and then face generic competition. That said, Keytruda's revenue should continue growing until 2028 even if ivonescimab hits the market before. The Food and Drug Administration (FDA) has approved the medicine across scores of indications, most of which ivonescimab won't touch before 2028. Merck is also working on a subcutaneous version of the drug. This formulation won't lose exclusivity in 2028 and should be somewhat successful.

Headwinds, such as the ones Merck is facing, are typical for pharmaceutical companies. The healthcare leader has survived and thrived for decades because of its ability to develop new medicines. That's the best defense against competition. And in that department, Merck should still excel. The company's pipeline features several dozen programs. It is also expanding it thanks to acquisitions. Its most-recent, brand-new approval of Winrevair, a medicine for pulmonary arterial hypertension, stemmed from the acquisition of Acceleron Pharma.

Merck also has several collaboration agreements with smaller companies, including Moderna, with which it is developing a personalized cancer vaccine. Here's the point: Focusing too much on Keytruda-related issues might cause investors to miss the forest from the trees. There will always be headwinds in Merck's way, but the things that have allowed the company to last as long as it has remained intact. The company also has a solid dividend record. Its payouts have increased by 71% in the past decade, and it currently offers a forward yield of 2.96%, higher than the S&P 500's average of 1.32%.