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Marjorie — The Diabetic Dog Who Helped Isolate Insulin For Human Treatment

At A Glance

The iconic Marjorie dog has etched its place in medical history because of its contribution to the research and use of insulin as a Type 1 diabetes treatment. It is only one of many science dogs used in experiments to find a cure for this human ailment.

  • Dr. Banting and medical student Charles Best successfully harvested insulin from another dog’s pancreas and injected it in diabetic Marjorie.
  • Marjorie was the first dog to live through the therapy, exhibiting positive results from the injection with her blood glucose levels dropping at unprecedented levels.

Last Updated on: Sep 30, 2022

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What do dogs and diabetes have in common?

Not many of us are aware of it, but they share a history.

Pre-insulin discovery as a diabetes treatment, millions of people died of the illness, usually within a year from diagnosis.

Thanks to medical scientists and the science dogs they used for research, we now have a way to control diabetes and extend patients’ lives.

The most famous of those canines is Marjorie.

Let’s revisit its landmark story and recognize its sacrifice that has benefited mankind.

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Why Is Marjorie A History-Making Dog?

Who was Marjorie the dog and what was its role in the discovery of insulin’s therapeutic potential?

But first, who discovered diabetes dogs can be used in finding the cure?

In 1921, Dr. Frederick Banting began research that led to the use of the hormone insulin as a type 1 diabetes treatment. The Canadian medical scientist enlisted the assistance of medical student Charles Best.

What Did Banting Discover?

Dr. Banting theorized and proved through research that insulin can be extracted from the pancreas and used to help patients suffering from diabetes.

Insulin is the hormone responsible for regulating blood sugar levels.

On July 27 that year, Dr. Banting and Best successfully isolated and harvested insulin for the first time in history. Their breakthrough research involved dog experiments, with the canines’ pancreas removed to extract the secretion.

The achievement revolutionized the medical landscape by making diabetes a manageable disease, not a life sentence.

Marjorie diabetes dog earned the moniker because it was the first successful case of injecting extracted insulin into the body of a diabetic dog for treatment.

Unlike other dogs that were studied, it was able to live through Marjorie dog insulin (as it is often referred to) therapy.

Marjorie proved insulin therapy was indeed effective as a diabetes treatment, a landmark discovery and “one of the medical miracles of the 20th century”, as pediatrician, clinical investigator, and ethicist Chris Feudtner calls it.

May 27, 1921 — Research Begins

Dr. Banting sought the support of University of Toronto Professor of Physiology John Macleod.

He submitted a proposal to conduct an experiment on ligating the pancreas of dogs to keep it from producing enzymes. The procedure would make it easier to isolate and extract isletin (old term for insulin).

Macleod approved Banting’s proposal and provided him with a laboratory at the university, an assistant, and ten dogs on which he could test his hypothesis.

Banting removed the pancreas from some of the dogs to cause diabetes, and ligated the pancreas on the others to degenerate and secrete insulin. The harvested insulin was then injected to the diabetic dogs to test for curative results.

newspaper about diabetes cure Image : Toronto Star

Research Roadblocks

Unfortunately, many of the dogs died from surgical infections. Banting and Best moved on with a new set of dogs they bought off the streets and performed the pancreas ligations again.

Some of the ligations loosened and had to be redone, but two of the five dogs died of complications. Meanwhile, two of the five whose pancreas were removed also passed away from infections.

It was a sad and discouraging phase of the research, but Banting and Best didn’t give up.

Experiment On Dogs 391, 410, 408, 92

Finally, Banting and Best produced one dog with a successfully removed pancreas (410), and another with a successfully ligated pancreas (391) following this procedure:

  • Removed and froze Dog 391’s pancreas using a saline-like solution.
  • Pancreas was ground, filtered, and brought back to room temperature.
  • Extracted 4cc of insulin from it and injected it to Dog 410.

The result was very promising. Dog 410’s glucose level went down from .20% to .12%, close to a dog’s non-diabetic sugar level of .09%.

Banting administered hourly injections but these didn’t significantly reduce the level.

