Avian Medicine: Avian Emergency Medicine:
Presenting problem: Voice Change in Birds
Date: April 12, 2012
Author: Christal Pollock, DVM, Dipl. ABVP-Avian Lafeber Company veterinary consultant
Reviewer: Tony Poutous, VMD; Pet Care Veterinary Hospital Virginia Beach, Virginia
Key words: Voice, syrinx, trachea, respiratory, aspergillosis, goiter, seed, avian.
- A change in voice or loss of voice in the bird localizes disease to the trachea, or more specifically the syrinx.
- The syrinx serves as the avian “voice box”.
- In addition to loss of voice or a change in voice, syringeal disease is often associated with a high-pitched squeak or clicking sound with each breath.
- Depending on the species involved, important differentials for tracheal/syringeal disease include aspergillosis, an inhaled foreign body (i.e. seed or seed hull), the tracheal mite, Sternostoma, or Syngamus trachea, “the gapeworm”.
Understanding voice change in birds
Understanding the anatomy
When a bird is presented for 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.
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 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.
Signs of dyspnea or increased respiratory effort include open-mouth breathing, increased sternal motion, tail bobbing, and/or tachypnea. The wings may also be held away from the body as the bird sits in a wide-based stance (Box 1).
|Box 1. Signs of increased respiratory effort|
+/- Wings held away from the body, wide-based stance
Signs of tracheal obstruction include tachypnea, dyspnea, and sudden death.
Tracheal disease is usually seen in conjunction with upper or lower respiratory problems. Therefore, it is possible that your patient can present with more subtle signs of illness such as a fluffed and ruffled appearance, exercise intolerance and a prolonged respiratory recovery rate (RRR). A bird that takes longer than 3-5 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 cardiovascular disease.
There are only a few diseases that COMMONLY cause tracheal disease in the bird. The likelihood of each condition will vary with signalment.
- 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 index of suspicion should increase when the bird is housed in an environment that can increase the load of fungal spores:
- Poor sanitation
- High relative humidity
- High temperatures
The bird with a weakened immune system due to corticosteroid administration or concurrent illness (particularly when treatment involves long term antibiotics) is also at greater risk for aspergillosis.
- 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 dyspnea, 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 the 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.
- 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 owner reports that the bird was completely fine, until respiratory distress suddenly developed while the bird was eating.
Papillomatosis of the oropharynx can also mechanically obstruct the airway (Fig 1), however the onset of signs should be more gradual.
5. Extraluminal tracheal compression secondary to goiter is an important cause of voice change or voice loss in the budgerigar parakeet (Melopsittacus undulates).
Goiter or iodine deficiency develops in “budgies” fed all-seed diets lacking vitamin/ mineral supplementation. Clinical signs are secondary to extraluminal compression of the trachea and/or crop by the hyperplastic thyroid gland. In addition to a clicking respiratory noise, voice change and dyspnea, affected birds can also demonstrate regurgitation.
Key points of urgent care
- HANDS OFF!
- Provide supplemental oxygen
Transfer the dyspneic bird to a quiet, calm, oxygen-rich environment.
- When the bird is presented in a relatively small cage, simply place the entire transport enclosure within a large oxygen cage.
- When it is necessary to restrain the patient to transfer it into oxygen, obtain a body weight using a gram scale and perform a quick, cursory exam if clinical condition allows.
- Humidify air providing 40-50% oxygen for at least 15-30 minutes. Two to four hours of supplemental oxygen prior to restraint may be preferable.
- An air sac cannula is indicated for severe tracheitis or obstruction to establish a patent airway and allow further case management.
Cautiously provide supplemental heat (80-85°F or 26.7-29.4°C) if the patient is fluffed and ruffled or thin. Monitor the patient closely since overheating can exacerbate respiratory distress, especially in the overweight bird.
Provide some form of visual security such a towel draped over part of the oxygen cage (Fig 2). See Basic Husbandry: Hospitalizing Non-Traditional Pets for additional advice.
- Obtain a complete history while the patient is being cage rested.
- Confirm signalment.
- Discuss the presenting complaint and the progression of clinical signs.
- Be sure to ask if a change in voice or loss of voice has been noted in any bird presented with respiratory signs or non-specific signs of illness.
