Chapter 43 - Diagnostic Tx upper respiratory tract Flashcards
What historical information is important when assessing a racehorse with poor performance?
Abrupt decline in performance or gradual deterioration at the end of a race.
What is the most common historical finding in sport horses with upper respiratory issues?
Presence of abnormal respiratory noise.
What can decreased or absent airflow through one nasal passage indicate?
Upper airway obstruction restricted to one nasal passage.
How can the alar folds be temporarily secured to test for exercise-induced obstruction?
By using umbilical tape over the bridge of the nose.
What can facial asymmetry in a horse suggest during examination of the paranasal sinuses?
Conditions like facial bone fracture, sinus disease, or suture line exostosis.
What does dullness during percussion of a horse’s sinus indicate?
Fluid accumulation or a space-occupying mass.
What condition is usually indicated by a prominent muscular process during palpation of the larynx?
Inability to maintain full abduction of the affected arytenoid cartilage during exercise.
What can indicate previous laryngoplasty during palpation of the larynx?
Incisional scarring or absence of vocal cords.
What symptom might firm palpation of the larynx elicit in cases of severe upper airway conditions?
Stertorous breathing.
What may trauma or infection to the jugular groove result in?
Recurrent laryngeal nerve dysfunction.
Why is chemical sedation generally avoided during videoendoscopic examination of the upper airway?
It interferes with upper airway function.
What is the primary purpose of nasal occlusion during endoscopic evaluation?
To assess full laryngeal abduction by inducing maximal arytenoid cartilage movement.
What is recurrent laryngeal neuropathy (RLN) indicated by during endoscopy?
Inability to fully abduct one arytenoid cartilage.
How is resting laryngeal function classified according to the Havemeyer grading system?
Based on symmetry, synchrony, and ability to achieve full abduction of arytenoid cartilages.
What diagnostic tool is preferred for identifying dynamic laryngeal function?
xercising endoscopy.
What anatomical abnormality is highly specific for dynamic dorsal displacement of the soft palate (DDSP)?
Prolonged displacement of the soft palate despite swallowing.
What are common observations during an endoscopy in horses with laryngoplasty?
Partially abducted arytenoid cartilage and possible vocal cord scarring or absence.
What might bruising of the nasopharynx near the guttural pouch indicate?
The horse is experiencing DDSP at speed.
What is suggested if there is discharge exiting the nasomaxillary opening during endoscopy?
Sinus disease
Why is the right ventral meatus preferred for endoscopic insertion over the left?
To reduce artefactual changes in left arytenoid positioning and movement.
What anatomical structures are examined first during an upper airway videoendoscopic evaluation?
The pharynx and larynx.
What condition is more commonly seen in younger horses during endoscopic evaluation of the pharyngeal walls?
Extensive lymphoid hyperplasia.
What feature of the epiglottis is typically evaluated during endoscopic examination?
The serrated edges and visible vascular pattern on its dorsal surface.
What movement patterns are critically assessed in the arytenoid cartilages during endoscopy?
Symmetry and synchrony of abduction and adduction.
What is the function of inducing swallowing or nostril occlusion during an endoscopic evaluation?
To assess maximal arytenoid cartilage abduction.
What resting laryngeal grade is characterized by asynchronous movement but the ability to achieve full abduction?
Grade II.
What grade of recurrent laryngeal neuropathy (RLN) refers to complete immobility of the arytenoid cartilage?
Grade IV.
What signs during static endoscopy may support a diagnosis of dorsal displacement of the soft palate (DDSP)?
Flaccid epiglottis, epiglottic hypoplasia, and ulceration of the soft palate.
What specific maneuver can be performed during endoscopy to induce DDSP?
Transient occlusion of the nostrils or flexing the head and neck.
What is the most specific but insensitive sign for diagnosing DDSP during rest?
Resting DDSP with prolonged displacement of the soft palate.
What anatomical region is evaluated for evidence of temporohyoid osteoarthropathy during endoscopy?
The dorsal aspect of the guttural pouch.
What structures are examined as the endoscope is withdrawn from the nasopharyngeal region?
The ethmoid recesses, turbinates, nasal septum, and nasomaxillary openings.
What is the significance of feed material found in the trachea during an endoscopy?
It suggests a dysfunction in swallowing or an upper airway defect.
What diagnostic tool is complementary to endoscopy in cases of nasal septal deviation or paranasal sinus disease?
Radiographic evaluation.
