Page 116 - BSAVA Manual of Canine and Feline Head, Neck and Thoracic Surgery, 2nd Edition

Chapter 8 · Surgery of the extrathoracic trachea

Permanent tracheostomy caused by a mucus plug at the stoma or elsewhere in the
respiratory tract. Around 40% of cats in both studies died
Permanent tracheostomy may be performed for manage-
VetBooks.ir ment of end-stage upper respiratory tract obstruction, for Stoma obstruction and death was 6.6 times more likely to
due to acute respiratory obstruction with a mucous plug.
example, advanced laryngeal collapse or palliation of upper
occur in cats with inflammatory laryngeal disease (Stepnik
respir atory tract neoplasia. Very careful client communica-
tion is required prior to this procedure, as there is a signifi- et al., 2009).
Patients that have undergone permanent tracheostomy
cant risk of postoperative complications and there must be require very intensive aftercare initially. The patient and the
a commitment to long-term aftercare. A permanent trache-
airway must be kept well hydrated by provision of intra-
ostomy is achieved by removing the ventral portions of venous fluids, and frequent nebulization and regular clean-
approximately four tracheal rings. The sternohyoid muscles ing of the distal extent of the stoma is necessary. The
are sutured together dorsal to the trachea and the tracheal irritation of the tracheal mucosa and secondary squamous
wall is sutured to the surrounding cervical skin (Figure 8.9); metaplasia results in significantly increased mucous pro-
the technique is described by Hedlund et al. (1982). A
duction following surgery, and dried mucous plugs may
recent publication reporting the outcome following perma- occlude the tracheal stoma. This change resolves over time,
nent tracheostomy in the dog indicated that a major com-
and around 16 weeks following surgery mucous production
plication occurred in around half of the patients; these is reduced (Hedlund et al., 1982) and management may
complications were most commonly a need for stoma
become straightforward; however, regular stoma cleaning
revision (due to skin fold occlusion or stenosis) or aspira- is still required. It is important that dusty environments
tion pneumonia. However, despite complications, 90% of are avoided and the animal must not be allowed to swim.
dogs were discharged alive. Whilst some dogs achieved
long-term survival at home without further problems
(median survival time 328 days; 25% of patients survived
1321 days or longer), around a quarter of the dogs died Tracheal collapse syndrome
acutely at some stage as a result of airway obstruction
(Occhipinti and Hauptman, 2014). The tracheal collapse syndrome comprises a variety of
Permanent tracheostomy in the cat is associated with tracheal disorders, leading to a wide range of clinical signs
particularly high rates of complications and mortality associated with compromise of the tracheal lumen. The
(Guenther-Yenke and Rozanski, 2007; Stepnik et al., 2009). most commonly recognized ‘traditional’ form is a progres-
Dyspnoea is frequently encountered in the postoperative sive degenerative condition of the tracheal rings (chondro-
period and is most often due to respiratory obstruction malacia) and/or dorsal membrane (trachealis muscle)
leading to dynamic respiratory difficulty, ranging from the
A permanent classic ‘honking’ cough to severe respiratory distress
8.9 tracheostomy in
a Yorkshire Terrier, which (Figure 8.10ab). Another more recently recognized type
was performed for (author’s observation) is the tracheal ‘malformation’ variety
management of grade 3 in which the normally C-shaped cartilage rings are
laryngeal collapse and W-shaped, leading to a fixed luminal obstruction at the
upper respiratory tract level of the thoracic inlet that can be associated with con-
obstruction. (a) Three days current dynamic collapse elsewhere (Figure 8.10cd). Once
postoperatively. (b) Two the condition has been differentiated from other causes of
months postoperatively.
respiratory difficulty, conservative medical management
can be useful to palliate clinical signs. Un -fortunately,
medical management may often achieve only a temporary
response (or may even be ineffective for cases involving
malformation), and progressive respiratory dif ficulty
requires more aggressive intervention. A number of surgi-
cal and interventional techniques have been described;
each has its own indications, limitations and associated
(a) complications. No single technique has demonstrated
clear superiority over others, or has delayed sub sequent
disease progression. Whilst the long-term prognosis
remains guarded, the clinician can offer techniques to pal-
liate these animals and, at least temporarily, improve the
remaining quality of life.
Aetiology

Tracheal collapse is typically a disease of middle-aged
small and toy breed dogs; Yorkshire Terriers, Poodles,
Pomeranians, Chihuahuas and Maltese dogs are over-
represented. However, no genetic cause has yet been
identified (Buback et al., 1996). Whilst the underlying
cause remains to be determined, a series of structural
changes has been identified in tracheal collapse that
helps explain the resulting syndrome. Trachealis muscle
weakness suggests a possible centrally mediated neuro-
logical deficiency that results in atrophy, weakening and
(b)
subsequent collapse of the trachealis muscle into the

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