How Dogs Helped Cure Rickets

We owe our dogs much more than most people realise

My in-house dog nutritionist is forever explaining to people how we humans only know as much as we do about our own dietary needs because of dogs. How we are so similar — we share 84% of our DNA with dogs — that experiments were carried out on dogs back in the 19th and early 20th century, in order to better understand the dietary needs of we humans.

Take rickets for example.

Rickets is a preventable condition that causes weak, soft bones in growing children. It most commonly occurs due to a severe, prolonged deficiency of vitamin D, calcium or phosphorus which are essential minerals required to build strong, healthy bones.

In exactly the same way they are with dogs which is really the point Gerald is making when he explains how much we humans owe to dogs about understanding our own dietary needs.

Historically, rickets was nicknamed the “English disease” during the 19th-century Industrial Revolution. Factory pollution blocked out sunlight in northern European cities, preventing children’s bodies from naturally producing vitamin D.

Back in 1919, British physician Sir Edward Mellanby discovered that rickets was a dietary deficiency disease through groundbreaking experiments on puppies. By feeding them an experimental, indoor diet of oatmeal (mirroring what impoverished populations with high rickets rates ate), he successfully induced the bone-softening condition. He then cured the puppies by administering cod liver oil.

Soon after, American scientist Elmer McCollum isolated the specific active curing agent inside the oil and named it vitamin D.

Medical researchers ultimately resolved the mystery of rickets by proving it could be cured in two ways:

• Dietary supplements: giving dogs cod liver oil or vitamin D directly.
• Light exposure: exposing dogs (or their food) to sunlight or artificial UV lamps, which triggered the skin to produce its own vitamin D.