Equine upper airway diseases Flashcards
(18 cards)
Explain what RLN in horses is + etiology.
Recurrent laryngeal neuropathy (RLN)
* The recurrent laryngeal nerve is part of the vagus (X cranial) nerve.
* More commonly a bilateral mononeuropathy affecting the left recurrent laryngeal nerve more severely.
The etiology is unknown.
More often affects male thoroughbreds and draft horses. Rare in ponies. Thus, maybe a genetic component.
Clinical signs of RLN.
Recurrent laryngeal neuropathy (RLN)
Inspiratory noise during exercise
* „Roaring“
* Many sport horses are unaffected until 5-6 years.
Poor performance due to decreased ventilation due to laryngeal collapse.
Physical exam of a Recurrent laryngeal neuropathy patient.
Check throat and cervical areas → signs of trauma or deformity.
Palpate the larynx – atrophy of the cricoarytenoid dorsalis muscle (see pic).
NB Horner’s syndrome can result from perivascular injection/trauma to the jugular area.
Pursue endoscopy if suspecting laryngeal neuropathy.
Describe endoscpy for recurrent laryngeal neuropathy (RLN).
Via endoscopy:
* Assessment of the laryngeal anatomy
* Arytenoid movement and synchrony
* Unsedated horse if possible
* Slap test: slap the withers area on left side. Look for any contraction of the adductor muscles? (Grading system A-D (I-IV))
Dynamic chec with scope (treadmill or overground with scope fixed in place):
* Precise diagnosis if laryngeal or vocal cord collapse is suspected.
Tx, prognosis and complications for recurrent laryngeal neuropathy.
To restore the diameter of the rima glottidis and prevent dynamic collapse of the vocal cords
and arytenoid cartilage during inspiration.
- Larynx has both digestive and respiratory functions
During swallowing its for protection of the airways.
Surgical therapy
* Method depends on the complaint
Prognosis depends on the activity of the horse
* Lower chance of returning to their same level for racehorses than show horses/jumpers.
Complications: continued exercise intolerance and respiratory noise, chronic coughing, loosening of the ‘prosthetic’ suture(s).
Describe sinusitis in horses.
Most clinically important sinusites are in maxillary or frontal sinuses.
Usually unilateral but can be bi-, mucopurulent discharge. Reduced nasal airflow, epiphora, facial swelling.
Primary and secondary sinusitis.
Primary sinusitis
* Accumulation of exudate within the sinus cavity
* Viral or bacterial upper respiratory tract infection e.g. Streptococcal (and rarely Staphylococcal) organisms
Secondary sinusitis
* Dental disease e.g. Infection of the tooth root, fractured teeth. Most commonly first molar.
* Sinus cyst
* Neoplasia
* Foreign body
* Trauma
Describe the anatomy of equine sinuses.
6 pairs of sinuses (dorsal, middle, ventral conchal and maxillary, frontal, sphenopalatine)
- Some communicate with each other
- Lined by a respiratory epithelium with Goblet cells & Serous glands.
Causes of primary sinusitis.
Accumulation of exudate within the sinus cavity due to viral or bacterial upper respiratory tract infection.
e.g. Streptococcal (and rarely Staphylococcal) organisms
Also, fungal infections of the sinuses.
Causes of secondary sinusitis. (5)
- Dental disease e.g. Infection of the tooth root, fractured teeth. Most commonly first molar.
- Sinus cyst
- Neoplasia
- Foreign body
- Trauma
Diagnosis of equine sinusisitis involves:
Based on the clinical history, age of the animal and nature of the clinical signs.
Do Endoscopy.
* Eliminate other causes; You must differentiate bilat. sinusitis from strangles so scope the guttural pouches to check for origin of the discharge.
- Do a Thorough dental examination.
- Lateral and lat-oblique radiographs: Look for fluid-air interfaces, abnormalities in the teeth, lysis of alveolar bone.
- Ideally CT but not available for horses in many places.
Take sinus discharge samples for Culture and cytology of the fluid. If sinus mass is found, do Biopsy of it.
Tx of sinusitis.
Surgical removal of the primary cause:
* Tooth, cyst, granulation tissue, neoplasia
Establishment of good drainage
* Surgical flap
* Standing horse
Copious lavage with NaCl, sometimes acetylcysteine.
Primary sinusitis should also be treated with:
* Broad-spectrum antimicrobials
* Anti-inflammatories
* Sinus lavage
Describe strangles etiology in horses.
Highly infectious upper respiratory disease caused by bacteria Streptococcus equi subsp.equi.
Can affect any age (young horses more often), sex or breed of horse.
Strangles is a reportable disease in many countries!
strangles is called “pääntauti” in finnish
zooepidemicus does not cause strangles but can cause endometritis
name 4 NSAIDs for horses
flunixin
firocoxib
ketoprofen
phenylbutazone
Clinical signs of strangles in horses.
- Pyrexia, Rectal temperature above 38.5°C
- Lethargy/dull and depressed
- Reluctance to eat/drink, difficulty swallowing and/or a lowered head and neck.
- Cough (although not always present)
- Thick yellowish nasal discharge
- Swelling of the submandibular lymph nodes which can also abscess and later, rupture.
Strangles abscesses can rupture into the guttural pouches causing guttural pouch empyema.
Prognosis for strangles.
- 98% of horses recover
- 20% of horses develop complications
Spread of infection in an individual can cause:
* Bronchopneumonia
* Bastard strangles/ metastatic abscesses (mainly in abdominal cavity)
Immune-mediated reactions
* Purpura haemorrhagica (vasculitis) is type 3 hypersensitivity reaction
* Immune-mediated rhabdomyolysis
* Muscle infarction
* Myositis with atrophy
Diagnosis of strangles.
Bloodwork
o Leukocytosis (neutrofilia) (viruses cause a leukoPENIA!)
o Hyperfibrinogenemia
Sampling to isolate bacterium.
o A needle aspirate from an enlarged or abscessed lymph node
o Nasopharyngeal swabs
o Nasopharyngeal and guttural pouch washes
Tx of strangles.
The majority of strangles cases require no treatment other than
* Rest
* Supportive care
* Soft, moist, and palatable food
Antibiotics yes or no?
If,
o Very high fever
o Profound lymphadenopathy and respiratory distress
o Bastard strangles and the cases of purpura hemorrhagica
o Guttural pouch infections treated locally and systemically to eliminate the carrier state
o Corticosteroids if immuno-mediated complications appear
If yes, use Penicillin IM q12h or IV q6h.
- Vaccination
- Prevention
