Tattoos Indicate Spay And Neuter


It won’t be long before more people have them than don’t.

Today, though, we’re talking about dog and cat tattoos.

These tattoos are not for decoration, but for conveying information.

Discreet, painless tattoos are performed while the patient is still under anesthesia.
Discreet, painless tattoos are performed while the patient is still under anesthesia.

Veterinarians use small, straight-line tattoos when pets are spayed or neutered to let future caregivers know that this particular pet no longer has internal reproductive organs.

Suppose circumstances, economic, medical or catastrophic made it necessary that your pet go to live with someone else. You may or may not be able to convey to the new owner whether your pet had been surgically altered.

Suppose, now, that the new owner observes problems with the pet and his new veterinarian suspects that those problems may be related to the reproductive tract. Do you want your pet to have to undergo a surgical exploration of the abdomen for organs that aren’t there? A little tattoo, a couple of millimeters wide and a couple of centimeters long answers that question as soon as it is asked.

“But my pet will have a scar showing that she’s had surgery, won’t she?”


Maybe not.

Another example of a spay tattoo. Notice that the surgical incision barely left a scar.
Another example of a spay tattoo. Notice that the surgical incision barely left a scar.

Some surgical incisions heal so well that no evidence is left behind that entry was ever made.

Even if there is a scar, it only tells us that there was interruption of the skin there.

Is the scar from an injury?

Is the scar from a Caesarean section?

Is the scar from bladder surgery?

There are only three ways to know: surgical exploration (painful and invasive), hormone assays (expensive) and tattoo (free and performed after surgical alteration while the patient is still under general anesthesia). Which do you want for your pet?

While it might seem that it would be obvious in the case of male dogs and cats, a condition called cryptorchidism demonstrates the necessity of a tattoo for them, too.

Cryptorchidism occurs when testicles fail to enter the scrotum and instead are retained in the abdomen. If neither the left nor the right testicle leaves the abdomen a scrotum will never be formed and a veterinarian is left to wonder whether the pet was neutered very early in life or has testicles in the abdomen.

Retained testicles are predisposed to two types of cancer and a condition called torsion of the testicle. Torsion results in a painful, potentially life-threatening condition that requires immediate emergency surgery.

A male pet presented for abdominal pain, with no testicles in the scrotum and no surgical tattoo may undergo unnecessary abdominal surgery looking for a torsed or cancerous testicle that isn’t even there.

So, when your pet’s doctor recommends a small, discreet surgical tattoo with your pet’s alteration surgery, don’t hesitate to say yes, although, like everything about your pet’s medical care, the decision is up to you. Tattoos are optional.

Dr. Randolph.

PS: A reader asked how to remove the small amount of ink left on her pet after tattooing. When we perform a tattoo, a small amount of ink always runs out onto the skin and hair. We find it’s easily removed with 3% hydrogen peroxide.


  1. I think an N for neutered. For male S for spayed if female and if they’re put under anesthesia it wouldn’t hurt them at all and it would be clear I saw one female that had a circle with a line drawn through it to signify that she had been spayed I’ve only seen it once🐶

    • Not a bad idea, but, that might tax the artistic abilities of some veterinarians, including me. Plus, we don’t want to do anything that would extend anesthesia time unnecessarily. You’ve spent a lot of time studying this topic, haven’t you? Thanks for reading, Dr. Randolph.

  2. I think this is a great practice. Having worked in a veterinary hospital for 4 years, the benefit of tattooing is clear. Odd thing is that my husband and I adopted a dog who was NOT neutered but still obtained a tattoo somehow… So also what is the ethics behind this practice? I have NO idea how our dog ended up with this tattoo but was clearly NOT neutered… Even if you don’t believe in the practice, what would cause you to tattoo a dog to create a misunderstanding when the tattoo is a clearly understood communication?

    • You are correct. That is extremely odd. If you ask the shelter who tattooed him and find the answer, we and our readers would be interested in the answer! Thanks for reading, Dr. Randolph.

    • Perhaps the owner did not want to neuter/spay the dog but need to put him/her in daycare that requires them to get fixed.

  3. We bought a female Great Pyrenees of Craig’s list she is about a year and some old we were told she was spayed but we were also told she was a convulsion support dog (she is not) she has one scar on her lower chest one nipple down towards one side and there is a green v right next to her who-ha very long wiggled and faint and one green line on ether side of her belly between the two nipples on each side closest to her who-ha we are very confused we should get her spayed if she’s not she’s had two previous owners one in the military and the one we bought her from we need answers my whole family is so confused

    • Your veterinarian can examine her, evaluate the scars and tattoos and determine whether she is a candidate for a blood test to determine whether ovaries are present. Thank you for reading, Dr. Randolph.

      • Why can’t a x-ray be done? Reproductive organs should be visible, especially in a dog that size. If it shows ovaries or an uterus you have an answer & save the expense of the blood test.

