You might think that size wouldn't be a problem for cat fanciers or breeder. After all, most breeds of domestic cat are fairly uniform in size. Shouldn't this make creating new breeds easier? Doesn't it mean that you can cross breeds and experiement without having to consider size?
The answer to the second quesiton is yes. The answer to the first is, unfortunately, no. Unlike dog breeders, who are able to work with a wide variety of sizes, cat fanciers and breeders are very limited in design. The difference between the largest breed and the smallest breed is barely 12 pounds in weight and less than 1 foot in length. The diffference between the largest and shortest facial profiles is only 2 inches. This isn't a lot to work with in terms of developing new breeds.
This presents a problem for cat breeders that dog breeders simply do not face. If you have only one size to choose from, new breeds, or even variations on a single breed, are difficult to come by. Despite this limitation, breeders have managed to create more than fourty distinctive and recognized breeds. While this may not be as many as dog breeders have been able to create, it is still impressive given the limited variables cat fanciers have to work with.
The eyes are often said to be the windows to the soul, and the eyes of a cat gleam more than most. The romantic notion that a cat's eyes gleam because they house great power or are otherwise mystical in nature is pretty, but there's actually a very scientific explanation for the mysterious luster you found in a cat's eyes.
Cats are the most efficient gleaners of light. Their pupils can dilate to a full half-inch in width or narrow to an almost-invisible slit. Their eyes can take in as much or as little light as they require to effectively see. This trait allows them to see in almost complete darkness. Contrary to popular belief, they cannot see in absolute darkness; Even their sensitive eyes need some light to make sense of the environment. But they can see their surroundings in great detail with only the smallest bit of light.
Cats are not completely color blind, though they can see red only in the emotional sense. By which I mean red is outside their visual abilities. They also can't see orange, since orange is a combination of yellow and red. They can, however, see striking shades of blue, shades we will probably never be able to appreciate.
Felines are also a little farsighted. In fact, their depth of field is in sharpest focus between 7 and 20 feet. This is not to say that they cannot see things outside this field. They can, but they'll see it in sharper detail if it's inside that range.
A cat's ears have a specific shape that is consistent throughout all breeds of domestic cat. There is a little variation (just look at the ears of a Cornish Rex), but they all stand straight up and form a little triangular cone that naturally faces forward. This is unlike the domestic dog, which varies in ear shape and position (to a certain degree) among the different breeds. The consistency of the shape of the ears provides all cats with the same natural abilities.
The ears of a cat, like the ears of other creatures, receive auditory signals. the upper limit of a cat's hearing is higher than a dog's and almost two full octaves higher than our own. From a distance of at least three feet, cats can discriminate between sources of sound that are as little as three inches apart. This ability is enhanced by the cat's ability to rotate their ears until they are almost pointed backwards. Finding and catching prey becomes easier when you can pinpoint exactly where that mouse is simply by hearing it shift in place, so the ears are a practical tool. The cat's ability to pinpoint and identify sound also lets them ignore the sound of their owners' voices from any distance at all! Any cat owner can sympathize with this.
But the ears can also send signals and are, in fact, one of the primary means of communication for a cat. Think about a cat with its ears flattened back. You know that means kitty is not in a good mood. Relaxed ears mean a relaxed body. Ears which are pricked forward slightly mean alertness. You can tell the mood of your cat simply by looking at the ears regardless of which breed your cat happens to be.
Beyond their practical functions, the ears of a cat are just plain cute. Who can resist the urge to stroke the soft hair that grows on the backs of the ears? And if you scratch the base of the ears, most cats almost fall over in ecstasy. So the ears are decorative as well as functional and are a necessary part of the anatomy of the cat.
Muscles and bone are the very foundation of the conformation of a cat. There are 244 bones in the feline skeleton that lend support and substance to the cat's body. These bones also provide protection for the internal organs. In some breeds of cat the bones are as sturdy as a hardwood such as oak. However, some of the more delicate breeds have bones that are more flimsy and less substantial.
In all breeds the bone is surrounded by muscle. The muscles respond to a series of electrical impulses that are originally issued by the brain. Once these impulses are received, the muscles convert them into contractions using a series of chemical transformations. The muscles produce movement, movement which the bones follow. This movement is usually the gracefulness that defines the cat and its delicate body.
At cat shows, the head sets the standard for the body in a physical sense. Many judges spend more time studying the head of the cat than any other part of the body. While the points allotted to the rest of the cat should certainly be considered, there can be no argument that the head is of utmost importance.
The largest part of the head is the brain. The brain is located in the cranial cavity and is an enlarged and highly modified continuation of the spinal cord. The nervous system begins and ends here. The brain is divided into two egg-shaped hemispheres whose surfaces are marked by folds which are both thick and numerous. The hemispheres make up the greatest part of the developed brain, and the brain itself is held by the cranial cavity, which is designed to cushion and protect the brain. The rear wall of this compartment is formed by the occiptal bone, whose lower section is perforated by an opening that is almost circular. This opening is for the spinal cord.
