growth from abscesses can be difficult.
Samples must be obtained not only from the abscess material but also from the wall of the abscess, to maximize the possibility of bacterial growth.
Anaerobic cultures must be considered, especially when there is no aerobic growth and in cases of malodorous discharge. 16s rRNA PCR is another tool that is becoming more readily available for bacterial identification.
Fungal cultures can also be considered, especially if hyphae are observed in the cytologic exam.
Hematology and Biochemistry
Some changes that may be observed include leukocytosis, heterophilia, and eosinophilia.
The heterophils may appear reactive (toxic granulation).
Thrombocytes are also activated
Mitosis may be observed in many leukocytes.
Total protein values (gamma globulins and alpha globulins), and the enzymes AST, CPK, and alkaline phosphatase may be elevated.
The majority of these changes are not consistent and may vary according to the nature of the abscess and how well encapsulated the abscess is.
Histology
Histopathologic exam of a suspected abscess can more definitively confirm the diagnosis and help identify the presence of infectious organisms.
Imaging
Radiographs—in cases where an abscess is firmly attached to underlying bone, radiographs can help determine whether there is bony involvement and osteomyelitis.
Ultrasound—abscesses (regardless of their location) have a hyperechogenic capsule that creates intense acoustic shadowing with a hypoechogenic interior, especially when they still have a liquid content (the first stage of internal caseum formation). In advanced stages, there is a thin layer of fibrin that surrounds the abscess and under it the inflammatory liquid that forms the internal caseum.
PATHOLOGICAL FINDINGS
Histologically, necrotic cell layers and a thin layer of phagocytic mononuclear cells in palisade are observed delimiting the core of the abscess. Organisms may be visible on numerous sections. A correct differential diagnosis of diseases such as mycosis, neoplasia, or myiasis must be carried out.
APPROPRIATE HEALTH CARE
Treatment often requires a combination of medical and surgical therapy for best results.
Any suspected or confirmed bacteria should be treated with appropriate systemic antibiotics until results of sensitivity panel confirm its effectiveness.
For suspected fungal infections, systemic therapy may not be necessary, as long as the infection is restricted to the abscess.
In conjunction with medical therapy, surgery to either remove or debride the abscess must be performed.
Complete removal of the whole abscess and capsule is preferred but often not possible due to size limitations for skin closure or involvement of underlying tissues. A debridement is more commonly performed.
The abscess should be opened to extract the purulent material and as much of the capsule as possible. It can then be irrigated with a disinfectant solution (iodine, clorhexidine, etc.) and left open to heal by secondary intention.
Daily flushing and cleaning should be performed until no more purulent material is observed.
Topical antibiotic ointments can also be applied within the abscess cavity. An additional treatment is the placement of antibiotic (amikacin, cephalosporins) impregnated beads, or dental antibiotic gels, such as doxycycline hyclate (DOXIROBE® gel, Zpetis, USA), or clindamycin hydrochloride 1% (ClinzGard®, VEDCO Inc, USA) especially in non‐responsive cases, fractious animals, or those that cannot be easily treated on a daily basis
Most abscesses will take between 2 weeks and 1 month to heal. In some cases, once the caseous material has been completely removed and there is certainty that only healthy tissue remains, then the wound can be sutured.
NUTRITIONAL SUPPORT
Proper nutrition is key for the prevention and treatment of anemia.
Diet should be as varied as possible and adapted to each species.
Nutritional support via gavage feeding should be implemented in very ill and/or anorectic animals.
CLIENT EDUCATION/HUSBANDRY RECOMMENDATIONS
Correct any husbandry deficiencies with special attention to hygiene, temperature, humidity, and ventilation.
Isolate animal from others in collection during treatment.
Important to ensure a full course of treatment to avoid recurrence.
DRUG(S) OF CHOICE
Broad‐spectrum antibiotics (e.g., fluoroquinolones, aminoglycosides, sulfamides)
Some penicillins (e.g., carbenicillin or ampicillin)
PRECAUTIONS/INTERACTIONS
Fluid therapy should be considered when administering systemic antimicrobials, especially aminoglycoside antibiotics (gentamicin, streptomycin, amikacin, kanamycin) due to their nephrotoxic potential.
Systemic antifungals should also be used and monitored cautiously.
PATIENT MONITORING
Abscesses should not grow out again 1 month after treatment.
If there is recurrence, a more aggressive approach is needed.
Scarring and pigmentation changes may be observed at the site of the healed abscess.
EXPECTED
