Are broken egg shells digestible to cats?

Do you know if broken egg shells are digestible for cats?


Response by Michael

Broken egg shells are 95% CaCO3 (calcium carbonate). This is not going to hurt your cat in reasonable or relatively small quantities. I am sure a cat can digest small quanities without problems. I presume you are asking because your cat likes eating egg shells or eats them when eating eggs. I guess you might like eggs, by the way! Seashells are made of the same substance.

You can buy supplements for humans that contain calcium because it is good for healthy bones, muscles, nervous system, and the heart. The anatomy of the cat is similar.

Within reason (a reasonable quantity), eating egg shells won’t be a problem for your cat unless it is habitual and goes on for a long time. If this is the case, please take your cat to a vet.

It is an alkaline substance (a low pH). If your cat is eating it, I wonder if she/ he has stomach acid problems? I am really speculating, here. I may be off target because your cat might just like eggs and eats some egg shell as a consequence – i.e. she eats small quantities as a side effect of eating raw eggs.

Calcium carbonate is used in some raw cat food diets so it is essentially good in reasonable quantities.

Another possible reason is that your cat is not eating the eggshell because of the nutrients in it but the remains of the contents of the egg which are stuck to the shell. The egg white part of an egg contains nutrients to feed the chick. These nutrients may be desirable to some cats.

Another alternative is that the shell has a nice texture to crunch on. It may be like eating bone (as part of prey). The cat ends up swallowing it. It may be predation instinct coming through because wet cat food is sloppy and there is no bone in it.

I hope some regulars can make a comment to add to my response. This is an unusual question. Thanks for visiting and asking.


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31 thoughts on “Are broken egg shells digestible to cats?”

  1. I found this thread from a google search because my 16 week old kitten has been eating them. It’s not a trash can issue. We eat a lot of eggs and she has never taken the shell out of the trash, but twice since having her I have peeled hard-boiled egg into a bowl and she goes crazy for the pieces of broken shell. Eating, not playing. Just crunching away! I don’t think it’s hurting her, and she isn’t eating huge quantities. I was just wondering if it was common. Sounds like it isn’t!

    P.S. Dewey doesn’t live in a book store does he?

    • Hi Amber, it is not that uncommon for a cat to eat eggshells. My theory is there is an ingredient in the eggshell which some cats instinctively like and want to eat because it is beneficial to them. That is the most likely reason. I’d just make sure your kitten’s diet is top quality. Mainly high quality wet food and a few treats and not much dry.

      Eating eggshells may provide a supplement the cat desires. If this is not the reason it is because it tastes interesting. It may be what is sticking to the eggshell (the egg white etc.) and not the eggshell itself, which the cat likes. Egg white has nutrients in it.

      I don’t know if Dewey lives in a book store. Sorry.

  2. I wanted to know about this too. I have a mom and 4 boys, all biologically related. One of the boys (the only long haired one actually) will occasionally steal eggshells while I’m cooking and go off to eat it. Generally just a half. I was just worried that the concentrated calcium might be a bit much for his system.

    The boys are not quite 2 years old, weigh between 10 & 12 lbs, all neutered, same diets.

    You mentioned stomach acids and calcium carbonate – that makes sense as that’s what is used in most ‘people’ antacids, Tums, etc.

    He doesn’t do it very often, it’s just that I actually watched him do it the other day and I wondered.

    Thank you for clarifying a mystery – I’ve never had a shell muncher before!!

    • He is an interesting cat. I wonder if he is deliberately eating egg shell to help reduce acid in the stomach. A self-help anti-acid home treatment.

      I would doubt it but I would doubt he is eating it because it tastes nice.

      • I wouldn’t think so either! If you’ve ever gotten a shell fragment in your breakfast or a cake, you know how awful they are. Gritty, sandy, nasty things!! Lol.

        Even more surprising is the fact that he’s really picky about people foods. Anything with any odor – he’s GONE! Each of the brothers have their little food ‘thing’: Dewey has eggshells, Fluffer steals lettuce, Quinn carries pepperoni around before he eats it and Soxy will try anything at least once, but really likes nacho cheese, with peppers!!

  3. Oh I’ve never heard of cats eating eggshells I’d be worried they cut their gums on any sharp bits or got a bit stuck in their throat.

  4. Egg shells are one thing I haven’t caught Monty eating. He thinks he’s starving all the time and will eat non-food items. I thought this would be a good article for me to read since it is only a matter of time.

    I love Marc’s story about his cats loving egg shells and he finds them around the house.

      • I have to put a lid on the garbage can or Monty will rummage around in there. If I don’t jam the lid on tight he could possibly pull some eggshells out of there. He should be happy today. He got wild caught salmon and a little deli ham on the same day. Both of us are lying around fat and happy with our bellies quite full.

  5. My cats love eggshells and I find them around the house if I don’t get them off the plate into the garbage quickly. They don’t eat them it seems but they seem to like the smell or taste and they like to transport them to funny places. Molly takes things to the bath and builds a sort of nest of stuff in it. Gigi and Lilly do the same at the foot of my bed. I find eggshells in both spots.

    • That is interesting. I am surprised. Well, not that surprised. Maybe the faint smell of egg is appealing together with the playability of the part of an egg shell or, perhaps, it is the calcium in the shell. Perhaps modern cat food does not contain quite enough calcium?

  6. Egg shells shoudn’t harm a cat but it makes me wonder if she is getting enough calcium in her food.
    Some people still believe the old wives tale that giving a cat or dog crushed eggshells gets rid of worms because it chops them up. Not true of course, only proper worm medication can do that.
    I’d look at my cat’s diet and make sure she was getting enough calcium in it. If the cat is unwell at all she should see the vet and you should mention the eggshells.

    • I wondered the same thing, but my resons may be a bit different (Ruth?)
      When you ask this q, I wonder if maybe you are not feeding your domestic cat high-quality canned (wet) food, supplemented with a good dry. If not, then look to supplementing her/his diet with canned mackerel and/or salmon. Both contain bones that are digestible, completely, from my understanding. Am I off-base here, Ruth? Eggshells, even though they are basically CaCO3 aka Calcium carbonate, are rarely fine enough tointroduce to a cat’s esophagus and gut. [Ruth?]

      • Canned mackerel and salmon are very rich for cats to digest, I’d say an occassional treat of either might be OK but I wouldn’t make it a regular part of their diet.
        Sometimes canned fish has uncrushed bones that got in by mistake and these can stick in a cat’s mouth or throat so you have to be very thorough at checking for them if giving them any for a treat.


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