Case of the month - January 14

January has our case of the month highlighting some incredible images taken to investigate a very wobbly guinea pig called Steve!   If you look at the bottom of the page you can watch a short 3D video showing the inside of his head!  We promise you it's not a dinosaur!

Steve is a rescue Guinea Pig from the RSPCA, we know little about his previous history but he was taken on in his lovely forever home in August as a young juvenile, with two lovely lady Guinea Pigs in his new home to keep him company.

All was very well with Steve however in December he suddenly developed worrying signs looking like a possible epileptic fit.  He would become very wobbly, with his eyes flicking and seem drunk and fall over. These episodes were short but variable in frequency - often the only sign on presentation at the surgery was his eyes flicking (called nystagmus).

Guinea pigs are prone to seizures if they have a particular skin parasite so treatment was stared straight away to combat this despite the fact his skin scrapes and swabs were negative. His ears where clean with no evidence of infection.

Blood sampling and plain x-rays of his head revealed no sign of any obvious problems.

With Veterinary Medicine our patients obviously can't talk to us so regardless of size we often work through a logical list of what most likely causes the clinical signs we are presented with and then rule them out with tests and often in the case of guinea pigs by response to treatment.

In Steve's case his differential diagnosis list looked something like this

1. Mites causing neurological signs - can rule out as treated for this.
2. Ear Disease - no obvious sign on physical, normal x-ray images although this is a basic test as changes can be very subtle on radiographs and specialised imaging like CT and MRI scans can be required.
3. Liver disease - normal blood results
4. Metabolic disease - normal calcium, glucose and electrolyte levels.
5. Meningitis - very unlikely from clinical signs of only intermittent problems and normal blood results.
6. Vitamin Deficiencies - Steve was on a great varied Guinea Pig diet and was already receiving vitamin supplements.
7. Tumours - brain tumours or inner/middle ear tumours were a possibility but further imaging would be required.

With a long list of rule outs we were still no further along in diagnosing Steve's problem - we contacted our local referral hospital Fitzpatrick Referrals to see if they could help.  Despite the fact they do not normally treat guinea pigs they were fantastic and agreed to help straight away.

Fitzpatrick Referrals has some of the best facilities around, putting most human hospitals to shame!  They specialise in orthapaedic and neurological disease so they have their own MRI and CT scanner.  Clare Rusbridge is the head of their neurology department and is a RCVS Specialist in Veterinary Neurology (the highest award you can achieve).  As you can imagine she is a very busy lady but despite this she freely gave her time to examine little Steve.  There are not many Guinea Pigs in the world who can say they've been examined by such an eminent vet!

After his examination he was then taken to the imaging suite.  Louise our vet was allowed to go with him and manage his anaesthetic whilst Jelena and her team took some amazing images of Steve.

First he went through the CT scanner.  A CT scan is in basic terms a very special X-Ray machine where a computer then generates a 3D image. With a simple x-ray you are looking at one image with everything layered on top of each other.  A CT image allows you can pick an individual slice and visualise the body part in much more detail.

As you can see from these images the pictures are amazing.  A short 3D video can be viewed at the bottom of the page but you can also see some other images here and here!  The CT scanner showed no sign of otitis media or interna which was excellent news and Steve's teeth and his sinus cavities all appeared normal too.

Next step was the MRI scanner - this is an incredibly expensive piece of kit that by magnetic waves gives an intricate 3D image of all of the soft tissue structures.  It is a much more detailed image and in Steve's case was used to evaluate his brain.

Steve sailed through his anaesthetic - which is not easy and more than a little stressful when you have to monitor through the window whilst the scan is taking place!  We were thrilled to see no evidence of any tumours in his brain.

Given his clinical signs Dr Rusbridge suspects that Steve is suffering from a condition called Labryrinthitis.  This is where the gyroscope inside the ear becomes inflamed causing wobbliness (ataxia) and eye flicking (nystagmus) and in people nausea and sickness.  With Guinea Pigs though they cannot vomit due to the design of their digestive tract!  The great news is that hopefully, just as in people this condition will rectify all by itself and fingers crossed so far so well Steve seems to be improving nicely.