- Take a detailed medical history. Has the bird been ill before? Is the bird currently on any medications? Has the bird recently been anesthetized? (Iatrogenic tracheitis and tracheal stenosis has been reported secondary to endotracheal intubation).
- Obtain a complete picture of husbandry practices. What diet is fed? What proportion of the diet is actually eaten? Are any vitamin/mineral supplements provided? Where in the house is the cage located? What is used to line the cage floor? (Soiled corncob bedding can promote fungal overgrowth). How often is the cage cleaned? Is the bird exposed to other animals or birds?
After taking a complete history and providing supplemental oxygen, the bird may improve enough to handle an abbreviated physical examination. Although it is prudent to gather supplies for all avian exams, it is particularly important for the bird with respiratory disease. It is also wise to have oxygen available for the dyspneic patient. Always warn the client in advance about the inherent risk of handling a critically ill bird.
In addition to standard supplies, gather a bright, focused light source like a transilluminator. Transillumination of the tracheal lumen may be performed in finches or canaries to look for the presence of tracheal mites, aspirated millet seeds or other tracheal foreign bodies (Box 2).
Box 2. How to transilluminate the small bird
- Part the feathers overlying the trachea.
- Wet the skin with alcohol.
- Hold the transilluminator to one side of the throat.
- Observe the tracheal lumen within a darkened room.
If the bird is dyspneic, the clinician’s initial response should be HANDS’S OFF!!! Dyspneic birds can die soon after presentation with the additional stress of restraint, therefore minimize handling and place the bird in an oxygen-rich environment (see below).
Obtain a minimal database when (and if) clinical condition allows. If the bird is dyspneic, even staged testing may not be possible and initial care will need to be empirical therapy that is guided by signalment and history.
- Complete blood count:
- Plasma protein electrophoresis:
- Biochemistry panel:
Obtain survey whole body radiographs that include the trachea. Depending on the size of your patient, the entire length of the trachea may not fit on the same film as the coelomic cavity.
Aspergillosis can be associated with a number of abnormalities including a profound heterophilic leukocytosis(Box 3).
|Box 3. Clinical pathologic findings common with aspergillosis|
Protein electrophoresis in the bird with aspergillosis may reveal hyperproteinemia and hypergammaglobulinemia.
Biochemistry panel results can be unremarkable, but may indicate organ involvement if advanced aspergillosis extends into the liver or kidney.
When performing a complete workup, advanced diagnostic techniques that may be performed by an avian veterinarian include Aspergillus serology and laparoscopic evaluation of the trachea, air sacs and lungs.
Treatment will vary with the underlying cause but frequently includes supportive care, such as fluids, cage rest and nebulization as well as anthelmintic (Ivermectin 0.2 mg/kg PO or SC) or antimicrobial therapy. Antimicrobials can be delivered systemically and via intratracheal injection.
Treatment of aspergillosis is often very difficult. Itraconazole is one of the most widely used antifungals in the avian patient. This drug is generally well tolerated during long term use, however anecdotal reports suggest that the African grey parrot is more sensitive to itraconazole. Adverse drug effects can be observed in grey parrots at normal dosage levels. See Fungal Disease in Avian Patients for specific antifungal recommendations.
It is extremely rare to find a treatment in modern avian medicine that relies upon medication in the water, however this is the case for goiter. There is significant risk of toxicity in parakeets given parenteral iodine supplementation. Instead Lugol’s iodine is placed in the water. The stock solution consists of 2 ml of Lugol’s iodine added to 30 ml of water. One drop of stock solution is then mixed with 250 ml of drinking water. This solution is provided as the only form of drinking water.
Advanced therapeutic technique that may be used by experienced avian veterinarians include laparoscopic debulkment or removal of plaques or even tracheotomy in rare instances.
Bowles HL, Odberg E, Harrison GJ, Kottwitz JJ. Surgical resolution of soft tissue disorders. In: Harrison GJ, Lightfoot TL (eds). Clinical Avian Medicine. Palm Beach, FL, Spix Publishing, 2006. P. 798.
Ford, S. Tracheal foreign body removal in small birds. Proc Annu Conf Assoc Avian Vet. 2007. Pp. 49-54.
Jankowski G, Nevarez JG, Beaufrere H, et al. Multiple tracheal resections and anastomoses in a blue and gold macaw (Ara ararauna). J Avian Med Surg 24(4):322-329, 2010.