How do you confirm the diagnosis of alar folds as cause of nostril disease?
the alar folds can be temporarily secured in an open position via umbilical tape over the bridge of the nose. Mitigation of abnormal respiratory noise
during exercise confirms the diagnosis
Thickening, ulcerations, or granulation tissueof the arytenoid cartilage indicate what?
Thickening, ulcerations, or granulation tissue likely indicate arytenoid chondropathy
Figure 43-1. Left arytenoid chondritis with a thickened, misshapen corniculate process and incomplete abduction.
Figure 43-2. (A) Scarred vocal cords (small arrows), and remaining normal vocal cords ventrally (arrowhead). (B) A close-up videoendoscopic view of the vocal cords. Absent left vocal cord from laser resection. Normal remaining right vocal cord (arrows)
Havemeyer grading system, name them
grade I refers to symmetric abduction/adduction and synchronous arytenoid cartilage movements, grade II refers to asynchronous movement but full arytenoid cartilage abduction can be achieved and maintained. Grade III refers to asynchronous and/or asymmetric movement and full arytenoid abduction cannot be achieved and maintained. Grade IV refers to complete immobility of arytenoid cartilage. Subgrades exist within grades II and III, which further define asynchronous and asymmetrical movement
The vast majority of horses with resting laryngeal grades I and II are able to fully abduct both arytenoid cartilages during exercise TRUE or FALSE
TRUE
horses with grade ____ and ___ resting laryngeal grade are much more likely to experience dynamic laryngeal collapse.
horses with grade III and IV resting laryngeal grade are much more likely to experience dynamic laryngeal collapse.
DDSP at rest is highly specific (___%) but very insensitive (___%) for dynamic DDSP
DDSP at rest is highly specific (95%) but very insensitive (26%) for dynamic DDSP
Bruising of the roof of the nasopharynx near the guttural pouch openings (“choke ring”) and/or ulceration on the dorsal aspect of the caudal free edge of the soft palate are indications that horses are experiencing
DDSP at speed
Figure 43-3. Enlargement of the stylohyoid bone at the temporohyoid joint within the guttural pouch (arrows).
Figure 43-5. Ventroaxial luxation of the corniculate process of the left arytenoid cartilage (small arrow) and axial deviation of the aryepiglottic folds (large arrows) induced during high-speed treadmill exercise only after increasing head/neck flexion. The larynx was normal without head/neck flexion. (
What is the primary purpose of using upper airway videoendoscopy during treadmill exercise in horses?
To diagnose respiratory pathophysiology and dynamic upper airway obstructions.
What physiological conditions are induced in horses during maximal exertional effort?
Hypoxemia and hypercapnia.
What percentage of horses may show increased severity of hypoxemia and hypercapnia due to upper airway obstruction?
Specific percentages are not provided, but obstruction is known to significantly worsen these conditions.
Identify some common dynamic upper respiratory obstructions observed during treadmill endoscopy.
DDSP,
arytenoid cartilage collapse,
vocal cord collapse,
palatal instability,
epiglottic entrapment,
axial deviation of the aryepiglottic folds,
and pharyngeal collapse.
What aspect of treadmill exercise protocols is crucial for simulating racing conditions?
Speed, head/neck flexion, and fatigue
How fast do horses typically exercise during the warm-up phase on the treadmill?
Approximately 7 m/s.
What is the distance horses typically cover during the warm-up phase?
1600 m.
At what pulse rate is a horse considered to have reached target maximal heart rates during exercise?
Greater than 200 beats/min.
What speed range can horses approach during maximal exercise exertion on the treadmill?
Up to or more than 12 to 14 m/s.
What does the term “exercising laryngeal grade A” indicate about a horse’s laryngeal function?
The horse can obtain and maintain full abduction of the arytenoid cartilages during inspiration.
What does the term “exercising laryngeal grade B” indicate about a horse’s laryngeal function?
are able maintain the affected arytenoid in a relative fixed but incompletely abducted position; a position between full abduction and resting position.
What indicates an exercising laryngeal grade C?
evere collapse of the arytenoid cartilage and vocal fold during exercise; abduction is less than the resting position.
What is the major criterion used to determine the probability of abnormal laryngeal function during exercise?
Failure to obtain and maintain arytenoid cartilage abduction at rest.
What correlation exists between resting endoscopy and exercising laryngeal function?
Horses that can fully abduct their arytenoid cartilages at rest generally have normal function during exercise.
What is the duration and nature of intermittent DDSP during exercise?
It is a dynamic event that may occur due to fatigue or changes in exercise intensity.
What anatomical movement may be noted immediately before an episode of DDSP?
Dorsoventral oscillatory movement (billowing) of the soft palate.
