Cat purring is like people talking with a vocal fry

I'll try and explain the title. The human vocal fry is vocalising in a deep, creaky, breathy voice. I think you hear it quite a lot in advertisements when a man speaks in a vocal fry register to compel people to be attracted to a product.

And it may surprise people to know that a recent study which I believe has been peer-reviewed but which requires follow-up studies, indicates that when a cat purrs it's a simple case of an airflow passing over connective tissue masses within the larynx of the cat. Human vocal fry requires a shortening of the vocal cords.

The study researchers compressed the larynx slightly and then passed air through it and they produced a purring sound. How did they achieve this? They received the consent of owners of cats who had been euthanised because of chronic illness. And they surgically removed the larynxes of the disease cats. They were then able to pass an airflow through the larynx having, I believe, restricted it slightly.

The point is this: it was a very simple test. It only required an airflow going over these tissue masses inside the larynx to create the sound. This is a very low rumbling sound as we know made by animals much larger than the domestic cat. It is therefore a very specialist sound.

It registers with a frequency in between 20-30 Hz as I recall. The study is called: "Domestic cat larynges can produce purring frequencies without neural input."

The referencing the title to "neural input" means that the brain doesn't have to send signals to the throat to constricted and then release it many times a minute which is what the experts originally thought was the process of creating the purr. It was more or less universally thought that in order to create the purring sound the throat had to be constricted and then released rapidly through a nervous system signal. We now know that that isn't the case.

Although, the people who conducted the study say follow-up work would be useful, the lead researcher in the study, Christian Herbst, believes that it should shed some light on animal and human vocal communication. It shows that the cat converts aerodynamic energy which is the flow of air caused by breathing into acoustic energy via the "passive, cyclical oscillation of tissue".

In the early days, many experts were mystified by the domestic cat purr and some proposed that it was created through the flow of blood through the cat's main veins into the heart. When it was increased it caused turbulence and the sound of the turbulence were transmitted to the animal's chest and amplified by the diaphragm. A very complicated and entirely incorrect hypothesis as it happens.

An interesting aspect of the study is that we know that kittens purr while they are drinking their mother's milk. So, cats can purr and drink at the same time. I would like that to be explained to me. There must be a simple explanation for the ability of a cat to do that.

The last point to make is that cats purr when they breathe out and in, which creates this continuous sound.

Cat ate 38 hair ties and survived

NEWS AND COMMENT: As reported in The State, a cat was abandoned with other cats by their owner when they moved away. And this particular cat was very ill. She was brought to an animal shelter run by the Charleston Animal Society. It is located about 9 miles north-west of Charleston and is a No-kill shelter with a hospital which cares for around 20,000 animals annually.

UPDATE: THE CAT DIED. SIGH

Sick cat after operation to remove 38 hair ties from her stomach. Image: Charleston Animal Society from video (screenshot).

This cat was therefore fortunate to end up at this shelter where she stopped eating. They x-rayed her and found a massive blockage in her stomach. Her stomach was completely full of ties. A domestic cat's stomach is quite small at about the size of a ping pong ball I am told. How do you get 38 hair ties inside a stomach that size!? It must stretch a lot.

The blockage constituted 38 hair ties which she had obviously eaten as if they were edible foods when in the ownership of the people who abandoned her.

The veterinarian who did the operation was very surprised to see that number of hair ties in her stomach. The associate director of veterinary care at the Charleston Animal Society, Leigh Jamison, said: 

"I've never seen anything like that."

The animal hospital was so taken aback by the finding that they took time to photograph the ties and here they are below.

The 38 hair ties removed from the cat's stomach. Photo: Charleston Animal Society Charleston Animal Society

Fortunately, her intestine is were not damaged but the obstruction to her digestive tract caused fat to build up in her liver which resulted in a major health issue. She is currently being fed through a feeding tube.

They are keeping up her electrolytes to ensure that they are in balance and she is improving but she is not out of the woods yet, they report.

Comment: one doesn't want to criticise but for a cat owner to allow their cat to eat 38 hair ties and then abandon them is beyond careless. It is callous and cruel. The woman (presumed woman but it might have been a man) must have noticed her hair ties going missing. She must have seen her cat playing with the ties and eating them but did nothing about it.

