Abscess

• Most common feline bacterial skin infection.
• Cause: common sequela to a bite or scratch.
• Signs: subcutaneous swelling, discharging pus.
• Diagnosis: history, clinical signs.
• Treatment: responds to drainage and antibiotic therapy.
• Prognosis: generally good.
  Print off the Owner factsheet on abscesses Cat bite abscesses (and castration All about neutering) to give to your client.

• Subcutaneous swelling.
• Drainage of pus from skin  .
• Pain.
• Anorexia.

• Pyrexia.
• Lameness in affected limb.
• Lethargy and depression.

• Organisms normally found within cats' mouths are also found within abscesses.
• Pasteurella multocida Pasteurella multocida, Bacteroides spp Bacteroides fragilis, beta-hemolytic streptococci, and fusiform bacilli.
• For non-healing wounds consider atypical mycobacteria.

General

• An intact male cat with access to the outside environment will fight for sexual favors.
• Cats in a population dense area will fight to maintain territory.
• Immunosuppressed individuals, eg with feline leukemia virus Feline leukemia virus or feline immunodeficiency virus  Feline immunodeficiency virus, may show more severe signs, or fail to respond to appropriate therapy.

• Cat bites and scratches are major cause   →   subcutaneous bacterial infection.

• Bacteria are injected under the skin.
• The small puncture wound heals rapidly.
• Over the next 2-4 days bacteria multiply.
• Normal defense mechanisms may fully clear the infection.
• The infection may be walled off by fibrous tissue and rupture to the surface exuding cream   →   green pus with fetid odor.
• Infection may spread locally or hematogenously, leading to cellulitis, local lymphadenopathy or other organ involvement.

• 2-4 days.

• Subcutaneous swelling.
• Fever.
• Lameness.
• Pain.

• Owner reports cat fight within previous 2-4 days.
• Swelling typically on head, shoulder, tail base or hindlimb.
• Off food.
• Recently moved to new area   →   territorial disputes.

• Cream to green foul-smelling purulent exudate from a skin wound  .

• Subcutaneous swelling, often painful, situated typically on the head or neck, tail base or a distal limb.
• Regional lymphadenopathy.
• May be few systemic signs.
• May be fever, anorexia, depression and malaise.
• Lameness.
• Pain over affected site, often severe.

• Cellulitis.

Hematology

• Mature neutrophilia Hematology: neutrophil.

Bacteriology

• May be considered in non-responsive cases.
• Aerobic and anaerobic culture necessary Bacteriology. Include culture for mycobacteria. Negative anaerobic culture does not rule out anaerobic infection.

• Concurrent infection with feline leukemia virus infection Feline leukemia virus disease or feline immunodeficiency virus infection Feline immunodeficiency virus disease.
• Other non-infectious causes of lameness.
• Other puncture wounds, eg penetrating foreign body.
• Mycoses.
• Sterile panniculitis.
• Mycobacteria spp infection Mycobacterium tuberculosis.
• Actinomyces spp infection Actinomyces viscosus.
• Nocardia spp infection Nocardia spp.

• If already ruptured, clip and clean abscess with saline, dilute chlorhexidine Chlorhexidine or dilute hydrogen peroxide Benzoyl peroxide.
• Liberal surgical drainage in non-ruptured abscesses will require general anesthesia General anesthesia: overview or heavy sedation Sedation or sedative protocol.
• Cases which require extensive incisions will merit bandaging. If this is not possible place drain or leave open wound, eg side of face.
• Oral antibiotics for 5-7 days. Choose bactericidal (clindamycin Clindamycin licensed for this use, but bacteriostatic) antibiotics with activity against the more frequently encountered organisms. Therapeutics: antimicrobial drug 
• Non-steroidal anti-inflammatories in cases with pyrexia and pain Analgesia: NSAID.

Treatment

• May get overlying skin necrosis necessitating debridement.

• Good in cats with healthy immune systems.

Refereed papers

• Recent references from PubMed and VetMedResource.
• Hoshuyama S, Kanoe M, Amimoto A (1996) Isolation of obligate and facultative anaerobic bacteria from feline subcutaneous abscesses. J Vet Med Sci 58 (3), 273-274 PubMed.
• Walker R D, Walshaw R, Riggs C M et al (1995) Recovery of two mycoplasma species from abscesses in a cat following bite wounds from a dog. J Vet Diagn Invest 7 (1), 154-156 PubMed.
• Beale K M (1995) Nodules and draining tracts. Vet Clin North Am Small Anim Pract 25 (4), 887-900 PubMed.
• Kanoe M, Kido M, Toda M (1984) Obligate anaerobic bacteria found in canine and feline purulent lesions. Br Vet J 140 (3), 257-262 PubMed.
• Ihrke P J (1984) Therapeutic strategies involving antimicrobial treatment of the skin in small animals. J Am Vet Med Assoc 185 (10), 1165-1168 PubMed.
• Love D N, Jones R F & Bailey M (1979) Description of strains of Peptostreptococcus anaerobius isolated from subcutaneous abscesses in cats. J Gen Microbiol 112 (2), 401-403 PubMed.