Tracheal Collapse

Tracheal Collapse (Abnormality of the Windpipe)- An Overview

  • “Upper respiratory tract” (also known as the “upper airways”) includes the nose, nasal passages, throat (pharynx), and windpipe (trachea)
  • “Lower respiratory tract” (also known as the “lower airways”) includes the bronchi, bronchioles, and alveoli (the terminal portion of the airways, in which oxygen and carbon dioxide are exchanged)
  • The windpipe or trachea is the large airway that carries air from the nose and throat to the airways (bronchi) that go to the lungs
  • “Tracheal collapse” is a reduction in the diameter of the lumen of the windpipe (trachea) during breathing; it is considered to be a “dynamic” process as the lumen’s diameter changes with the movements of breathing (inspiration and expiration)
  • May involve the windpipe (trachea) in the neck (known as the “cervical trachea”), the windpipe (trachea) within the chest (known as the “intrathoracic trachea”), or both segments
  • “Broncho-” refers to the bronchus (plural, bronchi); “malacia” refers to weakening or softening of an organ or tissue; “bronchomalacia” refers to a condition in which the bronchi and smaller airways collapse due to weakening of the walls of the bronchi—bronchomalacia may be present by itself or may be present at the same time as collapse of the windpipe or trachea (tracheal collapse)
  • Compression of the windpipe (trachea) or bronchi as a result of enlarged lymph nodes or the presence of tumors are not considered part of this condition

Genetics

  • Unknown

Signalment/Description of Pet

Breed Predilections

  • Miniature poodles, Yorkshire terriers, Chihuahuas, Pomeranians, and other small- and toy-breed dogs

Mean Age and Range

  • Middle-aged to elderly—onset of signs at 4–14 years of age
  • Severely affected pets may be less than 1 year of age

Signs/Observed Changes in Pet

  • Usually worsened by excitement, heat, humidity, exercise, or obesity
  • Dry, honking cough
  • May have long-term (chronic) intermittent coughing or difficulty breathing
  • Retching (attempting to vomit)—often seen due to attempts to clear respiratory secretions from the voice box (larynx)
  • Rapid breathing (known as “tachypnea”), exercise intolerance, and/or severe breathing difficulty (known as “respiratory distress”)—common
  • Breathing difficulty (respiratory distress)—seen during inspiration (breathing in) with collapse of the windpipe in the neck (cervical tracheal collapse); seen during expiration (breathing out) with collapse of the windpipe within the chest (intrathoracic tracheal collapse)
  • Bluish discoloration of the skin and moist tissues (mucous membranes) of the body caused by inadequate oxygen levels in the red blood cells (known as “cyanosis”) or fainting (known as “syncope”)—may see in severely affected individuals
  • Increased tracheal sensitivity
  • Whistling sounds (wheezing) or musical sounds over the narrowed area of the windpipe may be heard while listening with a stethoscope (known as “auscultation”)
  • A “snap” sound may be heard (when listening with a stethoscope) at the end of expiration, when large segments of the windpipe (trachea) collapses within the chest (intrathoracic tracheal collapse) during forceful expiration
  • Abnormal breath sounds on listening to the lungs with a stethoscope (auscultation)—increased intensity or breath sounds over the bronchi; short, rough snapping sounds (known as “crackles”); and squeaking or whistling sounds (known as “wheezes”)—indicate coexistent small airway disease
  • Heart murmurs (mitral valve insufficiency murmurs)—often are found in small-breed dogs with tracheal collapse
  • Normal to low heart rate
  • Loud second heart sound detected when listening to the heart with a stethoscope (auscultation)—suggests increased blood pressure within the lungs (known as “pulmonary hypertension”)
  • Enlarged liver (known as “hepatomegaly”)—cause unknown

Causes

  • Unknown cause
  • Defects in the development of cartilage in the windpipe (trachea) or nutritional factors are suspected
  • Long-term (chronic) small-airway disease suggested to contribute to development of weakening of the bronchi (bronchomalacia), but relationship is not clear

Risk Factors

  • Obesity
  • Infection or inflammation of the airways
  • Upper airway blockage or obstruction
  • Intubation with an endotracheal tube (passage of an endotracheal tube through the mouth and into the windpipe [trachea] to allow oxygen to reach the lungs)