And of course, it does bring to mind the dangers of hair ties and objects like them. Cats like to play with small, elastic objects. They are an ideal size as a cat toy. And as cat play is play-hunting, the end result is going to be eating the object if possible. And it is possible for a domestic cat eat a hair tie but of course they remain undigested in the stomach.

The obvious moral to the story is that a cat owner who uses her ties should make sure that they are not left lying around the floor or in any other place which is accessible to their cat. Obvious stuff. Nothing extraordinary in that statement (and it has been said a million times before) but if - as this person was - the owner is careless and doesn't care about the health and welfare of a cat you can end up killing your cat.

It seems purely fortuitous that this cat ended up at a cat shelter where there was an animal hospital attached. The story might well have ended completely differently and tragically but for that simple fact.

Here is a video which might or might not run! It may stop working. But if not great.

Can cats hear bats?

Can domestic cats allowed outside hear bats. The answer according to a specialist bat group in Essex, UK is that they can. They say that cats can hear most bats' calls. And it seems that because they are able to pick up their sounds they may sit on a wall or a roof beneath a bat roost and catch them when they emerge which will be between dusk and dawn.

The hearing range of the cat for sounds of 70 dB SPL extends from 48 Hz to 85 kHz. Bat calls can range from 9 kHz to 200 kHz. Humans can hear from 20 Hz to 15-20 kHz depending on age

The question in the title occurred to me because we know that domestic cats have an extended hearing range to a much higher frequency than that which is afforded humans. It therefore seemed natural to me that they might be able to hear the high frequency echolocation sounds emitted by bats.

Endangered bat attacked by cat in New Zealand but made a full recovery remarkably (being fed a grub). Image: Peter Drury.

This is another problem for bats because they are active at a time when indoor/outdoor domestic cats are also active.

Also, the kind of movements that bats make - quick and jerky - are the kind to which domestic cats are very responsive.

Therefore, cats attack bats as any other prey animal. Some people might not recognise this, but the Bat Conservation Trust in the UK say that bat carers estimate that over 30% of bats that they rescue have been attacked by cats and that only 14% of bats injured by cats are released.

Over half (56%) don't survive a cat attack while 30% cannot be returned to the wild.

New Zealand are particularly sensitive about their wildlife and predation by domestic and feral cats. There is a story on the stuff.co.nz website about a bat titled "Cat victim flies free after three months recovery at Hamilton Zoo".

A cat attacked a critically endangered, native long-tail bat. They say that the bat made a miraculous recovery.

"The bat had made a remarkable recovery from its injuries and had reached the point where it needed to be returned to a suitable natural environment to live out the rest of its life".

The bat was delivered to a veterinarian who contacted Hamilton Zoo where the bat could be treated. The membrane between the right leg and her tail was torn and they were concerned that it would not reattach and therefore that she would be unable to fly.

However, their concern appears to have been unfounded because through their special care in ensuring that the membrane recovered, and in allowing her fur to regrow (because she had been injured such that she had lost her fur over parts of her body), she was able to fly and be released.

The Bat Conservation Trust state that cats do not eat bats but like to play with them. And apparently, a small amount of cat saliva in a bat's blood stream can result in an infection requiring urgent treatment without which they are likely to die.

Once a cat has learned where bats roost, they can endanger the whole colony. People concerned with the conservation of bats would like cat owners to keep their indoor/outdoor cat indoors half an hour before sunset and kept in all night when bats are most active between April and October.

If owners are reluctant to do this, they can keep their cat in half an hour before sunset and keep him or her there for an hour after sunset.

Gluconeogenesis in cats

I'm referring to domestic cats and the process called gluconeogenesis. What is it? All animals including the domestic cat require glucose, which is a simple carbohydrate. It is essential in terms of the cat's metabolism and glucose fuels the brain. Cats do not appear to be able to tolerate a high-carbohydrate diet but they still need glucose. Because they are obligate carnivores, they don't get it from dietary sources of carbohydrate. And therefore, it is produced through the process called gluconeogenesis which is the metabolic process in which the cat produces glucose. The glucose is released into the bloodstream to be carried to the body's tissues. "Metabolic pathways in the liver and kidneys use other nutrients to produce glucose through a process called gluconeogenesis" - Linda P Case: The Cat. It's Behaviour Nutrition & Health. It is said that cats are in a constant state of gluconeogenesis because of their unique diet.

