Management of Traumatic Wounds in a Cat

Ashley Magee, DVM, DACVS, gives a play by play analysis of a cat’s wounds and how they healed through a combination of different bandage types, antibiotics, surgical intervention, and great nursing care.

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Management of patients with traumatic wounds is a common and often challenging situation. The injuries must be immediately assessed and a treatment plan made taking into account any comorbidities the patient may be experiencing. This may be as simple as clipping, cleaning and closing lacerations, but often wound care can be much more complex, requiring multiple surgical and medical procedures, prolonged recuperation time, and significant emotional and financial investment by the owner. To further complicate matters, in some wounds the full extent of tissue contamination or damage may not be apparent for several days, clouding the veterinarian’s ability to make an accurate prognosis and treatment plan for the patient. In other cases, a dramatic looking wound may seem overwhelming to treat, but if given the right wound healing environment, it may heal surprisingly well. The following case illustrates some of these points.

A 1 year old male DLH was referred to DoveLewis for evaluation and treatment of wounds to the right hind distal limb and foot resulting from an unwitnessed outdoor traumatic incident. During initial treatment, radiographs of the patient did not reveal any bony or ligamentous instability or fractures, but there was concern for viability of the foot and potential need for amputation.

The cat was evaluated in the ER where his wounds were extensively lavaged and a wet to dry bandage placed. He was started on intravenous antibiotics, fluids, and pain medication and transferred to the ICU for continued hospitalization. The following morning he was sedated for a surgical consult. The entire crus was markedly edematous and bruised. An inverted U-shaped wound, approximately 2 cm in length was present just above the metatarsal pad and the pad was avulsed from underlying attachments. The wound extended to the abaxial aspects of digits 2 and 5 and the skin was avulsed from its attachments to the toes with minimal bleeding appreciated. No bone was exposed, no ligamentous or tendinous laxity was appreciated, and no crepitus was detected. Digits 3 and 4 were markedly edematous. All pads had blistered superficial epithelium. The skin over the dorsum of the metatarsus and foot did not appear to be attached to underlying soft tissue and was cool to the touch. Assessment of the wounds at that time was that open wound management was necessary until several questionable skin areas could be confirmed viable and granulation tissue be allowed to form in the defect under the metatarsal pad. The client was advised that the foot did appear salvageable but several days of hospitalization would be required followed by outpatient wound management, bandaging, and strict confinement for approximately four weeks.

The cat was treated in the hospital for three days with bandage changes and debridements as needed every 12–24 hours along with pain medications and broad spectrum antibiotics. Wound care included sedation, peripheral cleaning with dilute chlorhexidene solution, lavage with warm sterile saline, and debridement of any devitalized tissue or foreign material. Wounds were treated with a combination of sugar and honey for osmotic and antibacterial effects, and then covered with a non-adherent foam dressing and a full limb soft padded bandage. After the initial three days, exudation had decreased and granulation tissue began to fill the open areas of the defect under the metatarsal pad, but edema of the limb and bruising was still significant.

three days post injury

three days post injury

three days post injury

The cat was reevaluated two days after discharge from the hospital (five days post injury) as an outpatient. At bandage change it was apparent the skin of the dorsum of the foot and several digits was non-vital. He was sedated and the dead skin debrided.

five days post injury

five days post injury

Three days later the wound was reexamined and healthy appearing granulation tissue was present in all wound beds with minimal additional skin necrosis. The wounds were lightly debrided, lavaged and bandaged. Osmotic dressings were discontinued and the wounds dressed with triple antibiotic ointment.

eight days post injury

eight days post injury

By 13 days post injury, the wounds were filled with healthy granulation tissue and the wound beds on the dorsum of the foot and under the metatarsal pad were starting to contract. The edema of the limb was resolved but the digits 3 and 4 were persistently swollen. Small areas of superficial epithelium were still discolored.  The bandage change interval was increased to every five days.

thirteen days post injury

By 26 days post injury, the wounds were significantly contracted allowing removal of the bandage. Exercise was gradually increased over the next weeks.

At two months post injury, the cat was seen for a courtesy recheck. All wounds had healed and his foot was fully functional despite significant loss of the metatarsal pad.

 

sixty days post injury

sixty days post injury

This case illustrates some of the challenges and rewards of managing traumatic wounds. Initially, the only large open defect was the inverted U-shaped wound avulsing the central pad, while irreversible damage to the skin of the metatarsus and digits took several days to become certain.  While aggressive debridement of questionable skin could have been initiated at the beginning of wound management, loss of excessive skin over a distal extremity may have resulted in the need for reconstructive surgery to close the defect. By managing the wound with serial conservative debridements, all surrounding viable skin was preserved and led to a successful outcome of healing by second intention in a reasonable amount of time. If aggressive debridement had been undertaken, the skin of the digits would likely have been removed along with the metatarsal skin and reconstruction with a flap or free graft would have been needed to cover the resulting defect. Despite persistent discoloration, the digital skin did survive and its presence was a significant contributor to epithelialization and contraction of the wounds.

Treatment with an osmotic dressing of sugar and honey was chosen for its minimal negative effects on vital tissue, ability to draw edema and exudates from the wound, promotion of granulation tissue and antibacterial effects. A combination of the two substances was used to create more of a paste that would stay on the wound beds better than honey alone.  Osmotic dressings were used until the wound bed appeared healthy and minimal debridement was necessary.

Non-adherent foam dressing (COPA™, Kendall Inc.) is a non-occlusive bandage material that allows creation of a wound environment optimal for selective debridement of non-vital tissue. Since the foam is non-adherent it decreases damage to developing capillaries and fibroblast networks in the wound when it is removed, a problem with standard gauze wet to dry dressings that non-selectively remove the adhered outer layer of the wound at removal. The material is superior to gauze pads in drawing and holding exudates away from the wound, allowing for less frequent bandage changes.

While not available at DoveLewis at the time of this patient’s hospitalization, vacuum assisted wound therapy (VAC) could have been used during the initial three days of hospitalization in order to facilitate debridement and may have promoted salvage of the undermined skin on the dorsum of the foot by allowing it to re-adhere to the underlying tissues and regain blood supply. One debridement followed by 72 hours of continuous VAC therapy would have replaced the sedations and bandage changes every 12- 24 hours in the initial three days of hospitalization.

Many modalities are available for management of veterinary patients with complex wounds, and all can be successful when used appropriately. This case study demonstrates success with selective debridement and open wound management for salvage of a cat’s hind foot.

References:
Pavletic, Michael M.: Atlas of Small Animal Wound Management and Reconstructive Surgery, Third Edition, Wiley-Blackwell, 2010

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