A wonderful bird is the pelican, his bill will hold more than his belican

A wonderful bird is the pelican,
His bill will hold more than his belican,
He can take in his beak
Enough food for a week
But I’m damned if I see how the helican
Dixon Lanier Merritt (1879–1972)


This handsome chap had to be put to sleep after a wound failed to heal on his abdomen.  Dixon was correct in his limerick; we found his beak was 10 litres in volume, compared to the one litre volume of his stomach.

His abdominal wound was too large to close with stitches, so a dressing was used to see if the wound would contract by itself.  Unfortunately it appears the skin became infected, so it was decided euthanasia was the kindest thing to do in his case.

The wound on his abdomen was infected and failed to heal, despite attempts to treat the infection

The wound on his abdomen was infected and failed to heal, despite attempts to treat the infection


Contagious Cancer; Transmissible Venereal Tumour (TVT)

Cancer and infectious diseases frequently appear in the news.  This is probably because they scare us, with headlines featuring news of outbreaks of infectious diseases, or suspected causes of cancer.  Similarly, there is much interest in developments of better methods of diagnosis, treatment, prevention and eradication.

But imagine if there was a cancer which was infectious.  We’re not talking about viruses or bacteria which may lead to the development of tumours (like human papilloma virus in cervical cancer, and helicobacter in stomach cancer).  But if the tumour cells themselves were contagious…

Unfortunately there are four known types of transmissible tumour in animals.  Transmissible venereal tumour (TVT) in dogs is the feature of this blog post.  The others are a tumour of Tasmanian devils (Devil facial tumour disease), a tumour of Syrian hamsters spread by mosquito bites, and a form of leukaemia in soft-shelled clams.

We recently had a case of suspected TVT in a dog.  The dog presented with a mass on it’s penis, from which a smear was made and examined (cytology).  The mass was removed and slides prepared for microscopic examination (histopathology) which confirmed that it was TVT.

TVT cytology x400

Microscopic appearance of TVT

Microscopic appearance of TVT

It is thought that the tumour cells originate from a type of cell called a histiocyte.  One of the reasons we know these tumours don’t arise from the dog’s own cells is that the tumour cells have fewer chromosomes (less than the 78 normally in a dog), and the chromosomes have a different appearance to dog chromosomes.  It has also been shown experimentally that the tumour can be transmitted from one dog to another, and even to other canine species, such as foxes.

The tumour spreads between animals during copulation, licking, biting or other contact with infected animals.  The tumour may spontaneously regress, if a sufficient immune response occurs, or the animal can be treated with surgery, chemotherapy and/or radiotherapy.

Parasites, What's this?

What’s this? #10 Bot fly larvae

Horse bot flies have a life cycle which is not very pleasant for the poor horse. The adult fly will lay her eggs on the hairs of the horse’s front-half (front legs, chest, shoulders and sides). After the first stage of the larvae has formed within the egg, the action of licking at the area by the horse prompts them to emerge. These larvae will then migrate to the mouth, or enter the mouth during licking, and embed themselves in the horse’s tongue. They sit in the soft tissues of the mouth for about a month before they moult into their second stage. They then crawl into the stomach and attach to the lining where they complete their growth and moulting into the third larval stage. They stay here for about a year, before detaching and passing out with the manure, where they will pupate and then hatch as adult flies a few weeks later…

When the stomach was opened the larvae crawled away and re-attached to the cut surface of the oeseophags!

When the stomach was opened the larvae crawled away and re-attached to the cut surface of the oesophagus!

Whilst they are migrating through the horse’s body they can cause irritation of the mouth and gastrointestinal tract. In large enough numbers they may even cause a blockage. Stomach ulcers, stomach rupture, oesophageal paralysis, and even tumours may result from the long standing infestation by these critters.

Rows of spines distinguish these as Bot fly larvae.  Well done to all those who guessed correctly!

Rows of spines distinguish these as Bot fly larvae. Well done to all those who guessed correctly!

Parasites, What's this?

What’s this? #10

Do you know what these creepy fellows are?  Bonus points if you know the species and organ they are found on…

Who are they and what are they eating?!

Who are they and what are they eating?!


The long lens of the law

We already use microbiology routinely in forensic pathology for identifying potential organisms which could be causing a disease or infecting a wound.  However work in recent years looks like it might be adding some more roles for the microbiologist in forensic investigations.

Bacteria are grown in labs to allow identification of the species.

Bacteria are grown in labs to allow identification of the species (Image from Wikimedia)

Forensic microbiology is an exciting area of research at the moment, including uses in forensic identification, tracking the interaction of people with their environment, and even deducing time since death in cadavers.

The bacteria which live on healthy individuals is called the human microbiome, and is similar between all humans.  However, it is the differences between individuals which has attracted the attention of some pioneering microbiologists.  The Human Microbiome Project is attempting to answer some basic questions about our microbiome (Blaser 2010):

  1. Which species of microbe inhabit humans?
  2. What are the microbes doing?
  3. How is the immune system responding to these microbes?
  4. What are the forces maintaining the balance between microbe and human?
  5. What are the unique characteristics between humans?

A group from Washington University School of Medicine (Fierer et al 2010) has shown that you can identify individuals based on the unique population of bacteria inhabiting their skin.  Not only that, but you can compare the population on their skin to the population on an inanimate object, such as your computer keyboard and mouse to identify who used it!

E coli

E coli (Image from Wikimedia)

Another group has shown that cell phones share the microbiome of their human owners (Meadow et al 2014) and Simon Lax (2014 and 2015) has shown you can link the bacterial population on people’s shoes  and the floor to work out where people have been…

Particularly exciting to pathologists is the potential to use the change in bacterial population on a dead body over time to estimate the time since death.  More work is required in this area, but the results from Jessica Metcalf at the University of Colorado at Boulder looking at mice are promising.

Of course, there are limitations to these applications which need more work, such as the effect of antibiotics and cleaning products which may be present in the person, cadaver or environment which could confuse results.

References and further reading:

Blaser MJ. Harnessing the power of the human microbiome. PNAS 2010;107:6125-6126.

Fierer N, Lauber CL, Zhou N, McDonald D, Costello EK, and Knight R. Forensic identification using skin bacterial communities. PNAS 2010;107:6477-6481.

Metcalf JL, Parfrey LW, Gonzalez A, et al. A microbial clock provides an accurate estimate of the postmortem interval in a mouse model system. eLife 2013;2:e01104.

Meadow JF, Altrichter AE, and Green JL. Mobile phones carry the personal microbiome of their owners. PeerJ 2014;2:e447.

Lax S, Smith DP, Hampton-Marcell J, et al. Longitudinal analysis of microbial interaction between humans and the indoor environment. Science 2014;345:1048-1052.

Lax S, Hampton-Marcell JT, Gibbons SM, et al. Forensic analysis of the microbiome of phones and shoes. Microbiome 2015;3:21.


Special interest

2014 in review – hopefully an exciting 2015 to follow!

The 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.

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