Having introduced a few new #vetfinal-ers from all over the place, with activities ranging from last minute revision and wine drinking to being sat in the first class lounge at Euston station, Tom introduced the case and away we went!
So we have an 8yo Warmblood gelding presenting with a mucopurulent nasal discharge… Initial questions please!
An important point to note in any horse presenting with nasal discharge is laterality (new favourite word right there):
So let’s think about work-up
Strangles is always an important differential that you need to consider if called to a horse with nasal discharge – be aware that it is very infectious and you don’t want to be the reason it spreads!
Let’s have a more detailed think about this horses history and what questions we’d like to ask:
And the answers:
So why would strangles be less likely in this case?
Whilst we’re on the topic, let’s have a quick review of strangles
Summary note: Strangles
Caused by infection with Streptococcus equi var equi, a Gram positive cocci, that is equine specific, causing a highly infectious bacterial infection affecting the upper respiratory tract and associated lymph nodes
Spread in nasopharyngeal secretions from acutely infected horses and carriers with some environmental survival
Incubation period: 3-14 days
inappetence, cough, abscessation of
mandibular, parotid or retropharyngeal lymph nodes, dyspnea and
dysphagia if abscesses compress larynx or interferes with cranial nerve supply
to pharynx, mucoid to purulent
bilaterally (coming from the guttural pouches which are behind the pharynx)
Diagnosis: nasopharyngeal swab (bacterial culture), guttural pouch endoscopy (GP empyema) and washes (PCR), serology
Individual treatment: supportive care if sick, usually sensitive to penicillin and oxytetracycline, can flush the guttural pouches then fill with a gelatine/penicillin
For more info and how to manage a strangles outbreak, check out:
– The HBLB Code of Practice 2013: http://codes.hblb.org.uk/index.php/page/99 …
– The ACVIM consensus statement on strangles: http://web.up.ac.za/sitefiles/File/40/753/Strangles.pdf …
Back to the case, and luckily strangles seems unlikely to be the cause
More questions and suggestions please!
And the answers:
So we’re still on the hunt for clues regarding the nasal discharge – what else is really important to consider?
So no history of previous respiratory tract disease…
…The discharge varies in consistency but is always purulent…
…And it really smells!!
He has also had a history of a puffy face – now we’re getting more clues!
As previously mentioned, strangles is always an important differential for nasal discharge, so ruling it out is a wise option.
Now, onto some differentials:
Let’s start with ruling out LRT disease:
And now we can think about our next steps:
Sadly portable CT is not an option so we will have to go down some more traditional routes to work out what’s wrong!
So to summarise our physical examination findings:
So we need to check airflow from both nostrils and compare. And also think about coughing as for any respiratory problem!
Epiphora is another important clinical sign when investigating nasal discharge, why?
So we’ve noted an ocular discharge, making a space-occupying lesion in the sinuses more likely.
Let’s start thinking more about what we are going to do with our scope to make our examination as useful as possible:
Now it’s time for a quick anatomy revision test…
So here’s a lovely image of our sinuses draining out into our middle meatus:
Before we get onto more detailed stuff, lets take a quick break to revise our equine dental anatomy!
Summary note: equine dental anatomy
Equine teeth are hypsodont, meaning they have reserve crown under the gums, that continually erupt as the occlusal surface is worn away.
The formula for deciduous teeth: 2 (I3/3 C0/0 P3/3)
The formula for permanent teeth: 2 (I3/3 C1/1 P3-4/3 M3/3)
Check out a nice picture of the dental formula here: http://cal.vet.upenn.edu/projects/grossanat/largemenu/hheadormenu.htm …
Interactions between the tooth roots and sinuses are really important to consider as well. Let’s start with some pictures to revise our basic sinus anatomy:
So which teeth are we most interested in and what else are we looking for on our oblique head radiographs? There is a nice summary of how to obtain our radiographs of the head here: http://www.cvm.umn.edu/vetrad/prod/groups/cvm/@pub/@cvm/@vetrad/documents/asset/cvm_asset_360308.pdf …
A quick summary before we move on:
So we have a diagnosis of sinusitis secondary to dental disease! Now what to do?
CT is a really good imaging modality when considering sinus or dental disease. This paper is a bit old, but has labelled images of CT cross-sections of the head (some good practice for those of us that don’t have portable CTs in our cars!!)
We’ve decided this manky tooth needs to go, now how do we go about it?
There are other things to consider as well as our tooth:
A quick word on antibiotics:
A mention towards analgesia/anaesthesia (yay!):
We’re all agreed this sinus needs flushing, so how are we going to go about it?
Before we start drilling holes in this poor ponies head, it’s important that we get our landmarks correct!
(The links in the dental anatomy section have some images showing the location of the sinuses)
And for the frontal sinus:
Another lesson in sinus anatomy: communication!
This link will take you to an overview of how the sinuses communicate:
We always need to consider how things could go wrong and problems we may face – then we know what we’re up against so stand a better chance of preventing/noticing early and fixing!
And now for the important question!
So there we go, another patient fixed in the happy online land of #vetfinals!
– This is a really nice In Practice article covering the techniques for sinus surgery and lavage in a bit more detail: http://inpractice.bmj.com/content/30/5/252.full.pdf+html?sid=b4b9a172-ec9f-472e-a3de-75b8f6940239 …
– This article is old but I think it is still relevant with some nice images and differentials lists (and a seriously cute photo of a falabella foal…): http://inpractice.bmj.com/content/8/2/49.full.pdf+html?sid=b4b9a172-ec9f-472e-a3de-75b8f6940239 …
This is something I always find helpful to think about when being quizzed about nasal discharge differentials, and once I got my head around it (tricky when blonde…) suddenly everything made more sense! I know it is obvious but sometimes it is important to revisit the basics, especially when being grilled and getting confused
– Bilateral nasal discharge: will be coming from the mid-lower respiratory tract, BELOW the pharynx. Anything producing discharge below the pharynx gives the discharge the option to run out of both nostrils e.g. guttural pouches
– Unilateral nasal discharge: will be coming from the upper respiratory tract, AFTER the pharynx where the discharge can only leave via one nostril e.g. sinus disease
I really hope this is helping you all and you are enjoying being part of #vetfinals! One last massive thankyou to Tom for another excellent session, and also massive congratulations need to go his way for being elected to RCVS Council (making him the first council member to take part in #vetfinals, what a claim to fame…). Fab achievements all round!