Case study: Dog - benign mass lateral stifle


29 September 2015




A six-year-old female neutered Bordeaux, presented with a large mass on the right hind lateral stifle. Cytology was performed and the mass was deemed non-neoplastic. The owners decided to leave the mass in situ, as it wasn't causing a problem.

Two years later the dog presented again. The mass was the same size however as the dog was solely kept outside and laying on concrete the mass was prone to becoming sore and bleeding. The owners therefore opted to have the mass surgically removed.

Due to the size of the mass the surgeon decided to place Expaniderm soft tissue expanders prior to removal of the mass in order that he would then be able to close the defect utilising the expanded skin resulting in primary closure at the time of the mass removal.

Nine Expaniderm devices of 27mm diameter and an expanded height of 30mm where placed around the lateral margins of the mass.

  • Implantation of devices proceeded well on the 12th of August 2015 (day 0)
    • The dog was anaesthetised in a routine fashion and the surgical site clipped and prepped
    • One incision was made for all nine devices to be placed through. Blunt dissection was used to make 2 individual sub-cutaneous pockets for the devices to sit in
    • Devices where places both cranial and caudal to the mass – see photos
    • The incision was closed in a routine fashion and the dog sent home
    • There was some post operative bruising but this resolved of its own accord
    • All the devices expanded as expected over a period of 16 days
    • There was no adverse reaction to the devices and the dog tolerated them well. The owner didn’t perceive any change in the dog’s demeanour throughout the expansion and there was no sign of lameness or any pain noted
  • Device removal and reconstruction 27th of August 2015 (day 16)
    • The dog was anaesthetised in a routine fashion and the surgical site clipped and prepped
    • The mass was removed – see photos
    • The Expaniderm devices were then removed and the excess extra skin used to close the defect
    • The surgeon said he couldn’t have got wound together without tension without the extra skin provided by the tissue expanders. He said that he got an extra 4 cm of skin along the wound edges from the devices
    • Minimal scoring of the fibrous capsule was done in order to release the fibrous tissue
    • The surgical wound healed well and sutures were removed at day 10 post reconstruction – see photos
Photographic record:
Expansion results:

All the devices expanded as expected, the expanded skin was of good quality and resulted in a very good outcome


The surgeon was very pleased with the devices. He said they were easy to use and he would definitely use them again.



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