Definition
An abscess is defined as “A collection of pus in tissue, organs, or a confined space, which is usually caused by a bacterial infection.”
A sterile abscess can be defined as a localized swelling filled with fluid where no organism growth
is obtained on culture.
Clinical Signs
Abnormal swelling of tissue filled with pus.
A swelling or lump that develops quickly from one to a few days. It may be located anywhere on the body and may cause tenderness.
The center of the lump may appear white as the skin starts to thin signifying rupture, or may show a scab at the site of the lump where injury was initiated.
If a deep abscess is present, or if there is systemic involvement, signs may include: anorexia, weight loss, possible limited mobility, and possible abnormal organ function.
Etiology
An abscess is caused by disruption of a normal tissue barrier through penetrating trauma, bites, established infections, or by migration of normal flora to other sterile areas of the body. It is an infection and inflammatory process; where by leukocytes (white blood cells which protect the body from invading organisms) form a wall around infectious agents in tissue, organs, or confined spaces, to localize inflammatory exudate (pus), in an attempt to prevent further spread of infection. Exudate (pus) is made up of dead leukocytes, dead organisms, and fluid from blood.
Exudate from an abscess may:
- autolyze and be reabsorbed resolving the inflammation and abscess
- further develop under the skin surface and appear visually as a pus filled lump. This pus filled lump may then ââ¬Åcome to a head” by itself, rupture and drain, or through local application of heat, break through the skin and allow the pus to drain thereby resolving the abscess
- rupture and drain through a sinus or tract to another organ or tissue resulting in further inflammation to those areas.
Should an abscess continue to develop deeper within the body and then rupture allowing infectious agents to enter the blood stream, bacteremia becomes present.
If the pathogenic agent multiplies and releases toxin into the blood then the result is septicemia.
The causative organisms are varied and may reflect the area where the abscess is located. Some examples include:
- Cutaneous or skin and soft tissue abscesses commonly associated with Staphylococcus aureus. Staphylococcal strains may show rapid necrosis, and early suppuration, with a large amount of pus. It liberates lethal cellular toxins, but is more able to be quickly walled off by surrounding tissue before it can spread.
- Oral and perineal abscesses may be produced by anaerobic bacteria and contain a brown foul smelling pus.
- Cervical abscesses may be produced by Klebsiella pneumoniae, Pasturella pneumotropica, and Streptococcus spp.
- Organism most often seen for facial, orbital and tail abscesses is Staphylococcus aureus.
- Abscesses of the abdomen may be a mixture of both anaerobic or aerobic Gram-negative bacilli such as klebsiella and E. coli, and anarobes such as Bacteriodes fragiles.
- Organisms affecting the preputial gland are Pasteurella pneumotropica and Staphylococcus aureus.
- Those abscesses produced by streptococcus show little to no necrosis, and contains serous exudate ( clear fluid with cellular debris ). Because the organism does not cause intense tissue destruction walling
off takes much longer, thus, allowing greater tendency to spread throughout the body.
Photo examples of abscesses have been provided in the following figures.
- Fig. 1: Abscess of cat bite in hairless rat
- Fig. 2: Facial abscess, scab removal
- Fig. 3 Retrobulbar abscess
- Fig. 4 Small groin abscess
- Fig. 5 Oral Abscess
- Fig. 6 Tooth Abscess
- Fig. 7 Facial abscess: Bramble’s case history.
- Fig. 8 Abscess on hairless rat
- Fig. 9 Rectal abscess in rat, a case history and photos.
- Fig. 10 Inguinal canal abscess, case history and photos.
- Fig. 11 Retrobulbar abscess with enucleation in 1 year old rat.
- Fig. 12 Multifocal abscesses in young rat, case history and photos by Dr. Mimi Ehrlich.
Factors which may contribute to the formation of abscesses are an impaired immune system, excessive fluid accumulation in tissue, hematomas, or where normal drainage of specific organs may be obstructed.
Diagnostics
Many abscesses can be diagnosed by fine needle aspiration of pus, or by spontaneous rupture of the abscess and the discharging of pus.
Cytologic evaluation
Gram stains of purulent exudate.
Lab work for culture and sensitivity may be obtained to determine the antibiotic of choice.
Treatment
If the abscess is relatively small and seems to have a point of entry, moist heat at 105 to 110 degrees F. or 40.6 to 43.3 degrees C.
may be applied. This causes peripheral vasodilation, which speeds leukocytes to the site, accelerating pus formation. Doing this may open the tract and allow the pus to drain. Refrain from leaving
a warm compress on for extended periods as this will cause vasoconstriction to occur.