Now the brain would be almost useless if it couldn't be kept informed of everything that happens in the body. This is where the cranial nerves come in. There are twelve pairs of cranial nerves. These of these -- optic, olfactory, and auditory -- are there purely to interpret the special sense of sight, scent, and sound. Five of the pairs -- oculomotor, abducens, hypoglossal, trochlear, and spinal accessory -- are for motor function. The remaining four -- trigeminal, facial, glosso-pharyngeal, and vagus -- are for both sensory and motor functions.
The head of the cat is the seat of most of the major functions of the body. Air intake, food intake, excretory abilities and many other functions are seated here. Though some of these processes are carried out in depth in other areas of the body (such as digestion), they are started in the head. For example, the head produces some digestive enzymes in the salivary glands, and so digestion begins in the mouth.
The head, by way of the pituitary gland (the principle control gland in the body), also influences the endocrine system. Almost a dozen separate function are controlled by hormones manufactured, released, or stored by the pituitary gland. Some of these many functions include growth and even the onset of estrus in female cats.
As the head is solely responsible for acquiring the oxygen and food the body needs, the head should never be ignored during your study of the cat. The brain does so much for the body, but it itself exists on the most simple of chemicals produced in the body. The brain, and the head, asks for very little in return for supplying essential life to the body.
A cat's heart beats 110 to 140 times per minute, sending blood rushing through the body in a mere 11 seconds. And though the circulatory system has many purposes, none is as important as sending oxygen throughout the body. And this is accomplished through the most numerous cell is the cat's body -- the red blood cell.
Red blood cells are so numerous in the cat that I'm not even going to bother typing out the numbers. I don't like seeing that many 0s in a row. But there are a lot and they only live for two to six weeks before they must be replaced. Thankfully, the cat's body is constantly making new red blood cells. This starts when tissue, anticipating a shortage of oxygen, sends out a hormone (erthropoietin) through the bloodstream and to the bone marrow in red blood cell construction sites. The hormone signals primitive cells to begin to grow.
The primitive cells develop into rubriblasts, which are sort of like adolescent red blood cells. Each of these rubriblasts divides into two separate cells, both of which continue dividing. Eventually, these two red blood cells (abbreviated to RBCs) become 16. The RBCs are composed mainly of water and hemoglobin. Each hemoglobin molecule contains four iron atoms. This allows for the transportation of over 1 billion molecules of oxygen throughout the cat's body.
The cells continue to grow until hemoglobin accounts for 95% of the dry weight of the red blood cell. This takes about three days (out of a six-day RBC production process). At this point, the cell ejects its nucleus in an act of self-sterilization. This leaves the cell free of all distractions. The cell can now work, and work it does. In fact, RBCs work themselves to death as they carry oxygen to the various organs of the body.
Even the shape of the red blood cell is important. It looks a little like an unperofrated doughnut and it is very flexible. So flexible that an RBC can squeeze through the smallest capillaries to deliver fresh oxygen and take away toxic carbon dioxide.
Without the all-important red blood cell, the cat would not be able to function. It is not an exaggeration to say that the red blood cell is the single most important cell in the circulatory system of the cat.
The circulatory system of the cat is comprised of the heart, a network of arteries and veins, and the spleen (which serves as a blood reservoir). A cat's heart rate, beating from 110 to 140 times a minute, is almost twice the normal heart rate of a human. The cat's body contains half a pint of blood, and this blood is circulated through the body once every 11 seconds. The blood, which is initially blue, goes through the heart to the lungs where it changes color, becoming crimson. The iron atoms in the blood discharge their carbon dioxide and grab some oxygen, which has been freshly inhaled through the lungs.
With the pulmonary part of its journey complete, the blood launches itself on a path through the body. It moves into the aorta and then into the smaller arteries that filter throughout the entire body. The blood slows slightly as it enters even the even smaller arterioles which regulate blood flow to the tissues of the body.
By the time the blood reaches the metarterioles (the conduits between arterioles and capillaries), the blood is moving at its slowest pace. The blood is now a purplish red after being stripped of most of its oxygen. The blood exits the capillaries through venules (little tiny veins) and begins its journey back to the heart. All this takes only 11 seconds.
The bloodstream is important, and not only because it allows for the exchange of oxygen and carbon dioxide throughout the body. The bloodstream is also responsible for the creation of the clots that patch up tears, control osmotic pressure, and adjust the cat's thermostat when the cat is either too warm or too cold by moving heat to other areas of the body. Excess heat is expelled from the body also thanks to the bloodstream. Blood is even responsible for shivering and the warming of the body. The bloodstream defends the cat against disease, helps with digestion after meals, and even helps the cat catch his breath after exertion. In other words, the circulatory system of the cat is perhaps one of the most important systems of all, and not just because it circulates blood.
