238 Diseases of the Nose, Sinuses, and Nasopharynx Gerhard Ulrich Oechtering
Nose
The nasal airways of the dog and cat are both anatomically and physiologically an
impressively complex structure. On the one hand, they provide a portal through which
air can stream to three different locations, each serving a distinct, vital function: (1) the
concha nasalis ventralis for thermoregulation and conditioning of air, caudodorsally the
(2) conchae ethmoidales for olfaction and via the caudal passageways the (3) pulmonary
alveoli for gas exchange. They are not only simple passageways but complicated branches
of the nasal conchae providing two huge, functionally different surface areas, serving as
active organs of thermal homeostasis and olfaction.
The two nasal cavities are separated by the nasal septum; each cavity is composed of four
main functional segments (Figure 238-1 [gJ ). The nasal airway communicates with the
paranasal sinuses and connects caudally to the nasopharyngeal airway. Although the
nasal part of the upper airway has a parallel oral passageway, dogs breathe
predominantly through the nose, except for when they are exercising or panting. The
importance of nasal breathing for dogs and cats is often severely underestimated: Human
noses fulfill two crucial tasks-respiration and olfaction. Dogs' and cats' noses fulfill a
third, vital function-that of thermoregulation.
FIG u RE 238-1 [gl Functional segments of the nasal-pharyngeal airway. 1, Nasal entrance: ...
Anatomy and Functional Considerations of the NasalPharyngeal Airway
The nasal-pharyngeal airway can be partitioned into four functional segments between
the nares and the ostium intrapharyngeum. This can be useful both for understanding
flow-relevant pathologies as well as for a systematic endoscopic examination or
systematic interpretation of cross-sectional images. Functional segments of the nose are
(1) the nasal entrance, (2) the respiratory chamber, (3) the olfactory chamber, and (4)
the nasal exit (see Figure 238-1 gl ). A rostral to caudal overview of the nasal-pharyngeal
passageways gives O Video 238-1 gl as a computed tomographic (CT) study and 0
Video 238-2 gl as anterior rhinoscopy.
P- 1060 The nasal airway begins with the naris, the visible rostral opening plane of a short
passageway through the vestibulum nasi. It is formed like a comma with a vertical broad
head and a smaller curved tail that rotates horizontally and laterally (Figure 238-2 gl ).
The nasal vestibule is primarily responsible for distributing the in- and expired air and
has the highest airway resistance of the upper airways. Unlike in humans, the canine and
feline nasal vestibule is not empty. It is filled nearly entirely by a voluminous bulb,
evolved from the fusion of the cranial termination of the plica alaris (alar fold) with the
internal part of the ala nasi (nasal wing). It is the most mobile portion of the nasal
entrance, because it receives the terminal fibers of the levator labii maxillaris and levator
nasolabialis muscles. These muscles abduct the bulb laterally, thereby increasing the
perpendicular opening within the vestibule ( 0 Video 238-3 gl ). The configuration of
this bulb modifies the nasal entrance into a complex three-dimensional opening. It circles
about 300° from ventrolateral around the bulb dorsolateral into a lateral recess, the
rostral continuation of the atrium of the medial nasal meatus (see Figure 238-2 gl ). The
nasolacrimal duct that conducts lacrimal secretions from the eye opens into the
vestibule by an orifice located rostro-medially to the vestibular bulb ( 0 Video 238-
4 gl).
FIGURE 238-2 gl Nasal entrance of a normocephalic dog (German Shepherd, physiologic ...
P- 1061 The nasal cavities are separated by the nasal septum. A medial septa! wall, a lateral wall,
a roof, and a floor define each nasal passage of the main nasal chamber. Attached to the
septum are two vertical protuberances, dorsal and ventral septum swell bodies. The
inferior one passes caudally into the wing of the vomer. Each nasal cavity is divided into
four air passages: the dorsal, middle, ventral, and common nasal meatuses (Figure 238-
3 gl ). Understanding and differentiating the nasal meatuses as air passages becomes
most obvious in the region caudal to the vestibule and cranial to the branching of the
ventral concha. Here, the so-called 5-folds-view1 explains exactly the relation of the nasal
folds with the nasal meatuses. Moving further caudally, the alar fold branches intensely
into the ventral conchae, nearly filling the entire cross-sectional area of the nasal cavity,
and disintegrating the contour of all meatuses except for the dorsal meatus (Figure 238-
4@ ). Functionally, the dorsal meatus, located above the straight fold, turns out to be a
bypass for odorant-bearing inspired air around the complicated structure of the ventral
concha during sniffing for olfaction (see Figure 238-1@).2•3
FIG URE 238-3@ Rostral nasal cavity of a normocephalic dog (German Shepherd, physiol. ..
FIG URE 238-4@ Middle nasal cavity of a normocephalic dog (German Shepherd, physiol. ..
Two types of conchae dominate in the nasal cavity; in the middle part is the huge ventral
concha, formerly called the maxilla-turbinate because of its attachment to the maxilla.
