A chicken egg with strange etchings. Experts say that the cause is likely internal scarring. Credit: Courtesy of Priscilla Provost

If you own chickens, you are probably familiar with the strange sight of an egg with aberrations or etchings. Chicken owner groups on Facebook often discuss these topics among themselves, marveling over the mystery lines like they are crop circles.

On Dec. 17, for example, Facebook user Priscilla Provost posted a picture of an egg with strange lateral lines all along the shell to the group, “Maine Poultry Connection (Maine Only).”

“One of the girls must be artistic,” Provost wrote. Her compatriots commiserated, saying they had similar problems and they were happy they were not the only ones.

Though these etchings may look like the work of a chicken carver, the problems might be internal.

“Hens would have a heck of a time putting a scratch in an egg [with its claws or beak] because the egg would break first,” said Anne Lichtenwalner, director of the University of Maine Veterinary Diagnostic Laboratory. “Given that, I think these scars on the eggs happened internally.”

A chicken egg with strange etchings. Experts say that the cause is likely internal scarring. Credit: Courtesy of Priscilla Provost

Though it is hard to say without seeing the bird and egg in person, Lichtenwalner said that for Proctor’s issue and other shell aberrations like it, the likely culprit is a scar or defect in the uterus or a shell gland issue that etched these aberrations as the hen pushed the egg out of its body.

“The eggshell material is very irregular, and then there are these long linear defects in it,” Lichtenwalner said. “I wonder whether that animal actually has some spots in the lining of the shell gland that are scarred.”

But those aren’t the only reasons that an eggshell might have aberrations. Lichtenwalner said that problems like this could have to do with diet.

“The bird [might not] have adequate calcium to create a really good eggshell for several reasons, [like] because there might not be enough calcium in the diet,” Lichtenwalner said. “Or it could be that there is inadequate sunshine to allow their body to activate vitamin D, which allows their body to absorb the calcium that they are fed. Finally, sometimes the birds aren’t getting much oil or fat in their diet, [which] is necessary for the body to absorb vitamin D. That’s a minor cause, but it could be a cause.”

Also, stress could play a role in the egg aberrations.

“Egg abnormalities can also be due to psychological factors,” Lichtenwalner said. “Anything that stresses your hens can change their ovulation rate and affect how the eggs look.”

There are several steps you can take to prevent such problems with your chickens. You can supplement calcium in their diets (ironically, ground up eggshells could be a good, inexpensive way to do this) and you can clean out their nest boxes more frequently.

“Nest boxes need to be cleaned out very frequently, especially if your birds, like mine, like to sleep in their nest boxes,” Lichtenwalner said. “Almost every day, I check the nest boxes wearing a glove and throw out manure that’s in the nest boxes, then put in a couple handfuls of fresh pine shavings. Pine shavings have a mild but real antimicrobial effect.”

Usually, these problems are easily solvable or, in the case of the scarring, don’t cause major health issues for the birds. However, sometimes, the problem might be more serious. Bacterial infections like coliform salvagitis or bronchitis can also cause aberrations in eggshells.

A chicken egg with strange etchings. Experts say that the cause is likely internal scarring. Credit: Courtesy of Priscilla Provost)

“There are definitely some infectious diseases that can lead to abnormal eggs, but you should never jump to that conclusion just because you’re getting an oddball egg now and again,” Lichtenwalner said.

If this is the problem, though, going to the veterinarian might be a lost cause.

“I don’t know that you’re going to have a lot of success,” Lichtenwalner said. “Prevention is always the best cure.”

Bacterial issues will likely manifest in the whole egg, so crack it open and take a look inside to see if there is something more serious at play.

“Certainly the bacterial infection that leads to coliform salpingitis manifests as changes in the whole egg that are pretty bad,” Lichtenwalner said. “When that happens, you get all kinds of problems inside the reproductive tract of the bird.”

If the inside of the egg looks normal, though, the problem is likely not bacterial — and, as an added bonus, they are likely safe to eat.

“You should keep an eye on the quality,” Lichtenwalner said. “Does it smell and look OK? Is the white translucent and pretty and clear? Is the yolk the right color? Is its consistency what you would normally expect? If you see anything off inside the egg, then you have a more serious problem.”

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