A 4 year old male intact bearded dragon (Pogona vitticeps) was presented for a 12 day history of audible tracheal noises and open mouth breathing.
It was reported that the animal may have aspirated water during a bath a few months before to initial presentation. The animal reportedly had the same symptoms 2 years prior that was resolved with an unknown dosage of ceftazidime. Otherwise, the bearded dragon was eating, drinking, and passing feces and urates normally with normal energy and activity.
This patient belongs to a colony of breeding bearded dragons. The enclosure at home was described as a 4 ft x 2 ft melamine cage with both a heat bulb and a UVB bulb as well as Astroturf substrate. The temperature gradient within the enclosure ranged from 80-95 F on the cool side to 99-101 F under the basking area. The bearded dragon’s diet consisted of crickets, superworms, Dubia roaches, pinkies, kale, dandelions, collard greens, carrots, and butternut squash. The animal had been treated with crystalline free acid (CCFA, 30 mg/kg SQ once, effect lasting 10 days) one week prior, following phone consultation for this condition.
On initial assessment, the bearded dragon was bright, alert, and responsive with normal vital parameters. Audible tracheal noises were noted on respiration with intermittent open mouth breathing. The remainder of the physical examination revealed no significant abnormalities.
A full body standing CT was performed to assess for tracheal or pulmonary abnormalities.
The nares are within normal limits bilaterally.
Several small linear strands of soft-tissue attenuating material are identified within the trachea, coursing perpendicular to the tracheal lumen, not limited to the dependent wall. The oral cavity and esophagus are unremarkable.
Thin, somewhat web-like tissue surrounds the periphery of the lungs, measuring up to 0.5 cm in thickness. In addition, The ventromedial aspect of the right cranial lungs are hypoinflated, resulting in an increase of soft-tissue attenuation within this region. The heart is normal. A small amount of mineral attenuating material is identified along the ventral aspect of the gastrointestinal tract, likely representing a small amount of sand or gravel. The included coelom is otherwise unremarkable. All osseous structures are normal in density. The mandible and all of the long bones are normal in shape. No osseous abnormalities are detected.
1. Intraluminal tracheal material, possibly representing mucus, with undulating tracheal margins.
2. Mildly increased soft-tissue attenuation of the right cranioventral lungs.
Comments: The abnormalities described with the respiratory tract are suggestive of an infectious process (either bacterial, viral, fungal, or parasitic pneumonia). Concurrent tracheitis is also possible to explain the excessive mucous accumulation.
The animal was treated with meloxicam (0.2 mg/kg SQ q48 hours, total of 3 doses) in addition to CCFA.
Two months later, the animal re-presented for the same symptoms. Reportedly, the symptoms had resolved temporarily, then returned. Sedated tracheal endoscopy was planned to rule out a tracheal mass, tracheal membrane redundancy, or tracheal bronchomalacia. The patient was sedated with ketamine (3 mg/kg IM once) and midazolam (1 mg/kg IM once), which did not produce profound relaxation. Following this, copious amounts of brown fluid were expelled from the trachea without manipulation. A sterile ET tube was placed and the material was aspirated from the trachea and submitted for anaerobic and aerobic culture and sensitivity. Aerobic culture revealed presumptive mycoplasma. Azithromycin (10 mg/kg PO q48h) was administered for 2 weeks after which time symptoms resolved.
Ten months later, the animal was found acutely dead. The night prior, he was reportedly noted to be active and eating normally. Two other acute deaths within the same colony had occurred over the four months prior; these were noted to be females that had mated with this male after symptoms had resolved. Additionally, other bearded dragons within the colony had previously tested positive for Atadenovirus.
Pneumonia and tracheitis were determined to be the most likely cause of acute death in this case. In addition, the intraluminal laryngeal material may have contributed to respiratory compromise or death. These findings were consistent with the respiratory tract abnormalities noted on CT imaging. Given the history of mycoplasma infection in this case and the positivity for Atadenovirus in bearded dragons within the same collection, viral and/or mycoplasma infection cannot be ruled out as etiologic possibilities.
The lesions in this case are somewhat similar to those found in a case report of pneumonia in a bearded dragon diagnosed with Helodermatid Adenovirus 2 and a novel mycoplasma species (M. pogonae).1Atadenovirus has been shown to cause systemic infection associated with pneumonia in some bearded dragons.2 Additionally, proliferative tracheitis and pneumonia have been attributed to Mycoplasma infection in other species.3
Ante-mortem diagnosis of Atadenovirus is usually accomplished through polymerase chain reaction (PCR) testing of cloacal swabs followed by sequencing;2 testing for mycoplasma may be performed through culture of respiratory secretions or tracheal swabs (as was performed in this case) or through PCR of these samples. As mentioned above, the most recent acute deaths in this colony prior to this were females that had mated with this male after resolution of symptoms. Pooled samples of these cases have been submitted for further evaluation of the presence or absence of viral, mycoplasma, and/or bacterial infection.