The caudal-dorsal part of the nasal cavity is filled with turbinates that are attached to the
cribriform plate of the ethmoid and therefore called ethmoidal conchae. Both conchae
differ not only in function, but also in the anatomical structure of the scrolls and in their
relative surface areas. The ventral concha, with the respiratory functions of
thermoregulation and air conditioning, shows a branching that is quantitatively more
contorted, revealing a very complex airway network. The ethmoidal conchae, with their
olfactory function, show a less complicated structure of the turbinates. The total surface
area contained within the ethmoidal region is, however, nearly twice the size of the
ventral con cha. 2•4
p. 1os2 The nasal exit is formed by the nasopharyngeal meatus, beginning with a wing of the
vomer that crosses dorsally from medial to lateral and ending caudally with the choanae
(Figure 238-5@ ). This meatus is very delicately constructed: Behind the large diameter
of the nasal cavity, the "outlet" is located as a comparatively tiny tube at the bottom. In
small dogs, this is only 1 to 3 mm high (see Figure 238-9 @). This hole can very easily be
obstructed. Dogs can usually compensate for the functional loss of one opening as, for
example, when a tumor is expanding into the nasopharyngeal meatus. However, as soon
as the contralateral meatus shows the first signs of obstruction as well, nasal respiration
is impaired severely and clinical signs start becoming obvious. Morphologically and
functionally distinct epithelia line the nasal passages-olfactory, respiratory, squamous
and transitional.
FIG URE 238-5@ Nasal exit of a normocephalic dog (German Shepherd, physiologic situa ...
Caudal to the vestibulum, most of the luminal surfaces of the nasal mucosa are covered
by a watery, sticky material called mucus. Its physical and chemical properties are well
suited for its role as an upper airway defense mechanism, filtering the inhaled air by
trapping inhaled particles and certain gases or vapors. Goblet cells and subepithelial
glands produce mucus. The mucociliary apparatus with its synchronized beating of
surface cilia propels the mucus at different speeds and in different directions depending
on the intranasal location. Mucus covering the olfactory mucosa moves very slowly, with
a turnover time of probably several days. By contrast, the mucus covering the transitional
and respiratory epithelium is driven along rapidly (1 to 30 mm/min) to the oropharynx
where it is swallowed into the esophagus. 5
The luminal surface of the vestibulum is lined by a squamous epithelium similar to that
of external skin. A narrow zone of nasal transitional epithelium covers the transition into
the main nasal chamber. The majority of the non-olfactory nasal epithelium is ciliated
respiratory epithelium. The ethmoidal conchae and the caudal surface of the septum are
covered with olfactory epithelium. This olfactory surface is about twice as large as the
area covered with respiratory mucosa. Olfactory mucosa is covered with non-motile
sensory cilia, enabling the dog to detect odorant concentration levels of roughly 10,000
to 100,000 times that of the human. 2,4,G-s Of note is the fact that organized nasal
associated lymphoid tissue (NALT) was not identified in normal puppies or adult dogs,
although the nasopharyngeal tonsil in this species is well developed. 9,10 The frontal
sinuses are covered with respiratory epithelium except where ethmoturbinates extend
into these cavities; here olfactory epithelium is found.11,
12
The normal canine respiratory tract is endowed with a range of different immune cell
populations and they have the greatest concentration in the mucosa of the nose. 9 The
lamina propria of the mucosa of the respiratory part also contains serous, mucous, and
mixed tubuloalveolar glands. These glands are also present in the mucosa of the nasal
vestibule. Goblet cells are present throughout the respiratory region, and olfactory
glands that contain yellow pigment granules(!) are located in the oltactory epithelium,
giving this surface a very typical color..13
Airway mucus plays a vital role in maintaining respiratory homeostasis. It provides the
first line of defense against airborne irritants in the nasal cavity, and is essential in the
mucociliary process, ensuring that no foreign particles reach the lungs. Not only does its
thick consistency trap foreign particles, but its protein constitution additionally contains
bactericidal enzymes, thereby reducing the risk of infection.14
Thermoregulation in the Dog
The lateral nasal gland, more commonly called Steno's Gland, 15 is the largest of the nasal
glands. The gland is located beneath the wall of the maxillary sinus and it releases its
product into an extremely long excretory duct, which opens latero-medially at the
transition from the nasal vestibule into the antrum of the medial meatus. The functional
significance of the lateral nasal gland is that it is part of the thermoregulatory system in
the dog.16,17 Whilst humans sweat to evacuate heat from the body, dogs cannot sweat;
they pant. But contrary to common beliefs, dogs do not cool primarily using the surface
of the tongue. Studies have shown that panting dogs inspire through the nose and expire
through the mouth, and this begs quite a different understanding of why dogs pant. 16 The
ventral nasal concha has an extremely large, richly vascularized surface of mucous
membrane rolled into very fine, space-saving, spiral lamellae. The inspired air flows
through these. In order for cooling by evaporation to occur, water is required. For this
purpose, the dog has a special gland, absent in humans: the lateral nasal gland (glandula
nasalis lateralis or Steno's gland), located in the maxillary recess. An excretory duct
extends rostrally and opens laterally into the nasal vestibule ( 0 Video 238-5 [gl ). Here,
the secretion drips into the gutter-like channel of the antrum of the middle nasal meatus
and runs caudally, driven by the inspired air. Where the plica alaris branches into the
concha nasalis ventralis, the liquid drips onto the broad ventral concha and is distributed
across the whole surface of this concha by the inspired air. The liquid can then evaporate
rapidly in the strong airflow, producing cooling by evaporation ( 0 Video 238-6 [gl ).