What is a significant diagnostic limitation of resting endoscopy for horses suspected of having DDSP?
A high false-negative rate; 85% of racehorses with respiratory noise or exercise intolerance may be misdiagnosed.
What are some other dynamic respiratory abnormalities aside from DDSP that require exercising endoscopic evaluation?
Axial deviation of the aryepiglottic folds, pharyngeal wall collapse, and epiglottic retroversion.
When was overground endoscopy first described as a method for diagnosing dynamic upper airway obstruction?
t allows exams in training environments, standardizes external factors like rider influence, and eliminates the need for acclimation to a treadmill.
What percentage of horses experienced significant injuries according to a multicentric study of treadmill exercise?
Only 0.6% incurred significant injuries.
What anatomical part’s function is evaluated during exercising endoscopy?
The larynx and upper respiratory tract.
What equipment is commonly used during treadmill testing for Standardbreds and Thoroughbreds?
tandardbreds use a bridle and harness; Thoroughbreds typically use only a halter
Why is it important to record the endoscopic examination during treadmill testing?
Most abnormalities occur rapidly within the respiratory cycle and slow-motion playback can help with diagnosis.
What is the typical transmission distance for the video image from the endoscopy system?
Typically ranges from 150 to 1000 m, subject to line-of-sight restrictions and
What is the false negative rate for diagnosing DDSP based solely on resting endoscopic findings?
85% for racehorses with respiratory noise or exercise intolerance.
Figure 43-11. Composite images obtained from the rostroventral acoustic window at three different locations in the transverse plane using a
12.5-MHz linear transducer. From left to right the images are progressing from rostral (A) to caudal (C) within the rostroventral acoustic window. (A) The lingual process (LP) is readily identified as a hyperechoic midline structure immediately dorsal (deep) to the paired geniohyoideus muscles. Commencing the exam at this site is recommended because the lingual process is easy to locate.
Figure 43-11. Composite images obtained from the rostroventral acoustic window at three different locations in the transverse plane using a
12.5-MHz linear transducer. From left to right the images are progressing from rostral (A) to caudal (C) within the rostroventral acoustic window. (B) From the level of the lingual process, moving the probe caudad to follow the lingual process along its entire length leads to the base of the basihyoid bone (BH). At this level, there is an association between the basihyoid bone depth and dorsal displacement of the soft palate.
Figure 43-11. Composite images obtained from the rostroventral acoustic window at three different locations in the transverse plane using a
12.5-MHz linear transducer. From left to right the images are progressing from rostral (A) to caudal (C) within the rostroventral acoustic window. (A) The lingual process (LP) is readily identified as a hyperechoic midline structure immediately dorsal (deep) to the paired geniohyoideus muscles. Commencing the exam at this site is recommended because the lingual process is easy to locate. C) At the junction of the lingual process and base of the basihyoid bone, one can roll the probe slightly rostrad from a midline position to image the left and right ceratohyoid bones (CH). The ceratohyoid bones are paired, flat hyperechoic structures coursing dorsad (deep) in the image. Only the more ventral portion of the ceratohyoids is imaged; it is generally not possible to follow them to the level of the stylohyoid bones.
Figure 43-12. The normal right (A) and affected left (B) lateral acoustic windows from a 3-year-old Thoroughbred with grade 2-C recurrent laryngeal neuropathy obtained using an 8.5-MHz microconvex probe. The probe is held in a rostrocaudal plane just caudal to the mandibles at a slightly ventral angle so the imaging plane is parallel with the line of the cervical vertebral column. The cricoarytenoideus lateralis (white arrow) muscle belly is imaged between the thyroid (TC) and arytenoid cartilages (AC) and has increased echogenicity with loss of normal muscular fiber pattern on the horses left side (B) compared to the normal right side (A).
Figure 43-13. Composite image of the lateral acoustic window obtained using a 15-MHz linear array transducer from a yearling Standardbred horse (A) and a 10-year-old Standardbred horse (B). In the yearling, the CAL muscle has normal appearance and the laryngeal cartilages are uniform and hypoechoic. In the older horse (B), disruption of the expected appearance of anechoic cartilage is seen with distinct mineralization of the thyroid cartilage (arrow) which casts and acoustic shadow over the CAL muscle, making it difficult to image. This type of mineralization, seen in older horses, can range from tiny pinpoint hyperechoic foci to more generalized mineralization that impedes the ultrasound examination as shown here.
Fig 1: (a) Optimum position for the transducer. (b) Dorsal plane ultrasound image of the lateral aspect of a normal larynx.
