Archive for February, 2012

A Border Collie resting during a game of fetch.

Image via Wikipedia

Animals like dogs use panting, rather than sweating, as their main method of reducing their body temperature.
Panting is not the same as fast breathing as panting is very shallow – very little air is taken into the gas-exchange parts of the lungs during panting.

So how does panting work to reduce body temperature?

  • The dog dilates the blood vessels to the tongue and increases its heart rate – this ensures that warm blood is pumped away from the body core and arrives at the surface of the tongue.
  • The tongue is made flatter and thinner to increase it’s surface area.
  • The tongue is moist as it has a layer of saliva (not sweat!) on its surface.
  • Air is passed quickly backwards and forwards over the surface of the tongue and, in the process, the moisture (saliva) begins to evaporate.
  • Evaporating moisture has a cooling effect, it carries the heat from the blood vessels in the tongue into the air.
  • This leaves behind cooler blood in the capillaries of the tongue which is then carried back into the body to reduce the core temperature.
The linings of the body cavities are named.
  • Lining the cranial cavity and spinal cavity are the protective membranes known as the meninges.
    Inflammation of the meninges is known as meningitis.
  • Lining the abdomen (belly) is a membrane known as the peritoneum.
    Inflammation of the peritoneum is known as peritonitis.
  • Lining the thorax (chest) is a membrane known as the pleura.
    This does not follow the usual naming conventions as inflammation of the pleura is known as pleurisy (although pleuritis is sometime heard).
Compassion in World Farming's founder Peter Roberts

Compassion in World Farming's founder Peter Roberts

The ‘Five Freedoms’ of Animal Welfare are a set of ideal standards for Animal Welfare rather than a piece of law.

They were originally developed as part of a UK government report into farm animal welfare in the early 1960s.  They have since been adopted for all aspects of animal welfare by many governments and organisations around the world.

As well as looking at the titles of the ‘freedoms’, it is important to understand their meaning:

  • Freedom from Hunger and Thirst
    This freedom relates to provision of fresh water as well as a diet to maintain full health and vigour.
    If you provide an animal with food but it is not the correct food to provide for the animal’s needs you are failing to meet this freedom.
    You may also be failing to meet this freedom if you provide food which makes an animal obese as you are failing to provide a diet which maintains full health and vigour.
  • Freedom from Discomfort
    This freedom is concerned with providing an appropriate environment, shelter and resting area.
    It is more concerned with provision of appropriate accommodation than with discomfort caused by disease or injury (which is covered by a different freedom).  If an animal does not have secure shelter from rain, wind or bad weather or has no bedding (or the wrong kind of bedding or substrate), the person responsible for this animal is failing to comply with this freedom
  • Freedom from Pain, Injury and Disease
    Complying with this freedom ensures that pain, disease or injury are prevented or that if they are not preventable, that any pain, disease or injury is quickly diagnosed and treated.
    It is important to realise that is not against welfare standards for a person to be responsible for an animal which is in pain or ill. If you are responsible for an animal, however, and it is in pain (or injured or suffering from a disease) and you choose to ignore it and fail to seek treatment then you are neglecting the welfare of this animal (and therefore breaking the law).
  • Freedom to Express Normal Behaviour
    This freedom points to the provision of sufficient space, proper facilities and, where appropriate, company of the animal’s own kind.
    These areas are concerned with allowing an animal to exhibit behaviours which are as close as possible to those it would exhibit in the wild.
  • Freedom from Fear and Distress
    This freedom concerns itself with removing circumstances which would bring about mental suffering.
    It could cover, for example, issues such as keeping prey animals in full view of predator species, subjecting an animal to an unreasonable workload or treating an animal cruelly that it became fearful.

Although, in itself, not a piece of law, the following extract from the Animal Health and Welfare (Scotland) Act, 2006 shows how strongly Scottish welfare legislation draws on these standards:

Section 24 – Ensuring welfare of animals

1) A person commits an offence if the person does not take such steps as are reasonable in the circumstances to ensure that the needs of an animal for which the person is responsible are met to the extent required by good practice.

3) For the purposes of subsection (1), an animal’s needs include—

(a) its need for a suitable environment,
(b) its need for a suitable diet,
(c) its need to be able to exhibit normal behaviour patterns,
(d) any need it has to be housed with, or apart from, other animals,
(e) its need to be protected from suffering, injury and disease. 

The Canine HeartRemembering the names of the valves of the heart can be difficult – especially trying to remember which valve goes on which side.
You may have heard names like Tricuspid Valve and Bicuspid Valve or even Mitral Valve.

There’s an easier way of naming the valves, however, where the names actually tell you about their position:
Between each Atrium and Ventricle is a valve, which is there to stop blood flowing in the wrong direction.  If you use the name Atrio-Ventricular Valve or A-V Valve, the name tells you that the valve is between the Atrium and Ventricle.  To make sure everyone knows which side you’re talking about, you should use the names Left Atrio-Ventricular Valve or Right Atrio-Ventricular Valve.

One of the main problems with diarrhoea is that it’s so bloomin’ difficult to spell.
If you have trouble remembering how to spell ‘Diarrhoea’, remember this handy phrase:

Dashing – In – ARush? – Really – Hurry – Or – Else – Accident.

Manga Boy

The first thing you have to get used to when you see a diagram of the heart (or any other organ) is that they always seem to be ‘back to front’.  When you see a picture of the heart, the left is always on the right and the right is always on the left.  This is simply because that’s how you would look at someone’s heart if you could look into their chest (or if you had ‘x-ray vision’!).  If you’re struggling with this idea, look at your friend’s face and you’ll see that their left ear is on your right and their right ear is on your left.

Heart Chambers

In mammals, the heart is divided into four chambers with two chambers on the left side and two chambers on the right side.  Between the left and right sides of the heart is a wall of muscle called the ‘septum’.

These four chambers have names and that’s the next thing you’ll have to learn.
The same chambers are found on both the left and right side, so you only have two new words to learn which are Atrium and Ventricle.

At the top left of your diagram you’ll see the Right Atrium and underneath it, you’ll see the Right Ventricle.  At the top right of your diagram you’ll see the the Left Atrium and under it, the Left Ventricle.

Do remember, it’s only back-to-front on the diagram, the dog’s right ventricle really is on the right side of its heart!

A final tip to help you remember to put the Atrium at the top and the Ventricle at the bottom is to make sure you write the name with a capital letter, draw a line from top to bottom through the first letter of each name and follow the direction of the arrows you’ve just created.

Atria at the Top, Ventricles at the Bottom

Kidney & Adrenal GlandCortex and Medulla are words which pop up all over the subject of anatomy.  The cortex is always the bit around the outside of a structure and the medulla is always the bit in the middle.

Examples include:

The Renal Cortex – the bit around the outside of the kidney
The Adrenal Cortex – the bit around the outside of the adrenal gland
The Cortex of bones (also known as Cortical Bone) – the thick dense bone tissue around the outside of bones
The Cerebral Cortex – the bit around the outside of the brain

Long Bone SectionThe Renal Medulla – the bit on the inside of the kidneys
The Adrenal Medulla – the bit on the inside of the adrenal gland
The Medulla of bones (also known as the medullary cavity) – the space in the middle of a long bone where the bone marrow is found

Use the similar sounds of the words MEDULLA and MIDDLE to help you remember!