Reduction of nasal airflow or thermoregulatory active surface of the ventral concha or
both can lead to serious heat susceptibility, as, for example, in brachycephalic animals
(see Figure 238-20 [gl ).
A rise of air temperature from 25 to 42° c caused a threefold increase in the mucous
secretion rate.18 The excellent vascularization of the nasal mucous membranes enables
heat to be exchanged rapidly and effectively. Nasal and lingual blood flow increase during
panting.19 Studies from Baker and Chapman20 showed that in exercising and panting
dogs, brain temperature iis lower than the temperature in the carotid artery. They
describe a vascular rete that is cooling arterial blood of the carotid artery with cold blood
draining from the nose. In another study they had shown that brain temperature rises
during physical exercise and panting if dogs are not able to use intact upper respiratory
passages but were forced to breathe directly through an experimental tracheostomy.21
This might be another argument to consider the decision for a permanent tracheostomy
very carefully.
Clinical Manifestations of Nasal Disease
Clinical signs of nasal disease (E-Box 238-1 gl ) can vary; they are, however, rarely
specific for the particular underlying cause. Even systemic diseases like coagulopathies
can cause nasal clinical signs (see eh. 29 +, and 197+, ). A thorough medical history can
best be obtained by structured questions to the owner (E-Box 238-2 gl ).
E-Box 238-1
Clinical Signs of Nasal Disease
Sneezing
Reverse sneezing
Nasal discharge
Serous
Mucoid
Mucopurulent
Purulent
Sanguineous
Mixed
Stridor (nasalis and/or pharyngeal is)
Open-mouth breathing and/or expiratory cheek puff
Dyspnea
Exercise i ntolera nee
Heat intolerance
Sleeping problems
Respiratory problems during feeding
Halitosis (see also eh. 36 +, )
Facial deformity or ulcerations of the nasal dorsum
E-Box 238-2
Key Questions for Obtaining a History in Nasal Disease
. Duration of nasal disease, acute or progressive onset, first signs, progress since
then, previous therapies and results?
. Occurrence of sneezing/reverse sneezing, nasal discharge (quality, frequency,
uni-/bilateral, changes over time)?
. Problems with breathing (respiratory noise during inspiration or expiration,
distinguishing between stridor nasalis and pharyngealis)
. Difficulties with breathing during sleep, specific noise during sleep, expiratory
cheek puff, open-mouth breathing at rest?
. Influence of exercise and ambient temperature on breathing?
Sneezing and Reverse Sneezing (also see eh. 27., )
Sneezing is a protective reflex. It manifests as an explosive expiratory airflow that is able
to dislodge and expel foreign particles from the nasal cavities. Any cause of nasal
mucosal irritation or nasal discharge is a differential diagnosis for sneezing. Reverse
sneezing is defined as a mechanosensitive aspiration reflex. It is a labored, short and
often stertorous inspiratory effort. Sometimes dogs get into a position with head and
neck extension and elbow abduction. Other times, reverse sneezing occurs paroxysmally
in certain conditions (i.e., after drinking), though often without recognizable trigger or
cause ( 0 Video 238-7 [gl ; also see Video 27-1 [gl ). Powerful contraction of inspiratory
muscles and adduction of laryngeal cartilages generate negative pleural and tracheal
pressure. The strong tracheal occlusion pressure with a sudden opening of the glottis
while the mouth is closed produces a rapid inspiratory airflow through nose and
nasopharynx. This rapid inhalation tends to tear off irritant particles and accumulated
mucus, resulting in aspiration from the nasopharynx to the oropharynx, effectively
supporting mucociliary clearance and allowing subsequent elimination by swallowing or
coughing. 22,23
While most owners are used to seeing their dog sneeze, they sometimes panic when
witnessing their dog with a reverse sneezing attack for the first time (see Videos 238-7 [gl
and 27-1 [gl ). In spite of the fact that reverse sneezing is not associated with obstructive
dyspnea, dogs may appear as if they are having extreme air hunger and being close to
asphyxia. In general, dogs behave normally again right after the reverse sneezing
episode. Even regular episodes of reverse sneezing can be seen in individual dogs
without any detectable nasal or nasopharyngeal pathology and it has to be regarded as a
physiological cleaning procedure of the nasal-pharyngeal airway. However, as it is the
case with sneezing, a sudden onset and continuation of pronounced reverse sneezing
attacks can be the first clinical sign of a nasopharyngeal problem (for example, a foreign
body). If frequency, duration and intensity of reverse sneezing seem unusual, posterior
rhinoscopy should be recommended (see eh. 27+, ).
