Spider Bites Dog

By Roxanne Hawn from Champion of My Heart

Lilly, the fearful border collie who serves as the canine heroine in my life, is a bit famous for being bitten. She turned 7 years old this spring and her tally includes:

Lilly's Rattlesnake bite
We’ll never know what kind of spider led to the hardboiled-egg-sized lump in her neck. 

It could have been a brown recluse or simply a “no name” spider in our pastures at 8,200 feet above sea level in the Rocky Mountains of Colorado.

I found the bite while looking for another lump I wanted our veterinarian to check during Lilly’s routine wellness exam.

I was groping around for the pea-sized lump when I found a big, fairly squishy mash.

I had bathed her days earlier and brushed her that morning and feel positive I would have felt it then, so based on her behavior as the day wore on, the lump’s discovery that afternoon, and the bloody discharge my veterinarian drew out with a syringe, we’re fairly certain the spider bite happened the same day I found the lump.

Most people don’t discover spider bites on their dogs until days later when the aspirate comes out as mostly puss from a vibrant infection.

Still, after shaving a spot on Lilly’s neck and drawing out 12-15 ccs of bloody fluid, our veterinarian squirted some on a paper towel and took a whiff. “Yep, that’s pretty rank,” she said. “It’s already badly infected.”

Spider Bites in Dogs: What to Look For

Unlike snakebites, with clear fang marks and extreme, rapid swelling in a matter of minutes, spider bites tend to show up with these symptoms:
  • Swelling and itching within 1-2 hours of a spider bite
  • Noticeable bruising around the spider bite lump
  • A squishy outer lump with a firm spider bite center
  • Possible muscle pain, cramping that makes dogs reluctant to stand up or move
  • Possible drooling

Dogs tend to process spider bites a bit better than cats, who can even develop paralysis from black widow spider bites.

Some bites, including those from poisonous brown recluse spiders, can become quite swollen, red, and tender to the touch. 

They can even begin sloughing dead tissue, revealing a nasty open wound that can take a long time to heal.

Spider Bite Treatment for Dogs

We sprung into action, giving Lilly shots of both powerful antibiotics and powerful steroids. Fair warning, the injection hurt like crazy … causing Lilly to fling herself to the floor screaming and writhing. So, if your dog ever needs an injection like this, hold on tight.

I had pre-dosed Lilly with Benadryl in anticipation of vaccines to which she has less-than-ideal reactions, so it didn’t hurt that she already had an antihistamine in her system before we arrived at the veterinary hospital.

We went home with both antibiotics and steroids to give her twice a day, with recheck veterinary appointments every few days.

Surgery would be needed if the:
  • Spider bite lump grew
  • Spider bite lump didn’t shrink fast enough
  • The dog developed any other complications such as fever, trouble breathing, tremors or seizures, extreme lethargy

In those cases, veterinarians want to do surgery to cut out the necrotic (dying) tissue and put in drains to get infected fluids out of the body.

The primary risk is that the infection might go septic (into the bloodstream), which can be deadly in a matter of hours. 

I assume the bite being so close to big arteries in Lilly’s neck put her at greater risk for sepsis and organ shutdown.

Spider Bite Recovery for Dogs

Other than showing more generalized fears the first few days and running a low-grade temperature, Lilly seemed mostly normal, but tired, during her spider bite recovery. We did, however, keep her quiet in the house:
  • Only going outside to potty
  • Not going on long (or any) walks
  • Not playing or roughhousing with us or our other dog

Lilly needed several follow-up appointments so that our veterinarian could check the spider bite lump. We kept Lilly on both steroids and antibiotics for several days past when the lump felt completely gone. Then, we finished the prescribed antibiotics and carefully tapered her off the steroids over about a week.

Spider Bite Dog Emergency

If you find a sudden, suspicious lump on your dog, consider it a veterinary emergency and seek diagnosis and treatment immediately.


