Abscess

Abscess in animals are circumscribed collections of purulent material (pus) in a cavity, found in several species of animals (Cattle, Goat, Sheep, Buffalo, Dog, Cat, Horse, Poultry etc.) in a variety of locations.

This purulent inflammation is usually caused by one of four pyogenic (pus producing) bacteria: Corynebacterium, Pseudomonas, Streptococcus and Staphylococcus.

Parts of abscess–

Abscess consists of a wall, pyogenic membrane and pus (Liquor puris). The pyogenic membrane that lies between the wall and pus, controls spread of infection, and helps in phagocytosis and granulation tissue formation.

Pus (Purulent material)

Pus contains necrosed tissue, dead bacteria, leukocytes and proteins of blood and tissues.
Pus cells mainly consist of polymorphonuclear leukocytes along with a few mononuclear cells.
Pus is alkaline in nature and yellow in colour.
Pus serum will not clot, since the fibrin of exudates is digested by the proteolytic enzymes of the leukocytes.

Etiology of Abscess-

Pyogenic organisms like Staphylococci, Streptococci, Escherichia coli and Pseudomonas aeruginosa.

Specific organisms like Corynebacterium pyogenes, Actinomyces bovis etc. Chemicals like mercuric chloride and Zinc chloride also responsible for Abscess.

Common seats of abscess–

Cattle: Yoke, udder and prominences
Horses: Shoulders, sub-maxillary and post pharyngeal lymph nodes
Dogs: Anal region, and mammary glands

Classification of Abscess-

Abscess may be classified as-

Acute Abscess (Hot abscess): Inflammatory symptoms are more active.
Chronic Abscess (Cold abscess): Inflammatory symptoms are less active.
Superficial or deep abscess: based on location.

Chronic abscess may be-
1. Hard with inspissated pus
2. Soft with liquid pus and thin abscess wall

Acute abscess–

Acute abscess forms in 3 to 5 days following infection. In long duration abscess, the liquid part is absorbed and the solid part is left. This is called Inspissated Pus.

Acute superficial abscess appears as a local painful swelling.

The dead tissues and dead inflammatory cells are continuously thrown into the cavity which leads to a gradual increase in the amount of pus. Thus the abscess enlarges till it reaches the surface of skin or mucous membrane.

The center of abscess becomes soft (pointing) and later ruptures, discharging pus.

Local acute inflammatory symptoms without fever are observed in superficial abscess.

Deep abscess has no local symptoms, but fever and pain on manipulation of the part are evident.

Chronic abscess–

A chronic abscess develops slowly without any inflammatory symptoms. It may be painless or slightly painful.

Primary chronic abscess usually occurs from repeated injuries and observed on the prominences of limbs and ribs due to bed sores.

Secondary chronic abscess develops in the course of various local affections.

Chronic abscess may be hard in consistency surrounded by fibrous tissue and containing small amount of pus or it may be soft and thin walled with comparatively larger amount of pus.

Treatment of Abscess-

Treatment should correspond to the stage of development of an abscess.

In time, abscesses may become inactive or enclosed (sterile); the body defenses having killed all of the causative bacteria.

The accumulated pus, with no route of escape, will slowly become liquefied and be absorbed. Measures to accelerate maturation of abscess by using liniments, fomentations and mild blisters. Once mature, abscess must be early cleared up of pus by aspiration and subsequent washing of the purulent cavity.

The abscess should be opened by syme’s abscess knife or a scalpel at the place of pointing. The pus should be drained and the cavity is to be irrigated with a mild antiseptic lotion. In cases where the pointing of abscess is not at a dependent Part, then drainage will not be perfect. A counter opening is made at the most ventral part (dependent Part) of the abscess.

Tincture of Iodine soaked gauge is be packed to keep the openings patent. This should be changed once in 24 hours. The quantity of gauze used to pack the abscess cavity has to be reduced daily as the cavity is being filled up by granulation tissue. Gauze soaked with 0.5% silver nitrate is best against most of the micro-organisms. Further therapy is the same as that of a granulating wound.

A chronic abscess is converted into an acute abscess by applying blisters, and then treated as acute abscess. Sometimes the chronic abscess is enucleated under local infiltration analgesia, and the skin is sutured.

Differential diagnosis of Abscess-

Cellulitis or Phlegmon

Cellulitis or Phlegmon is diffuse, suppurative spreading inflammation of loose connective tissue, with predominance of necrotic events over suppurative.

Pustule

Pustule is a circumscribed cavity with pus, situated in epidermis.

Furuncle or Boil

Furuncle or Boil is suppurative inflammation of hair follicle or a sebaceous gland due to Staphylococcus aureus. A group of furuncles is called Furunculosis.

Carbuncle

Carbuncle is small boil, which drains to outside by multiple small openings. It is caused by Streptococci and Staphylococci.

Acne

Acne is an abscess of sebaceous gland. It appears as single or multiple pustules containing greyish white pus. Antiseptic ointments externally and systemic penicillin gives good relief.

Empyema

Empyema is collection of pus in a body cavity. Example: Empyema of frontal sinus, empyema of joint.

Antibioma

Antibioma is a clinical condition resulting from improper treatment of an abscess.

Tumor

Tumor may be defined as “an abnormal mass of tissue, the growth of which extends uncontrolled, in comparison to the normal tissue and persists in the same excess even after cessation of the stimuli which evoked the change”.

Cyst

A cyst is a closed sac having a distinct inner lining of secreting membrane.

They may contain air, fluids, or semi-solid material. Cyst may contain a solid structure like tooth (dentigerous cyst) or hair (dermoid cyst) also.

Haematoma

Haematoma forms due to coagulation of blood or serum. It is doughy on palpation and forms immediately following an injury. Haematoma does not point like an abscess and no pain sensation present.

Hernia

History of recent injury and swelling. Hernial ring can be palpated.