Animal bite | |
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Military working dog training to attack by biting | |
Specialty | Emergency medicine |
An animal bite is a wound, usually a puncture or laceration, caused by the teeth. An animal bite usually results in a break in the skin but also includes contusions from the excessive pressure on body tissue from the bite. The contusions can occur without a break in the skin. Bites can be provoked or unprovoked. Other bite attacks may be apparently unprovoked. Biting is a physical action not only describing an attack but it is a normal response in an animal as it eats, carries objects, softens and prepares food for its young, removes ectoparasites from its body surface, removes plant seeds attached to its fur or hair, scratching itself, and grooming other animals. Animal bites often result in serious infections and mortality. Animal bites not only include injuries from the teeth of reptiles, mammals, but fish, and amphibians. Arthropods can also bite and leave injuries.
Bite wounds can cause a number of signs and symptoms
Bites are usually classified by the type of animal causing the wound. Many different animals are known to bite humans.
Involuntary biting injuries due to closed-fist injuries from fists striking teeth (referred to as reverse bite injuries) are a common consequence of fist fights. These have been termed "fight bites". Injuries in which the knuckle joints or tendons of the hand are bitten into tend to be the most serious.
Teething infants are known to bite objects to relieve pressure on their growing teeth, and may inadvertently bite people's hands or arms while doing so. Young children may also bite people out of anger or misbehaviour, although this is usually corrected early in the child's life.
A reverse bite injury (also called a clenched fist injury, closed fist injury, or fight bite) results when a person punches another person in the face, and the skin (and sometimes tendons) of their knuckles are cut against the teeth of the person they are punching. [2] The proximity of the wound is often located over the metacarpophalangeal joint resulting in tendon injury. [3]
The medical treatment of this injury is similar to those of a human bite, but may also involve damage of the underlying tendons. [4]
These injuries should be managed as other human bites: wound irrigation and antibiotics are essential as human saliva can contain a number of bacteria. [5] The nature of these injuries is such that even if the injury is optimally managed, poor outcomes may still occur. [2]
The bites of arthropods have some of the most serious health consequences known. Mosquito bites transmit serious disease and result in millions of deaths and illnesses in the world. Ticks also transmit many diseases such as Lyme disease.
A natural consequence of a bite is tissue trauma at the site. Trauma may consist of scratching, tearing, punture or laceration of the skin, hematoma (bruising), embedding of foreign objects, for example a tooth or hair, damage to or severing of underlying structures such as connective tissue or muscle, amputations, and the ripping off of skin and hair. If major blood vessels are damaged, severe blood loss can occur. [6]
Pathogen organisms can be introduced into the bite. Some of the pathogens can originate from the mouth of the 'biter', the substrate onto which the injured person or animal can fall or from the naturally occurring microorganisms that are present on the skin or hair of the animal. The advent of antibiotics improved the outcome of bite wound infections. [6]
Animal bites where skin has been penetrated, most commonly by dogs and bats, transmit rabies to humans. [7] Rabies from other animals is rare. [7] If the animal is caught alive or dead with its head preserved, the head can be analyzed to detect the disease. Signs of rabies include foaming at the mouth, growling, self-mutilation, jerky behavior, red eyes, and hydrophobia.
If the animal cannot be captured, preventative rabies treatment is recommended in many places. Several countries are known not to have native rabies, see the Wikipedia page for prevalence of rabies.
The first step in treatment includes washing the bite wound. [8] If there is a low risk of infection the wound may be sutured. [8] Debridement and drainage of bite wounds was practiced in the pre-antibiotic era, but high rates of infection still occurred. A 2019 Cochrane systematic review aimed to evaluate the healing and infection rates in bite wounds based on if/when they were stitched closed. The review authors looked for studies that compared stitching wounds closed straight away, leaving them open for a short time or not stitching them at all. Due to a lack of high-certainty evidence, the review authors concluded that more robust randomised controlled trials were needed to fully answer this question. [9]
Antibiotics to prevent infection are recommended for dog and cat bites of the hand, [10] and human bites if they are more than superficial. [11] They are also recommended in those who have poor immune function. [8] Evidence for antibiotics to prevent infection in bites in other areas is not clear. [12]
The first choice is amoxicillin with clavulanic acid, and if the person is penicillin-allergic, doxycycline and metronidazole. [11] The antistaphylococcal penicillins (e.g., cloxacillin, nafcillin, flucloxacillin) and the macrolides (e.g., erythromycin, clarithromycin) are not used for empirical therapy, because they do not cover Pasteurella species. [11]
Rabies prevention is generally available in North America and the Northern European states.
Tetanus toxoid treatment is recommended in those whose vaccinations are not up to date and have a bite that punctures the skin. [8] Tetanus immune globulin is indicated in people with more than 10 years since prior vaccination. Tetanus boosters (Td) should be given every ten years.