Breakdown of the word. 'Gluco' refers to glucose. 'Neo' refers to new and 'genesis' refers to the creation of something.

Picture of a domestic cat showing webbed feet

This is a great picture showing us that the domestic cat has webbed feet. Of course, it is a Sphynx cat which is hairless, which in turn allows us to see their toes more clearly. And what is readily apparent is the enormous amount of webbing between the toes. It couldn't be more obvious. And there is nothing to suggest that the hairless cat have more webbing than non-hairless cats. This is what you might expect for any domestic cat. So why do domestic cats have webbed feet? There can only be one reason which is that they evolved to be able to swim at least reasonably adequately in order to survive in the water and prey for animals in and around water.

Photo of Sphynx cat with webbed feet typical of all domestic cats. Photo in public domain.

There are, as you might know, some wild cat species which spend a lot of their time in and around water. One of these is the aptly named fishing cat. Another is the flat-headed cat. They are both small cats. The wild cat ancestor of the domestic cat is the North African Wildcat and this cat normally lives in quite arid scrub land which is why they are bad drinkers but no doubt they encounter moments when they have to wade into the water and swim, and through evolution over millennia, they ended up with webbed feet. That is the theory, those are my thoughts and they are based upon common sense.

How can cats jump so high?

Cats can jump high because their hind legs are made up of long levers and they are driven by fast-twitch fatiguing muscles. Long levers create speed. Think of those plastic devices in which you placed a tennis ball at one end which are used to throw the ball a long distance for your dog to chase. This plastic extension to your arm with a clamp at the end to hold a tennis ball extends the leverage of the arm. In extending the leverage the ball is thrown further and with less effort. Long levers increase the mechanical advantage.

Caracal jumping vertically. They are perhaps the best vertical jumper of all the cats. Photo: public domain.

As for the muscles, they mainly consist of fast-twitch fatiguing cells. These muscles propel cats to leap several times their own length in a single jump. They use up all their energy in that moment. These levers and fast twitch muscles also allow the domestic cat to reach impressive speeds of about 48 km/h or 30 mph, maximum. 

Running at speed is enhanced by the fact that the domestic cat has a floating shoulder. Unlike a human's collarbone which connects the shoulder and breastbone the domestic cat's vestigial clavicle floats and is only anchored by muscle. This allows a freedom of movement which lengthens the cat's stride and range of motion.

Cats need to be good jumpers because they like to be high up for safety. They live in a vertical world and many wild cat species like to climb trees. I guess you know all that. The leopard takes large prey items into trees which reminds us of this cat's enormous strength. The small margay lives in trees and has a double jointed ankle to allow them to hang onto branches like monkeys. Yes, the cat is a beautifully engineered predator and their muscles and levers maximise their jumping ability. Finally, the medium-sized wild cat species, the caracal can jump the highest of all cats and certainly relative to their size vertically from a standing start (see picture).

Cat With Emerald Eyes

The brightest emerald color cat eyes that I have seen. Sorry the picture quality is not great. It is a close up and the photographer, a veterinarian or vet tech, probably forgot that the camera could not focus that close.

I don't think it matters that much and it may even help as it throws into focus the unusual color of this cat's eyes.

This is a straight photograph. There is no post-editing of any kind as far as I am aware to enhance the colors. I added the pictures of the uncut emerald stone as reference and lightened the picture a fraction.

Grey cat emerald eyes. Photo Nottingham Vet School on Flickr

This cat was at a UK vet's clinic. I have no idea what he or she was in for. The fur color is grey (gray in the USA) and called "blue" in the cat fancy. The face is that of of blue British SH or Chartreux. But the cat might well be random bred. Anyway the Chartreux is rare and has copper/orange colored eyes under the standard. The eye color of the British SH is not set by the breed standard.

There it is; the cat with the emerald eyes. I'd like to know more about this cat because the eyes look a little unnatural if I am honest.

