Vets have a hard job. They care for sick and injured animals, often seeing things no one wants to see. Sometimes, vets see things that even the most experienced can’t explain. Dr. Marcus Greene met Lola, a pregnant chocolate Labrador retriever, and helped deliver her puppies. He discovered something unusual.

Mrs. Thompson brought Lola to Dr. Greene’s office. She was excited and nervous about her first pregnancy going well, and Dr. Greene said it would.

Lola was her chocolate labrador retriever. 

Puppies can often be delivered safely home, but Lola was a first-time mom, so the vet clinic was safer.

However, they were shocked by what they found.

Lola gave birth to 12 puppies, which is rare.

Lola had six girls and six boys, all different colors. 

Dr. Greene and Mrs. Thompson didn’t know that the big litter and stillborn puppies were just the start of a long journey to understand what made Lola’s puppies so special.

Lola’s puppies were unique. Black is the original Lab color. Chocolate Labs are rare.

Dr. Greene examined the puppies one by one, starting with some who had opened their eyes. He started with Miracle, who had a white spot on her chest.

That wasn’t the strangest thing about her. Labradors usually have brown eyes, but Miracles are brown and blue. She had a rare eye condition caused by a genetic mutation.

He asked Mrs. Thompson if any other puppies had heterochromia.

One did. Her name was Destiny, and she had the same white markings and curled tail as her sister.

Dr. Greene decided to test all of Lola’s puppies for DNA. 

Dr. Greene sent the samples to a lab. 

One day, Dr. Greene got the results from the genetic lab. He and Mrs. Thompson had been waiting for them. He quickly opened the letter after finishing the exam.

The results confused and surprised him. He knew Miracle and Destiny were unique, but he didn’t know how unique. They weren’t ordinary siblings.

Miracle and Destiny were monozygotic twins. 

Miracle and Destiny were identical twins—true miracles! Dr. Greene was shocked and didn’t know how it happened. It was the strangest thing he’d ever seen.

They decided to get a more advanced DNA test. This time, they tested Miracle, Destiny, and the whole litter of 12 puppies.

The results were surprising. Lola’s puppies were conceived by superfecundation. Lola was carrying two litters of puppies at once!

Dr. Greene and Mrs. Thompson were shocked. How could Lola have two litters of puppies from two fathers? The good news was that it explained why Miracle and Destiny were different from their siblings.

Dr. Greene now knew what made Lola’s litter special. He wondered if Mrs. Thompson knew why Lola’s puppies had two fathers. She did.

One night, Lola went out and about. Mrs. Thompson thought Lola had only been with one male, but she’d been with two!

Dr. Greene and Mrs. Thompson were satisfied. They finally knew why Lola’s puppies were different from other dogs Dr. Greene had treated.

Lola had twins and two litters, making her a rare dog mom. The best part was that while the humans wondered why her puppies were so strange, Lola was happy to care for her babies.