Treatment

Health Care

  • Outpatient—stable pets
  • Inpatient—oxygen therapy and sedation for severe breathing difficulty (respiratory distress) or for severely anxious pets

Activity

  • Severely limited, until the pet is stable
  • During management of disease—gentle exercise recommended to encourage weight loss

Diet

  • Most affected dogs improve after losing weight
  • Institute weight-loss program with a high-fiber reducing diet
  • Feed 80% of total daily requirement of calories; use a slow weight-loss program

Surgery

  • Surgery—may benefit some pets, primarily those with collapse of the windpipe (trachea) in the neck (cervical tracheal collapse)
  • Treatment of upper airway obstructive disorders (such as elongated soft palate or turning inside-out of a portion of the voice box or larynx [known as “everted laryngeal saccules”])—may reduce tracheal signsPlacement of stents to keep the lumen of the windpipe open, in selected pets (primarily with collapse of the windpipe [trachea] in the neck [cervical tracheal collapse]) by a skilled surgeon—will enhance quality of life and reduce clinical signs when adequate stabilization of the airway can be achieved and when weakening of the bronchi (bronchomalacia) does not limit resolution of disease
  • A “stent” is a medical tube used to hold open an airway; stents can be life-saving in certain cases with airway collapse within the chest

Medications

Medications presented in this section are intended to provide general information about possible treatment. The treatment for a particular condition may evolve as medical advances are made; therefore, the medications should not be considered as all inclusive.

  • Sedation and cough suppression—butorphanol; addition of a tranquilizer (acepromazine) may enhance sedative effects and further reduce the cough reflex; narcotic cough suppressants (butorphanol or hydrocodone) effective for long-term (chronic) treatment
  • Drugs to dilate the bronchi and bronchioles (known as “bronchodilators”); dilation of small airways and lowering pressure gradients with lower airway disease—sustained-release theophylline or terbutaline; bronchodilators have no effect on the diameter of the windpipe (trachea)
  • Bacterial infection is uncommon; however, doxycycline is an antibiotic that is sometimes beneficial by decreasing the number of bacteria in the airway or by reducing inflammation
  • Reduction of inflammation of the windpipe (trachea)—prednisone; consider inhaled steroids given via face mask and spacer chamber
  • Robitussin DM—may provide relief to pet, reduce the severity of the cough, but is not a cure (known as “palliation”); use any medications only under the direction of your pet’s veterinarian

Follow-Up Care

Patient Monitoring

  • Body weight
  • Exercise tolerance
  • Pattern of breathing
  • Incidence of cough

Preventions and Avoidance

  • Avoid obesity in breeds commonly afflicted with tracheal collapse
  • Avoid heat and humidity
  • Use a harness rather than a collar (a collar puts pressure on the windpipe, and may aggravate the problem)

Possible Complications

  • Severe breathing difficulties that do not respond to medical treatment (known as “intractable respiratory distress”) leading to respiratory failure or euthanasia
  • Consider likelihood of complications after surgery (such as persistent cough, severe breathing difficultly [respiratory distress], or paralysis of the voice box (larynx; laryngeal paralysis]);
  • Some pets may require a permanent surgical opening into the windpipe or trachea (known as a “permanent tracheostomy”)

Expected Course and Prognosis

  • Combinations of medications, along with weight control, may reduce clinical signs; however, pet likely will cough throughout life and can have periods when clinical signs worsen
  • Surgery—may benefit some dogs, primarily those with collapse of the windpipe (trachea) in the neck (cervical tracheal collapse)
  • Stent placement—benefits some dogs, primarily those with windpipe (trachea) collapse within the chest
  • Prognosis—based on evidence and degree of airway blockage