Roxanne Hawn is freelance writer and award-winning blogger. Roxanne’s work has been published in many national outlets, including The New York Times, Reader’s Digest, The Bark, HealthyPet, Bankrate.com, WebMD and many more. Her blog Champion of My Heart is a real-time memoir of life with fearful border collie. 

You can find Roxanne and Lilly on the blog as well as:

Twitter – @roxannehawn, @champofmyheart
Facebook – Facebook/ChampionofMyHeart


  1. I guess one good thing about living where it's colder (Fargo, N.D.) is that we don't have to deal with many spiders, bugs, snakes and so on.

    That sounds scary what happened to Lily. That bite must have swelled up really fast. I'm glad she is recovering OK.

  2. Yes, that is definitely one advantage of colder climates. Plus dog do generally better in colder climates all together :-)

    Poor Lilly has had some very bad luck with bites, she seems like a magnet for these things.

  3. I had a bad experience with brown recluse few years ago.
    My 9 years old dog betty almost die from infection..that was terrible shock for me i didn't know that spider can produce such a dangerous bite on dogs..

    1. So sorry about Betty, glad she recovered though! Yeah, not something one would think of. Most spiders are fairly harmless, but there are some that are very nasty.

      Would you like Betty's story shared here on the blog?

  4. Yeah, sure, thank you for invite.
    Tell me about article on mail bojanwish2@gmail.com (Betty story)

  5. I have an Australian Cattle Dog that is 5 years old. He has now been in the hospital for 2 days on IV antibiotics and steroids. Vets think it is a spider bite. I'm so worried about my little buddy. He's been stable for the last day but with no real improvement. He is very puffy, swollen, and tender. Poor little guy. What a nasty infection. Say a little prayer for my best friend because he's such a good boy and I'm really worried about him.

    1. So sorry about your baby! Stable is good, hopefully improvement will come soon. Healing prayers.

  6. A lump just "showed up" suddenly on my American Bulldog/Pit mix. Poor baby. I love her so much.
    I was walking her, and noticed a lump. As soon as I touched it, she flinched. And liquid/blood came out. So, I immediately took her inside the house, and applied a warm compress, softly pushing the fluid out. I took a nap, and woke up noticing that more blood had come to the surface. So I, again, gave a warm compress. I also shaved the area so I could see what I was up against. At this point, the lump was gone, and now it is just an open wound. I'm leaving it uncovered so as to dry it out. And placing the compresses on her every three to four hours. So far, it seems ok. She still hasn't eaten her food today. I took her temperature, and it was 102.2 which is in "normal" range for dogs, so that gives me some relief. I called the vet, but she (of course) wanted me to bring doggie in so she could see what was wrong. I KNOW it's some sort of bite, because two days ago, she was rolling around in the grass alot more than usual. I think she was reacting to a sting or a bite (now that I think back on it). So, here I am now (12:46 a.m.) and sitting next to my dog, monitoring her to make sure she is ok. So far (except for the open wound, which appears to be healing) she seems to be in good health (altho she still hasn't eaten today, except her snacks - - she did eat those! :)

    1. I would agree with your vet that it would be good for them to see this. I don't like the words "open wound". If it was me, I would take her in, just to make sure there is no infection going on and the wound is indeed healing.

  7. I had a similar experience where my dog started off vomiting and then was acting quiet - also he was making a grunting noise as he drank water and the only thing that really tipped me off was that he didnt come with me to feed the cats in the warehouse. After that I watched him more carefully. His breathing seemed shallow and a small lump appeared on his jowl - it got larger and yet he still ran outside with me - 4 hours passed - I really gave him a good looking over and decided he was in distress. My vet was leaving for the day - I begged her to let me come in - She said I just made it - They stabbed him with a steroid in his back and gave him another injection in his leg - I cant believe I waited so long to get him to the vet. They said it was a reaction to something - maybe a spider. We hardly have any spiders in our place because it is new construction but we took putty and filled in any cracks we could find.

