Bite wounds are among the more common injuries seen by veterinarians. The severity of these injuries can be very deceptive. Some bite wounds are relatively minor in nature, requiring limited wound care. Other wounds can appear minor from external examination, but the amount of tissue destruction can be massive. Complete examination of the patient and early surgical/medical intervention are critical to bite wound management.

Emergency Assessment

Most bite wounds seen by a veterinarian are not life-threatening injuries, upon presentation. A careful physical examination and a complete history are useful in assessing the patient: location of bite wounds can be problematic in dogs and cats with long hair coats. Unstable patients will require emergency supportive therapy to ensure the airway is intact, the patient is breathing satisfactorily and the circulatory system is maintained. Blood samples (complete blood count, serum chemistry profile) and a urine sample are taken to establish a baseline for subsequent comparison of future samples in these critical patients. Radiographs and other diagnostic techniques may be advisable to assess thoracic and abdominal trauma, as well as possible orthopaedic and neurological injuries. Careful examination and palpation of the patient are useful for identifying muscle tears, hernias and damage to structures beneath the skin. Lastly, consider the body region(s) bitten, and the underlying anatomical structures in the path of the teeth. The canine teeth of many animals can penetrate deep into the body, as tissues are compressed or crushed between the dental arcades. For example, lumbar bite wounds in small dogs and cats may penetrate the underlying kidneys; shaking of a small animal may result in fractures of the spinal column or extremities.

Depth of Tissue Injury

Clipping of the fur coat is needed to better assess bite wounds. Teeth do not always perforate the skin. Indentations or tangential abrasions may be noted on examination, whereas other wounds may be obvious perforations or lacerations of the skin and underlying tissue. It is again important to note that deeper tissue compression/crushing may occur despite the fact the canine teeth have not breached the skin surface. Careful palpation may reveal rents in the musculature and other underlying structures. Radiographs and ultrasound examination may help determine the integrity of the underlying tissues. If vital organs or tissue structures may be jeopardised, surgical exploration is warranted. Clinical examples seen by the author include: tears to the diaphragm and mesenteric vasculature from compressive abdominal bite wounds without open skin wounds; intact cervical skin with a perforation of the trachea (palpable) causing regional emphysema.

Temporary Wound Care

In unstable patients, initial wound management can be accomplished by clipping, cleansing and lavaging the puncture wounds. A small haemostat can be used to gently spread the puncture wound open sufficiently to allow ingress/egress of saline lavage solution. A sterile dressing can be applied to the area. Intravenous broad-spectrum antibiotics should be instituted as early as possible. Definitive wound care can be undertaken once patient stabilisation is accomplished.

Bite Wound Exploration

Administration of an intravenous broad-spectrum antibiotic, such as cephalexin, should be initiated as soon as possible. In some situations, the injuries sustained may require emergency surgical intervention after institution of emergency medical support. In more stable patients, general anaesthesia is administered, followed by wound prep-aration/exploration. Areas surrounding bite wounds are best clipped of fur liberally; seemingly small wounds may require substantially greater exploration than originally anticipated. Extensive bite wounds entering the abdomen must be explored. In most cases, bite wounds that have penetrated the thoracic cavity are best explored to preclude the risk of infection secondary to extensive soft tissue trauma. Pneumothorax is a concern if air has an external pathway into the chest; laceration to the lung also may be present. In short, the chest should be prepared for the possibility of thoracotomy unless the wounds are clearly of a more superficial nature. Deep penetrating wounds to the neck also may require exploration: perforation of the oesophagus, trachea and pharynx are occasionally noted, especially in smaller dogs and cats attacked by larger animals.

The initial surgical approach to puncture bite wounds is to grasp the puncture wound and resect it with a scalpel blade. This small hole will give you visual access to the underlying hypodermis and muscle. If needed, a linear incision can be made over the puncture for more detailed examination/debridement of the underlying tissues. A single incision can be used to connect two adjacent penetrating wounds. Debridement and lavage are performed: vacuum drains often are ideally suited for postoperative drainage of the traumatised area(s).

Skin can be difficult to assess for viability after extensive injury; it is largely dictated by the severity of circulatory compromise. In body areas where there is an ample amount of loose skin, more aggressive debridement can be performed. However, a more conservative approach is advisable for lower extremity injuries, until it is apparent which area(s) will undergo necrosis. Other lectures will discuss wound closure options for skin defects.

The keys to preventing or controlling infection in serious bite wounds include:

 Removal of devitalised tissue as early as possible

 Prompt intravenous (broad-spectrum) antibiotic therapy

 Establishment of effective wound drainage

References

1.  Pavletic MM. Atlas of Small Animal Wound Management and Reconstructive Surgery. 3rd ed. Ames, Iowa: Wiley-Blackwell, 2010.