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6-Month-Old Rescue Rat Terrier with a Large, Strange Bump

October 7, 2012

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Rescue Dog was Perfect, Now Lumpy

brown and white short-haired rat terrier mixed breed dog (cute!)

Just adorable!

Imagine you found the perfect dog.  Small, compact, able to play with your other dog with no problems. You rescued her from who-knows-what horrors.  Yet she is playful, affectionate, and really just perfect in every way. You are the luckiest person!

2 weeks later, a bump the size of a modest watermelon appears overnight on your dog’s side.  No kidding.  Overnight, a large lump just sits right there on your dog.  She’s not in pain.  It doesn’t hurt when you touch it.  Your dog is only 6 months old, how can it be cancer? Maybe your other (bigger) dog played too rough and it’s a bleeding problem?  You have no idea.  And it does not go away after a day or two.  You freak out and head to Doc Truli’s office for advice.

Doc Truli Assesses the Lump

View of Trixie on her left side, with the lump sticking 3-4 inches (6-8cm) up in the air before exploratory and hopefully curative surgery.

The thing in the middle is the lump!

“Doc, I think maybe my other dog injured her when they were playing,” said Trixie’s concerned mom. “But she never cries or complains. She’s eating well. Everything else seems normal.”

Doc Truli performed a needle aspirate cytology test to try and identify what made up the lump.  Was it blood? No.  Was it cancer? No.  What then?

“We must perform surgery to diagnose the problem and to remove it because it is not healing on its own,” said Doc Truli.

“Okay,” said Trixie’s mom. “I thought you might say that, so I withheld her food this morning.  Could we just get it other with today?”

“Of course,” said the Doc.

The Disgusting Puppy Lump Revealed

After the initial skin incision, Doc Truli saw disorganized swirls of purple-red muscle and fat and connective scar tissue.  Some of the scar tissue moved easily with light digital (by finger) pressure. Some scar tissue adhered tightly to  the ribs and the stomach muscles.  Doc Truli worked slowly and carefully left only healthy puppy muscles and skin, not disturbing the healthy normal post-op healing process.  Once Doc Truli removed the majority of the disgusting, unhealthy lump, an indentation 4 inches (9 cm) in diameter remained.

At the end of surgery, the lump is gone. There is a depression in her side behind the rins where the deep parts of the lump were removed and a latex tube called a Penrose drain is sticking out of the surgery area.

Post-op sutures and Penrose drain.

“If a surgery site is left with a ‘pocket,’ or possible space under the skin, then the skin may have difficulty re-adhering to the underlying layers of the body.  That space can fill up with protein-laden serum which makes good food for opportunistic bacteria,” says Doc Truli. “A surgical drain allows the serum, blood, and any marauding bacteria to flow out of the surgical wound for 3-5 days after the surgery to prevent post-operative complications.”

What Was the Lump on the Puppy?

Trixie received her puppy vaccines at the animal shelter just before her mom adopted her.  While the records did not show the anatomical site of the vaccines, the side of the body by the ribs is a common location for administering vaccines.  We also know vaccines can stimulate a vaccine-site reaction.  In Trixie’s case, the reaction was unusually large and vehement.  She obviously has an immune system that responds vigorously and violently to certain types of stimulation. Histopathology revealed inflammation and necrosis typical of an injection reaction.  The only injections in her medical record were various core, basic dog vaccines.

Trixie Makes a Full Recovery

At the 5 day post-op recheck, the drain is clean and dry. There is slight swelling over the surgery area due to post-op inflammation, not the tumor growing back.

5 days post-op

Just 2 weeks after surgery, the incision scar is barely felt and short-stubby new fur covers the shaved surgery area on Trixie's side.
2 weeks post-op

5 days after the surgery, the surgery site was slightly swollen.  The drain worked well and Doc Truli removed it 5 days post-op.  Two weeks after surgery, Trixie’s stitches came out. She is a normal, happy dog in every way.

Vaccine-Associated Bumps

The vaccines given to your dog usually have a 1 cc volume.  It causes a tiny bump under the skin where the vaccine is given just by sheer fact of being a liquid volume.  But, in most pets, the liquid absorbs in minutes and you don’t even see it.  Especially if your pet has fur.

Some pets experience pain at the injection site for a few hours to a day or so. Rarely, a pet will grow an inflammatory bump at the site of the injection.  Under the microscope, it is made up of activated immune cells. You should have your veterinarian check any persistent lump to get a professional opinion about a reasonable course of action.  Also, your veterinarian may wish to change your vaccine protocol in the future.

“As a general guideline, if a lump or bump after a vaccination, that has been checked by the veterinarian, does not disappear within 3 months, or grows bigger, it should be removed and sent to a qualified pathologist for diagnosis,” says Doc Truli.

Trixie’s case was truly unusual.  Always consult your pet’s healthcare provider to discuss merits and risks of vaccines.  In Trixie’s case, she experienced the routine vaccinations of the animal shelter, so Doc Truli and Trixie’s mom had no control over how she got sick.  One surgery later, Trixie is surfing the back yard deck in search of dropped barbecue morsels and playing with people and dogs alike.

VirtuaVet goes into more detail about…

needle aspirate cytologies

other reasons for bumps on your dog

Or search for “bumps” on VirtuaVet in the search box or the tags. (There’re lots more stories!)

3 Comments leave one →
  1. September 26, 2017 5:55 am

    My 13 yr old chocolate lab has a huge lump like this. It showed up seemingly overnight and is in the same place as her rabies vaccination injection site.

  2. April 30, 2014 12:32 pm

    Hi,Did Trixies have any more trouble from it?
    My gsd had a collision with a car but was fine.. 4 weeks later a lump developed overnight exactly the same as Trixies. I had him to the vet who operated immediately and discovered no infection just hard gristle like tissue.
    Blood work etc were sent for analysis ..all came back clear.
    Vet diagnosed it as sterile panniculitis following the trauma of the collision. Dog was on antibiotics for 4 weeks and all seemed ok.
    The problem is.. The lump re appears every 5 weeks .. It comes up in hours.. And if given antibiotics it’s gone in days..this has been going on for 12 months now he has a lump the size of a coconut! I fear more surgery may be on the cards ..don’t know how or why it comes and goes I’m at my wits end with worry for him.

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