Key Points

  • “Tracheal collapse” is a reduction in the diameter of the lumen of the windpipe (trachea) during breathing; it is considered to be a “dynamic” process as the lumen’s diameter changes with the movements of breathing (inspiration and expiration)
  • Obesity, overexcitement, and humid conditions may precipitate a breathing crisis
  • Use a harness instead of a collar
  • Combinations of medications, along with weight control, may reduce clinical signs
  • Tracheal collapse is irreversible; treatment is designed to decrease triggers of cough
  • Complications may occur following surgery; complications include persistent cough, breathing distress, or paralysis of the voice box or larynx (laryngeal paralysis)
  • Some pets may require a permanent surgical opening into the windpipe or trachea (permanent tracheostomy)
  • Extensive follow-up is required for pets that have stents placed in the airways, to monitor for damage to the stent and for migration of the stent

Infectious Canine Tracheobronchitis/Kennel Cough

Infectious Canine Tracheobronchitis/Kennel Cough – An Overview

  • Any contagious respiratory disease of dogs that is manifested by coughing

Signalment/Description of Pet

Breed Predilections

  • None

Mean Age and Range

  • Most severe in puppies 6 weeks–6 months old
  • May develop in dogs of all ages and often with preexisting subclinical airway disease (such as abnormal development of the respiratory tract or long-term inflammation of the bronchi [known as “chronic bronchitis”])

Signs/Observed Changes in Pet

  • Related to the degree of respiratory tract damage and age of the affected dog
  • May be nonexistent, mild, or severe with pneumonia
  • Most viral, bacterial, and Mycoplasma agents spread rapidly from seemingly healthy dogs to other dogs in the same environment; signs usually begin about 4 days after exposure to the infecting agent(s)
  • Uncomplicated—cough in an otherwise healthy dog is characteristic; may be dry and hacking, soft and dry, moist and hacking, or sudden and sharp, followed by gagging or spitting up of mucus; excitement, exercise, changes in temperature or humidity of the inspired air, and gentle pressure (such as from collar) on the windpipe (trachea) induce a sudden onset of coughing
  • Uncomplicated—cough readily induced with pressure on the windpipe (trachea) during physical examination; lung sounds often normal; otherwise appears healthy
  • Severe—decreased appetite (known as “inappetence”) to loss of appetite (known as “anorexia”); cough (when noted) is moist and productive; may see sluggishness (lethargy), difficulty breathing (known as “dyspnea”), and exercise intolerance
  • Severe—may have constant, low-grade, or fluctuating fever (39.4–40.0°C; 103–104°F); may have increased intensity of normal lung sounds; short, rough lung sounds (known as “crackles”) heard with a stethoscope; or (less frequently) whistling or squeaking sounds (known as “wheezes”)

Causes

  • Viral—canine distemper virus; canine adenovirus-2; canine parainfluenza virus; canine adenovirus-1; canine respiratory coronavirus; canine reovirus type 1, 2, or 3; canine herpesvirus-1; canine influenza virus
  • Canine adenovirus-2 and canine parainfluenza virus may damage the lining cells of the respiratory tract to such an extent that invasion by various bacteria and Mycoplasma cause severe airway disease
  • Bacterial—Bordetella bronchiseptica, (with no other respiratory disease-causing agents) produces clinical signs indistinguishable from those of other bacterial causes; Pseudomonas, Escherichia coli, Klebsiella, Pasteurella, Streptococcus, Mycoplasma, and other species equally likely

Risk Factors

  • Dogs housed with multiple other dogs, such as pet shops, humane society shelters, research facilities, and boarding and training kennels
  • Housing with less than ideal hygienic conditions; overcrowding conditions
  • Preexisting subclinical airway disease, such as abnormal development of the respiratory tract or long-term inflammation of the bronchi (chronic bronchitis)

Treatment

Health Care

  • Outpatient—strongly recommended for uncomplicated disease
  • Inpatient—strongly recommended for complicated disease and/or pneumonia
  • Fluid administration—indicated for complicated disease and/or pneumonia

Activity

  • Enforce rest—for at least 14–21 days with uncomplicated disease; for at least the duration of x-ray evidence of pneumonia in severely affected dogs

Diet

  • Good-quality canned or dry commercial food

Medications

Medications presented in this section are intended to provide general information about possible treatment. The treatment for a particular condition may evolve as medical advances are made; therefore, the medications should not be considered as all inclusive.

