Special interest

2014 in review – hopefully an exciting 2015 to follow!

The WordPress.com stats helper monkeys prepared a 2014 annual report for this blog.

Here’s an excerpt:

The concert hall at the Sydney Opera House holds 2,700 people. This blog was viewed about 12,000 times in 2014. If it were a concert at Sydney Opera House, it would take about 4 sold-out performances for that many people to see it.

Click here to see the complete report.

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Special interest

It’s beginning to look a lot like Christmas

Warning: Images from real post-mortems and bad decorating to follow.

As the first couple of doors of the advent calendar are opened, and adverts for everything Christmassy are starting to drive you a little insane, we thought it would be a good time to remind pet owners of some of the risks the holiday season brings to our pets. Vets come across as gigantic Debbie Downers at this time of year, but hopefully with a little advice the necropsy room will be nice and quiet as a result.

The necrospy room is decorated to help lift the mood

The necropsy room is decorated to help lift the mood

Most owners are aware of foods that shouldn’t be shared with pets. A few of the more common culprits are listed here (don’t forget about them after they’ve been mixed into something else!) but there are many other toxic ‘treats’ so it’s best to stick with products specifically made for pets.

Chocolate is everywhere this time of year – keep it out of reach of your pets!

Onions, garlic and chives mangle red blood cells in cats and dogs, leading to severe anaemia.  Don’t forget gravy and stuffing often contain lots of onion!

These red blood cells have been damaged by oxidative damage (e.g. onion toxicity)

These red blood cells have been damaged by oxidative damage (e.g. onion toxicity)

Animals are much more sensitive to alcohol. It can depress breathing and lead to aspiration pneumonia (choking on vomit).

The avocado fruit and plant is toxic to many species, and severely toxic to rodents and birds. Cherries are also poisonous to cats and dogs.

That's right Grumpy; stick to cat food

That’s right Grumpy; stick to cat food

Grapes and raisins, often hidden in fruit cakes, mince pies and Christmas puddings, can lead to kidney failure in dogs.  Macadamia nuts and blue cheese are also harmful to pets.

Bones are bad news all round! They can choke, cause obstructions (in the airways and guts), and tear the intestines.  Bones are best avoided altogether – our domestic dogs aren’t quite as smart or robust as their ancestors!

A bone lodged in the larynx of an unfortunate young dog

A bone lodged in the larynx of an unfortunate young dog

Xylitol, an artificial sweetener, can cause severe hypoglycaemia (low blood sugar) in dogs, leading to coma and death.  It is common in commercially available food for diabetics (chocolates and sweets), as well as ‘diet’ versions of soft drinks.

As if Christmas dinner was enough of a minefield for your furry friend, decorations are also a danger! This time of year sees lots of animals visiting the hospital (and sadly, the necropsy room too) after swallowing all sorts of objects including baubles, tinsel, and batteries.

Real Christmas tree needles can be irritant to dogs, causing skin reactions, sores in the mouth, vomiting and diarrhoea.

Holly, mistletoe and poincetta are all toxic to animals – keep them securely fastened out of reach of the curious dog and cat.

And don’t leave candles unattended in case your mischievous cat knocks them over, nor electrical cables accessible to the dog who is bored of his chew toy, or house rabbit who likes to nibble at everything…

 

Have a safe and happy holiday from Vetforensics!

tinsel skulls

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Special interest

Bending over backwards to see the past

What killed the dinosaurs? Or more specifically, what killed these dinosaurs?

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Rearing up with their heads thrown back, mouth open and teeth bared, their final poses seem to bring them to life. But could this body position, called opisthotonic posture (or death pose), give us clues about how and why they died? That’s right, it’s time to play Dino-Detective!

Artist impression of what dinosaurs might have looked like

Opisthotonic death pose is very common in fossils, and so characteristic that you can generally spot it with ease in even the smallest of fossil exhibits. The head and tail are arched over the animal’s back, and the legs are often drawn into rigid-looking positions. But despite being known about and discussed for 150 years, people are still unsure why exactly dinosaurs so frequently adopt this petrified posture.

Many different reasons for the posture have been suggested, ranging from the very plausible to the downright bizarre.  For example, it’s been suggested that the pose it is actually a sleeping posture (does that look relaxed to you?!), or that the animal dived headfirst into mud and got stuck (it probably happened rarely, but is very unlikely in the case of large theropods or Camarasaurus, unless they were particularly stupid).