Picture of Cat's Ingrowing Claw

A very clear, clean picture of a cat's ingrowing claw. You can see how the claw has grown into the paw pad. Cats tend to tolerate this despite the discomfort. This can happen quite easily in cats that are inactive and/or full-time indoor cats. Older cats are particularly susceptible even if they do go outside because of a much reduced activity level. This means that the claw is not worn down naturally during use. The claws of a cat's polydactyl thumbs are sometimes not worn down as they are off the ground and need to be trimmed and not surgically removed, please.

The moral is to check a cat's claws from time to time and trim them when necessary. I realised that my old cat had a claw problem when I heard the claws clattering against a hard floor. This indicated to me that at least one claw was too long. A cat's claws retract and don't make contact with hard surfaces if the cat is walking normally over the surface. Teeth and claws need to be checked routinely!

You can see from this picture of a cat's ingrowing claw provided by Cuyahoga Falls Veterinary Clinic, how painful it is. It is not that difficult to trim a cat's nails but to trim the nail in the picture will be very difficult and probably or possibly requires a vet to do it. It's a bit late in the day - proactive is best.

Cat ingrowing claw (nail). Photo copyrightCuyahoga Falls Veterinary Clinic

This photo has been used with permission for teaching/educational purposes at this website.

Note: Never declaw a cat (see some declaw posters to see why). You don't need to. Evolution (or God depending on your point of view) gave a cat all his or her anatomy for a reason. It is wise and the decent thing to do, to leave it all in place. We shouldn't play god for our convenience.

Picture of a cat watching in silhouette

Original photo by Jo Jakeman - creative commons license

Domestic cats can spend endless hours in the dusk watching and waiting. The domestic cat likes to watch at dusk. They might be under a tree or on a roof, both places are safe. When prey arrives it will wait before pouncing. The attack has to have the highest probability of success. Cats have poor color vision and see less detail than humans but can see movement better and can see much better under dark conditions.

How can cats jump so high?

ANSWER: Because the cat has a combination of fast-acting muscles and a specialized skeleton. The cat's muscles consist mainly of "fast-twitch fatiguing" cells. They work fast but tire quickly. These powerful fast acting muscles give the cat the ability to jump to incredible heights relative to body size. The cat however has relatively few "fast-twitch fatigue resistant" muscles. The cat is a sprinter not an endurance runner.

The cat's skeleton has evolved for bursts of speed and agility. The spine is supple. The legs are slender and strong. The long limbs provide excellent leverage. Cats are digitigrades - walking on their toes. The "feet" are long adding to leverage. The longer limbed, more slender cats with long tails for balance are the better climbers. The margay is the top of its class. Below is a short video of Magic jumping. She is slender (less weight relative to size) with long limbs providing excellent leverage. Her father is a serval. The serval has the longest leg length to body size of all the cats, wild and domestic.

Long legged cat is a good jumper

sleeping cat
Originally uploaded by kyramas

This feral cat is a solid a white cat. He (I would say he is a he!) has very long legs and a long tail to match. He is actually quite high up on a window ledge.

I would say that he is a good jumper because he is skinny (low weight) and has good leverage with his leg length.

Cat jumping ability (and therefore take off velocity - TOV) depends on relative limb length, relative extensor muscle mass (the size of the leg muscles), body mass (is the cat overweght - this has significant negative impact) and the percentage of fast-twitch muscle fibers (some cats and people have the kind of muscles that can retract very fast making he leg move fast and thereby increasing take off speed).

Often feral cats are much thinner and lighter than domestic cats because domestic cats are over feed and ferals underfeed.

Timmy, a stray cat that I feed from time to time, is a typical muscular stray cat with a massive jump. He can effortlessly jump up about 7 feet to the top of a wall when he goes home (wherever that is). He has long limbs, is of a perfect weight and very athletic.

My girl cat is old and overweight and I have to lift her up to the bed (she calls me to do it).