The aspiration of pus from an abscess that appears ready to rupture can also be done. Once the pus is drained or aspirated, the small abscess can be cleaned twice daily. The solution of choice for abscess care would be normal saline .9%. (If using sterile contact lens solution make sure it is preservative/additive free.) If further treatment solutions are required then diluted chlorhexadrine (not greater than 1 % concentration) flush once daily, or a diluted betadine solution of 1:5 twice daily may be used as indicated.
A small abscess that has been drained and irrigated can also be treated by applying an antibiotic ointment (such as polysporin).
In abscesses that are large or deep, where an incision is required to be done over the suppurative area, irrigate the wound with normal saline twice a day or as directed by your veterinarian, and keep the incision open to allow drainage and promote healing. Irrigating a surgical wound with solutions other than normal saline should be done only at the direction of your veterinarian. Using an antibiotic ointment in a large or deep abscess may cause the abscess to heal from the outside trapping bacteria in. Abscesses heal more efficiently from the “inside out.”
In addition granulated sugar may be used twice a day to gently pack wound. The use of granulated sugar aids in inhibiting the presence of bacteria in the wound, and helps with granulation and healing.
Home made sterile saline solution
16 ounces water (use distilled if your tap water is hard)
1 teaspoon table salt
You can use warm water or you can boil the solution then cool to room temperature before use.
*Note: boiling is usually not necessary when flushing a non sterile wound such as an abscess.
Antibiotic Therapy
*Note: Broad spectrum antibiotics may be prescribed for large, deep, or persistant abscesses. Keep in mind that the abscess itself does not have a blood supply, and that the antibiotics
are used to prevent recurrence and possible spread of infection.
In the event surgery intervention is required the following post-op analgesia may be given:
For severe pain or first 24 hours post-op: butorphanol (Torbugesic).
For mild to moderate pain: Banamine (flunixin meglumine), or carprofen. Do not use if a corticosteroid has already been prescribed.
Refer to the Rat Medication Guide for information on medications.
The goal in keeping an abscess open to drain is to prevent reaccumulation of pus, and allow the wound to heal from inside to outside.
Nursing Care
Prevent using chlorhexiderm at a concentration of more than 1% or even more than once a day, since it will delay wound healing in granulating wound beds of abscess pockets. Diluted solution should appear lighter than a robin’s egg blue.
Continue treatment or followup care until wound heals.
If antibiotics are given remember to include Benebac, or yogurt with live active cultures, to prevent normal gut flora from being destroyed by the antibiotics.
For those abscesses that require surgical intervention:
Provide hospital cage in the event of surgery and during recouperation if there are concerns that their cage mates may groom wound site.
Provide additional warmth using a hot water bottle or heating pad, if needed, in order to maintain body temperature within normal limits. Use low heat settings and place under one half of cage to ensure rat does not become overheated or dehydrated.
Provide clean bedding daily such as cloths or ink-free paper towels. Avoid litter-type bedding in open wounds to prevent the chance of wound contamination or infection.
Provide pain medication if needed post-op, based on pain severity. Check with veterinarian for most appropriate pain medication to give.
Provide high calorie foods or food supplements such as Nutri-Cal Paste, canned Ensure, soy or soy formula, during recouperation.
Encourage fluid intake while recuperating, such as water, Jello water , or electrolyte replacement drinks such as Pedialyte or Gatorade (which can be found in local grocery stores). Please note that Pedialyte is only good refrigerated for 24 hours after opened, but can be frozen as ice cubes and thawed as needed.
*Note: a juicy type of fruit also provides an additional fluid source in the diet.
Observe and contact veterinarian if there are: further signs of infection, if the wound does not appear to be healing, or if the wound heals but elevation or lump returns.
Outcomes
Although abscesses can be persistent in returning, requiring additional treatment, many do resolve.
Some of the factors that may affect the outcome are:
- Age
- Nutritional status
- The status of the immune system and the ability to initiate and resolve inflammation.
Desired outcome:
Abscess resolved.
No advanced systemic infection.
Prevention
Practice good sanitation of cage environment.
Cover wire floors, or rough surfaces with a sturdy covering to prevent abrasions. Examples of coverings can include vinyl floor covering, plastic needlepoint canvas, carpeting, towels, self stick tiles, plastic placemats, fiberboard, and plexiglass.
Treat all wounds promptly and seek attention at the first sign of infection.
References
Abstracted From Wound Management
Using Sugar
http://www.vetsci.psu.edu/Ext/Newsletters/Companion%20Animals/VN03026.HTM
Posted on June 28, 2003, 10:06,
Last updated on June 16, 2008, 17:07
| Integumentary / Skin