Note the position of the cricoarytenoideus lateralis and vocalis muscle (small arrowheads) between the thyroid cartilage
(small arrows) and the arytenoid cartilage (large arrowhead). The cricoid cartilage (large arrow) is caudal to the thyroid
cartilage. Rostral is to the left of the image and caudal to the right
Fig 2: Dorsal plane
ultrasound of the lateral
aspect of a normal larynx.
This image is slightly dorsal
and caudal to that shown
in Fig 1b. The cricothyroid
articulation (small
arrowhead) is formed by the
caudal cornu of the thyroid
cartilage (small arrows)
and the articular process of
the cricoid cartilage (large
arrow). The muscular
process of the arytenoid
cartilage is also imaged
(large arrowhead). Rostral
is to the left of the image
and caudal is to the right
Fig 3: (a) Transverse plane
ultrasound of the lateral
aspect of a normal larynx.
Note the position of the
cricoarytenoideus lateralis
muscle (CAL) between the
thyroid cartilage (arrows)
and the arytenoid cartilage
(arrowheads). The vocalis
muscle is deep to the CAL,
but the distinction between
the muscles can often not
be seen, as in this case. The
arytenoid cartilage has a
trumpet bell shape and the
cricoarytenoideus lateralis
and vocalis muscles have
a striated appearance
with heterogeneous
echogenicity. Dorsal is to
the left of the image and
ventral is to the right
(b) Position of the
transducer
Fig 4: Dorsal plane
ultrasound of the
dorsolateral aspect of
a normal larynx. This
image is dorsal to that
shown in Fig 1. The
cricoarytenoid articulation
(small arrowhead) is
formed by the muscular
process of the arytenoid
(large arrowhead) and
the dorsolateral cricoid
cartilage (large arrow).
The lateral portion of the
cricoarytenoideus dorsalis
muscle is imaged (small
arrows). Rostral is to the
left of the image and caudal
is to the right
Fig 5: Transverse plane ultrasound of the ventral aspect of
the cricoid cartilage (arrows) of a normal larynx. Left is to
the right of the image and right is to the left
Fig 6: (a) Transverse
plane ultrasound image
of the ventral aspect
of the thyroid cartilage
(arrows) of a normal larynx
at the level of the vocal
folds (arrowheads). The
movement of the vocal folds
can be observed during
respiration. Left is to the
right of the image and right
is to the left of the image.
(b) Transducer position
Fig 7: Transverse plane ultrasound of the basihyoid bone
(arrowheads) and the ceratohyoid bones (arrows) of a
normal larynx, obtained with the transducer positioned
ventrally. Left is to the right of the image and right is to the
left
Fig 8: Comparison of echogenicity of the cricoarytenoideus lateralis and vocalis (arrows)
and cricoarytenoideus dorsalis (arrowheads) musculature. Horses with recurrent
laryngeal neuropathy have increased echogenicity and more homogeneous echogenicity
of the cricoarytenoideus lateralis and cricoarytenoideus dorsalis muscles. Dorsal plane
ultrasound images of the cricoarytenoideus lateralis muscle of (a) a horse with recurrent
laryngeal neuropathy and (b) a normal horse.
Transverse plane ultrasound images of the
cricoarytenoideus lateralis and vocalis muscles of (c) a horse with recurrent laryngeal
neuropathy and (d) a normal horse.
Dorsal plane ultrasound images of the cricoarytenoideus
dorsalis muscle of (e) a horse with recurrent laryngeal neuropathy and (f) a normal horse. In
the dorsal plane images, rostral is to the left and caudal is to the right and in the transverse
plane images, dorsal is to the left of the image and ventral is to the right
Fig 9: Transverse plane ultrasound image of the lateral
aspect of the larynx of a horse with arytenoid chondritis.
The arytenoid cartilage (arrows) is severely thickened
with irregular margins and increased echogenicity in its
interior. Dorsal is to the left of the image and ventral is to
the right
Fig 10: Transverse plane ultrasound image of the lateral
aspect of the larynx of a horse with laryngeal dysplasia.
The thyroid lamina (arrowhead) extends dorsal to the
muscular process of the arytenoid cartilage (arrow).
Dorsal is to the left of the image and ventral is to the right
Fig 11: Dorsal plane ultrasound image of the lateral
aspect of the larynx of a horse with laryngeal
dysplasia. The thyroid cartilage (arrow) and the
cricoid cartilage (small arrowhead) do not articulate.