Nasal Discharge (also see eh. 27., )
In contrast to humans, mucopurulent nasal discharge in dogs is generally not a symptom
of a transient and self-terminating rhinosinusitis! Often, owners of affected dogs assume
that their pet had a head cold and tolerate mucopurulent or purulent nasal discharge for a
while. However, usually mucopurulent nasal discharge in dogs bas a serious underlying
cause, requiring intensive diagnostics. Nasal discharge can be produced within the nasal
cavity as a reaction to mucosal inflammation and/or infection. Discharge can also drain
from the paranasal sinuses, predominantly the frontal sinus. This can be due to blockage
of the natural caudal drainage way through the nasopharyngeal duct and the
nasopharynx as, for example, with nasopharyngeal stenosis or a completely obstructing
nasopharyngeal polyp. Pure mucous congestion can turn purulent after secondary
bacterial infection.
Neither quality, nor laterality, nor duration of nasal discharge confirms a diagnosis of
nasal disease and none of this information can replace subsequent advanced
diagnostics. 24
Airflow Obstruction
Knowing the unique importance of nasal breathing for dogs and cats, one can conceive of
the consequences of nasal airway obstruction. Obviously, the nose is provided with such
a reserve capacity that a 50% loss of function, meaning the obstruction of one of the two
nasal cavities, may be tolerated at rest. 22•25 During resting respiration, the nasal cavity
accounts for about 79% of inspiratory resistance and about 74% of expiratory
resistance.26 Dogs attempt to complete inspiration through the nose, even against a high
anatomic nasal resistance. Dogs with partial bilateral nasal obstruction showed other
systemic effects, such as a considerable loss of body weight. 25 Taking this into account
and considering the meaning of nasal thermoregulation, the dog should be considered an
obligatory nose breather.
Obstruction of the nasal-pharyngeal airway, either as a consequence of a permanent
stenosing process or due to intermittent collapse of the nasopharyngeal airway, can lead
to severe sleeping problems and subsequent day sleepiness (see Video 238-29 gJ ).
Owners of affected animals often report on attempts to sleep in a sitting position and on
sleeping pauses of variable length, regularly interrupted by waking up and gasping for
breath. 27 This corresponds quite well to the problem of obstructive sleep apnea ( OSA) in
humans28 (see also Brachycephalic Syndrome gJ, below).
Examination of the Nose
The diagnostic approach to nasal disease can be challenging. Medical history and
physical examination of the awake patient alone rarely provide a definitive diagnosis. 29
Further means of diagnosis require general anesthesia of the patient. However, a well
planned combination of clinical examination, diagnostic imaging and endoscopy with
tissue biopsies is a promising approach, establishing a diagnosis in over 90% of dogs30
and cats.31
Physical Examination
A thorough medical history (see E-Box 238-2 gJ) is followed by an examination of the
external nose. The symmetry or deformity of the face and the external nose, the size of
the nares, possibly the mobility of the alae nasi (see Video 238-3 gJ ), the pigmentation of
the plan um nasale and the character of unilateral or bilateral nasal discharge can be
visible. Expiratory puffing of the cheeks might also be visible, indicating a complete
obstruction of the nasal airway ( 0 Video 238-8 gJ ). Stridor or stertor indicate stenotic
airway segments within the nose or the nasopharynx, respectively. The rostral movable
portion of the external nose is palpable (E-Box 238-3 gJ ).
E-Box 238-3
Specific Physical Examination of the Nose
• Breathing sounds (strider)
• Symmetry of the face and muzzle
• Character of nasal discharge, laterality
• Facial deformity or ulceration
• Patency of airflow through each nostril
• Condition of the teeth and gums
• Examination of the roof of the mouth to the pharynx (to degree possible)
• Ability to retropulse the eyes
• Pain on opening the mouth or manipulating the muzzle
• Epiphora
• Pigmentation/Depigmentation of the nasal planum
• Size and texture of submandibular lymph nodes
Special Diagnostic Procedures
P- 1053 However detailed the obtained medical history is and however thorough the clinical
examination of the patient was, in the vast majority of cases with suspected nasal or
nasopharyngeal disease, this will neither provide a reliable diagnosis nor allow specific
treatment in the awake patient.30,32 It is advisable to communicate this to the owner early
on. Even in the anesthetized patient, many important structures are more or less hidden
behind bony walls inside the skull, being neither visible nor palpable. Advanced
diagnostic tools like endoscopy and/or cross-sectional imaging in combination with
his to logic examination are often indispensable to establish a definitive diagnosis. 3o,33,34
Once the decision for anesthesia is made, careful planning is required: which special
diagnostic procedures should be used within the timeframe of anesthesia and in which
order. The owner should be advised that in some cases, combining different special
examinations might be a better option to the conventional-and usually preferred
stepwise diagnostic evaluation. The likelihood of establishing a diagnosis of a specific
nasal disease relies on a combination of techniques, including radiologic examination
(cross-sectional preferred), rhinoscopy (rigid preferred), cytology/histopathology of
biopsy samples and culture.31,32 The final choice of diagnostic modalities depends on
both the availability of technical equipment and the owner's preferences and means.