The complex feline skeleton is composed of 244 separate bones. These bones together with cartilage (the connective tissues that bear weight) form the skeletal system of the cat.
The bones can be classified into three broad categories based upon their shape: long, flat, or irregular. If you think about it, you can probably classify most of the bones yourself simply by thinking abou their shape. The bones in the legs, for example, are long bones. These include the radius, ulna, tibia, and fibula. Flat bones can be found if you look at the scapula, skull, or face. Irregular bones are those that doesn't fit in the other categories and include bones such as the metatarsals and metacarpals.
Things get a little more complicated than that, however, because in additional to have three distinct shapes, the bones of the cat also can come in three varieties of ossification: intramembranous, endochondral, and heterotopic. Heterotopic bones occur after birth, usually under disease conditions, and are formed where you wouldn't normally find bone. These formations can be harmless little extra bits of bone or they can be dangerously close to vital organs. In the last case, they would have to be removed.
Endochondral ossification is the process of bone groth in an area previously occupied by cartilage. The cartilage is slowly replaced by bone. Intramembranous ossification is the development of bone under or with in a connective-tissue membrane.
So why is this important? Because most of the bones in the body are formed using the last two processes. The flat bones of the skull are created through intramembranous ossification while the bones at the base of the skull and in the face and trunk are a combination of intramembrous and endochondral ossification. Bone mass, by which I mean the compact bone of the shafts of the long and flat bones, is formed intramembranously. However, bones grow in length through the endochondral process.
What this all means is that the conformation of the cat is solely determined by the relative prominence of each type of bone growth. Which type of bone growth is prominant is usually dependent on the breed. For example, cats which are lean and lithe, such as the Siamese, have more endochondral ossification. Stockier cats such as the British Shorthair have more intramembranous ossification.
From the first day a kitten is born and begins to slither towards its mother, it is attempting to control its voluntary muscles. These muscles will eventually allow the kitten to crawl, wobble, stand, walk, and even play with its littermates. The voluntary musclesare sometimes called striped or striated muscles because they exhibit longitudinal stripes. More commonly, they are called skeletal muscles because their chief function is to move the cat's skeleton from place to place. Skeletal muscles, which are secured by tendons and bones, are always arranged in pairs.
To understand how the skeletal muscles work, and why pairs are important, imagine a cat jumping. The cat must crouch down on its heels by contracting two flexor muscles, the hamstring and the tibialis. The hamstring is the muscle located behind the thigh bone while the tibialis is a muscle in front of the tibia and fibula bone. At the same time, the corresponding extensor muscles that were stretched while the hamstring and tibialis were contracting, contract themselves. This powerful contraction of all four muscles propels the cat forward, creating those gravity-defying leaps cats are so famous for.
The involuntary muscles, which are not under conscious control of the cat, are functioning even before the kitten is born. These muscles are known as smooth muscles and are found in the alimentary canal, the urinary tract, and the respiratory system, among other places.
The systems that make up the feline are all rather remarkable. The most important physical systems of the cat include: nervous, endocrine, respiratory, lymphatic, digestive, reproductive, urinary, circulatory, and musculoskeletal.
The nervous system is made up of the cerebrum, cerebellum, midbrain, spinal cord, twelve pair of cranial nerves, and paired sets of peripheral nerves that extend from the spinal cord to all parts of the body. There are many functions governed by the nervous system, including learning, reasoning, memory, and judgment. Involuntary action, which is controlled by the cerebrum, is also considered a part of the nervous system. Blood pressure, respiratory rate, and heart rate are monitored by the midbrain and so also contained within the nervous system.
The endrocine system comprises the glands that secrete hormones into the bloodstream. The most important gland, sometimes referred to as the master gland, is the pituitary, located at the very base of the brain. The pituitary gland, in addition to producing growth-stimulating hormone, controls the activities of the other glands, including the thyroid, adrenal gland, and the testicles or ovaries of the cat. In turn, these glands control the activities of the body.
The respiratory system includes the nose, throat, larynx (voice box), trachea (windpipe), bronchial tubes, and lungs. This system is vitally important to the cat as a cat at rest completes 25 to 30 breaths a minute. This is approximately twice as many as a human completes. In the cat, inhaling takes about half as long as exhaling.
The lymphatic system is one of the main defenses of the cat's body. It is a network of vessels that transport lymph, which is made up up excess tissue fluids, protein, and other substances. This system functions without the benefit of a pump and carries out its mission through the venous side of the circulatory system. Lymph nodes, another important component of the lymphatic system, filter out foreign particles found throughout the body. Lymph nodes contain lymphocytes, a types of white blood cell, which produce antibodies that neutralize bacterial poisons.