Charlie
My three legged cat, Charlie, can jump up beautifully as he has long hind legs and a strong back but cannot jump down as he has lost his front right leg and the remaining leg cannot take the weight on landing. He wriggles half way down and drops sideways so that his rear legs hit the ground at the same time as his single front leg. He also likes to take up the meerkat positon. It comes naturally to him and he uses it frequently. This is unusual for a cat and it is due to his extra strong back muscles which in turn in due to he absent leg at the front! Here is the little fella:

Cat Allergies and Realities

The reality is that if you think that you have a cat allergy you may not. If you have an allergy it may not be the cat. If you love your cat and she loves you it would be a hell of a shame (for the cat :)) to part company on a mistake. Or, if you do have an allergy to cats you may have allergies to more than just a cat allergen so kissing your cat goodbye won't help.

First things first, find out what your allergic to. This can be done through a blood test I believe. Try and convince your doctor to do a thorough check of all the possible irritants - get the figures, the data before taking big steps.

Timmy the stray boy cat who has set up home here is the first cat to whom I am slightly allergic. I'm a bit shocked in fact. He makes me itch as if I've got dermatitis. But it won't stop me seeing him and I think it's starting to ease a bit. Perhaps I am adjusting to the allergen in his saliva.

If the tests establish that you are allergic to cats, the tests may also show that you are allergic to other things. You can take steps to minimize the allergic reaction to the other things. In doing this you reduce the number of allergens to the point where you have no or minimal symptoms.

In addition to allergy shots try these steps:

• vacuum more often using a vacuum cleaner that has a HEPA filter and try and wet wipe all surfaces and use a mask when vacuuming (pain the back side I know) - or get someone else to do it
  
• Some cats are better for people who are allergic to cats. The well know Allerca comes to mind and the siblings the Ashera GD and the Chakan GD. These cats though are for the rich as they are very pricey. There is also the Siberian and the Sphynx come to mind
  
• You might try and set up a cat free zone for a period of time in day to allow some relief from the cat allergen causing the allergy
• Bathe your cat frequently (every few weeks)
• Watch out for a dusty litter type. Try and find one that produces less dust when doing the litter
• there may be some products on the market for shampooing your cat which help reduce the allergen
• Apparently a tannic acid stray (Allersearch ADS is the product - not sure if this is a US product - it probably is) of 3% tannic acid sprayed onto carpets, curtains and bedding can help by killing allergens
• wash your hands after handling your cat and don't kiss her :)
  

This advice comes from Abyssinian Rescue
Photo copyright messtizza - creative commons

Cat's Laser Eyes

There are masses of photographs on the internet of cats that have been taken with flash on the camera.

When the flash is on the camera the light from the flash reflects off objects at an angle which results in the reflected light returning close to or at the position on the camera lens.

If you are photographing a cat this way you often get a picture of a cat with laser eyes and a funny cheeseburger caption. You get "red eye" when the same thing happens to a person.

Why are cat's eye reflections brighter? This phenomenon has been known for decades hence the term "cats eyes" when referring to the center lines on roads (there are much fewer than years ago).

The reason is bound up with the cat's ability to see better in the dark than humans. Behind the retina of the cat's eyes is a reflective material which is designed to boost the image received by the eye. In modern parlance it is an image intensifier.

Human eyes reflect red (the color of blood, which feeds the retina). For the cat it is a bright light from this reflective material.

When it is completely dark, however, cats can't see in the conventional sense. They fall back on their other outstanding senses namely smell, sound and her sensitive whiskers that detect air currents.

Photographs reproduced under creative commons. Copyright (top) Maggie Osterberg (bottom) r11132a (Flickr)

Monkeys have better memories than undergraduates

"Look you dummy, I'll show you one more time how to tie that knot.."

I've been hammering away saying that in many areas other animals are smarter or better equipped than us and that as a result we should ensure that we respect all animals. We don't know enough about them. We are still learning.

I have written about some of the cat's skills and physiological attributes on this Blog. Recent scientific tests have established that Chimpanzees (some people living in London eat Chimpanzees as a delicacy, it's called bushmeat) have better memories than university undergraduates.

Tests were carried out in which humans and chimps were asked to remember the position on a screen where a particular number from 1-9 came from that had flashed up. The young chimps beat smart humans.

This is the first time that it has been demonstrated that young chimps have a better memory capability for numbers than us.