Radiography
For many decades, plain film nasal radiographs have been a key diagnostic feature in
nasal disease. Today, computed tomography (CT) or magnetic resonance imaging (MRI)
provides significant, additional information and increases diagnostic sensitivity.
However, questions of availability and cost may still be a limitation.
CT and MRI
Both CT and MRI allow excellent evaluation of the structures within the lumen and the
tissues adjacent to the nasal cavities, the nasopharynx and the paranasal sinuses.
Depending on their physical working principle, the depiction of bone, air and soft tissue
is different. Nasal CT is a powerful tool and it greatly enhances the ability to establish an
accurate, definitive diagnosis of nasal disease in dogs (see Video 238-1 gl ). It provides an
accurate assessment of the extent of nasal disease and readily identifies areas of the nose
to examine via rhinoscopy, as well as suspicious regions to target for biopsy. 33 When
there is suspicion of a neoplastic process, MRI is considered the superior technique.35 For
a comparison of imaging techniques for dogs with nasal disease, see E-Table 238-1 gl and
Figure 238-6 gl
E-TABLE 238-1 Comparison of Imaging Techniques for Dogs with Nasal and Paranasal
Disease
Modified from Cohn LA: Canine nasal disease. Vet Clin North Am Small Anim Pract 44:75-89, 2014.
Sensitivity to detect
bony changes (lysis
or proliferation)
Show cribriform
plate integrity
Sensitivity to detect
soft-tissue changes
Ability to
discriminate
between tissue and
mucus
Ability to take
controlled biopsies
Detection of foreign
bodies
Guided extraction of
foreign bodies
Visualize mucosa I
surfaces/fungus
plaques
Visualize conchal
structure
Mucosa I contact
points
Visualize
nasolacrimal duct
Visualize duct of
lateral nasal gland
Ability to evaluate
the lumen of the
paranasal sinuses
PLAIN CT MRI RHINOSCOPY
RADIOGRAPHY
Moderate Excellent Good Poor
Impossible Excellent Good to Poor
excellent
Poor to Good Excellent Excellent for
moderate intraluminal
structures
Impossible Moderate Excellent Excellent
to good
(with
contrast)
Impossible Moderate Poor Excellent
Poor Good to Good to Excellent
excellent excellent
Impossible Moderate Poor Excellent
Impossible Poor Poor Excellent
Poor Good to Good Good to
excellent excellent
Impossible Moderate Poor Excellent
Moderate Good Excellent Excellent for the
with opening
contrast
Moderate Excellent Excellent Excellent for the
with with opening
contrast contrast
Moderate Excellent Good to Moderate to
excellent good for
maxillary recess
and sphenoid
sinus
Excellent for
frontal sinus in
advanced
sinonasal
aspergillosis
Poor for intact
frontal sinus
FIGURE 2 3 8-6 gl Diagnostic imaging of nose and nasopharynx in dog (left) and cat (right) ...
Rhinoscopy
See eh. 96 � (E-Box 238-4@ and O Video 238-9 gl ).
E-Box 238-4
Endoscopic Landmarks for Anterior Rhinoscopy
Nares and Nasal Vestibulum
Nares and alar wing
Vestibular bulb
Plicae parallelae
Plica alaris
Opening of nasolacrimal duct
Opening of the duct of the lateral nasal gland (advanced experience level)
Nasal Cavity {5-Folds-View Dog, 4-Folds-View Cat)
Nasal septum with dorsal and ventral swell body
Plica recta
Plica alaris
Plica basalis
Nasal meatus (dorsal, medial, ventral, common)
Concha nasalis ventralis
Nasal Exit (After Decongestant, Advanced Level)
Ethmoid turbinates and olfactory mucosa
Ala vomeris
Meatus nasopharyngeus
Choanae
View into nasopharynx
Rhinotomy
In the past, without today's possibilities of modern endoscopic equipment (especially
rigid rhinoscopy) and knowledge of intranasal explorative rhinoscopy, rhinotomy was a
helpful diagnostic tool in certain cases of nasal disease. There is, however, no longer a
real indication for explorative rhinotomy. Together with modern cross-sectional imaging
techniques, anterior and posterior rhinoscopy provides a sufficient diagnostic spectrum.
In most dogs, an experienced endoscopist can visualize nearly all compartments of the
nose and the standard landmarks (see E-Box 238-4 gl ) should be recognizable even for
the less-experienced endoscopist.
Diseases of the Nose
Stenoses and Obstructions of Nasal Passageways
Hereditary malformations due to excessive breeding selection for morphological
extremes (miniaturization, exaggerated brachycephaly) can cause obstructions on all
three segmental levels-the nasal entrance, the nasal cavity itself and the nasal exit (see
Diseases of the Nasopharynx below and Figure 238-9 gl ).
Stenoses of the Nasal Entrance
Injuries of the nasal entrance due to trauma (bite wounds, car accidents, gunshot injury),
chronic ulcerative inflammation (e.g., long-lasting sinonasal aspergillosis) or surgery at
the nasal entrance using excessive thermal energy (HF-surgery, electrocautery, surgical
lasers) can lead to constrictive and stenosing wound healing (Figure 238-7 gl ). Surgical
therapy can be challenging due to a high tendency for re-stenosing and temporal
stenting; a flap technique may be used to prevent this.