The digestive system comprises the mouth, teeth, esophagus, stomach, small and large intestines, liver, pancreas, and rectum. Of all the carnivores, cats have the fewest number of teeth, barely 30. These teeth were not made for chewing, but rather for killing prey ad tearing their flesh. Therefore, cats tear off chunks of food and swallow them whole.
The kidneys, ureters, bladder, and urethra make up with urinary or excretory system in both sexes. Closely related to the urinary system is the reproductive system. The testicles and sperm ducts comprise the male reproductive system with the fallopian tubes, uterus, womb, and vagina are part of the female reproductive system.
The other systems mentioned here, such as the circulatory and musculoskeletal, are complex systems deserving of elaboration. The musculoskeletal systems is the bedrock of conformation and body type at its most elementary. The circulatory system is the medium through which many of the body's other systems function. However, the details of these two systems are deserving of their own articles and will be covered in detail in coming weeks.
Cats, just like people, can go blind. Blindness is defined as the loss of vision in both eyes and may arise from illness, disease, or even an accident. In cats, it is often difficult to detect the onset of blindness because they have such extraordinary and sense of smell. They often compensate so well that the cat owner does not notice at all.
However, when vision is completely lost in both eyes, there are usually signs the cat owner can watch for. If a change in environment confuses your cat, the feline may be dealing with blindness. For example, if you move your living room couch, your cat may walk into it unexpectedly. Often this leads owners to conclude that their cat has suddenly gone blind, but the reality is that the cat has probably been having vision problems for some time, but had memorized his surroundings to compensate. When the surroundings change, memory no longer serves its purpose and little things happen, such as walking into a couch, table, or open cupboard door.
The Causes of Blindness in Cats
There are several things that might cause blindness in cats. Corneal disease is one of the most common, but it's not the only cause of blindness. Cataracts, which can be diagnosed by the white opacity of the lens of the eye, can occur in older cats, though younger cats seldom suffer from this ailment. Other illness and diseases that can result in blindness include:
- Severe anterior and/or posterior uveitis
- Retinal inflammation or infection
- Retinal detachment
- Glaucoma
- Diseases of the optic nerve, visual pathways, or the occipital cortex
If you cat has had any damage to the eyes, there is an increased chance of blindness. Scratches due to cat fights might seem like they're no big deal, but have them checked by a veterinarian anyway, just in case. The longer you wait, the greater the chance of blindness.
Symptoms of Blindness in Cats
You'll have to watch your cat carefully to detect vision loss, as cats are quite good at hiding this particular disability. However, if you notice any of the following symptoms, take your cat to the veterinarian immediately.
- Clumsiness, even if it's only occasional
- Inability to locate food, water, or the litter box if any of these things are moved even a few feet
- Excessive sleeping or chronic inattentive behavior
- Suddenly fearful and easily startled
- No longer plays or exhibits normal hunting behavior
- Bumps into objects that are plainly visible but not always present
If you even suspect that your cat may be going blind, you should take your cat to the veterinarian immediately. Blindness, especially sudden-onset (acute) blindness, is not something you can treat at home, regardless of the cause.
I've often been asked if cats can see color. In truth, this is a difficult question to answer with certainty. Asking a cat is only likely to get you a blank stare. And in all honesty, it doesn't really matter. Cats are hunters, so brightness is more important to their vision than color. They have to be able to see movement and texture. While hunting, color is of little use.
However, an answer to the question of colorblindness and cats can be divined by studying the construction of a cat's eye. The retina is the nerve center at the back of the eye. This retina is composed of cells called cones and rods. Cones are responsible for converting light into color. Rods are responsible for black and white. In the eye of a cat, rods greatly outnumber cones, which is why cats are generally considered to be colorblind.
It's important to note, however, that a cat still has cones. So it is possible, even likely, that a cat can see color. But the number of cones is limited, so your cat probably can't see shades of red. Blues, certainly, and probably greens and yellows.
But your cat doesn't need to see very many colors. Your cat has another advantage. He can see even in the dimmest of lights. Take a look at the eyes of your cat and you'll see why. He can open his eyes wider than you can and his pupil expands to full almost the entire eye, letting as much light in as possible. So hunting in the dark is no trouble for your cat.
In scientific terms, your cat's retinas allow him to see in about one-sixth of the light you need to see clearly. Objects at night appear six times brighter to him than you do to you. And the added rods allow him to detect minute movement, which is only beneficial when hunting.
So, your cat can't see all the colors you can. But he can see some colors and his vision is sharper than yours. It's a trade-off. Less color means more visual acuity. And a cat needs all the visual acuity he can get.
