Temperature-Sensitive Genes

After reading ‘Cat Sense’ by John Bradshaw, I wanted to find out more about interactions between genes and the environment. Bradshaw mentioned that the darker patches of fur on the face, paws, ears and tail of Siamese cats are caused by a temperature sensitive mutation which causes the hairs to be darker the colder the temperature. This means that when Siamese kittens are first born they are white all over because their mother’s womb is uniformly warm. However, as they grow, the coolest parts of their bodies – the extremities including face, paws, ears and tail – become darker in colour. Furthermore, cats living near the equator or in very warm houses tend to be lighter than those living in cooler climates.

The colour of a Siamese cat has been compared to oculocutaneous albinism in humans which causes white skin, very pale hair and light-coloured irises. In humans, oculocutaneous albinism is the result of a genetic change producing a
temperature-sensitive tyrosinase polypeptide. This protein’s enzymatic activity is reduced even at 31°C and is almost abolished at 37°C. Tyrosinase is the enzyme that catalyzes the production of melanin. Therefore, the higher the temperature, the less enzyme activity and the less melanin produced, resulting in albinism. It is thought that a very similar phenomenon is happening in cats, where enzymes are directly affected by their surrounding temperature are controlling the fur colour.

 

References:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC329910/

http://en.wikipedia.org/wiki/Tyrosinase

RSPCA Ashford Garden Cattery

For the past year, I have been volunteering regularly at my local RSPCA Cattery in Ashford. Having had very limited experience handling and working with cats previously, I was keen to get involved. The RSPCA is a fantastic charity and the work they do invaluable. From the very first day I volunteered – 20th August 2013 – I have been amazed at the overwhelming number of cats cared for and rehomed through the cattery. There have been court cases and strays, as well as dearly loved pets who cannot be looked after any longer because of changing circumstances or owners’ ill health. They really need and appreciate their volunteers and as a result, we all love what we do for them.

Every morning at the cattery, volunteers come in at 8.30 to clean all the pens. This involves scooping out litter trays, brushing hair out of blankets and wiping down surfaces before sweeping then mopping the floor of each pen. With a small team of volunteers working alongside the staff, all the pens are clean by 10.30, ready for the cattery to open to the public at 11.00. During the day, other volunteers come in to help in the garden or socialise the cats. Socialising is great fun and involves letting the cats out to play with each other and get used to human company, ready for when they are rehomed. However, in everything we do, we have to be very careful. Every cat must be regarded as an individual. Some cats are not allowed to interact with other cats because of suspected illness so it is important that we do act as carriers of potential disease. Therefore, we always have to wash our hands regularly. Furthermore, it is our responsibility to respond to the cats’ behaviour. If they hiss or refuse to move, it would be wrong to try and force them to come out and socialise, for it could result in scratches or bites.

On a Wednesday, the cattery is shut to the public and the vet comes in to check up on the cats. I have been around to observe this several times. Very often the problem is fleas, in which case the cat(s) are put in quarantine to prevent the fleas invading the entire cattery. However, I have also seen several cases of feline herpes virus. One in particular was very interesting because to test for the virus, the vet used fluorescein in its eye. This highlighted an amazing ulcer which looked like a river with tributaries spreading out from it. Luckily, herpes is not a huge problem for the cattery because although it affects the individual cat, all the other cats are routinely vaccinated against it.

During the past year, I have been regularly going to the cattery for 1 1/2 hours every other Wednesday afternoon. My main job is to rinse all the scoops and brushes which have been left to soak for their weekly disinfect. I then put all the scoops and brushes back into the pens, giving me the chance to see and interact with the cats. Very often there are kittens which I play with, observing how they develop hunting techniques through this playing. Recently, I spent a lot of time with several very shy cats. They had been confiscated from their owners by the RSPCA due to neglect, leading to a court case. Their ears were very tatty and initially I thought it was because they had been in fights resulting in the rips and tears – one of the cat’s barely had any outer ear remaining. However, after asking one of the staff, I was told that this damage was all due to ear mites. Therefore, each one of the six cats in the household had suffered with it. This made it clear why the RSPCA had taken action.

