of animals to toxins such as organochlorines, which inhibit the synthesis of vitamin A, or have an immunosuppressive effect must also be considered.
DIFFERENTIAL DIAGNOSIS
Nutritional secondary hyperparathyroidism
Neoplasia
Parasites
Upper respiratory tract disease
DIAGNOSTICS
Cytology
A cytological imprint or aspiration of the abscess helps in determining whether bacteria and/or fungi are involved.
Microbiology
Culture and sensitivity of the abscess material is recommended for proper identification of the bacteria involved (usually Staphylococcus, Streptococcus or Pseudomonas) and to ensure a proper antibiotic was selected.
Imaging
In cases with perceived skull deformities or non‐responsive to therapy, radiographs or CT are recommended to determine whether osteolytic changes are present.
Histology
If the material extracted from the site does not have the appearance of an abscess or is closely attached to the bone, it should be submitted for histopathological evaluation to rule out neoplasia.
PATHOLOGICAL FINDINGS
Lesions of the tympanic epithelium include hyperplasia, squamous metaplasia, hyperemia, cellular sloughing, granulomatous inflammation, and bacterial infection.
Histopathologic changes in turtles with aural abscesses are consistent with a syndrome involving hypovitaminosis A.
APPROPRIATE HEALTH CARE
Aural abscesses require a dual approach of surgical debridement and medical therapy.
Ophthalmic antibiotic drops may be instilled in the canal for local therapy in addition to the use of systemic antibiotics.
The use of ointments should be reserved for the period when all the material can be easily flushed out of the canal.
Some may elect to administer vitamin A (5,000–10,000 iu IM as a single dose), but this should be reserved for the most severe cases, as hypervitaminosis A from parenteral administration is a concern.
NUTRITIONAL SUPPORT
Natural sources of vitamin A in the diet (herbivorous—parsley, carrot, tomato, spirulina; carnivorous—liver, fish, eggs).
CLIENT EDUCATION/HUSBANDRY RECOMMENDATIONS
Ensure a proper balanced diet for the species and consider oral vitamin A supplementation at a rate of 2–8 iu/g of feed.
Improve hygiene to decrease bacterial load in the water/enclosure.
Avoid fights or scratches among animals housed together.
SURGICAL CONSIDERATIONS
The debridement must be performed with the animal under sedation or anesthesia with proper analgesia (NSAIDs and opioids, local block, etc.).
The tympanic membrane can then be incised either in a vertical or horizontal manner.
A horizontal incision on the ventral aspect of the membrane may allow for better drainage postoperatively.
The tympanic membrane is usually edematous and vascularized leading to appreciable bleeding upon incision.
If excessive bleeding occurs, topical hemostatics (silver nitrate) may be used.
Once an opening is made, the caseous material must be removed in its entirety via manual manipulation and flushing.
Chelonian ears have an inverted L shape, which means that there is often a dorsocaudal pocket that harbors more material.
A cotton‐tip applicator can be placed on the dorsocaudal aspect of the head/ear followed by applying pressure in a cranioventral direction, to help expel the material.
Forceps are also helpful to remove excess material.
It is not uncommon to remove a volume of material two to three times the size of the external swelling.
Once the material is removed, the ear canal can be flushed with a disinfectant solution (iodine, chlorhexidine, etc.) and saline.
The membrane is left open to heal by secondary intention.
The ear canal can continue to be flushed once to twice daily until it closes.
DRUG(S) OF CHOICE
Antibiotics: broad‐spectrum antibiotics (fluoroquinolones, cephalosporins) until resolution of clinical signs.
Preventive vitamin A is recommended at 1000–2000 iu/kg every 7 days, but is best done by dietary supplementation at 2–8 iu/g of feed) to avoid overdosing.
PRECAUTIONS/INTERACTIONS
With preventive vitamin A it is advisable to use a minimum dose.
Overdosage of oily vitamin A causes exostosis, hepatomegaly, and skin lesions.
PATIENT MONITORING
A thorough physical examination will confirm the healing of the tympanic membrane.
It usually takes between 2 and 4 weeks.
If