More comfortable/less horrifying sleeping posture

A more comfortable/less horrifying sleeping posture

Such suggestions are pretty easy to rule out, and aren’t talked about seriously. Rather, the big bone of contention revolves around whether the opisthotonic pose occurred before or after the dinosaur bit the dust.

Many people think that the pose is a post-mortem change, meaning that it happens after death. Different causes have been suggested, from water currents manipulating the body, to rigor mortis, to the ‘pull’ of drying tendons. However, Faux and Padian, writing in 2007 had a different idea. A background in veterinary medicine gave the authors a different perspective – rather than a change after death, perhaps the pose was a clinical sign of underlying pathology. Faux and Padian thought that these dinosaurs were still alive when they assumed the position, and the posture was a symptom of impaired brain function. It’s a symptom that medical professionals and many others will recognise…

Opisthotonos as a symptom of meningitis infection

Opisthotonos as a symptom of meningitis infection

Muscles are pretty trigger happy, and need inhibitory messages from the central nervous system to stop them contracting all the time. A problem in the brain or spinal cord can interfere with this inhibition. When that happens, the muscles all contract at once. Some are stronger than others (usually the extensor muscles) and pull the body into opisthotonic posture by force.

If Faux and Padian are right, it gives us clues about what might have killed these dinosaurs – severe head injuries, infections (e.g. tetanus and meningitis), poisoning, heat stroke, and lack of oxygen (e.g. drowning) can all cause opisthotonus and eventually death.

A dog with tetanus infection, which survived with intense veterinary nursing. Image credit.

A dog with tetanus infection. Without this intense veterinary care she would not have survived. Image credit.

 

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Special interest

Fly On The Wall Biology

A fruit fly clumsily approaches my wineglass, and I know that, inevitably, it will encircle my head a number of times while I throw misjudged swipes, interrupt the conversation and make me appear tipsier than I am. Because of this, I generally regard them as an annoyance. But then I spent a summer actually getting to know them, and started thinking of fruit flies – one species in particular; Drosophila melanogaster – as something of tiny heroes.

Surprisingly, this insect is one of the most intensively studied creatures ever to have lived on earth, likely surpassing even ourselves. Drosophila are an ‘invertebrate model’; useful analogues to humans for studying a massive number of biological processes.

But why the fruit fly? Surely it is one of the last animals you would choose to compare to humans? In fact, there are equivalent genes for 77% of known human diseases in Drosophila. Fruit flies share the fundamental cell chemistry of us and other animals, making them ideal for studying the way our cells work. They are cheap to look after and reproduce quickly. The entire genome is sequenced and available for scientists to study, and having only four pairs of chromosomes (compared to our 23 pairs) are easy to manipulate in studies.

Drosophila melanogaster

Drosophila melanogaster

Neuroscience is one example of a field which has benefitted fantastically from the use of Drosophila in research. First introduced into the field over 100 years ago, the humble fruit fly helped to decipher the complicated development of the nervous system. The genes involved in this development also turned out to be involved in leukaemia and some other cancers. Further research using Drosophila enlightened scientists on the molecular workings of behaviour, memory and circadian rhythm – which also revealed genes responsible for genetic sleep disorders.

Devastating degenerative diseases of the brain are currently being studied ferociously. They are expected to affect 35% of the European population, and Drosophila has once again come to the aid, being used in Alzheimer’s, Parkinson’s, Huntington’s, and prion disease studies. Scientists use them to study disease genetics, pathogenesis (how the disease progresses), and pathophysiology (how the disease alters normal body function). Exciting also, is the testing of new drugs which could prove useful in treating people with these debilitating diseases.

The prion diseases (also called transmissible spongiform encephalopathies, because of the spongy appearance they cause in affected brains) are a group of invariably fatal neurodegenerative diseases, including ‘mad cow disease’, Scrapie and variant Creutzfeldt-Jakob Disease (vCJD). Recently a research group developed the first Drosophila model of prion disease, using Scrapie (the sheep version of the disease) as a prototype for studying prion diseases.

Spongiform change in the brain.  The holes in the brain are characteristic of prion diseases like mad cow disease.

Spongiform change in the brain. The holes in the brain are characteristic of prion diseases like mad cow disease.

Drosophila don’t actually have the prion protein, a normal cellular protein of mammals which misfolds and accumulates in the brain of animals with prion disease, so first the gene had to be introduced into the flies. This was achieved and various experiments were undertaken to ensure the presence of this normal protein would not cause disease in the flies. Once satisfied, the flies could be fed the misfolded prion protein, believed to be the infectious agent in the prion diseases, to see if the disease could be mimicked in the flies.

