Animal Bites

Animal bite can result in simple wounds or life-threatening wounds infection.

Cause

Most animal bites are from dogs. Cat bites are the second most common cause of bites. The risk of infection from a cat bite is much higher than a bite from a dog. The other possible bites are snake bites and monkey bites.
A major concern about an animal bite is the possibility of rabies. Dog bites are the most common source of rabies.

Symptoms

Even if a bite does not break the skin, it may cause crushing and tearing injury to underlying bone, muscles, tendons, ligaments and nerves. If the skin is broken, there is the additional possibility of infection.
Signs of an infection include:

• Warmth around the wound
• Swelling
• Pain
• Discharge of pus
• Redness around a puncture wound
• Skin inflammation
• Lymph gland swelling
• Rabies and cat scratch fever

Signs of damage to tendons or nerves include:

• An inability to bend or straighten the finger
• A loss of feeling over the tip of the finger

Immediate First Aid

The bitten area should not be put into the mouth. The mouth contains bacteria, which can cause infection.

For Superficial Wounds

The area should be washed thoroughly with soap and water or an antiseptic, such as hydrogen peroxide or alcohol. An antibiotic ointment should be applied and the wound should be covered with a nonstick bandage.
The area should be watched carefully for signs of damaged nerves or tendons. Some bruising may develop. The wound should heal within a week to 10 days. If it does not, or if there are signs of infection or damage to nerves and tendons, medical help should be sought.

Presence of Bleeding

Direct pressure should be applied to the area using a clean dry cloth and the area should be elevated. If an area is not actively bleeding, it should not be cleaned. The wound should be covered with a clean sterile dressing and medical attention should be sought.
If the wound is to the face, head or neck, medical help should be sought immediately.

Snakebite

Snakes are cold-blooded. Thus, they are unable to increase their body temperature and stay active when it is cold outside. They are most active at 25-32°C .

During the bite that injects venom or poison, the venom passes from the venom gland through a duct into the snake's fangs, and finally into its prey. Snake venom is a combination of numerous substances with varying effects. In simple terms, these proteins can be divided into 4 categories:

• Cytotoxins cause local tissue damage.
• Hemotoxins cause internal bleeding.
• Neurotoxins affect the nervous system.
• Cardiotoxins act directly on the heart.
• 8000 are venomous snakes.
• Which snakes bite: Two major families of snakes account for most venomous snakes dangerous to humans.They are Cobras and the Vipers.

Snakebite Symptoms

Bites by venomous snakes result in a wide range of effects, from simple puncture wounds to life-threatening illness and death. The findings following a venomous snakebite can be misleading. A victim can have no initial significant symptoms, and then suddenly develop breathing difficulty and go into shock.
Signs and symptoms of snake poisoning can be broken into a few major categories:

• Local effects: Bites by vipers and some cobras are painful and tender. They can be severely swollen and can bleed and blister. Some cobra venoms can also kill the tissue around the site of the bite.
• Bleeding: Bites by vipers can cause bleeding of internal organs such as the brain or bowels. A victim may bleed from the bite site or bleed spontaneously from the mouth or old wounds. Unchecked bleeding can cause shock or even death.
• Nervous system effects: Venom from certain snakes affect nervous system directly. The venom can act particularly quickly by stopping the breathing muscles, resulting in death without treatment. Initially, victims may have vision problems, speaking and breathing trouble, and numbness.
• Muscle death: Venom from certain snakes can directly cause muscle death in multiple areas of the body. The debris from dead muscle cells can clog the kidneys, which try to filter out the proteins. This can lead to kidney failure.
• Eyes: Spitting cobras can actually eject their venom quite accurately into the eyes of their victims, resulting in direct eye pain and damage.

When to Seek Medical Care?

Any snakebite victim should go to a hospital emergency department unless the snake is positively identified as nonvenomous. Remember, misidentification of the snake species could be a fatal error.
Bites by nonvenomous species require good wound care. Victims should receive a tetanus booster if they have not had one within the last 5 years.

Prevention of Rabies

Transmission

The rabies virus can penetrate broken skin and intact mucosa. Humans are usually infected by bites from rabid animals. Inhalation of the virus as a mode of transmission among cave dwelling bats has been reported from South America. Transmission of rabies through corneal transplants has also been reported in recent literature.

Pathogenesis

Virus inoculated through a bite multiplies locally in muscle fibers. It accumulates in neuromuscular and neurotendinal spindles and, after an uncertain interval of days or weeks, gains access to the peripheral nerves. Finally, it moves to the CNS where it spreads through the CSF. After entering the peripheral nerve, the rabies virus is inaccessible to hum oral defenses (antibodies) except perhaps at the dorsal root ganglion.

Clinical Features

The incubation period varies from 4 days to several years. However, I average between 30-90 days in 90 % of cases. The incubation period tends to be shorter in cases of bites on face (average 35 days) as against those on limbs (average 52 days).

