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