A Wander in Vetland by John Hicks

Author:John Hicks
Language: eng
Format: epub
Tags: pets, farm, humour, farm animals, medical history, animal tales, veterinary stories, veterinary history
Publisher: John Hicks

Chapter Fifteen

Holes in the Head: Windows to the Soul

Such is the human race. Often it does seem such a pity that Noah and his party did not miss the boat. – Mark Twain

One of the life forms on board with Noah must have been Coenurus cerebralis, perhaps developing in the brain of one of his sheep. The name does not explain that Coenurus is the larval cyst, in sheep, of a tapeworm called Taenia multiceps – which infects dogs. The two names bear no resemblance because when they were named, the connection was not realised. The eggs of this tapeworm pass out in dogs’ faeces which, when disintegrated and dried, can be blown by the wind for miles. The eggs hatch into larvae in the intestines of sheep which have had the misfortune to ingest pasture contaminated with them. Eventually the larvae travel through the blood and take up residence in the spinal cord or, classically, the brain (hence cerebralis), where the cyst grows. The life cycle of the parasite is completed when another dog eats the cyst in the carcase of the sheep.

There are other tapeworm species which share similar dog-to-sheep lifecycles. Echinococcus granulosus is perhaps the most infamous of these. Its larval forms can develop into massive hydatid cysts in the abdominal cavity. Here there is space for them to grow into sacs containing many litres of fluid. Unfortunately, they can infect people as well as sheep and have caused many deaths and untold misery throughout history. Hydatid disease has been all but eradicated in New Zealand, but only after many years of concerted effort.

It has not been recorded how Noah elected to perpetuate all these nasty tapeworms. He had several options with these multi-host parasites: via sheep infected with larval cysts, via tapeworm infested dogs or by separating the tapeworm eggs from the dog faeces and storing them. Tapeworm eggs are extremely durable and resistant to desiccation, so the latter would have been the most pragmatic solution, especially with space on board at such a premium. No matter which, humanity has no cause to celebrate the success of his efforts.

The expanding Coenurus cyst causes a variety of signs in affected sheep because the brain tissue surrounding it is slowly compressed within the bony confines of the skull. These include head tilting, walking in circles, or head pressing – where the animal presses its head hard against a wall or a post. The common name for these afflictions is “gid”. If the cyst is close to the surface of the brain, the overlying bone is sometimes softened, especially in young animals.

A very valuable and strapping young Suffolk ram was brought into the Liverpool University Veterinary hospital. He was circling. What a gift for tutors trying to expand our clinical thinking!

“OK Miss Coster, if he’s circling anticlockwise, which hemisphere of the brain do you expect to be affected?”...

“And if he was blind, in which eye would you expect impaired vision?”...

“How would you check a ram’s eyesight? You can’t exactly

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.