Symptoms

Furious or frank rabies: This is the most common form of rabies, where high motor activity, tremors, spasms and shortness of breath are observed. Due to the spasms in the gullet, it becomes impossible for the patient to swallow. (Hydrophobia).followed by aerophobia and increased salvation.

Paralytic or Dumb Rabies: This form of rabies occurs in 1/5^th of the cases. Noticeable symptoms include flaccid paralysis of the limbs, starting with bitten limb. Dumb rabies often gets misdiagnosed as a case of encephalitis.

Rabies Frequently Asked Questions

What is rabies and how is it transmitted?

• Rabies is a preventable viral disease. The rabies virus infects the central nervous system and causes disease in the brain. There is no effective treatment and once symptoms start, death is inevitable. The rabies virus is transmitted from infected animals to humans through scratches, bites, or licks on mucous membranes of the lips or eyes. The virus cannot be transmitted through intact skin, so touching, petting or being close to the animals is not a risk. In addition to dogs, many other animals can transmit rabies. In South Africa, these most importantly include: cats, cattle, bats and mongoose.

Can rabies be prevented?

Yes! By following a few easy steps:

• Vaccinate your pets: You should ensure that your dogs and cats are regularly vaccinated against rabies - it is a legal requirement. Dogs and cats should be given vaccine at 3 months of age, a booster within the following 9 months, and every 3 years thereafter. In high risk areas, yearly vaccinations are recommended. If you are not sure if your pet has been vaccinated, when your pet last received a vaccine, or if overdue for a vaccine then visit your local veterinarian immediately.
• Avoid being bitten: Not every bite poses a risk of rabies, but a bite or scratch from a stray animal, sick animal, an animal that is behaving strangely, or an unprovoked attack would suggest a rabies risk. Never handle stray animals or animals that appear sick.

If exposed to a suspected rabid animal

• Wash the wound: Washing of the wound very well for at least 10 minutes with water or soap and water to wash out the virus.
• Seek treatment early if exposed: Rabies can be prevented in almost 100% of human cases if correct preventative treatment is given timely after being exposed to suspected rabid animals. Visit your doctor as soon as possible. The doctor will asses your risks and, if required, will give a course of rabies vaccinations. In certain instances, you may also require rabies immunoglobulin to be injected into the wounds.

What are the symptoms and signs of rabies disease?

• In humans: The first symptoms of rabies are flu-like, including fever, headache and fatigue, which then progresses to involve the respiratory, gastrointestinal and/or central nervous systems. There may be signs of hyperactivity (‘furious’ rabies) or paralysis (‘dumb’ rabies). In both furious and dumb rabies, there is progressive paralysis, followed by coma. Death occurs during the first seven days of illness.
• In animals: Rabid animals behave abnormally. They may show a lack of fear, be aggressive, seem disoriented, paralyzed or partially paralyzed (particularly in the hind quarters), and salivate excessively, or they may show none of these symptoms. An infectious rabid animal may be healthy in appearance and behaviour for a period of time prior to the onset of clinical rabies.

How is rabies diagnosed?

• In animals, rabies is diagnosed using a test which looks for the presence of rabies virus in brain tissue. In humans, several tests are available to confirm rabies disease once a person becomes ill; however, there are no tests which can detect if rabies has been transmitted from exposure to a rabid animal before a person becomes ill.

Who is most at risk?

• People most at risk of rabies live in rural areas of Africa and Asia, where access to healthcare and animal health facilities is limited, stray dogs are more common, and fewer pets are regularly vaccinated against rabies. Children are at the highest risk of dog rabies; about 30% to 60% of the victims of dog bites are children less than 15 years of age, and children often play with animals and are less likely to report bites or scratches. In areas known for rabies, persons with frequent exposure to animals (e.g. veterinarians or animal health workers, wildlife specialists or researchers) are also at high risk.

Is there immunization against rabies?

• Yes, there is an effective, safe vaccine against rabies. Certain groups of people at higher risk of being exposed to rabid animals should consider vaccination to protect themselves: Those who work with animals (including veterinarians, animal health workers, conservationists, zoologists etc). Travellers who are planning to visit remote areas where there is a risk of rabies, and medical care is difficult to obtain or may be delayed (for example, hiking through remote villages where dogs are common). Although vaccination does not eliminate the need for additional therapy after a rabies exposure, it simplifies management by eliminating the need for anti- rabies immune globulin and decreasing the number of doses of vaccine needed.

Things to remember

• Rabies can be caused by bite or scratch of rabid animal such as dogs, cats etc
• Do not apply chillies, mustard oil or any other irritant on the bite wounds
• Wash the wound immediately with plenty of soap & water
• Do not apply dressing & Do not get the wound stitched
• Consult your doctor immediately or rush to nearest antirabies clinic
• Complete the course of antirabies vaccination, as advised by your doctor
• Vaccinate your pets against rabies every year

Source: Portal Content Team

Related Resources

1. National Guidelines on Rabies Prophylaxis