FIG u RE 23 8- 7 gl Stenosis and lesions of the nasal entrance. Injuries of the nasal entrance ...
Stenoses of the Nasal Cavity
Causes of intranasal obstruction can be any kind of benign or malignant mass: tum ors,
expanding granulation tissue induced by chronic inflammation and intranasal cysts of
varying origin. Foreign bodies frequently lodge in the nasal cavity. However, they rarely
obstruct the intranasal airway due to their size but induce inflammation and purulent
discharge. The inspissated discharge can cause complete obstruction of the affected nasal
cavity, especially in smaller dogs and in cats. Oronasal defects and other diseases causing
purulent rhinitis can lead to intranasal obstruction via the same pathomechanism ( 0
Video 238-10 [gl ). Deviations of the nasal septum have probably been more often
recognized now that computed tomography (CT) and magnetic resonance imaging (MRI)
examinations are widely available. The incidence seems to be higher in small dog breeds
and particularly in brachycephalic dogs.1,36
,37 Septal deviations are also described in
cats. 38 With that, the question about the clinical relevance of marked deviations arises. In
principle, there should be no rise in intranasal airway resistance as long as the smallest
intranasal cross-sectional area is larger than the cross-sectional area of the nasal entrance
(within the vestibulum) and exit (nasopharyngeal duct). Usually the size of the ventral
nasal concha coapts both in the smaller and in the larger nasal cavity, filling the entire
lumen.
Stenoses of the Nasal Exit
Because of functional considerations, the stenoses of both the meatus nasopharyngeus
and the nasopharynx are described together (see Diseases of the Nasopharynx below;
also see eh. 121., ).
Nasal Foreign Bodies
Various materials have been found lodged in the nasal cavity, mostly parts of plants or
foreign material. They can enter the nose either from anterior inhaled via the nares or
from posterior during swallowing or regurgitation into the nasopharynx or nasal cavity,
respectively. If not immediately expelled by sneezing or removed by a reverse sneezing
maneuver, they cause direct trauma and irritation of the nasal mucosa. Depending on the
time a foreign body is lodged, its size and location, chronic irritation, inflammation and
local tissue destruction may occur. Nasal foreign bodies often result in an acute onset of
sneezing and facial pawing, but they can remain in place for a long period, resulting in
chronic nasal discharge. Removal techniques for nasal foreign bodies vary. In simple
cases, the foreign body is endoscopically detected "at first sight" and can be grabbed
with a small forceps that is introduced alongside a rigid endoscope ( 0 Video 238-11 [gJ ).
In any case, a thorough systematic endoscopic exploration of the nasal cavity is indicated
(see also eh. 96., ). There is no guarantee that there is not more than one part of the
foreign body. Larger pieces in the posterior part of the nasal cavity can possibly be
pushed through the nasopharyngeal meatus into the nasopharynx.
Oronasal and Oronasopharyngeal Communications (also see eh. 272�)
P-1064 Congenital or acquired communications between the oral cavity and the nose,
respectively the oropharynx and the nasopharynx, allow food and fluids to enter the
nasal-pharyngeal passageways. Solid particles, if not expelled by the sneezing reflex or
removed with the reverse sneezing maneuver, can cause pronounced inflammatory
reactions of the nasal-pharyngeal mucosa. Secondary bacterial infection is common and
sometimes even fungal growth can be observed. After severe mucosa! damage stenosing
wound healing is not uncommon. Congenital deformities are clefts of the lip and palate.
Palatal defects usually affect the midline; however, lateral clefts can be seen in the soft
palate as well ( 0 Video 238-12 [gl ). Although the exact cause of clefting is unknown, it is
commonly agreed to be multifactorial with a hereditary component. There are a variety
of problems associated with facial clefting. Nursing is the major problem of neonates.
Due to the close embryologic, anatomic and physiologic connection of the nasopharynx
and the middle ear, soft palate clefts, especially the lateral ones, are likely to affect the
auditory tube and the middle ear. 39-41 Acquired oronasal communications result from
trauma of car accidents or due to high-rise trauma (cats). Acquired oronasopharyngeal
defects can be the result of oral stick lacerations or complications after palatal surgery.
Dental problems, malocclusion and deformity of the normal nasal architecture and lips
occur in more rostral defects. In longer-lasting processes, expanding granulation tissue
due to chronic secondary bacterial inflammation and/or inspissated discharge can
obstruct nasal passageways ( 0 Video 238-13 gJ ).
Rhinitis
Bacterial Rhinitis
Primary bacterial rhinitis is uncommon in both dogs and cats. In dogs, bacterial rhinitis
occurs most commonly as a sequela to the presence of a foreign body or as a consequence
of gross anatomic changes (primarily loss of turbinates) resulting from prior mycotic
disease, trauma, or irradiation.42 Antibiotics can improve clinical signs temporarily.