Amazingly, the flies did show signs of neurological disease after being exposed to diseased sheep brain! The prion diseases cause ataxia in mammals – the inability to move in a coordinated fashion. The flies were having difficulty moving, and died younger, as the misfolded prion protein in their food caused the prion protein their cells to misfold too. But that was not all. The misfolded prion protein within these flies could be transmitted from one fly to another – similar to the way natural infection occurs in mammals.

Suddenly, the experiments could occur in a matter of weeks. The acceleration in data collection should mean this mysterious disease, thought to be caused by proteins rather than a virus, bacterium, fungus or parasite, could see the mechanism of protein misfolding revealed in the near future.

Luckily the incidence of mad cow disease has dropped significantly since the changes in the food chain introduced in the 1990’s. However, the way in which prion protein misfolds and causes further normal prion protein to misfold, is very similar to a number of other diseases. Notably, Alzheimer’s, Parkinson’s and Huntigton’s diseases. Elucidating the mechanism of protein misfolding could see drugs developed to halt this misfolding, thereby stopping the progression of these horrendous diseases.

Next time the fruit fly is encircling me and my wine, I think I’ll raise a glass to this heroic little critter and to the scientists devoted to revolutionising the way we study disease and reducing the number of animals in research.

 

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Special interest

We need to talk about Kev-lar

Reading the newspaper this weekend, I was sad to learn that Stephanie Kwolek, inventor of Kevlar, died recently. Kevlar is best known for making body armour, but it’s also used in heat-protection gear, helicopter blades, bike tyres, ping pong bats, bowstrings, boat sails, tennis raquets, musical instruments, fire dancing props, frying pans, ropes, optical fibre cables, F1 racing cars, building construction, brake pads, rubber hoses, CERN particle physics experiments, wind and tidal turbines, and smartphones. Because it is such a ubiquitous product, I was surprised that one person was responsible for its invention, and that Kevlar has only been around since 1975.

We use Kevlar everyday; woven into gloves to protect our hands in post-mortems from over-enthusiastic scalpeling. (The idea of ‘bulletproof gloves’ is quite exciting when encountered for the first time, and therefore must always be accompanied with the disclaimer: “These gloves are glance-proof not stab-proof. They are designed for glancing blows ONLY. Please DO NOT stab yourself in the hand as an experiment.” Nevertheless, there’s always one…). You wouldn’t think Kevlar gloves would be so necessary (after all, how difficult is it to keep track of a blade?) but there are always a disconcertingly large number of slices out of the latex over-gloves by the end of a PM.

1965_A_StephanieKwolek_Detail_Vertical_630x815

So to Stephanie Kwolek, with our unscarred hands we salute you.

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Yeeeeeeaaaaaahhhh!

A day in the life of a Veterinary Forensic Pathologist!

Everything I think of is already a thing

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Exactly what Veterinary Forensic Pathology is like.

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Cross eyed

Disclaimer: This blog is for educational purposes and please be warned that this blog contains pictures from real animal post mortems and graphic descriptions of disease.

Did you know that eyes just are outgrowths of the brain? They develop from cups of cells sitting on the forebrain. Most of the eye acts like a camera by focusing light onto the retina – the light sensitive layer of brain cells at the back of the eye. Signals from the retina travel up the optic nerve, which leaves the back of the eye and goes to the brain. If there is a problem with vision, we can work out where the damage is, by knowing the pathway the signals take. What’s interesting is that the optic nerves meet and ‘cross over’, to the opposite side of the brain.

The white X is the optic chiasm, where optic nerves from the eyes (right side of pic) 'cross over' to the opposite side of the brain.

The white X is the optic chiasm, where optic nerves from the eyes (right side of pic) ‘cross over’ to the opposite side of the brain.

The percentage of nerve fibres within each optic nerve that cross over depends on the species. In most fish, amphibians, reptiles and birds, 100% of fibres cross over, meaning that all vision from the left eye is processed by the right side of the brain and vice-versa. In other animals, there is a more even split of crossed and uncrossed nerve fibres so that each side of the brain receives signals from both eyes. This allows images from both eyes to be combined, giving us creatures with forward-facing eyes stereoscopic 3D vision with better depth perception.

There is even an animal that starts out with the nerves completely crossed, but later on ends up with split crossed and uncrossed nerves…

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