        • While it sounds reasonable, such small soft-tissue organs aren’t going to be visible by radiography. They might be visible by ultrasound (in a big dog), but then you’re talking about the same expense as the blood test. Thanks for reading, Dr. Randolph.

  4. I on the other hand don’t like that they tattooed an ugly line on my cats with out telling me. If they’re going to do that they should tell me before hand. And if so why can’t they do a little simple Daisy or something? Lol. My grandson’s thought something was on them was freaking out wait wouldn’t come off l

  5. My male cat just got neutered and he has a green tattoo on his stomach but he keeps eating it and I am trying so hard to stop him but he just won’t stop licking and chewing it . Please get back to me ASAP about this thank you!

  6. Spay/neuter tattoo is an excellent idea. Wish it would become a law. The University Vet college uses a plain, straight green line, but a “V” (for Veterinarian?) makes sense. Both not only indicate the surgery, but also that it was done by a trained, caring DOCTOR. My Sister took in a stray male dog, no testicles. He had pain when he sat down. Surgery revealed that someone had wrapped some kind of wire around them and never removed it. The skin grew over it so that it was not readily visible. (He lived a long happy life). Tattooing is more noisy than painful so that should not be a concern. People who are conscientious and or have strong family/friend support that includes their pets may think that their pet may never have to endure an unnecessary surgery. I hope they don’t but sometimes the unthinkable can happen. Thunderstorms spook some, natural disasters, evacuation, outright theft, are but a few reasons they can get separated. I have volunteered at my local shelter for 12 years, it’s sad when they have to endure yet another surgery. Plus it’s expensive, and the Doctor’s time could be better spent.
    Thank you for caring and sharing!

  7. I adopted a male kitty with a green line tattoo on his abdomen, a little more than half an inch long. I read through his medical records and found out he was tattooed at the Maui animal shelter after being neutered. My previous cats were never tattooed, and with all the fur they grew it would have been hard to tell if they were spayed or neutered. I think it’s a great idea! If I hadn’t been rubbing his belly, I wouldn’t have seen the tattoo, so I don’t know why people are so upset about their animals getting a tattoo. I had a tattoo placed on my neck when I had radiation therapy, I wasn’t asked about it, they just tatted two dots where the beams were to be focused. Unfortunately I can’t grow fur to hide my tats, but since no one sees them unless I point them out, it’s kind of hard to go around complaining about them.

  8. I am wanting to speak at a commissioner meeting this week asking them to encourage our local animal control to tattoo spayed dogs so save them from unnecessary surgery and in doing so, saving the county money. Is there a reason some vets do not tattoo? are they all capable of doing it?

  9. You should still have the right to not get a tattoo. All of my dogs have impeccable records kept both online and original paper form. Wife and parents know this and even if I died the dog would stay in the family. While its not a huge deal I think you should have a choice as I recently found the local vets demanded it be done so I had to drive 3hrs to a previous vet to have it done without.

      • My hairless Chinese Crested had the 2 line tattoo, but a week before he died from a tumor on his spleen the tattoo spread out and was no longer 2 straight lines. Also, I have since then adopted another hairless Crested and her lines are starting to spread as well but not as much as my dog with the cancer. Do you know why this is happening?

        • I suspect it’s a normal reorganization of skin cells. I’ve noticed other dogs, and cats, whose lines became “blurred” as they aged. We once had a beagle named Sam. He was a tricolored beagle, and he had a little, round white spot over his left hemipelvis when he was a puppy. As he aged, the white became smaller and smaller, but still circular, until, a year or so before he passed, it was completely black. Thanks for reading, Dr. Randolph.

    • Agree with Giovanni 100%. We were not even told it was going to happen. Appalling and senseless because we were taking her to be neutered not tattooed. We have no need for a tattoo because the odds are overwhelming that this family will look after the dog through her entire life. A black crossed out female sign is revolting imagery. Who even thought of that symbol? Not to mention it was probably very painful. Can it be removed?

      • Can it be removed? Of course, but it would require a surgical excision. “A black crossed out female sign?” Odd, since the standard is one or two short, straight lines. No pain involved, as the tattoo was performed while still under anesthesia. No one has a crystal ball, and no one knows when one’s pet will get away from us, or we die in a calamity the pet survives, then who is left to know the pet has been spayed? Our surgical permission form includes a line for the pet owner to have the option to decline the tattoo, but we’ve never had anyone elect not to have the tattoo.

    • I just adopted a spay and she underwent unnecessary surgery and was already spayed. When I worked at the Humane Society, this happened all of the time. Even though you have impeccable records, you can’t guarantee that your dog will never go missing. The unexpected happens.

  10. I found my cat on the side of a building in San Diego about three years ago. She was sick, and had a scar showing that she had been spayed in the past few months. I noticed that she had a pink heart tattoo a few inches away from her scar, but when I took her into the vet they didn’t know what it was, and they scanned her for a microchip but couldn’t find one. Someone else told me they got their cat from the Humane Society and it had a similar heart tattoo, but I could never find any information about it. Any thoughts?

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