Aural Abscesses

This fact sheet has been updated on 10/15/19.

Cause

An aural abscess, or ear abscess, is the internal swelling of the tympanic (middle ear) cavity caused by a bacterial or viral infection. Such abscesses frequently affect reptiles, particularly box 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 or has excessive exposure to organochlorine compounds. It is thought that organochlorine compounds impact the turtle’s ability to metabolize or use Vitamin A, thus resulting in hypovitaminosis 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. Immunosuppression, such as when a turtle hibernates, can also lead to aural abscesses. Other factors thought to be associated with the development of aural abscesses in turtles include: poor or suboptimal environmental conditions, and traumatic injuries. 

Significance

Aural abscesses are the second most common cause of morbidity in eastern box turtles, though they generally do not influence 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. Common species of turtle that are affected 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 are thought to occur primarily when a turtle is deficient in vitamin A. Recent studies have shown that in the wild, this deficiency 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 affected. The infectious pathogen (bacteria or virus) begins to grow and forms a plug of caseous material (i.e., pus-like substance) 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 deficiency, captive turtles may develop aural abscesses if they are subjected to poor or unsanitary living conditions. This includes improper water conditions, unsuitable temperatures, insufficient access to natural or artificial sunlight, or environmental stressors such as overcrowding, small tanks, insufficient docking areas, insufficient 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, just behind the eye(s). This swelling can become so large that the turtle may not be able to retract into its shell. The turtle’s head may be asymmetrical, if the aural abscess appears on only one side. Other signs include the presence of caseous material behind the eardrum, loss of appetite, and noticeable difficulty in opening the mouth. 

Diagnosis

Aural abscesses are most commonly diagnosed through visual confirmation of a swelling over the ear. Additional testing includes obtaining and analyzing a sample of the caseous material to determine what pathogen is responsible for the infection. Pus protruding from the eustachian tube into the mouth may be considered diagnostic of an aural abscess.

Treatment

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

Management

At this time aural abscesses do not appear to 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 sufficient vitamin A to help prevent the development of aural abscesses.

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.
  • • Wilder C.J. et al. 2003. Aural abscesses in wild Eastern Box Turtles (Terrapene carolina carolina) from North Carolina: Aerobic bacterial isolates and distribution of lesions. Journal of Herpetological Medicine and Surgery: 13(2), 4-9.

Images

Eastern box turtle with an aural abscess. Photo by Dr. Suzanna Brown Vaino.Eastern box turtle with an aural abscess. Photo by Dr. Suzanna Brown Vaino.