Pets Gone Wild: A Review of Animal Attacks

October 1, 2014

By Thomas Lee

Peer Reviewed

The age-old question that every one of us has been asked at least once: Are you a cat or a dog person? The answer is subjective, as both choices depend on a person’s values, preferences, and lifestyle. A different question, and perhaps a more objective one is: Which would you rather be bitten by? With news stories of pit bull attacks, the common sight of German shepherd police dogs in New York, and the relatively benign appearance of most domesticated felines, many might spring to answer with the cat. However, the data suggest a more nuanced response.

Animal bites are extremely common: an estimated 2-5 million occur each year in the United States alone. Dogs represent the overwhelming majority of attacks at 90%, cats a distant second at 5%, and rodents pulling up in third with 2-3%[1]. Around 20 deaths in the US can be attributed to animal bites each year, along with high morbidity rates in bites around the hand due to the plethora of superficial bones and joints in that area [2]. The most worrisome complications include trauma and infection.

German shepherds, pit bull terriers, and mixed breeds are implicated in most dog bites in the US [3]. Victims, usually males between the ages of 5 and 9, frequently know the dog who attacked them [4]. The animal can inflict a wide range of injuries including scratches, deep cuts, puncture wounds, and crush injuries [5]. Larger dog breeds can cause more severe crush injuries due to their powerful jaws that are able to produce up to 450 pounds per square inch of pressure; this leads to a greater risk of major organ or vessel injury [6]. The head and neck are the most common sites of injury, most likely due to a child’s head being near the level of a larger dog’s mouth [7]. Dog attacks rarely cause death, except in infants [6]. Even so, around 2-5% of all bites will go on to develop a local infection, usually polymicrobial, by common human skin flora and other microorganisms that are part of the dog’s normal flora [8]. Pasteurella is the most common bacteria found in dog bite infections, present in almost 50% of cases, and can cause septic arthritis and osteomyelitis [9]. Capnocytophaga is a part of normal flora in animals that can cause fulminant sepsis and meningitis and is most dangerous in asplenic patients. Brucella may lead to fever with nonspecific symptoms. The rabies virus is capable of causing a lethal viral encephalopathy [5].

Cat injuries can be dangerous as well. Cats can cause painful wounds using their teeth and claws, with bites usually affecting the arms and hands, and scratches common on the face [5]. The rate of deep puncture wounds sets cat injuries apart from most dog bites. A cat’s long, thin, sharp teeth can cause a wound that is difficult to clean properly. This leads to infection rates that have been reported to range from 20-80% [10]. Hand wounds are at even greater risk; one can see rapid redness, swelling, and intense pain as fast as 12-24 hours after a bite [11], with complications including osteomyelitis and abscess formation. The zoonoses are similar to dog attacks, but also include potentially life-threatening Bartonella that causes cat scratch disease. Interestingly, kittens more commonly transmit Bartonella infection than full-grown cats due to their more playful nature and higher propensity to host the organism [12].

Initial management of bites from both animals is identical: stabilize, debride and irrigate, x-ray deep injuries to assess bone or foreign bodies, and dress the wound [13]. Primary intention using sutures is performed to reduce scarring unless the injury is crushing, involves the hands or feet, occurred more than 12 hours ago, or the victim is immunocompromised. If any of the above, general practice dictates simply irrigating and dressing the wound with adequate elevation to allow drainage of the extremity if indicated, and close follow-up [14]. Antibiotic prophylaxis, with the standard of care being amoxicillin-clavulanate for 3-5 days, can be indicated in deep puncture wounds, crush injuries, hand bites, and the immunocompromised [6]. Tetanus and rabies prophylaxis should always be considered as well. One study showed that antibiotic prophylaxis is most effective between 9-24 hours after injury; if the patient is seen and treated within 8 hours, there was no benefit seen [14]. Moreover, some data suggest that antibiotics may only reduce infection rates in injuries to the hand [15]. Regardless, even with prophylactic treatment, cat bites are much more prone to infection than their counterparts [5].

Overall, data show that dog bites are more frequent than cat bites, and can lead to greater initial trauma. However, cat bites have significantly higher infection rates due to the difficulty inherent in cleaning a puncture wound, which leads to high morbidity, particularly in the vulnerable hand. Both should be a rare occurrence. Responsible pet ownership, education, and safety precautions can make a significant impact on the morbidity and mortality of these attacks.

Thomas Lee is a 2nd year medical student at NYU School of Medicine

Peer reviewed  by Thomas Norton, MD, NYU Langone Medical Center

Image courtesy of Wikimedia Commonds


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