However, when administered in patients with sinonasal aspergillosis, after initial
improvement antibiotics can cause a dreadful worsening of the aspergillosis infection.
Lymphoplasmacytic Rhinitis
P- 1oss Idiopathic lymphoplasmacytic rhinitis (LPR) is an important cause of chronic nasal
disease in dogs with clinical signs similar to those of other chronic nasal disorders and
may be more common than previously believed. In a recent study, idiopathic LPR was
diagnosed in 30% of the total population that was evaluated. 43 It is one of the most
common forms of chronic, non-infectious rhinitis in dogs and cats30 and it possibly has to
be considered a key contributor to chronic nasal disease in dogs. The diagnosis is made
by the histopathological identification of a lymphoplasmacytic infiltrate within the nasal
mucosa and exclusion of other specific causes of chronic nasal disease. Although the
etiology of idiopathic LPR has not been determined, infectious, allergic and immune
mediated mechanisms have been suggested.34,44
-46 Windsor etal44 reported LPR in dogs
of various ages and predominance in large dogs. Nasal discharge was both unilateral and
bilateral, and the mean duration of signs was several months. In a recent study, the best
response to therapy was seen in dogs that underwent desensitization therapy, followed
by those that were treated with both corticosteroids and cyclosporine.43
Allergic Rhinitis
Allergic rhinitis is either an unusual or an underdiagnosed condition in small animals.
There are sporadic reports of rhinitis of presumptive allergic basis in the dog and cat.
Such animals present with oculonasal discharge, sneezing, nose rubbing or head shaking
and significant numbers of eosinophils can be demonstrated in nasal exudate or nasal
lavage fluid, and infiltrating the nasal mucosa on tissue biopsy. 9,46
Viral Rhinitis
Despite the widespread use of vaccines (see eh. 208 +, ), respiratory disease caused by
feline herpesvirus-1 (FHV-1) and feline calicivirus (FCV) remains a significant clinical
problem (see eh. 229 +, ). In general, the disease is most commonly seen where cats are
grouped together, particularly in young kittens as they lose their maternally derived
antibody. The initial clinical signs are paroxysmal sneezing, conjunctivitis, and serous
ocular and nasal discharge. About 5 days after the onset of sneezing, the nasal discharge
becomes mucopurulent and there may be ocular complications. The condition usually
persists for 2 to 3 weeks. 47 Viral rhinitis is a prominent clinical sign of canine distemper
(see eh. 228, ). Vaccination has reduced the occurrence of the disease to sporadic cases
in countries where stray dogs are rare and veterinary care is adequate (see eh. 208, ).
Herpesvirus infection in newborn puppies is characterized by profuse mucopurulent
nasal discharge. The diagnosis is usually made at autopsy47 (see eh. 228, ).
Nasal, Sinonasal and Nasopharyngeal Tumors
Sinonasal tumors are rare in dogs and occur mostly in middle-aged and old dogs.
Approximately one-third of all dogs with chronic nasal disease have nasal neoplasia. 80%
to 90% of the nasal masses are malignant. They are primarily locally invasive; metastasis
is, however, uncommon, or occurs late in the cause of the disease. 60% to 75% of
malignancies are epithelial in origin. The three most common ones are adenocarcinoma,
lymphoma, and undifferentiated carcinoma. Mesenchymal tumors include fibrosarcoma,
chondrosarcoma, osteosarcoma, hemangiosarcoma, and undifferentiated sarcomas.
Clinical signs in dogs and cats with nasal tumors include respiratory, ocular, and nervous
system-related signs. The most common clinical signs are attributed to upper airway
obstruction with decreased airflow through the affected nasal passage, epistaxis, and
sneezing. In unilateral nasal obstruction, clinical signs may become obvious to the owner
only after the mass has grown through one meatus nasopharyngeus, expanding caudally
to the septum and obstructing the contralateral meatus. Other reported signs include
reverse sneezing, stertorous breathing, serous, mucoid or mucopurulent nasal discharge,
dyspnea, lethargy, weight loss, facial deformity or swelling, and pain. Central nervous
system signs include seizures and behavior changes. Sinonasal tumors in dogs can rarely
be cured without treatment and euthanasia is generally elected within a few months due
to the progression of local disease. Radiation therapy, with or without aggressive
cytoreduction, can significantly improve the expected median survival time, and
constitutes the treatment: of choice.24,30,31,34,48·51
Non-Malignant Nasal Masses
Non-malignant nasal masses are rare and infrequently described .. Benign tumors,
intranasal cysts, inflammatory granulation tissue and other miscellaneous tissues (e.g.,
hamartoma) have the potential to expand intranasa11y. They can obstruct the nasal
passageways completely. Angioleiomyomas are benign tumors that originate from the
smooth muscle of vessels. 52 In dogs, there are few descriptions of nasal or
nasopharyngeal angioleiomyoma resulting in clinical signs of sneezing and bilateral nasal
discharge53,54 ( 0 Video 238-14 gJ ) (see eh. 344, , 346, , and 348, ) .
expertconsult.inkling.com/ .. ./chapter-344-hematopoietic-tumors
Nasopharynx V
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Overview
V
< Chapter 238: Diseases of the Nose, Sinuses, and Nasopharynx -· + "'"
"" * X
I.ii Figure 238-1
Functional segments of the nasal
pharyngeal airway. 1, Nasal entrance:
distribution and regulation of in- and
exhaled air. 2, Respiratory chamber:
thermoregulation and conditioning of
inhaled air. 3, Olfactory chamber (with
dorsal meatus): olfaction, the dorsal
nasal meatus serves as bypass during
sniffing. Nasal exit (4 & 5). 4, Meatus
nasopharyngeus: connection to
nasopharyngeal airway. 5, Nasopharynx:
functional occlusion during swallowing.