Prior toxoid | Clean minor wounds | All other wounds |
< 3 doses | TT: yes, TIG: no | TT: yes, TIG: yes |
≥ 3 doses | TT: if last dose ≥ 10yr TIG: no | TT: if last dose ≥ 5yr, TIG: no |
TT = tetanus toxoid; TIG: tetanus immune globulin
Antihistamines are effective treatment for the symptoms from bites. [13] Many diseases such as malaria and dengue are transmitted by mosquitoes.
Human bites are the third most frequent type of bite after dog and cat bites. [6] Dog bites are commonplace, with children the most commonly bitten and the face and scalp the most common target. [14] About 4.7 million dog bites are reported annually in the United States. [15] The US estimated annual count of animal bites is 250,000 human bites, 1 to 2 million dog bites, 400,000 cat bites, and 45,000 bites from snakes. Bites from skunks, horses, squirrels, rats, rabbits, pigs, and monkeys may be up to 1 percent of bite injuries. Pet ferrets attacks that were unprovoked have caused serious facial injuries. Non-domesticated animals though assumed to be more common especially as a cause of rabies infection, make up less than one percent of reported bite wounds. When a person is bitten, it is more likely to occur on the right arm, most likely due to defensive reactions when the person uses their dominant arm. Estimates are that three-quarters of bites are located on the arms or legs of humans. Bites to the face of humans constitute only 10 percent of the total. Two-thirds of bite injuries in humans are suffered by children aged ten and younger. [6]
Up to three-fourths of dog bites happen to those younger than 20 years-old. In the United States, the costs associated with dog bites are estimated to be more than $1 billion annually. The age groups that suffer most from dog bites are children 5 to 9 years-old. Often, bites go unreported and no medical treatment given - these bites go unreported. As many as one percent of pediatric emergency room visits are for treatment for animal bites. This is more frequent during the summer months. Up to five percent of children receiving emergency care for dog bites are then admitted to the hospital. Bites typically occur in the late afternoon and early evening. Girls are bitten more frequently by cats than they are by dogs. Boys are bitten by dogs two times more often than girls are bitten by dogs. [6]
The bites of humans are recorded during the biblical era. Reports of secondary infection occurring after a human bite in children have been noted in the United States since at least 1910. Morbidity and mortality rates improved with the use of antibiotics. [6]
Septicemic plague is one of the three forms of plague, and is caused by Yersinia pestis, a gram-negative species of bacterium. Septicemic plague is a systemic disease involving infection of the blood and is most commonly spread by bites from infected fleas. Septicemic plague can cause disseminated intravascular coagulation and is always fatal when untreated. The other varieties of the plague are bubonic plague and pneumonic plague.
Post-exposure prophylaxis, also known as post-exposure prevention (PEP), is any preventive medical treatment started after exposure to a pathogen in order to prevent the infection from occurring.
Dirofilaria immitis, also known as heartworm or dog heartworm, is a parasitic roundworm that is a type of filarial worm, a small thread-like worm, that causes dirofilariasis. It is spread from host to host through the bites of mosquitoes. There are four genera of mosquitoes that transmit dirofilariasis, Aedes, Culex, Anopheles, and Mansonia. The definitive host is the dog, but it can also infect cats, wolves, coyotes, jackals, foxes, ferrets, bears, seals, sea lions and, under rare circumstances, humans.
Rat-bite fever (RBF) is an acute, febrile human illness caused by bacteria transmitted by rodents, in most cases, which is passed from rodent to human by the rodent's urine or mucous secretions. Alternative names for rat-bite fever include streptobacillary fever, streptobacillosis, spirillary fever, bogger, and epidemic arthritic erythema. It is a rare disease spread by infected rodents and caused by two specific types of bacteria:
The health of dogs is a well studied area in veterinary medicine.
Ear mites are mites that live in the ears of animals and humans. The most commonly seen species in veterinary medicine is Otodectes cynotis. This species, despite its name, is also responsible for 90% of ear mite infections in felines.
A dog bite is a bite upon a person or other animal by a dog, including from a rabid dog. More than one successive bite is often called a dog attack, although dog attacks can include knock-downs and scratches. Though some dog bites do not result in injury, they can result in infection, disfigurement, temporary or permanent disability, or death. Another type of dog bite is the "soft bite" displayed by well-trained dogs, by puppies, and in non-aggressive play. Dog bites can occur during dog fighting, as a response to mistreatment, by trained dogs working as guard, police or military animals, or during a random encounter.
Veterinary surgery is surgery performed on animals by veterinarians, whereby the procedures fall into three broad categories: orthopaedics, soft tissue surgery, and neurosurgery. Advanced surgical procedures such as joint replacement, fracture repair, stabilization of cranial cruciate ligament deficiency, oncologic (cancer) surgery, herniated disc treatment, complicated gastrointestinal or urogenital procedures, kidney transplant, skin grafts, complicated wound management, and minimally invasive procedures are performed by veterinary surgeons. Most general practice veterinarians perform routine surgeries such as neuters and minor mass excisions; some also perform additional procedures.
