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As obligate nasal breathers, how do horses increase airflow during exercise?
dilate nares, nasal passages, and nasopharynx
why should xylazine NOT be used as a sedative during endoscopy of upper respiratory?
- can affect swallowing and allow collapse of pharynx
- can affect ab/adduction of arytenoids
what structures can be identified in the nasopharynx with endoscopy?
- ethmoid turbinates
- nasal septum
- dorsal pharyngeal recess
- soft palate
- opening for guttural pouch
which cranial nerves run through the guttural pouch? what are other important nervous and vascular structures in this area?
- sympathetic trunk
- cranial cervical ganglion
- internal carotid a.
where is the esophagus found?
as a potential space above the rima glottis in the larynx
Of the 6 equine sinuses, which are the most affected by disease?
frontal and maxillary sinuses
what is the most common etiology of primary sinusitis? which sinus most commonly?
- Streptococcus spp. (can follow viral infection)
what is the most common cause of secondary sinusitis? which sinus?
- tooth root infection (PM4, M1,2,3)
- (other causes include cysts, fractures, tumors)
what are common clinical signs associated with sinusitis? what is a sign of chronicity?
- uni or bilateral nasal discharge +/- foul smell
- ocular discharge/epiphora
- malaise, fever, inappetance
- chronic: facial deformity
how can patency of nasolacrimal duct be assessed?
fluoroscein stain in the eye should be seen at nasal puncta
if rads reveal fluid line in maxillary sinus, what is diagnosis? how is it treated?
- abscess (from tooth root abscess or other cause)
- start Abs (c/s pending)
- lavage w/balanced polyionic solution via trephine, sinoscopy, sinus flap, or balloon sinuplasty
what is causative agent for Strangles? is this contagious?
- strep equi
- yes, highly contagious via inhalation/ingestion
what is age of horse commonly affected w/strep equi? how long in incubation?
- young horse
- incubation 3-14 days
what are major clinical signs associated with strangles?
- *fever*, depression, decr. appetite
- respiratory distress
- +/-nasal discharge (depends on which lnn. effected)
- +/- anemia if chronic
which lymph nodes are typically affected by strangles? what clinical signs are seen depending on which is affected?
- submandibular - swell/rupture - drain out the nose
- retropharyngeal - swell - tracheal compression
- parotid - swell/rupture - drain out skin
What do you do if horse presents with severe respiratory distress due to very enlarged retropharyngeal lymph nodes from strangles?
what is cause of dysphagea in strangles patient?
cranial neuritis from guttural pouch infection if lymph nodes rupture here
how is strangles diagnosed?
- anamnesis (new horse on property, travel)
- clinical signs
- endoscopy (pus) + *culture* nasal wash/abscess/GP
how is strangles treated?
- controversy but must isolate affected and exposed (highly contagious) + NSAIDs for fever/pain
- +/- penicillin (many will opt to "let it run its course")
With strangles, when does shedding occur in relation to apparent fever?
- shedding 2-3 days after fever onset
- (best if catch first sign of fever then isolate before shedding)
what is isolation protocol for horse with strangles? how long is it?
- no nose contact and tx last to avoid spread via staff
- isolate >2-3 wks following resolution of signs + negative culture
- (may persist in environment)
Do horses develop lasting immunity after recovering from strangles?
- 75% get lasting immunity >5yrs
- 25% reinfect in months if not strong IgA
what are potential complications of strangles?
- GP empyema
- bastard strangles
- purpura hemorrhagica
if horse presents with clinical signs resembling strangles but culture of abscess reveals strep zooepidemicus (negative for staph equi), does horse still need to be isolated?
- no, strep zoo is not contagious
- strep zoo is *zoonotic*
what are condroids? how does the horse present?
- inspisated pus
- may be asymptomatic/carrier - can spread to environment
how are condroids diagnosed and treated?
- endoscopy of GP
- remove + lavage/instill penicillin gel
what is bastard strangles? what are symptoms?
- hematogenous spread of strep equi -
- wt loss, pneumonia
- + reflect organ that becomes infected (neurological, colic/adhesions, lameness)
how is bastard strangles treated? what is prognosis? is it zoonotic?
- long term Abs
- guarded prognosis
- zoonotic potential
if horse has previous infection with staph equi, should you vaccinate him? why or why not?
check titers first- if titers high then NO vx - incr. risk of purpura hemorrhagica
how is strangles prevented?
- vaccine protocols 2-3 doses (vx parent helps too)
- want mucosal immunity to block entry of agent
- isolate new horses at least 21d
- minimize farm traffic/good husbandry
why should intranasal strangles vx not be given at same time as other IM vaccines?
intranasal highly immunogenic - if sneeze particles into IM site, abscesses
is intranasal live or killed product? how many need to be given and how often?
- initially 2-3 doses 2 weeks apart then annual booster
when should the killed strangles vx be given to pregnant mares? how long does immunity last with this vx?
- 4-6 weeks before foaling
- ~6 months
with pharyngeal lymphoid hyperplasia, how does horse present with the various stages?
- 0-3 performance may be effected but otherwise normal
- 4 - hemorrhagic, horse more symptomatic
are horses with pharyngeal lymphoid hyperplasia febrile? systemically ill? anorexic? what age are they?
- no fever, no systemic illness
- normal appetite, BAR
- young, 1-2yrs
what are the most common viral diseases of the upper respiratory?
- *equine influenza* - most frequently diagnosed
- herpes 1, 4
(less common: EVA, rhinovirus)
what are the two surface proteins for host specificity w/influenza?
- hemaglutinin (HA)
- neuraminidase (NA)
what is the most common flu strain seen in horses?
- A1 and A2
- (in USA, A2 H3N8)
what is age affected with flu? morbidity/mortality?
- young <3yrs
- high morbidity/low mortality
- comingled horses at greatest risk
What tissue does flu have tropism for?
celiated respiratory epithelium in trachea/bronchi - damaged mucociliary clearance = prone to 2nd bacterial infection