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Name
Tracheal Collapse, Canine
Short Description
Tracheal collapse, obstructive upper airway disease
Affected Animals: Dogs, especially older small or toy breeds. Dogs
affected by congenital tracheal collapse can show symptoms at an
earlier age. Commonly affected breeds include the miniature poodle,
Yorkshire terrier, Chihuahua, and Pomeranian.
Overview:
Small breed dogs are particularly susceptible to
a condition called tracheal collapse. The tracheal rings, which are
made of cartilage, can become weak and fail to keep the trachea open
during breathing. When the trachea collapses, air is no longer able
to move through the respiratory tract. Depending upon the stage of
respiration in which the collapse occurs, air may become trapped
within the lungs or blocked from entering them.
A collapse is more likely to occur when the animal is moving air
within the airways at a faster rate than normal, or if there is
added pressure around the outside of the trachea. Excitement,
exercise, obesity, and allergies are factors that may incite
tracheal collapse.
Treatment options vary according to the severity of the condition.
Some dogs may require stabilization with medications while others
may need surgery. Attempts to decrease risk factors, such as placing
an obese canine on a diet, can be beneficial in preventing or
minimizing the effects of tracheal collapse.
Clinical Signs: Some dogs with tracheal collapse will have an
intermittent, dry "goose honk" cough. Dyspnea, or difficulty
breathing, will be noted in most animals with this disease. Retching
or gagging can occur in dogs that are trying to clear secretions
from their throat. Clinical signs typically worsen when the animal
is excited, drinks water quickly, or becomes overheated. In severe
cases, the animal may appear cyanotic, having a bluish tinge to the
mucous membranes. Some dogs will faint, or experience syncope, due
to a lack of oxygen supply to the brain, which occurs when the dog
is overexerted or anxious.
Symptoms:
See clinical signs.
Description: The trachea is the upper airway tube that carries
inspired and expired air between the nose and mouth and the airways
and lungs. The trachea is formed by separate incomplete
cartilaginous rings, which are connected by fibrous connective
tissue and muscle. In normal dogs, the trachea remains open or
patent at all times. If the tracheal rings become weak for any
reason, the normal action of breathing can result in the collapse of
the trachea in that area.
If the tracheal rings are abnormal in the neck of
the dog, the collapse usually occurs when the animal inhales.
Conversely, the trachea tends to collapse during expiration when the
abnormal tracheal rings are inside the dog's chest cavity. This
distinction is the result of varying pressure gradients created
during the different stages of respiration. Once the trachea has
collapsed, the airway is obstructed and air is no longer able to
move.
Dogs with tracheal collapse may have any of various symptoms
depending on the severity of the condition. Some dogs may make an
almost musical sound when breathing, and gag or cough to try to
reopen the airway. Some may faint if severely affected.
Treatments range from medications to help control excessive coughing
to surgical stabilization of the tracheal rings. Some preventive
measures may decrease the incidence of tracheal episodes.
Diagnosis: Several techniques are used to diagnose tracheal
collapse. During a physical exam, the veterinarian will assess
whether the trachea is sensitive to palpation, which, in cases of
collapse, also may induce coughing. Additionally, a thorough oral
exam under anesthesia commonly is performed. Both inspiratory and
expiratory x-rays are taken of the chest and the cervical trachea,
or the part of the trachea within the neck, in order to define the
area that is affected. Often, the dog's general health will be
screened using blood and urine tests.
Because there are other disorders that obstruct the upper airways,
the veterinarian may need to rule out these diseases before making a
diagnosis of tracheal collapse. However, more advanced diagnostic
procedures such as bronchoscopy, blood gas analysis, and fluoroscopy
require referral to a veterinary internist or teaching hospital.
Fluoroscopy is a real time x-ray that demonstrates the movement of
the trachea as the dog is breathing.
Prognosis: The prognosis for dogs with tracheal collapse
depends on the severity of the disease and their response to
treatment.
Transmission or Cause: The cause of tracheal collapse is believed to
involve multiple factors. Genetics, nutrition, abnormal development
of the trachea, and chronic airway disease are all possible factors
in the evolution of tracheal collapse. Risk factors such as obesity,
degeneration of the cartilage comprising the tracheal rings,
allergies, and chronic pulmonary disease can exacerbate a collapsing
trachea.
Treatment:Severely affected dogs require
hospitalization for cage rest, medication administration, and oxygen
supplementation. Once the animal is stable, it can be sent home with
drugs that can help alleviate the symptoms of tracheal collapse.
Common treatments include medications that suppress excessive
coughing, open up the airways, reduce inflammation, fight off
infection, and eliminate overabundant airway secretions. Obese dogs
should be placed on an appropriate weight-reduction diet. Until the
dog is stable, exercise should be very limited; afterwards, light
activity can be resumed.
For those animals that fail to respond to medical treatment, there
are surgical techniques that provide structural support for the
trachea. It is possible to construct a prosthesis that wraps around
the exterior of the trachea and holds the trachea open when it is
sutured in place. Possible complications of this procedure include
infection and necrosis (or death) of the trachea, which can lead to
serious consequences. Consequently, an experienced veterinary
surgeon should perform this highly specialized surgery.
Prevention: Owners should do their best to prevent risk
factors such as obesity, allergens, excessive temperatures or
humidity, overexertion, and respiratory infections. A harness,
instead of a collar, is recommended for walking dogs susceptible to
tracheal collapse so that pressure is not applied to the neck.
