Bite Wounds

Please note: Some images of wounds will be presented in this article

We see a significant number of bite wounds, here at Exclusively Cats. Sometimes, the wounds are on indoor/outdoor cats, other times, we find them on stray or feral cats that are brought in for limping. Occasionally, we are called on to treat bite wounds in indoor-only cats - usually after a fight between housemates that got a little out of hand.

Bite wounds often harbor multiple kinds of bacteria

Sometimes, we see the bite wound when it is fresh, and we can prescribe medications and treatments to decrease pain and inflammation, as well as prevent infection. Other times, we see bite wounds after they have become abscesses. An abscess is a pocket of infection that can develop after a wound. This occurs because the canine teeth create small punctures in the skin that do not bleed much. The sharp, conical tooth acts like a needle, injecting bacteria deep into the skin or muscle. Since the wound does not bleed much, the bacteria remain at the bottom of the wound, and when the injury scabs over, a warm, moist area is left behind, which is a great environment for bacterial growth. As the bacteria grow, white blood cells flock to the area to fight the infection. Eventually, there is too much "stuff" (bacteria, diseased tissue, white blood cells and other inflammatory cells) to fit in the puncture wound and the abscess starts to swell. It may be warm to the touch. As it swells, eventually damaged tissue will fail and the abscess will open to the outside and begin to drain. If antibiotics are not started, the wound will scab over again and the process will start anew. 

A bite wound or abscess can happen anywhere on the body, but common locations are on the legs and feet, especially the hind legs, as many cats will get bitten while running away. Other common places to find these wounds are the head and neck, ears, and tail.

If an abscess or bite wound is not obvious due to moist hairs around the wound, or hair loss, you may notice a strong, unpleasant odor - this foul odor is characteristic of  infection. A cat that does not have other obvious signs of a wound may seem painful to the touch, may lick at an area excessively, or may run a fever. Feverish cats often do not have an appetite, so weight loss or disinterest in food can also be signs of a bite wound or abscess. Depending on the location of the wound, you may also note limping, squinting, ear-flicking or the holding of an ear at a strange angle, a reluctance to lie on one side or the other, restlessness, or discomfort when sitting.

Usually, when we are examining a bite wound, we will find a set of 4 wounds (from all four canines), but not all four wounds will be the same severity - some teeth will puncture further than others. Sometimes only one of the four wounds becomes infected. Most of the time, a wound can be flushed and cleaned while the cat is under anesthesia, and then sutured as needed if the wound is large. Warm compresses twice daily will allow the wound to remain open to drain, which will help the wound heal more quickly and prevent the wound from scabbing over and beginning the process all over again. In some cases, the wound is in a location where it can't drain well, and a drain tube will have to be placed. In other cases, the wound has started to heal, but some of the tissue around the wound is too badly infected to recover. In these

This wound required a 12 day stay in the hospital for intensive wound care

cases, the diseased tissue will need to be surgically removed to allow healthy tissue to replace it. This is called "debriding". In extreme cases, there may be enough badly diseased tissue that needs to be removed that the wound cannot be sutured closed and we must use special bandaging techniques to encourage the wound to heal.

An important thing to remember when dealing with bite wounds is that, aside from bacterial infections, other complications can arise from this situation. A cat that has been bitten by another cat will be at high risk for feline-specific viral diseases that can be transmitted through saliva, such as Feline Immunodeficiency Virus (FIV) and Feline Leukemia Virus (FeLV) (although FeLV is more likely to be transmitted by long term contact between two individual cats than a single bite wound, the fact that a cat has obvious contact with other cats outdoors suggests that a bitten cat should be tested for FeLV out of due diligence).  Additionally, a cat that has been bitten by any other mammal - cat, dog, raccoon, fox, bat, etc. runs the risk of rabies exposure. If the animal that bit your cat is known - for example a neighbor's cat or dog, it is a good idea to ask what that pet's vaccination status is. If the animal that bit your cat is unknown, it is recommended to have your cat re-tested for FeLV and FIV about 2 months after the bite wound occurred. In Michigan, if your cat's rabies vaccine is up to date, the bitten cat should be re-vaccinated and observed carefully for 45 days for any signs of illness. If the bitten cat has not been vaccinated for rabies, or the vaccine has lapsed, the situation becomes more complicated, as the choices outlined by the Michigan Department of Community Health are either immediate euthanasia or strict quarantine for 6 months. This is one of the reasons that we emphasize keeping your cat's rabies vaccine current.

Michigan Department of Community Health Rabies Protocol

For more about bite wounds:
Frequently Asked Questions About Bite Wounds
Abscesses From Bite Wounds
Bite Wound Abscesses in Cats

Cuterebra infection: Not really that cute...

