Aural Abscesses

Cause

An aural abscess is the internal swelling of the tympanic (middle ear) cavity caused by a bacterial infection. They frequently affect reptiles, particularly turtles. Though the definitive cause of aural abscesses in wild turtles is unknown, they are believed to form when the animal is deficient in vitamin A. Captive turtles develop aural abscesses when they are vitamin A deficient, live in unsanitary or cramped conditions, are kept at unsuitable temperatures, or are deprived of sunlight. 

Significance

Aural abscesses are the second most common of morbidity in eastern box turtles, though they generally do not inuence population levels.

Species Affected

Aural abscesses occur in many species of wild and captive reptiles, though they are most common in turtles that are aquatic or semi-aquatic. Some species of turtle that are aected by these infections include the eastern box turtle, the painted turtle, and the red-eared slider.

Distribution

Aural abscesses can occur wherever reptiles are present.

Transmission

Aural abscesses occur primarily when a turtle is decient in vitamin A. Recent studies have shown that in the wild, this deciency may be due to a high body burden of organochlorine compounds (chemicals found in many pesticides) in wetland turtle habitats. Low levels of vitamin A cause abnormalities in the lining of the middle ear, allowing bacteria to enter the body and lead to infection. The skin, eyelids, conjunctiva, and respiratory tract may also be aected. This bacterium begins to grow and form a plug of rm pus in one or both ear canals. Turtles with a weakened immune system (such as from another disease) may also be more susceptible to developing aural abscesses. Along with vitamin A deciency, captive turtles may develop aural abscesses if they are subjected to poor or unsanitary living conditions. This includes improper water ltration, unsuitable temperatures, insucient access to natural or articial sunlight, or environmental stressors such as overcrowding, small tanks, insucient docking areas, insucient access to water, and over-handling. 

Clinical Signs

The most obvious sign of an aural abscess is swelling on one or both sides of the head. This swelling can become so large that the turtle may not be able to retract into its shell. Other signs include the presence of pus behind the eardrum, loss of appetite, and noticeable diculty in opening the mouth. 

Diagnosis

Aural abscesses are most commonly diagnosed through visual conrmation of swelling over the ear. Additional testing includes obtaining and analyzing a sample of pus to determine what bacteria is responsible for the infection.

Treatment

Treatment of aural abscesses involves surgically opening the ear and removing the hardened pus, followed by ushing the ear canal with antibiotics. Treatment is commonly used for captive turtles, but may be administered to wild turtles in a wildlife rehabilitation clinic. 

Management

Aural abscesses do not cause high rates of mortality in reptile and turtle populations and thus management is not necessary. Captive turtles should be kept in suitable living conditions and be given sucient vitamin A to prevent infection. 

Suggested Reading

  • Brown, J.D. et al. 2004. Pathology of aural abscesses in free-living eastern box turtles (Terrapene carolina carolina). Journal of Wildlife Diseases. 40(4). 704-712.
  • Holladay, S.D. et al. 2001. Aural abscesses in wild-caught box turtles (Terapene carolina): possible role or organochlorine-induced hypovitaminosis A. Ecotoxicology and Environmental Safety. 48. 99-106.
  • The Center for Avian and Exotic Medicine. 2013. Aural Abscesses in Aquatic Turtles.
  • LafeberVet. 2011. Ear or Aural Abscesses in Turtles.