  • Antibiotic therapy—amoxicillin/clavulanic acid or doxycycline—initial treatment of uncomplicated disease
  • Antibiotic therapy—cephalosporin (such as cefazolin) with gentamicin or amikacin or enrofloxacin—usually effective for severe pneumonia; continue antibiotic therapy for at least 10 days beyond resolution of pneumonia as seen on x-rays (radiographs)
  • Bordetella. bronchiseptica or other resistant bacteria—some antibiotics may not reach adequate levels in the lower respiratory tract to be effective, so administration of these antibiotics by mouth or injection may have limited effectiveness; treating with a fine medicated spray (known as “nebulization”) containing kanamycin, gentamicin, or polymyxin B maybe effective, when administered daily for 3–5 days; also administer systemic antibiotics in dogs with lung disease
  • Cough suppressants (such as butorphanol or hydrocodone)—effective in decreasing the dry, nonproductive cough, not associated with bacterial infectionDrugs to increase the openings in the bronchi and bronchioles (known as “bronchodilators,” such as extended-release theophylline)—may be used to control narrowing of the bronchi and bronchioles due to contraction of smooth muscles in the walls of these airways (known as “bronchospasm”); bronchospasm is detected clinically by whistling or squeaking sounds (wheezes)

Follow-Up Care

Patient Monitoring

  • Uncomplicated disease—should respond to treatment in 10–14 days; if the pet continues to cough 14 days or more after adequate treatment, dog should be evaluated again by your pet’s veterinarian
  • Severe disease—repeat chest x-rays (radiographs) until at least 14 days beyond resolution of all clinical signs

Preventions and Avoidance

  • Shedding of the causative virus and/or bacteria of infectious canine tracheobronchitis (kennel cough) in respiratory secretions of dogs undoubtedly accounts for the persistence of this problem in kennels, animal shelters, boarding facilities, and veterinary hospitals; thorough cleaning and disinfecting of kennels is necessary to control spread of disease-causing organisms
  • Do not use cocoa bean hull mulch in areas accessible to pets

Viral and Bacterial Vaccines

  • Available to control disease caused by the principal infectious agents involved
  • Bordetella bronchiseptica and canine parainfluenza virus vaccine—may vaccinate puppies using a vaccine applied into the nose (intranasal vaccine) as early as 2–4 weeks of age, without interference from maternal antibody; follow-up vaccinations should be administered as directed by your pet’s veterinarian; may vaccinate mature dogs with a one-dose intranasal vaccination (at the same time as their puppies or when they receive other vaccinations, as directed by your pet’s veterinarian)
  • Inactivated injectable Bordetella bronchiseptica vaccine—administered as two doses, 2–4 weeks apart; initial vaccination of puppies is recommended at or about 6–8 weeks of age; administer second vaccine at 4 months of age
  • Inactivated canine influenza virus vaccine is available

Expected Course and Prognosis

  • Natural course of uncomplicated disease, if untreated—10–14 days; simple restriction of exercise and prevention of excitement shortens the course
  • Typical course of severe disease—2–6 weeks; may be fatal in pets that develop severe pneumonia, affecting multiple lung lobes

Key Points

  • Isolate the dog from other pets; infected dogs can transmit the disease-causing virus and/or bacteria before onset of clinical signs and afterward until immunity develops
  • Dogs with uncomplicated disease should respond to treatment in 10–14 days
  • Once infection spreads in a kennel, it can be controlled by removing all dogs from the premises for 1–2 weeks and disinfecting with commonly used chemicals, such as sodium hypochlorite (bleach; 1:30 dilution), chlorhexidine, or benzalkonium (NOTE: never mix disinfectants; follow directions for use carefully)

Brachycephalic Airway Syndrome

Brachycephalic Airway Syndrome – An Overview

Upper Airway Problems Seen in Short-Nosed Breeds

  • Partial upper airway obstruction in short-nosed, flat-faced (brachycephalic) breeds of dogs caused by any combination of the following conditions: narrowed nostrils (known as “stenotic nares”); overly long soft palate; turning inside-out of a portion of the voice box or larynx (known as “everted laryngeal saccules”), such that the space for air to pass through the larynx is decreased; and collapse of the voice box or larynx (known as “laryngeal collapse”)
  • An abnormally small windpipe or trachea (known as “hypoplastic trachea”) often is present as well, and can worsen breathing difficulty (respiratory distress)
  • “Upper respiratory tract” (also known as the “upper airways”) includes the nose, nasal passages, throat (pharynx), and windpipe (trachea)

Genetics

  • No specific genes have been identified
  • Short-nosed, flat-faced, broad (brachycephalic) head shape was initially an inherited defect in development of skull bones; has been perpetuated by selective breeding in certain breeds of dogs

Signalment/Description of Pet

Breed Predilections

  • Common syndrome in brachycephalic breeds of dogs

Mean Age and Range

  • Young adults, most diagnosed by 2–3 years of age
  • If diagnosed later than 4 years of age, another disease or condition may be adding to upper airway obstruction leading to diagnosis; older dogs may have a worse outcome post-operatively, but most have some improvement
  • Collapse of the voice box or larynx (known as “laryngeal collapse”) reported in short-nosed, flat faced (brachycephalic) breed puppies as young as 6–7 months of age

Signs/Observed Changes in Pet

  • Snoring; high-pitched, noisy breathing (stridor); noisy breathing when inhaling (stertorous breathing)
  • Rapid breathing (known as “tachypnea”), frequent panting
  • Coughing and gagging
  • Difficulty eating and swallowing
  • Excessive salivation (known as “ptyalism”), regurgitation (return of food or other contents from the esophagus or stomach back up through the mouth), and vomiting
  • Occasionally, fainting (syncope) and episodes of collapse
  • Narrowed nostrils (stenotic nares)
  • Increased breathing (respiratory) effort—may see pulling back of the lips with each breath, open-mouth breathing or constant panting, increased breathing rate, turning of the elbows away from the body (abduction of forelimbs) in an effort to open up the chest, increased abdominal effort during breathing
  • In severe breathing distress, may have increased difficulty in breathing while lying flat (known as “orthopnea”), even to point of reluctance to lie down; and bluish discoloration of skin and moist tissues of body (known as “cyanosis”)
  • Increased body temperature (known as “hyperthermia”) may be present

Causes

  • Brachycephalic airway syndrome results from inherited defects or developmental/growth defects of the upper airway. These defects include the following:
  • Elongated soft palate—reported in over 90% of surgical cases in dogs
  • Narrowed nostrils (stenotic nares)—reported in about 50% of cases in dogs
  • Voice box or laryngeal disease—everted laryngeal saccules (over 50% of affected dogs) and/or laryngeal collapse (approximately 10% of affected dogs)
  • Abnormally small windpipe (hypoplastic trachea); primarily in the English bulldog

Risk Factors

  • Brachycephalic breed
  • Obesity—worsens airway obstruction; associated with poorer outcome following surgical correction; may contribute to backward or reverse flow of stomach contents into the esophagus (known as “gastroesophageal reflux”) and development of aspiration pneumonia
  • Excitement and/or warm, humid weather—increased panting can lead to fluid buildup (edema) in the tissues of the airway, further narrowing the airway opening, and leading to increased body temperature (hyperthermia)
  • Exercise—dogs often are unable to exercise because of airway compromise and low levels of oxygen in their blood (hypoxia)
  • Sedation may cause relaxation of the muscles of throat (pharynx) and soft palate, and may cause complete airway obstruction
  • Lung disease (such as pneumonia, pulmonary edema)—will cause additional breathing compromise
  • Endocrine disease (such as low levels of thyroid [known as “hypothyroidism”] or high levels of steroids [known as “hyperadrenocorticism” or “Cushing’s syndrome”])—could worsen weight gain and cause excessive panting

Treatment

Health Care

  • Surgery recommended for pets with significant clinical signs
  • Emergency presentation with pet in severe breathing distress requires rapid medical intervention, including oxygen supplementation
  • If the pet has high body temperature (hyperthermia), cool with iced water and by directing a fan to blow over the pet (increase convective heat loss); intravenous (IV) fluids should be administered, up to a shock rate if has an extremely elevated body temperature (greater than 106°F)
  • If the airway is completely obstructed, the airway must be opened; this may be accomplished by passing an endotracheal tube through the mouth and into the windpipe (known as “orotracheal intubation”) and/or by a surgical incision into the windpipe (known as a “temporary tracheostomy”)
  • Dexamethasone can be administered to reduce inflammation
  • Pets need 24-hour monitoring because of risk of acute airway obstruction and death
  • Breathing rate and effort, heart rate, pulse quality, color of gums and moist tissues (mucous membrane color), time for pink color to return to gums after blanching them with one’s finger (capillary refill time), temperature, and other physical parameters should be monitored
  • Pulse oximetry and arterial blood gases to determine oxygen levels in the blood may be monitored, depending on severity of condition
  • Intravenous fluids are administered at maintenance rate and handling and stress are minimized

Activity

  • Usually self-limited by the pet

Diet

  • Weight loss is recommended for all overweight dogs
  • For obese, stable pets, weight loss is recommended prior to surgery

SURGERY

  • Evaluation for elongated soft palate generally is performed under general anesthesia when the pet is stable
  • Surgical incision into the windpipe (temporary tracheostomy) can be performed to facilitate exposure or to treat airway obstruction
  • Narrowed nostrils (stenotic nares) are corrected by surgically removing a wedge of the nasal tissue and closing the incision in such a manner to allow the nostril to be enlarged
  • Elongated soft palate is treated by surgically removing a section of the soft palate using surgical scissors, carbon dioxide laser, or a bipolar sealing device
  • Everted laryngeal saccules are treated by surgically trimming the tissue
  • Permanent surgical opening into the windpipe or trachea (known as a “permanent tracheotomy”) may be necessary if severe laryngeal collapse is present

Medications

Medications presented in this section are intended to provide general information about possible treatment. The treatment for a particular condition may evolve as medical advances are made; therefore, the medications should not be considered as all inclusive.

  • Dexamethasone to reduce fluid buildup (edema) and inflammation
  • Broad-spectrum antibiotics are indicated if aspiration pneumonia is present, until culture and sensitivity results are obtained
  • Omeprazole, cisapride, and magnesium hydroxide after meals or sucralfate resulted in improvement in dogs that also have inflammation of the esophagus (known as “esophagitis”), inflammation of the stomach (known as “gastritis”) and/or inflammation of the upper small intestine (known as the “duodenum”; condition known as “duodenitis”)

Follow-Up Care

Patient Monitoring

  • Post-operatively, 24-hour monitoring to observe for airway swelling and obstruction, which may require surgical incision into the windpipe (temporary tracheostomy)
  • Breathing rate, effort, heart rate, pulse quality, mucous membrane color, capillary refill time, temperature, and other physical parameters should be monitored

Preventions and Avoidance

  • Selection by breeders for dogs without severe conformational changes—may be difficult because breed standards encourage these structural changes
  • Avoid risk factors, particularly weight gain

Possible Complications

  • Overheating and heat stroke
  • Aspiration pneumonia (inflammation of the lungs, caused by accidentally inhaling food, vomit, or liquids into the airways)
  • Death in about 10% of affected pets as a result of airway disease
  • Most common post-operative complication is airway swelling and obstruction within the first 24 hours, may necessitate surgical incision into the windpipe (temporary tracheostomy)
  • Continued breathing difficulty after corrective surgery
  • Excessive shortening of the soft palate resulting in aspiration of food contents into the nasal cavity due to inability to close off the area between the nose and throat (known as the “nasopharynx”) during swallowing

Expected Course and Prognosis

  • Prognosis is good for improvement in breathing (80% of cases have good to excellent results following surgery) but airway is still far from normal
  • Prognosis better for dogs other than English bulldogs and for dogs that have correction of narrowed nostrils (stenotic nares) and elongated soft palate during same surgery
  • Without surgery, prognosis is poor due to continued progression of brachycephalic airway syndrome
  • Lifelong avoidance of risk factors recommended to decrease chance of developing clinical signs or worsening of disease

Key Points

  • Avoidance of risk factors is critical
  • Dogs with brachycephalic airway syndrome are at increased anesthetic risk, and an even higher risk occurs if they also have obesity, heart disease, or aspiration pneumonia (inflammation of the lungs, caused by accidentally inhaling food, vomit, or liquids into the airways)
  • Surgery often improves the clinical signs but does not result in a completely normal airway