    1. Sometimes things seem less scary than they really are. The important thing is that you did get him in on time!

  8. My lab had a bug bite and 2 days later he had a seizure. They checked the blood and everything looks normal. The doctor said he had an epilectic seizure and these kind of dogs have it starting around the age of 3-4. I was wondering if the bug bite can cause seizure after 2 days later and not showing in the blood test? Thanks!

    1. It seems kind of logical to connect the bit and the seizure, I think. Which doesn't mean it couldn't have been a coincidence; would be quite a coincidence IMO.

      What were they looking for in the blood specifically? What kind of bugs do you have where you live? Any other symptoms your dog was showing?

      I think I'd consult with another vet for a second opinion.

  9. My one year old pit bull has a lump that I was thinking from either a bee sting or spider bite. It was sensitive at first but now it's just a little hard but no symptoms like seizures or fever. She's still very playful but should I be concerned if it doesn't go away in a certain amount of days?

    1. Yes, bumps that stick around should always be checked.

  10. My 2yr old cockapoo was licking or nipping at something in the area on her ribcage on the upper side, I can see it while she's laying on her side. I took a look and there's a little "pea size" ball but her little blonde hair is red w blood in a tiny little area. I pulled the hairs apart and it's bloody and a bit shiny, I can't tell if it's puss or from her nipping at it that the skin is raw.. she woke us up around 430am today, vomitting a little but dryheaving for about 10mins after. We were gonna try today but vet is closed we were going to wait til monday, as its Sunday today. But now that I have typed this out and see it in words, I think we will take her to the hospital. Thanks for sharing your story!

    1. Hi Jennifer,

      shiny to me would mean swollen. Does sound like she's got bitten by something, I would not want to delay veterinary care if she's also vomiting and having diarrhea.

      I hope you can get her to the hospital.

  11. Did your baby have any long term issues after healing? My boy still has slight skin slothing around the area and lost quite a bit of muscle mass. He's 16 --

    1. Yes, Lilly recovered fully from her spider bite. (She has since died from something else, but there were no lasting effects from this bite / infection.) I'm sorry that you're seeing ongoing issues. If your boy stayed on steroids for a while, that *can* cause some muscle mass loss, but I'm guessing at his age that's more likely the cause of the muscle loss. We just lost our nearly 16-year-old boy, and he lost a lot of weight / mass toward the end.

  12. We have a very similar story, a noticeable lump on the lower jaw/chin. Took to vet 12 hours later, diagnosed as probable bee sting. He's acting completely normal, eating, no fever. But 4-5 hours after leaving vet I noticed a new open wound/drain on the center of the bump, immediately called vet, got oral antibiotics immediately and exam the following morning where it was examined, irrigated and filled with Tritop Ointment. Now watching and applying ointment over holiday weekend, if the drain gets larger or looks grayish we are headed to EVet. We are in Midwest, I think it's s spider bite, am worried about where the spider is now (family) and praying that this open wound heals rather than worsens. Glad to find this post and your experience. Thank you for sharing!!

    1. Sorry about your dog. Here is hoping the treatment he's on will do.

  13. my dog Yeti,has a very muscular neck and a lot of thick hair(she is a mixed breed ) she presented with a nickle size knot that we watched and in 1/2 a day it was a 2x5 inch knot that had opened.There was so much putrid pus coming out of it ,(on top).
    We took her to the vet and he started antibiotics and kept her for 3 days .He said for us to leave it open and let it drain ( I think he should have placed a drain in the bottom of the knot)She had no problem eating drinking and never acted sick.she did start to scratch and I put a sock on her foot and she settled down. The day before she went for recheck she scratched again and now she has 2 holes instead of one. The vet looked at her and all he said was "I don't like the looks of that,it's not healing right,leave her here for a couple of days and let me see what I can do for her."I was giving her the meds he gave me.
    So here I sit worried about my baby,waiting and praying that GOD gives the vet the knowledge to help my little girl to get well and come home.
    Please pray for her.
    Will return and give you an update !Thank you,I feel a little bit better.

    1. Praying with you that it all heals up nice and fast.


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