SA URT surgery and nasal disease

Question 1

Explain BOAS

Answer 1

• Brachycephalic obstructing airway disease
• Bulldogs normally suffering from upper airway obstruction and will present with sturtor (snooring)
• If an animal has stridor = obstruction in larynx or cranial trachea and this is seen in laryngeal paralysis or obstruction.

Question 2

Pathophysiology of BOAS (primary and secondary factors)

Answer 2

• Primary and secondary factors. The primary factors - the animal will be born with cf. the secondary which will develop as they age.

Primary factors

• Stenotic external nares
• Relative overlength of soft palate
• Relative oversize of the tongue
• Tracheal hypoplasia/stenosis
• Sliding hiatal hernia

Secondary factors

• Hypertrophy of soft palate
• Tonsillar hypertrophy
• Everted laryngeal ventricles
• Laryngeal collapse
• Pharyngeal collapse
• Glosso-epiglottic mucosa displacement
• Scrolling of epiglottic cartilage
• Vomiting/regurgitation

Things that we worry about are:

• External naras
• Relative overlength of soft palate
• Big tongue
• May be born with abnormally small trachea.

Question 3

What is the radiograph showing?

Answer 3

Tracheal hypoplasia

• This dog has a very small narrow trachea – trachea hypoplasia as part of its airway obstruction disease. Cannot surgically manage.

Question 4

Explain the different stages of laryngeal collapse

Answer 4

NB: can do surgery for this (seen as a secondary factor of BOAS). Each breathe they take, they have to generate greater negative pressure to get air into lungs, so have a tendency to collapse.

Stage 1: Eversion of laryngeal ventricles

Stage 2: collapse of the arytenoid cartilage

Stage 3: Medial deviation of the corniculate process of the arytenoid cartilages.

Question 5

Management techniques for BOAS?

Answer 5

• Excision of everted laryngeal saccules
• External nasal aperture stenosis managed with rhinoplasty wedge-resection
• Surgery of the soft palate - staphylectomy or palatoplasty
  
  • No right way, just personal preference but staphylectomy is more common
• Tonsillectomy

Question 6

Different surgical techniques for soft palate surgery?

Answer 6

1. Staphylectomy – do through mouth, dog is hung on the table, so can get access to back of throat, trim shorter, so about level of the tonsil crypts. (more common in UK cf. palatoplasty)
2. Palatoplasty – taking some of the thickness out of the palate and shortening. You make an incision in palate and role forwards so folded back on itself, so cutting some of the muscle out of it.

Question 7

Clincial signs of BOAS

Answer 7

• Stridor
• Cough
  
  • due to lack of control over larynx and therefore more prone to aspiration of mucoid material
• Dyspnoea
• Change in phonation
  
  • Bark
• Exercise intolerance
• Collapse
• Signs are related to the severity of paralysis present
• Most dogs present late in the course of the disease
• Clinical signs worse when the dog is hot, excited and exercised.

Question 8

Diagnosis of BOAS?

Answer 8

• Layngoscopy
  
  • GA and under light plane, observe laryngeal movement of arytenoids with handheld laryngescope.
  • If over GA, you will obliterate arytenoid movement anyway, so won’t be able to assess it!
  • Seeing adduction on inspiration – as air flows through, get change in pressure (drop) and this will draw the arytenoids together.
• Characteristic clinical signs
• Auscultation of the larynx and the thorax
• Laryngoscopy (under a light plane of general anaesthesia)
• Straight-bladed laryngoscope (Miller)
• X-ray
• Often part of a polyneuropathy
  
  • Give thorough neuro exam.

Question 9

Emergency medical management for BOAS?

Answer 9

• Supplemental oxygen
• Cooling
  
  • Often hyperthermic: fan, wet towels etc. surgical spirit can be used too.
• Sedation
  
  • Contentious as can make it worse esp. ACP with opioid – can make case more wound up and anxious, so can be a double edged sword.
• IV access
• IV corticosteroids (?)
  
  • Will depend on what you’re doing with the case, med’s it is already on etc.
• Anaesthetise –> tracheostomy tube placement (?)

Question 10

Explain the process of arytenoid lateralisation (tie back)

Answer 10

• Aims to widen the rim glottis and stabilise the unstable arytenoid (only operate on one side in the dog – side you pick will depend if you are right or left handed)
• Aims to widen the rima glottdis and prevent dynamic collapse of the arytenoid cartilage
• Don’t do both sides as massive increased risk of aspiration pneumonia.
• Most dogs, for the degree of exercise they do, they will do extremely well with unilateral procedure.
• Aims to widen the rima glottis and prevent dynamic collapse of the arytenoid cartilage
• Almost invariably performed as unilateral procedure
  
  • Side can depend on whether right or left hand sided surgeon (lefts are easier to operate if left handed..)
  • If one side is more paralysed then operate on this side - often only partial paralysis when disease develops but significant paralysis is when they actually present
  • Don’t do both sides due to risk of aspiration pneumonia - no protective mechanism for larynx
• Most have a good prognosis with tie back surgery
• Done through side of the neck and anchor the arytenoids back with suture/sutures through thyroid signet ring shaped cartilage and through articular facet

Question 11

Tracheal collapse: clinical signs and medical management

Answer 11

• Generally refers to a condition of excessive collapsibility of the trachea which usually results in dorsoventral flattening of the tracheal lumen.
• Congenital nature, but see in adult as an acquired onset timeframe.
• Classic goose-honk cough
• Take x-rays and incl. neck and on lateral film you will commonly see an area where there is no tracheal shadow as it has collapsed.

Clinical signs:

• Classic ‘goose-honk’ cough
• Pulling on collar & lead
• Exercise
• Anything that makes the dog cough

Medical management:

• Antitissuves
• Bronchodilators
• Antibiotics
• NSAIDS
• Corticosterioids (inhaled)
• Bronchodilators (inhaled)

Question 12

Tracheal collapse: surgical treatment?

Answer 12

1. Open ring prosthesis

• Put a number of ridged plastic polyprelene rings extraluminal to the trachea and force trachea back into a normal shape.
• Done generally in the cervical site, harder in chest to gain access.

2. Stenting

• More common
• Intraluminal
• Self expanding stents
• Stent expands to fill whatever lumen you have put it into, made of non-reactive slightly pliable metal.

Question 13

What is chronic rhinitis in cats?

Answer 13

• Common cause of chronic nasal discharge in cats.
• Inflammation and swelling of the conchae; there is increased mucus production and usually secondary infection, mucopurulent secretion may contain blood.
• In some cats the inflammation continues and becomes more severe, resulting in loss of conchae.
• This can be mild or severe.
• Cats with chronic destructive rhinitis look similar endoscopically to dogs with aspergillosis of the nasal passages.
• It has been suggested that feline herpesvirus 1 could play a role in chronic nasal inflammation, resulting in destructive rhinitis