The health of domestic cats is a well studied area in veterinary medicine.
Rabies is a viral disease that causes encephalitis in humans and other mammals. It was historically referred to as hydrophobia due to the symptom of panic when presented with liquids to drink. Early symptoms can include fever and abnormal sensations at the site of exposure. These symptoms are followed by one or more of the following symptoms: nausea, vomiting, violent movements, uncontrolled excitement, fear of water, an inability to move parts of the body, confusion, and loss of consciousness. Once symptoms appear, the result is virtually always death, regardless of treatment. The time period between contracting the disease and the start of symptoms is usually one to three months but can vary from less than one week to more than one year. The time depends on the distance the virus must travel along peripheral nerves to reach the central nervous system.
Wound licking is an instinctive response in humans and many other animals to cover an injury or second degree burn with saliva. Dogs, cats, small rodents, horses, and primates all lick wounds. Saliva contains tissue factor which promotes the blood clotting mechanism. The enzyme lysozyme is found in many tissues and is known to attack the cell walls of many gram-positive bacteria, aiding in defense against infection. Tears are also beneficial to wounds due to the lysozyme enzyme. However, there are also infection risks due to bacteria in the mouth.
Almost all human deaths caused by rabies occur in Asia and Africa. There are an estimated 59,000 human deaths annually from rabies worldwide.
In animals, rabies is a viral zoonotic neuroinvasive disease which causes inflammation in the brain and is usually fatal. Rabies, caused by the rabies virus, primarily infects mammals. In the laboratory it has been found that birds can be infected, as well as cell cultures from birds, reptiles and insects. The brains of animals with rabies deteriorate. As a result, they tend to behave bizarrely and often aggressively, increasing the chances that they will bite another animal or a person and transmit the disease.
Streptococcus canis is a group G beta-hemolytic species of Streptococcus. It was first isolated in dogs, giving the bacterium its name. These bacteria are characteristically different from Streptococcus dysgalactiae, which is a human-specific group G species that has a different phenotypic chemical composition. S. canis is important to the skin and mucosal health of cats and dogs, but under certain circumstances, these bacteria can cause opportunistic infections. These infections were known to afflict dogs and cats prior to the formal description of the species in Devriese et al., 1986. However, additional studies revealed cases of infection in other mammal species, including cattle and even humans. Instances of mortality from S. canis in humans are very low with only a few reported cases, while actual instances of infection may be underreported due to mischaracterizations of the bacteria as S. dysgalactiae. This species, in general, is highly susceptible to antibiotics, and plans to develop a vaccine to prevent human infections are currently being considered.
A splinter is a fragment of a larger object, or a foreign body that penetrates or is purposely injected into a body. The foreign body must be lodged inside tissue to be considered a splinter. Splinters may cause initial pain through ripping of flesh and muscle, or infection through bacteria on the foreign object.
Animal attacks are violent attacks caused by non-human animals against humans, one of the most common being bites. These attacks are a cause of human injuries and fatalities worldwide. According to the 2012 U.S. Pet Ownership & Demographics Sourcebook, 56% of United States citizens owned a pet. In the United States in 1994, approximately 4.7 million people were bitten by dogs. The frequency of animal attacks varies with geographical location, as well as hormonal secretion. Gonad glands found on the anterior side of the pituitary gland secrete androgens and estrogens hormones. Animals with high levels of these hormones, which depending on the species can be a seasonal occurrence, such as during rutting season, tend to be more aggressive, which leads to a higher frequency of attacks not only to humans but among themselves. In the United States, a person is more likely to be killed by a domesticated dog than they are to die from being hit by lightning according to the National Safety Council.
A feline zoonosis is a viral, bacterial, fungal, protozoan, nematode or arthropod infection that can be transmitted to humans from the domesticated cat, Felis catus. Some of these diseases are reemerging and newly emerging infections or infestations caused by zoonotic pathogens transmitted by cats. In some instances, the cat can display symptoms of infection and sometimes the cat remains asymptomatic. There can be serious illnesses and clinical manifestations in people who become infected. This is dependent on the immune status and age of the person. Those who live in close association with cats are more prone to these infections. But those that do not keep cats as pets are also able to acquire these infections because of the transmission can be from cat feces and the parasites that leave their bodies.
Cat bites are bites inflicted upon humans, other cats, and other animals by the domestic cat. Data from the United States show that cat bites represent between 5–15% of all animal bites inflicted to humans, but it has been argued that this figure could be the consequence of under-reporting as bites made by Felis catus are considered by some to be unimportant. Though uncommon, cat bites can sometimes cause Rabies lead to complications and, very rarely, death.
A monkey bite is the bite of a monkey and is the second most common animal bite after dogs in India. Monkey bites account for 2–21% of animal bite injuries. Monkey bites are an important risk among travelers and after dog bites is the most common animal bite for travelers. Treatment depends upon many factors including the suspicion of rabies. Management involves: