Feline Reconstructive Surgery

There are many different causes of skin defects in both cats and dogs. Traumatic wounds such as degloving injuries, dog or cat bites, burns, deep fungal infections, and extensive wounds caused by surgical removal of neoplastic disease are examples of clinical situations where reconstructive surgical techniques may be necessary.

Before considering extensive reconstructive surgery a clear diagnosis of the disease process should be known. Fine needle aspiration and incisional biopsies should be liberally used for diagnostic purposes which will facilitate rational therapeutic planning. A knowledge and/or diagnosis of the local disease process is important however knowledge of the animals general health is also critical. For example, the presence of thoracic metastasis in an animal with neoplasia, Cushing's disease or diabetes, or FELV + status in a cat would potentially influence the therapeutic decision making process.

Local causes of Non-Healing Wounds

-Neoplasia

-Excessive movement (joints)

-Tension

-Foreign Body

-Infection

• Bacterial

• Fungal

-Hematoma & Seroma

-Radiation

Systemic causes of Non-Healing Wounds

-Anemia

-Endocrine Disease

• Cushing's Disease, Diabetes mellitus

-Obesity

-Nutritional

-Hypoproteinemia

-FeLV, Feline lentivirus

The surgical closure of cutaneous defects requires proper timing and planning. For example, infected wounds are treated as open wounds so multiple debridements can be performed and to allow formation of healthy granulation tissue. Interestingly, cats do not form granulation tissue in as vigorously as dogs. Closure of skin defects resulting from tumor excision (fibrosarcomas) is often performed at the same surgery as tumor excision. If tumor excision and reconstruction are performed concurrently, it is advisable to change instruments and gloves prior to the reconstructive procedure.

I. Axial Pattern flaps

These skin flaps are pedicle flaps based on direct cutaneous arteries. Since these flaps contain an arterial supply, they can be constructed in long lengths and mobilized to cover large distant or trunk defects.

Many types (about 10) of axial pattern flaps have been described in the dog and at least several have been evaluated and found to be useful in the cat as well.

Theory/How to construct- The flap is constructed based on its anatomic landmarks, lifted from its donor bed by dissecting deep to the panniculus muscle and subcutaneous tissues, and rotated to the recipient site. If the recipient site is close by a "bridge incision" is made between the base of the flap and the recipient site. If the recipient site is distal or some distance away, a "bridge incision" is made OR the intervening flap may be "tubed" to allow the flap to be used correctly. If "tubed", the tube is usually incised and removed for cosmetic reasons 3-4 weeks after the initial surgery. Since this involves an additional procedure most surgeons prefer the "bridge incision" when possible.

A. Caudal Superficial Epigastric

1. This flap is based on the named artery, which supplies the caudal 3 mammary glands in the cat.

2. Landmarks of this flap include the ventral midline from an area level with the inguinal rings, cranial to the 2nd nipple, and then lateral 2x the distance between the nipple and the ventral midline.

3. This flap may be rotated upto 180 degrees and used for reconstruction of the ventral abdomen, flank, perineal, and medial aspect of the rear limb. This flap will reach the metatarsal area distally.

B. Thoracodorsal

1. This flap is based on the thoracodorsal artery, which exits the shoulder depression on the caudal aspect of the scapula.

2. Landmarks:

• Cranial border= Scapular spine

• Caudal Border= Line parallel to the scapular spine twice the distance from the spine of the scapula to the shoulder depression

• Dorsal border= Midline

3. This flap will reach to the carpus of the forelimb.

C. Superficial Temporal

1. Useful for maxillofacial area.

2. Landmarks:

• Base= Zygomatic arch

• Rostral= Eye

• Caudal= Ear

• Length= Midorbital rim of the contralateral eye

D. Caudal Auricular

1. Useful for facial area, dorsum of head or ear.

2. Landmarks:

• Base= Depression between the lateral aspect of the wing of the atlas and the vertical ear canal.

• Dorsal= Close to dorsal midline

• Ventral= Ventral 1/3rd of the lateral cervical area

• Length= Spine of scapula

II. Skin Fold Advancement Flaps

Definition: Use of flank folds and elbow folds of skin for closure of large skin defects.

A. Indications/Use

1. Sternal and inguinal wounds, lateral body wounds.

2. Division of the attachments to the limb creates a U-shaped flap which allows closure of defects in the above locations.

3. Can create bilateral flaps that allow even more area to be covered.

4. No definitive guidelines on length vs width ratio but probably 2:1 ratio is limit.

5. This flap is classified as a subdermal flap.

III. Skin Grafts

The need for skin grafts in the cat is seemingly uncommon. Use of local tissues and flaps and perhaps axillary pattern flaps when indicated have more predictable results than the use of grafts. Grafting involves the free transfer of skin from a donor site to a more distant defect (recipient) site. The recipient site should have a healthy bed of granulation tissue. In general, since tissue is freely movable on the trunk and flaps are possible, grafts are more likely to be used on the distal extremity than other areas.

A. Graft Success

1. Graft needs healthy granulation tissue with no infection thus wounds are usually bandaged with wet-to-dry bandages until granulation tissue appears health, usually 5-7 days after initial wounding.

2. Graft should be placed where there is NO MOTION or the area must be totally Immobilized by a bandage, external fixator, or cast. We do not examine the graft for 34 days after bandaging has taken place.

3. Be sure to control hemorrhage well prior to applying the graft. Hematoma under the graft may prevent revascularization of the graft.

B. Graft Technique

1. The donor skin is harvested knowing that the graft will be "meshed" thus increasing the area it will cover. Be sure you can close the donor site reasonably by pinching skin before you take the graft.

2. Remove all of the subcutaneous fat from the graft. You should be able to visualize hair follicles easily on the back of the graft. Sharp Metzenbaum scissors usually work well for this task.

3. Mesh the graft by using a#15 blade to create sequential defects