Sadly, Dog 410 eventually went into a coma the next day and died. However, the decreased blood sugar level proved that the researchers were onto something big.

On August 3, 1921, Banting and Best experimented on Dog 408, whose pancreas was also removed. They injected it with liver and spleen extracts as well as isletin (insulin).

The result was a drop from 0.26% to 0.16% of its blood glucose in less than an hour.

So, even if Dog 408 died of infection on the fourth day, the findings were very encouraging.

A New Trial Approach

Come August 11, Banting and Best experimented on two dogs, 92 and 409. Both had their pancreas removed, but only Dog 92 was going to be injected with the extract.

As expected, Dog 409 died soon after. Dog 92, on the other hand, showed positive signs of health, which meant the extract worked.

Banting and Best tried a different approach because pancreas ligation was time-consuming and toxic. Purifying through boiling was effective but it destroyed the isletin so they had to replace it with another process.

They experimented with pancreas stimulation using secretin but it proved to be a complex and lengthy process. So they performed the secretin procedure on a cat pancreas and injected the extract to Dog 92. It resulted in a bad reaction and shock.

Thus, the Dog 92 experiments were halted and the dog eventually died on August 31.

On this sad passing, Banting remarked, “I have seen patients die and I have never shed a tear, but when that dog died, I wanted to be alone for the tears would fall despite anything I could do.”

The experiments and deaths broke Dr. Banting’s heart, but he had to stay on track with a goal that ran deeper than his emotions.

Dealing With The Toxins

It wasn’t easy to purify the isletin from toxins that were causing infections and negative reactions, but on November 19, 1921, Dr. Banting struck an idea.

Fetal pancreas do not have digestive enzymes yet, which makes them better alternatives to mature animal pancreas.

Consequently, the scientists used fetal bovine pancreas, extracted the isletin, and injected it on Dog 27. Its blood glucose level dropped within 24 hours and its urine also became sugar-free.

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Dog 33: Marjorie

Dr. Banting shifted the preparation solution from saline to alcohol because it worked better in concentrating the extract. He administered the alcohol extracted isletin on Dog 33 (Marjorie) and Dog 23. Both yielded great results.

Marjorie was able to live for 70 days before it died of abcesses in its surgery wounds.

The feat is considered a medical science triumph. It led to the successful application of insulin on human medical treatment for diabetics.

Dr. James Collip, a biochemist, helped Banting and Best further purify the extract to make it safer for human use.

The First Human Beneficiary Of Insulin Treatment

After the animal experiments provided positive findings, Dr. Banting and his team proceeded to do human tests.

Fourteen-year-old Leonard Thompson, a diabetes patient, received the very first insulin dose on January 11, 1922.

His blood glucose level dropped from 440 to 324 mg/dL. However, it also caused an infection.

On their second attempt, Dr. Banting used a more purified extract. It significantly reduced Leonard’s blood glucose level from 520 mg/dL to 120mg/dL and also got rid of his ketones.

They continued his insulin therapy and his symptoms continuously improved.

A New Meaning To “Man’s Best Friend”

The discovery of insulin is a literal life-altering victory for medical science and diabetes patients worldwide. And it came at a time when the only treatment available was starvation dieting to keep their blood sugar low.

It took the lives of Marjorie diabetes dog and many other experimental science dogs to bring us to where we are now. Millions and millions of diabetic patients receive therapy because some animals were wounded in the name of wellness.

Ethical issues surround these medical science experiments that even Dr. Banting himself felt the weight of the animals’ deaths. Those diabetes dogs did not volunteer to be used, but they were sacrificed so we can have a fighting chance against diabetes, whether human or animal.

And for this achievement, Banting and Macleod received a joint award of the Nobel Prize for Medicine in 1923.


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Meet Paul, a devoted dog dad to the delightful French Bulldog, Cofi. With a flair for humor and a deep understanding of Frenchie quirks, Paul brings a lighthearted touch to his writings. His relatable stories and practical insights are a blend of laughter and valuable advice and resonate with fellow dog owners.

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