Cats obviously can't do this (maybe they can actually - we just don't know). We do know that cats have much higher levels of smell, hearing and with their whiskers a kind of radar. They can jump much higher than us and run faster. I could go on. They deserve out respect.

Photograph reproduced under creative commons copyright anzaq78 Flickr

High TECH. Cat's Whiskers - "Vibrissae"

Some 40 years ago my sister then about 10 years of age took it upon herself to trim the whiskers of a Siamese cat we lived with at the time. She didn't realize (and I don't blame her of course) that she was amputating a very important part of a cat's anatomy.

I love to play with and touch my cat including her whiskers. But she doesn't really like me playing with her whiskers, why?

Here's another example of how cats are better than humans in some ways. Most people think that a cat's whiskers are simple feelers that allow the cat to judge the width of a passageway or a hole. They are far more sophisticated than that.

When you are stroking your cat and tweaking her whiskers, you're teaking a piece of high technology that humans cannot emulate in machinery. A cat won't like you fiddling with her whiskers because they are so sensitive.

A cat's whiskers can sense air currents around objects. In the dark her whiskers assist her to maneouvre around objects with great precision.

The accuracy of the information that a cat's whiskers sends to the brain is astonishing and demonstrated in a cat's ability to kill cleanly and efficiently.

Her whiskers act as a guidance mechanism for her jaws allowing her to bite with great precision at the exact spot on the neck of her victim (the nape) that will kill the animal quickly. The whiskers apparently can almost be said to be feeling the prey by wrapping around the animal as the jaws approach. Without whiskers in good condition a cat is unable to kill cleanly at night.

Whiskers are much thicker than ordinary hair as we know and the ends are deeply embedded into the upper lip to connect with a mass of sensitive nerves. They are not just found on the upper lip. If you look closely you can see them over the eyes, on back legs and on the chin. They all detect movement.

The long whiskers on the upper lip are the most important however. When we next look at our cat we should remind ourselves that we are looking at some fabulous high tech machinery well beyond the ability of man to manufacture.

Photograph reproduced under creative commons copyright itakebetterphotos (Flickr)

Celebrate the cat for her skills

Lets remind ourselves of the beautiful innate skills of our cats. Some people think of animals as lesser creatures. This leads them to thinking that hunting them (killing them for pleasure) is acceptable. No thought is given to the animals feelings, pain etc. when this happens.

Yet, as an example, the cat has many fabulous skills well beyond ours. Take her sense of smell. It's 14 times better than ours. She has a "device" called the Jacobson's Organ just behind her front teeth in the mouth which allows her to maximizes her sense of smell.

When a cat wants to get all she can of the odor she will open her mouth and suck in air to pass over the Jacobson's Organ and into her nose. This gives phenomenal smelling power.

Add to that, heightened senses in other areas and you have an animal that can sense earthquakes before any man made machine, for example.

Her whiskers are so sensitive that they can pick up minute air currents passing over them. This allows her to "see" in the dark. As she approaches an object that she can't see clearly, the air current around the object changes due to her presence. Her whiskers pick this up so she is able to recognize that the object is there.

These are just a few examples of the sensing power of a cat. We don't have these skills. Unfortunately, as we cannot readily see these skills in action we often fail to recognize their existence. This is a common failing of mankind. For example, if polluted air was colored pink we would stop polluting the air.

Education is the answer. If all people recognized a cat's extraordinary skills perhaps there would be more respect for her in certain quarters of the world. Lets love and celebrate our fellow creatures, particularly cats.

China and lead

Here's something that I picked up on Yahoo Groups. You have probably heard about children's toys made in China that have high levels of toxic material such as lead in them. They have been removed from shops.

It occurred to a person called Mike L on a Yahoo Group that cat bowls made in China may have similar defects. I am sure that there are feeding bowls out there in the UK or USA that are made in China. It would seem possible therefore that some may be painted. Some paint made in China has high levels of lead in it.

Lead in paint makes it more durable. In fact lead was routinely used in paint made in Western countries until it was realized that it was dangerous in much the same way that lead in petrol (gas) is now known to damage children (hence lead free petrol).

It's just that China is behind the West in certain areas. If I were buying a cat's feeding bowl that was made of metal and painted I would check if it was made in China and if so not buy it.