Eqine respiratory conditions Flashcards
Which lymph nodes can we feel around the head for lymphadenopathy
Submandibulars
cannot feel retropharyngeals externally
What type of virus is equine influenza
ssRNA orthomyxovirus type A
CLinical signs of equine influenze
Pyrexia, inappetance, lethargy, nasal discharge
Dry persistent cough very noticeable often
Diagnosis of equine influenza
Do nasopharyngeal swabs while animal is sick
How does vaccination against equine influenze help
Reduces shedding and severity but does not prevent infection
Vaccine schedule for influenza
First vaccine
Then second one within 21-60 days
Third one 120-180 days
Then booster 6-12 monthly
How to deal with equine influenza case
Isolation for 14 days
Long rest and recovery
NSAIDs
Only do antibiotics if there is a secondary infection
What is the cause of strangles and what type of bacteria is it
Streptococcus equi v equi
= gram +ve cocci
Pathogenesis of strangles
Bacteria enter oro-nasal cavity and enter cryp cells of tonsil –> spread to regional lymph nodes and cause lymphadenopathy
Then a few days later get lymphoid hyperplasia and abscessation
From 7 days + can get rupture of the LN which causes infectious pus to come out of nose via floor of guttural pouch
How can we try and isolate horses before LN rupture in strangles
They have pyrexia before the rupture so isolate them then
Should do 2X daily temperature checks for any in contacts of a confirmed case
Can we get endemicity of strangles
Yes because a small % remain persistently infected
Why is strep equi v equi so important
Can be fatal via asphyxiation or by high cost of treatment
Can spread easily in residential premises
What aerosolises more out of influenza and strangles
Influenza
(strnalges does not aerosolise much)
Clinical signs of strangles
Pyrexia, lethargy, mucopurulent nasal discharge, submandiular/retropharyngeal lymphadenopathy, inappetance/dysphagia
+ less commonly, higher resp rate and effort, stridor, can mimic choke with water/food down nose
Which LNs are located near the floor of the guttural pouch
Retropharyngeals
Why can horses with strangles be dysphagic
1) Physical obstruction due to enlarged LNs
2) Some neuropraxia because enlargeds LNs are interfering with nerves on floor of guttural pouch
Are horses with strep equi v equi chondroids a large risk to population
Not really bceause chondroids usually PCR negative
If they have empyema though they are
What should we consider if we see empyema but negative strangles test
Probably still strangles
What is an appropriate screening test for strangles i.e pre-movement
SCoping guttural pouch and submitted aspirates
ELISAs are NOT useful if there is no clinical suspicion
How does strangles survive in the environment
Not well; especially not in summer
So leaving horses outside with it is a good idea
What can mild strangles look like
Unexplained pyrexia, mild cloudy nasal discharge
In any unexplained pyrexia should check the guttural pouches
What is bastard strangles
Where there is haematogenous or lymphoid spread of strep equi v equi
Leads to purulent material and abscessation wherever the bacteria go
e.g meningitis, skin swelling, mesenteric abscessation
Which animals do we typically see bastard strangles in
Very ill animals that haven’t been given antibioitics
What is purpura haemorrhagica
Severe vasculitis triggered by illness such as strangles
Requires high steroid doses
What does the strangles ELISA detect (and when might it be low or high)
SEM
May not be expressed in persistently infected genomes
Very high titre with purpura haemorrhagica
What are some potential complications of strangles
- Bastard strangles
- Purpura haemorrhagica
- Myopathies
Treating strangles
NSAIDs +/- paracetamol
Give penicillin if horse is persistently pyrexic, dull and miserable, if there is dysphagia or stridor
Flush out guttural pouch via scope or foley catheter (may instill penicillin here)
WHat must we advise owners when giving antibiotics for strangles
Can get poorer seroconversion and may get flare up of abscess after therapy
But if they need it must give
What types of viruses are EHV1,4
alpha herpesviruses
Characteristics of equine herpes virus infection
~80% infected as youngsters
Pyrexia, nasal discharge, cough, lethargy
Abortion may be first clue
Get latency in trigeminal ganglion; rarely get recrudensce
Do we need to isolate latently infected herpes cases
No
What is gold standard for diagnosing equine herpes virus
Virus isolation (but it is slow)
Vaccination schedure for EHV1/4
1st one from 5 months, then another 4-6 weeks later, boost at 6 months
Then give at 5, 7 and 9 months gestation to mares
NB: this vaccine reduces shedding and severity but not prevent abortion or neuro signs; it is licensed for respiratory disease
How does EHV1,4 enter body and proliferate
Enters respiratory epithelial cells, goes to monocytes/lymphocytes then to blood vessels/LNs
Get a cell associated viraemia and replicatino in vessel endothelium
How much rest to give pyrexic horses
1 week for every day of pyrexia
What type of virus is equine viral arteritis
RNA alpha-arterivirus
What does equine viral arteritis cause
Pyrexia, inappetence, conjunctivitis, vasculitis so oedema, abortion
= can be maintained in carrier stallions so should not be kept for breeding
What is the use of a rebreathing exam
Increases the inspired CO2 of horses, making them breathe more heavily and improving sensitivity of auscultation
Becomes easier to hear harsh sounds, crackles from fluid
Or areas of no nosie
What can bloods be useful for in a respiraotry work up
Systemic inflammation is indicative of pneumonia
vs in asthma, the bloods will look normal
What tests is BAL best for
Cytology
What method can be used for resp secretion culture
Tracheal wash if a triple lumen catheter used
Or transtracheal wash is best
What areas do BALs vs TW samples and what does this make them good at identifying
BALs sample just a single region of lung; so good at identifying diffuse disease
TWs sample everything