In total I have now spent about 40 hours at the garden cattery, which consists of cleaning, socialising cats and generally helping out, it even includes an early morning clean on Boxing Day when they were short of volunteers. Over the coming year, I am going to be spending several hours cleaning every other Wednesday morning. Despite having a few scratches, I love working at the cattery and have learnt so much about cats and the people who choose to abuse them or love them.

Hiccups

After reading ‘Your Inner Fish’ by Neil Shubin, I wanted to find out more about hiccups. A lot is still unknown about them, however, Shubin suggested a phylogenetic hypothesis.
Hiccups are caused by a disruption to the ventilatory central pattern generator resulting in a spasm in the diaphragm causing a sharp inspiration of air pulling the epiglottis shut, creating the ‘hic’ sound which characterises hiccups.

Although hiccups are only found in mammals, a link has been found to amphibians. Tadpoles are bimodal breathers because they have both lungs and gills. Therefore, they exhibit a motor pattern during gill ventilation, similar to that causing hiccups. Tadpoles gulp water allowing it to wash over their gills, however to do so without the water filling their lungs as well, their glottis has to snap shut immediately after inspiration. Further evidence shows that both hiccups and amphibian gulping can be stopped when the concentration of inhaled air is increased.

Although this seems like good evidence, it is very hard to prove phylogenetic connections. Other reasons for hiccups which have been suggested include to clear air from the stomach of a suckling infant to allow room for more milk. The air bubble could stimulate the contraction of the stomach and oesophagus, triggering the hiccup which creates suction in the chest, pulling the air from the stomach up and out. This is supported by the observation that hiccups are more common in infants.

Sometimes, hiccups can also be caused by infections such as pneumonia or nerve damage.

References:
http://onlinelibrary.wiley.com/doi/10.1002/bies.10224/abstract
http://en.wikipedia.org/wiki/Hiccup#Phylogenetic_hypothesis

Ticks

A couple of years ago, I looked after a hedgehog during the winter because when we found it it would have been too small to survive hibernation. During this time we fed it lots and it grew big and fat by spring. However, during this time Twix the hedgehog got some ticks. We read in the St Tiggywinkles Animal Care book that ticks should be left and they will fall off eventually. So this is what we did and after some time, the ticks fell off and we never thought twice about them.

But, a few months ago, my dog got a tick. At first we were unsure of what to do, however we assumed that this case would be very similar to the hedgehog one, although the tick was a lot smaller and looked very different. But after leaving it for a few days we could see no progress from my careful monitoring, so we looked to the internet. Reading on lots of sites various methods to remove ticks, we thought we had better try something. Action was provoked when, the same evening as we were doing research, I looked to Simba and saw that his nose was covered in blood. Quickly assessing, I realised that this must have been caused by the tick. Looking back on it now, I think that he must have brushed against something or scratched himself, causing the tick to detach slightly from his skin. As I cleaned up his nose with antiseptic to get a better look, we resorted to the most convenient and quickest option we had read. This was to apply alcohol. Apparently, covering the tick in alcohol paralyses it and therefore loosens its jaw and causes it to fall off. Dabbing on some whisky, the parasite immediately fell off on the cotton bud leaving Simba fit, healthy and unaffected.

But the tick problem came back to haunt us. When on holiday in August in North Yorkshire with Simba, I was brushing him when I came across a burr stuck in his fur. This is not an unusual occurance for Simba, as he loves to dig around in the bushes. However, on closer inspection, I saw that this burr was not going to be pulled out easily. In fact, it was another tick. After having spent time on work experience at Kingsnorth Vets, I had seen a tick remover being used for the obvious purpose of removing ticks. Now I knew that alcohol was probably not the best option, and so we went in search of a pet shop. Here we bought a tick remover in two different sizes and removed the nuisance with a quick twist. Problem solved.

Tick Remover

But what is a tick?

From my experience, ticks are very interesting creatures. They are parasites and attach themselves to animals (including humans) to drink blood until they have had their fill so drop off.

On looking further into it, I have discovered that they are in the arachnid family, hence the eight legs, in the order Ixodida (leach). They can also carry a number of diseases.

What especially interests me at the moment, is the significant difference I was able to observe between the ticks on the hedgehog and those on Simba. This must be down to species.

 

Classification of the Tick

This shows the classification of the tick, of which there are three families. The family nuttalliellidae only contains one species. This is found in Southern Africa so is of no significance to me. There are also hard ticks and soft ticks, hard being the most common.

