In part one of this series we discussed the important questions to ask when taking a history from owners of dogs and cats that are having seizures. In this part, we look at the differential diagnoses for these cases.
There are many ways to classify the different causes of seizures, but the simplest is as follows:
Structural – where intracranial pathology is causing the seizures.
Reactive – where an extracranial issue is causing a seizure response in a normal brain.
Idiopathic – a diagnosis of exclusion where we are unable to identify a reason for the disturbances in brain activity.
Structural
Intracranial differential diagnoses include:
inflammatory processes (meningoencephalitis), such as steroid responsive meningitis-arteritis
viral diseases (for example, distemper)
metabolic storage diseases
neoplasia
vascular accidents involving clots or bleeds
hydrocephalus
trauma
Reactive
Extracranial differentials include:
hepatic encephalopathy due to hepatic failure or a portosystemic shunt
various toxicities, such as lead, chocolate, caffeine, ethylene glycol, parasiticides and slug/snail bait
metabolic issues, such as hypoglycaemia, hypocalcaemia and thiamine deficiency
Idiopathic
If diagnostic investigations (including advanced imagery, such as MRI) are unable to identify an underlying cause of recurrent seizures, this is referred to as idiopathic epilepsy.
To break down this list of differentials into a more relevant and concise list is to consider the most common differentials according to signalment.
Fertility work makes up a large proportion of cattle veterinary work in the UK and, after spending a month on the farm rotation at university, I can appreciate the importance of getting it right – and how hard it can be.
Experienced large animal vets make it look easy – they scan the uterus and ovaries, and decide what drug to give to aid getting the cow in calf, all in a minute or two.
In the meantime, I’m still fumbling about trying to palpate what, I think, may be the uterus or ovaries while the cow squeezes and gradually cuts off the circulation in my arm until I can barely feel my fingers.
Meanwhile, the vet has zipped through several cows already.
When things go wrong
What happens if you misdiagnose a pregnant cow as negative and administer prostaglandin, or give a cow steroids without realising she’s in calf?
On one fertility visit this week, we discussed when things go wrong. For example, what if:
you misdiagnose a pregnant cow as negative and administer prostaglandin (PGF2α)?
a vet gives a cow steroids for any number of reasons without realising she’s in calf?
The outcomes of both of these scenarios are almost inevitably abortion, which can have a number of repercussions on the farm – and, potentially, the vet.
Negligence or misconduct?
Many new graduates are terrified of being called up for “fitness to practice” for making a mistake such as those aforementioned. However, during a Veterinary Defence Society (VDS) workshop at the SPVS Lancaster weekend earlier this year, it was emphasised a difference exists between negligence and misconduct in the eyes of the RCVS.
What I took away from this session was, in simple terms, negligence involves making a mistake – such as missing a diagnosis, giving the wrong treatment accidentally, eliciting side effects from something due to missing something in the case history – whereas misconduct is actively doing something you know you shouldn’t – such as trying to cover up a mistake, lying or misleading a client.
Mistakenly giving PGF2α to a pregnant cow would be classed as negligence and, on the whole, the VDS would have your back; the farmer may receive some compensation for his losses, but the incident wouldn’t tarnish your career. In the same situation, misconduct would be denying you had administered any treatment.
In short, you won’t get struck off for easily made, one-off mistakes, but you may if you lie about them.
In the news
Our conversation about accidentally aborting cows led us to discuss the case of Honey Rose, the optometrist convicted of gross negligence manslaughter. News reports vary, but, from what I can gather, she failed to diagnose papilloedema (swollen optic discs) in an eight-year-old boy, which would have been an indication of the hydrocephalus he died of five months later.
It is reported she claimed to have been unable to examine his eyes properly because he had photophobia – a claim considered false by the judge. However, she had also failed to look at retinal photos taken by a colleague, on which the papilloedema was evident.
Going by the RCVS’ rules, missing the diagnosis or not looking at the retinal photos would be negligent. However, denying she’d been able to carry out a thorough examination, despite written records suggesting otherwise, would be misconduct.
Rose was found guilty of gross negligence manslaughter and was handed a two-year prison sentence, suspended for two years, and a 24-month supervision order, and was ordered to complete 200 hours of unpaid work.
In your defence
As vets, we have the VDS to help us in these situations – and, while it would be truly awful to make a mistake resulting in an animal’s death, we would not be at risk of imprisonment.
Doctors and dentists also have defence societies that will fight their corner, but optometrists? To my knowledge, an equivalent does not exist – and this was the first case of an optometrist convicted of manslaughter in the UK, which added to the complexity of the legal battle.
The death of a little boy is devastating, but, as medical professionals know, death is a risk with many procedures, no matter how small the risk may be. It’s frightening to think jail could be a consequence for those in the medical profession.
So, while I gradually lost the sensation in my right arm as I tried to reach an ovary of the 10th cow in a row, I mulled this over and realised I was extremely thankful for the safety net the VDS provides and would not take working with animals for granted.
After all, if I’d decided to be a doctor instead, I could be rummaging around in another human’s back end rather than a cow’s!
For further details of the Veterinary Defence Society and its services, visit www.thevds.co.uk