Gryffin

Meet Gryffin, a tiny little kitten found wedged between the wall of a gas station and the ice machine. He weighed less than two pounds, and had a wound on his leg. Upon examination by the doctor, it appeared to be a run-of-the mill bite-wound abscess. Once under anesthesia, we were able to take a closer look - clipping up the hair and scrubbing the wound with antiseptic scrub. Bite wound abscesses have a tendency to become infected, so Dr. Brooks removed the scab and flushed the wound. As would be expected, the wound was infected. After cleaning it out, the doctor gently probed the wound and determined that it was clean. We treated Gryffin with pain medication and antibiotics.

But, Gryffin didn't get better. His wound still seemed to bother him, and we examined him again. The wound was free from infection - what could it be? Dr. Brooks commented that it was a remote possibility that it was a Cuterebra breathing pore, but no Cuterebra was found in the wound, and the pores do not scab over while the larvae are inside. It was also an unusual site for a Cuterebra infection, since Cuterebra larvae generally infect the head and neck regions of cats. She decided to satisfy her curiosity non-invasively, by placing the ultrasound probe on Gryffin's leg. This is what she saw:

Ultrasound image of a cuterebra larva

Deep within the wound, far from the scabbed opening, a dead Cuterebra lay - acting essentially like a sliver under the skin, causing irritation and infection and pain. Dr. Brooks was now able to locate the larva and remove it, much to Gryffin's relief! We measured the Cuterebra once it was removed, and determined that it was the biggest one we had ever seen, at 4cm in length.

Cuterebra larva after removal

Cuterebra. It doesn't sound too bad, and usually, they don't cause too much trouble, but Cuterebra larval infection can cause problems for cats.

The Cuterebra larvae are immature bot flies - a large bumblebee sized fly. The adult flies are harmless - in fact, they live for such a short time, they do not even have mouth parts for eating!

Adult Cuterebra

They lay thousands of eggs in the environment (blades of grass, wood chips - areas near rodent burrows) or on other insects (such as mosquitoes), or even directly on the host (such as horses) - usually in clusters of 5-15 eggs. Cats and dogs are not the normal host of the Cuterebra, but can become infected if they spend time in areas where the eggs have been deposited. The eggs tend to hatch quickly when exposed to the warmth of a nearby body. Most of the time, cats will become infected by coming into contact with a newly-hatched Cuterebra larva with the nose or mouth, but the Cuterebra can also enter the body through open wounds.

Once in the body, the larva forms a small cyst under the skin - most commonly near the face and neck. These lumps are usually very easy to distinguish from a cancerous lump by the 2-4mm breathing pore that the larva creates. Often, the larva can be seen moving towards and away from the pore to breathe. These lumps are called "warbles". It is most common to see the warbles in late

August and September. Some years, we see a lot, other years, we see none. In the Waterford area, kittens tend to be most commonly affected, but any cat that goes outside could come into contact with a Cuterebra larva.

Sometimes, a sneezing cat may have a Cuterebra infection in its nose. On some rare occasions, a Cuterebra infection may occur in or near the eye or spinal cord. These situations are very rare. Cats that develop eye infections may or may not have damage to the eye. Neurologic signs of Cuterebra infection may include "head pressing", circling in one direction, or other behavioral changes. Cats that develop spinal cord infections may fully recover once the Cuterebra larva is removed.

The most effective treatment for Cuterebra infection (called "cuterebriasis") is surgical removal of the larva. In some situations, this can be quite complicated, depending on the location of the larva. It is important to be able to remove the entire larva, and not to break the larva while it is inside the cat, or a severe allergic-type reaction can occur (called "anaphylaxis"). 



It is important to remember that you can NOT get a Cuterebra infection from an infected cat, but you may have Cuterebra present in your yard.

Two weeks after removing Gryffin's parasite, he looks great!

In Michigan, late summer and early fall is the time of year that Cuterebra infections become evident. The larvae are very difficult to see until they become large, due to the fur coat your cat wears. Some years, we do not see any cats with Cuterebra infections, other years we see quite a few. This year, we saw a cluster of 4 cats with Cuterebra infection, all in a row at the end of August and early September. Two of the cats had Cuterebra larvae in the neck region, Gryffin had his infection in a hind leg, and one Cuterebra was located up a cat's nose! He had a "chronic upper respiratory infection" that would get only a little better with antibiotics. Some might have written that off as a viral infection (viruses do not respond to antibiotic treatment), but Dr. Brooks took a look up the cat's nose and there was the source of the chronic sneezing! Once the Cuterebra was removed from the cat's nose, he fully recovered.

These days, Gryffin is doing much better, without his creepy-crawly passenger!

EDIT: 11/4/14 Gryffin came in for a recheck and had gained almost a pound since his last visit. His wound is healed and he is looking and feeling great!


For more information:
Article on Cuterebra from the American Association of Veterinary Parasitologists