But whatever the tick, there is always a prominent risk of infection from them. It is made especially bad because ticks often carry multiple pathogens, all of which can be passed into the body if the tick is not removed as quickly as possible. The most well known one of these is Lyme Disease which is caused by at least three species of bacteria. However, other illnesses include carried by bacteria, viruses and toxins which can pass into the body. Although most of these diseases are not life threatening to an animal, it is very important to remove ticks from pets as quickly as possible. This is the best form of prevention and although ticks are strange, yet fascinating creatures, they should not be allowed to accompany one’s for any longer than necessary.

References

http://en.wikipedia.org/wiki/Tick

http://www.dartmoorcam.co.uk/dartmoortickwatch/photos/photos.htm

The Ethiopian Wolf

This summer, I am going on an expedition to Ethiopia with my school. So when I came across an article on the Ethiopian Wolf in the BBC Wildlife magazine, I was especially interested.

Ethiopian wolves are the world’s rarest dog and their numbers are rapidly declining, with a prediction of less than 450 individuals remaining in the wild. This is because of other dogs who came to the highlands of Ethiopia with the human population. These dogs are semi-feral and are often left to their own devices to run wild. Because of this, they hunt the same rodent food as the Ethiopian wolves, leaving the wolves in danger of not getting enough food for themselves or their families. Although this may sound concerning, a greater worry is the diseases the dogs bring. These diseases can easily pass to the wolves through contact with infected dogs or even dead infected animals and these can then pass to the entire wolf pack. The most prominent of these are rabies and canine distemper virus (CDV).

Everyone has heard of rabies. It is that disease which is carried by dogs and fatal. I remember reading the ‘Roman Mysteries’ books by Caroline Lawrence when I was younger and I remember when I first came across this terrifying disease in the first book, ‘The Thieves of Ostia’. Although this is only a children’s book, it is based on underlying fact. According to it, rabies ’causes fatal hydrophobia’ – the fear of water.
When looking at some more scientific resources, rabies is in fact a virus. It is neurotropic, meaning that it preferentially infects nerve cells. This of course leads the disease to damage the central nervous system. To get to the CVN the rabies can travel from the wound in which it has entered, along the neural pathways extremely quickly. This, as well as the binding to an interferon antagonist (http://en.wikipedia.org/wiki/Interferon) protein helps to decrease the immune response. Having entered the CVN, the rest of the body is promptly infected, leading to symptoms starting with behavioural changes, then hyper-reactivity and madness, then paralysis because of damaged motor neurones, and finally death by respiratory arrest.
This rapid infection and almost immediate death can be obviously seen as a huge risk to any population, especially one as rare as the Ethiopian wolves.

I have also come acroos Canine Distemper Virus and I know that this, unlike rabies, is a problem in the UK. As its name suggests, this is also a viral infection and most commonly affects dogs and ferrets. I can immediately see the risk this must be to any animal, as it is spread through aerosol droplets, rather than open wounds. This means that it can be caught through a dog simply sniffing infected urine, faeces or drinking from water which contains the contaminated fluid. Once in the body, CDV initially replicates in the tissues of the respiratory tract, before progressing into the blood stream to infect many other cells, including those of the central nervous system. It also suppresses the immune system by decreasing the tissue responsible for producng antibodies (lymphoid depletion), this results in a high risk of secondary infections. The suffering of an infected animal is most prominent in gastrointestinal and respiratory symptoms like diarrhea and laboured breathing. But more seriously, neurological symptoms can arise which are likely to be life threatening.
In England, symptoms such as these can be readily identified and efforts can be made to treat the dog, but for a wild, such as the Ethiopian Wolf, there is little chance of survival.

After looking into these diseases, I have realised the threat human settlement poses to the Ethiopian Wolf, and the need for us to change the direction this population is taking and ensure that sufficient vaccination programmes take place. Rabies has been eradicated in the UK due the success of vaccination; could vaccination offer the same hope for Ethiopia and the stunning wolves that live here?

References

http://en.wikipedia.org/wiki/Rabies_virus

http://en.wikipedia.org/wiki/Rabies

http://en.wikipedia.org/wiki/Canine_distemper

http://www.ethiopianwolfproject.com/