When a pet bird has a change in or loss of voice, this will localize lesions to the trachea, or more specifically the syrinx. The syrinx is the “voice box” of the bird, a collection of membranes and muscles located at or near the tracheal bifurcation (the termination of the trachea, where it divides into two principal bronchi). When compared to the cat or dog, the bird trachea is relatively wide until the level of the syrinx. The airway normally narrows at this point, creating turbulent airflow. This turbulence means that some disease agents, such as an inhaled foreign body or Aspergillus spores, are most likely to drop out in the syrinx.
Signs of Tracheal or Syringeal Disease
Signs of tracheal disease are usually not very subtle and may involve cough-like noises and gurgling breath sounds. When the syrinx is the site of disease, common findings include a loss of voice or a change in voice. Birds often emit a high-pitched squeak or clicking sound with each breath. In some cases, these noises can be heard for days or weeks before the bird becomes truly dyspneic (has difficult or labored breathing).
Signs of dyspnea, or increased respiratory effort, include open-mouth breathing, increased sternal motion, tail bobbing, and/or tachypnea (rapid breathing). The bird might also hold its wings away from its body and sit in a wide-based stance.
Tracheal disease is usually seen in conjunction with upper or lower respiratory problems. Therefore, it is possible that a pet bird can have more subtle signs of illness, such as a fluffed and ruffled appearance and a prolonged respiratory recovery rate (RRR). A bird that takes longer than three to five minutes to breathe normally after being manually restrained has a prolonged RRR. A prolonged RRR may be observed with a host of problems, including respiratory disease, obesity and/or heart disease.
Important Differential Diagnoses
There are only a few diseases that commonly cause tracheal disease in birds. The likelihood of each condition can vary depending on the bird’s species and medical history:
Fungal infection caused by Aspergillosis fumigatus is a very important cause of tracheitis in raptors. Aspergillosis is less common in companion parrots; however, disease is more prevalent in African grey parrots (Psittacus erithacus), Amazon parrots (Amazona spp.), Pionus parrots (Pionus spp.) and macaws. The likelihood of a fungal infection is increased if the bird is housed in an environment in which there is poor sanitation, high relative humidity and high temperatures, which can increase the load of fungal spores. A bird with a weakened immune system due to steroid administration or concurrent illness (particularly when treatment involves long-term antibiotics) is also at greater risk for aspergillosis.
2. Exposure to Mites/Worms
Sternostoma tracheacolus mites of the trachea, air sacs, and lungs are seen in the Gouldian finch (Erythrura gouldiae), and less frequently in canaries (Serinus spp.). In addition to difficulty breathing, wheezing, squeaking and loss of voice, clinical signs can also include sneezing, nasal discharge and head shaking.
Syngamus trachea is a nematode, which can be found in the tracheas of backyard poultry, pheasants, guinea fowl, and many wild birds, such as corvids. Infection occurs either by direct ingestion of the third-stage (L3) larvae or through ingestion of a paratenic host, such as an earthworm. Therefore, infection is much more common in birds with access to the outdoors. The smaller male and larger female worms are locked in a state of permanent copulation creating a characteristic “Y” shape. Young birds are most severely affected as the worms migrate through the lungs, leading to pneumonia. Adult worms attach to the trachea and bronchi, where lymphoid nodules form at the points of attachment. Hemorrhaging and formation of large quantities of mucus can plug the trachea leading to dyspnea, gasping or gaping, asphyxiation and even death. Pheasants seem particularly susceptible, with mortality rates approaching 25% in some outbreaks.
3. Foreign Body Inhalation
Mechanical obstruction of the trachea can occur secondary to inhalation of foreign bodies, such as seeds or seed hulls. Inhalation of millet seed seems to occur most commonly in cockatiels or similarly sized birds. Onset of clinical signs is often peracute in the bird suffering from a seed foreign body. The bird might appear completely fine until respiratory distress suddenly develops while the bird eats.
4. Goiter/Iodine Deficiency
Goiter is an important cause of voice change or voice loss in the budgerigar, or parakeet (Melopsittacus undulates). Goiter, or iodine deficiency develops, in “budgies” fed all-seed diets lacking vitamin/ mineral supplementation. Clinical signs develop secondary to compression of the trachea and/or crop by the enlarged thyroid gland. In addition to a clicking respiratory noise, voice change and dyspnea, affected birds might also regurgitate.
What To Expect: Care & Treatment
A change in your bird’s voice or loss of voice, as well as any sign of labored breathing, warrants a prompt checkup by your avian veterinarian. If the bird is dyspneic (has labored breathing), the clinician’s initial response is often hands off. Dyspneic birds can die soon after presentation with the additional stress of restraint. Therefore, the veterinarian or clinic staff will want to minimize handling and place the bird in an oxygen-rich environment. If the bird is in a relatively small cage, the vet can place the entire cage within a large oxygen cage.
While the bird is resting, a complete health history can be obtained.
After taking a complete history and providing supplemental oxygen, the bird may improve enough to handle an abbreviated physical examination. The avian veterinarian might order whole body radiographs that include the trachea, as well as a complete blood count, and other diagnostic tests.