It is easy to see how eating meat harms animals, but many people struggle to understand how dairy could cause any harm. The truth is that the dairy industry leads just as inevitably to death as the meat industry does, and often with more suffering for the animals before they get to slaughter.
In the beginning of the 20th century, the average annual milk production of a Holstein cow was 7,000 lbs. Today the average dairy cow is forced to produce 19,000 lbs. a year. While the natural lifespan of a cow is 25 years, a dairy cow is usually slaughtered between three and five years, at which point, her body is destroyed, and she can hardly stand due to calcium depletion. It is estimated that 40% of dairy cows are lame by slaughter at 4 years. 
As dairy cows only produce milk for about 10 months after giving birth, they are impregnated annually to keep up the milk flow. Female calves are kept to replenish the herd, and male calves are usually sent to veal crates, where they live a miserable, dark, and lonely existence until their slaughter. When dairy cows become unable to produce adequate amounts of milk they are sent to slaughter and turned into low-quality ground beef.
Veal calves are kept in small wooden crates which prevent movement and inhibit muscle growth so that their flesh will be tender. They are fed an iron deficient diet which makes them anemic in order to keep their flesh pale, which is for some reason, appealing to the consumer. Veal calves spend their whole short lives in confinement, alone and deprived of light for a large portion of their four-month lives. Veal calves are a “by-product” of the dairy industry.
The United Sates Department of Agriculture explains that “[v]eal is the meat from a calf or young beef animal. A veal calf is raised until about 16 to 18 weeks of age, weighing up to 450 pounds. Male dairy calves are used in the veal industry. Dairy cows must give birth to continue producing milk, but male dairy calves are of little or no value to the dairy farmer. A small percentage are raised to maturity and used for breeding.”
 “Overview of Cattle Laws,” by David S. Turk, Animal Legal and Historical Center, 2007, Michigan State University College of Law, http://www.animallaw.info/articles/ovusbovine.htm