12 Bite Injuries

Introduction

There are two immediate issues to be addressed when examining an animal with possible bite injuries. The first is to decide whether the lesions are the result of bites. The second is the differentiation of dog bite injury from that caused by other predators such as foxes, cats (large or small), ferrets, otters, badgers, mink, stoats, etc.

Some of the features that help decide which species may have inflicted the injuries are common sense. For example, the relative sizes of the predator and the victim are important. Thus, it would be extremely unlikely that a European otter would attack a Texel ram by biting it over the shoulder blades. Distribution of puncture marks may also give clues to the attacker. Cats commonly kill by biting the neck and head to immobilise the prey quickly and prevent struggling. This is particularly true if the victim is relatively large. Stoats show similar tactics when killing birds, chicks being wounded over the sternum and furculum (wishbone) whereas bigger birds are bitten on the head and neck.¹ Dogs, however, bite whatever they can.

Other useful clues to predator type include estimates of the size of the mouth, calculated by measuring the intercanine distance of ‘bite pairs’. This is straightforward if the investigation requires a distinction to be made between a ferret and a Doberman pinscher. It is less easy if there is an overlap in jaw size, as occurs, for example, with a ferret to a young cat.¹

The anatomy of the teeth and the biting process influence the marks left. The sharp canine teeth of the cat readily cause distinct puncture wounds, but the relatively blunt teeth of the dog do not penetrate skin so easily. Although foxes are often considered to have sharper pointed canine teeth than dogs, care should be taken in attempting to differentiate fox-bite marks from those of similarly sized dogs. Other clues (e.g. witness accounts, claw marks, footprints, and clear evidence of predation rather than attack) may be invaluable in assisting with decision-making in these cases.

Dog-bite injuries

From a veterinary perspective, forensic investigations of bite injuries are more commonly related to dog attack than biting by other animals.

Hares

Hares are usually caught and injured by large fast dogs such as greyhounds, Salukis or deerhounds. These dogs hunt by sight, catch up with the fleeing hare, and bite the body.

In a series of 53 hares examined by the Universities Federation for Animal Welfare (UFAW),² 79% suffered abdominal injury, 77% had chest injury and 74% damage to the hind limbs. Research commissioned by the Hunting with Dogs Inquiry in England showed somewhat similar results with 75% of hares with chest injuries, 41% with abdominal damage and 58% with significant bites to the hind limbs.³

Detailed examination in the authors’ laboratories of seven hares, each killed on separate occasions by greyhounds or lurchers, revealed that the external appearance of these hares was highly misleading. Cursory examinations revealed only leakage of blood from the nostrils and irregular loss of hair from the hind limbs. No punctures of the skin were present despite massive injury to the chest and abdomen. From a forensic viewpoint, it is essential that thorough post-mortem examination is conducted and that reliance is not placed on the lack of obvious bite marks.

Chest injuries

Chest injuries consist of fractures of multiple ribs, irregular holes in the chest wall (Fig. 12.1) (often associated with the fractured ends of ribs), emphysema in the chest wall, puncture wounds and laceration of the lungs, haemothorax and, occasionally, puncture wounds to the heart. The sternum and the spinous processes of the thoracic vertebrae may be fractured during these attacks. These major thoracic injuries are accompanied by extensive subcutaneous and intramuscular haemorrhage over the chest walls, shoulder and back (Fig. 12.2).