Dorsal partition ofWaldeyer's tonsillar
ring and connection to middle ear.
0 Notes l·UJtlH·hd
< Chapter 238: Diseases of the Nose, Sinuses, and Nasopharynx -· + .. ,.
.. � * X
I.ii Figure 238-2
Nasal entrance of a normocephalic dog
(German Shepherd, physiologic
situation). A, View on the plane of the
nares; notice the comma-shaped
opening. B, View into the left nasal
vestibule; notice the voluminous bulb
that modifies the nasal entrance into a
complex three-dimensional opening. C,
CT image: This opening circles about
300° from ventro-lateral around the bulb
into a dorsolateral vestibular recess
(arrow). This region serves the tasks of
airflow regulation and distribution. See
also Video 238-2.
0 Notes iitUl#•IIQ
< Chapter 238: Diseases of the Nose. Sinuses, and Nasopharynx -· + * X
I.ii Figure 238-3
Rostral nasal cavity of a normocephalic
dog {German Shepherd, physiologic
situation). A, CT image of nasal folds and
the four nasal meatus. B, Endoscopic "5-
folds-view." Nasal meatuses: C, common;
D, dorsal; M, medial; V, ventral. Five-folds
view of nasal folds: 1, dorsal septa! swell
body; 2, ventral septa I swell body; 3, plica
recta; 4, plica alaris; s, plica basalis.
0 Notes iitUl#•IIA
< Chapter 238: Diseases of the Nose, Sinuses, and Nasopharynx -· + ... ,.
.... * X
l,iJ Figure 238-4
Middle nasal cavity of a normocephalic
dog {German Shepherd, physiologic
situation). Respiratory chamber with
tasks of thermoregulation and
conditioning of air. A, Endoscopic view of
the (1) dorsal spiral lamella of the left
ventral nasal concha. B, CT image of the
ventral nasal concha with (1) dorsal and
(2) ventral spiral lamellae. There are no
more meatuses except the (3) dorsal
meatus as bypass for sniffing.
0 Notes IUJlliHOW
< Chapter 238: Diseases of the Nose, Sinuses, and Nasopharynx -· + ... ,.
.... * X
l,iJ Figure 238-5
Nasal exit of a normocephalic dog
(German Shepherd, physiologic
situation). A, CT image (B) anterior and
(C) posterior rhinoscopic pictures of the
nasal exit. Picture (B) represents the
white closed circle in picture (A). 1, View
into nasopharynx; 2, nasal septum; 3,
right wing of the vomer; 4, entrance into
the right sphenoid sinus; 5, view into the
right meatus nasopharyngeus with the
choanae (white dotted circle), the
internal nares as counterpart of the
external nares.
0 Notes illlliMifi
< Chapter 238: Diseases of the Nose, Sinuses, and Nasopharynx -· + ""
""' * X
I.ii Figure 238-6
Diagnostic imaging of nose and
nasopharynx in dog {left) and cat {right)
(physiologic situation). A, Plain
radiography. B, Computed tomography.
c, Magnetic resonance imaging.
0 Notes iitni#tlld
< Chapter 238: Diseases of the Nose. Sinuses. a1d Nasopharynx -· + ""
"" *
l!!l Figure 238-7
X
Stenosis and lesions of the nasal
entrance. Injuries of the nasal entrance
due to chronic ulcerative inflammation or
surgery at the nasal entrance. Using
excessive thermal energy (HF-surgery or
surgical lasers) can lead to severe lesions
and constrictive and stenosing wound
healing. A, Nares stenosis after long
lasting sinonasal aspergillosis (Golden
Retriever). B, Stenosis after failed nares
surgery with C02-laser (French Bulldog).
C, Stenosis after failed nares surgery with
HF-technique (French Bulldog). D, Severe
lesion of the nares after failed surgery
with diode-laser (Chihuahua).
0 Notes iilllliHOW
< Nasopharynx -· + ""
""' * X
I.ii Figure 238-8
Nasal exit�meatus nasopharyngeus:
Sagittal and transverse computed
tomographic views of the meatus
nasopharyngeus (yellow) and the
nasopharynx (ochre). Top right, the
postrhinoscopic view into the meatus
nasopharyngeus (German Shepherd,
physiologic situation). 1, Wing of the
vomer; 2, lumen of the meatus
nasopharyngeus; 3, caudal border of the
septum; 4, caudal border of the septum,
postrhinoscopic view.
0 Notes iitnid•IIQ