The cricoarytenoideus lateralis and vocalis muscles
(large arrowheads) are positioned between the thyroid
cartilage and cricoid cartilage in the gap between the two
cartilages. Rostral is to the left of the image and caudal is
to the right
Figure 4. A resting endoscopic image of the left arytenoid
cartilage, which is clearly paralyzed. The amount
of abduction is clearly less than on the right side (courtesy
of Fabrice Rossignol).
Figure 5. The palatopharyngeal arch is often more
prominent at resting endoscopy in horses with a fourth
branchial arch defect (courtesy of Fabrice Rossignol).
Figure 7A. Longitudinal view of a normal thyroid and
cricoid cartilage. There are no signs of dysplasia.
Figure 7B. The dysplasia is clearly visible as there is a
gap between the thyroid cartilage (TC) and the cricoid
cartilage (CC) (courtesy of Fabrice Rossignol).
name the dixon grade
Figure 9A. Postoperative endoscopic image of a thoroughbred
racehorse that was treated by laryngoplasty
and laser
name the dixon grade
Figure 9B. Postoperative endoscopic image of a sport
horse that was treated by laryngoplasty and laser (Dixon
grade 3)
Fig. 2. Transverse ultrasound images from the rostroventral window.
Left—the lingual process (LP) of the basihyoid bone. Right—the base of the
basihyoid bone (BH). Both structures are easily identified in the transverse
plane.
Fig. 4. Longitudinal ultrasound image in the midventral window. Note
the caudal aspect of the basihyoid bone (BH), the cranial aspect of the
thyroid cartilage (TC) (Cr, cranial).
Fig. 3. Transverse ultrasound image from the rostroventral window with
the probe rolled slightly rostrally showing the base of the basihyoid bone
(BH) and the ventral aspect of the ceratohyoid bones (CH) on either side
coursing dorsally
Fig. 6. Transverse ultrasound image from the caudoventral window
(cricothyroid notch). Note the right and left vocal folds (VF) on either side of
the airway lumen (lumen).
Fig. 7. Left: left lateral view of a gross dissection of the larynx with distraction
placed on the thyroid cartilage (TC) and cricoid cartilage (CC) to
reveal the cricoarytenoideus lateralis muscle (CAL). Right: longitudinal ultrasound
image of the left lateral window. Note the caudodorsolateral aspect
of the TC, the rostrodorsolateral aspect of the CC and the CAL. The
arytenoid cartilage (AC) is seen deep to the thyroid cartilage.
Fig. 8. Composite images of the left lateral window in three horses with arytenoid chondritis (Cr, cranial is to the left in all images, AC, arytenoid cartilage in
all images). (A) Longitudinal image of a 3-year-old female thoroughbred with arytenoid chondrits. There is focal thickening with mass effect of the arytenoid
cartilage (white arrow). (B) Longitudinal image of a 5-year-old male thoroughbred with arytenoid chondritis. The perilaryngeal tissue, specifically the fascia
between the arytenoid and the thyroid cartilages, is hyperechoic (white asterix). The left arytenoid cartilage has normal margins, thickness, and echogenicity. (C)
Longitudinal image of a 2-year-old male thoroughbred with arytenoid chondritis. There is diffuse thickening of the arytenoid cartilage with irregular axial
(white arrow) and abaxial (black arrow) surfaces. The abaxial lesion was not identified with endoscopy.
Figure 43-14. (A) Lateral skull radiograph with multiple fluid lines. Rostral maxillary sinus (large arrowhead), caudal maxillary sinus (arrow), conchofrontal sinus (small arrowhead). (B) Oblique radiograph of the skull with complete opacity of the left paranasal sinuses from chronic disease.
Figure 43-15. Lateral radiographic image of a foal with persistent dorsal displacement of the soft palate. The epiglottis (small arrows) is unable to assume its normal position because of a large cyst (large arrowhead) on the free edge of the palate. A feeding tube is in the esophagus (small arrowhead).
Figure 43-16. Right lateral (A) and dorsal (B) skull nuclear scintigraphic images. There is diffuse increased radiopharmaceutical uptake outlining the maxillary and frontal sinuses consistent with primary sinusitis.
Figure 43-17. (A) Right dorsal-left ventral oblique radiograph of a horse with purulent drainage from the left side of the face and from the ipsilateral nostril. There is no bony lysis around any tooth roots to confirm a suspected diagnosis of tooth root infection. (B) The cross-sectional computed tomography image at the level of the first molars of the same horse in dorsal recumbency and under general anesthesia. The root structures of the 209 (first upper left molar) are abnormal (arrows) and consistent with infection.
