Now I’m going to focus on feline eyes. Cats, like dogs and many other animals, have a tapetum lucidum. Which is a reflective layer behind the retina that sends light passing through the retina back into the eye. While this improves the ability to see in darkness, it appears to reduce net visual acuity, thus detracting when light is abundant. In very bright light, the iris closes to a slit, reducing the amount of light on the sensitive retina, and improving depth perception. The tapetum and other mechanisms give the cat a minimum light detection threshold up to seven times lower than that of humans. Variation in color of cats’ eyes in flash photographs is largely due to the reflection of the flash by the tapetum. Cats have a visual field of view of about 200°, while humans only have 180°. But their binocular field (overlapping the images from each eye) is narrower than that of humans. As with most predators, their eyes face forward, affording depth perception at the expense of field of view. Field of view is largely dependent upon the placement of the eyes, but may also be related to the eye’s construction. Instead of the fovea, which gives humans sharp central vision, cats have a central band known as the visual streak. Cats can see some colors, and can tell the difference between red, blue and yellow lights, as well as between red and green lights. They are also able to distinguish between blues and violets better than between colors near the red end of the spectrum. I’ve noticed a “win some lose some” pattern with different kind of eyes, Humans can’t see well in the dark, cats can’t see all the colors, And chameleons can’t focus on two different things. But that’s for next week.
To see the inside of a cat’s eye, click here to watch my video.
Now we’re going to look at a different kind of organ. The feline spleen. The spleen is an elongated organ located near the stomach in the left forward part of the abdomen. The exact location of the spleen depends upon its size and shape and is affected by the size of the surrounding organs, such as the fullness of the stomach. The spleen is a relatively large, dark red organ that is supplied with numerous blood vessels. A normal spleen is shaped somewhat like a tongue and is considerably longer than it is wide and slightly constricted in the middle. It is also covered by a tough capsule of fibrous tissue. The spleen has a few main functions. Though not essential for life, the spleen does make life a lot easier. Performing important functions like filtering particles in the blood and lymph systems like old or abnormal blood cells and foreign proteins. Acting as a storage site and filtration system for red blood cells and platelets (clotting elements). It is the major site outside the bone marrow where red blood cells are made. And last but not least, the body has the ability to contract the spleen suddenly if additional red blood cells are needed in the bloodstream. So even though it is not essential for life, the spleen sure makes life a lot nicer.
It's the cats turn for the spotlight this week. As we focus on cat paws. Cats, like dogs, are digitigrades. Which means they walk directly on their toes, with the bones of their feet making up the lower part of the leg. Felines are unique, they directly register; that is, they place each hind paw almost directly in the print of the corresponding forepaw, minimizing noise and visible tracks. This also provides sure footing for their hind paws when they navigate rough terrain. And makes them capable of walking very precisely. Also, the two back legs are muscular to allow falling and leaping far distances without injury. There are seven pads on the front paws made up of five digital pads, one central or plantar pad that takes most of the weight, and a small wrist pad. The hind paws on the other hand (or should I say "paw") have only five pads, four are digital and there is one plantar pad. Unlike most mammals, when cats walk, they use a "pacing" gait; that is, they move the two legs on one side of the body before the legs on the other side. This trait is shared with camels and giraffes. As a walk speeds up into a trot, a cat's gait will change to be a "diagonal" gait, similar to that of most other mammals. Cats are a lot more agile than dogs are, and much of this has to do with their paws and the way they walk.
This week I’m going to educate you on feline epidermis. Also known as cat skin. Cats possess rather loose skin; this allows them to turn and confront a predator or another cat in a fight, even when it has a grip on them. This is also an advantage for veterinary purposes, as it simplifies injections. The particularly loose skin at the back of the neck is known as the scruff, and is the area by which a mother cat grips her kittens to carry them. As a result, cats tend to become quiet and passive when gripped there. This technique can be useful when attempting to treat or move an uncooperative cat. However, since an adult cat is heavier than a kitten, a pet cat should never be carried by the scruff, but should instead have its weight supported at the rump and hind legs, and at the chest and front paws. Some cats share common traits due to heredity. One of these is the primordial pouch, sometimes referred to as “spay sway” by owners who notice it once the cat has been spayed or neutered. Its appearance is similar to a loose flap of skin that might occur if the cat had been overweight and had then lost weight. It provides a little extra protection against kicks, which are common during cat fights as a cat will try and rake with its rear claws. In wild cats, the ancestors of domesticated felines, this pouch appears to be present to provide extra room in case the animal has the opportunity to eat a large meal. This stomach pouch allows the cat to bend and expand, allowing for faster running and higher jumping. So if your cat is a little flabby, it just means they have more athletic capability. For what cats do best, eat, sleep, and uh sleep some more…
Cat with yellowing eyes (Photo credit, Thinkstock)
This week I’m going to tell you about the gallbladder. The feline gallbladder to be precise. The gallbladder rests in the abdomen, firmly affixed to the liver and serving as a storage receptacle for bile, a fluid that is essential for digesting food in the stomach and intestines. The bile duct transports bile from the liver into the gallbladder and into the small intestine, and the liver functions in the secretion of the bile. Inflammation of the gallbladder is often associated with obstruction and/or inflammation of the common bile duct and/or the liver/bile system, and is sometimes associated with gallstones. Severe cases of inflammation can result in rupture of the gallbladder and subsequent severe inflammation of the bile duct (bile peritonitis), necessitating combined surgical and medical treatments. Some of the symptoms that can be indicative of an inflamed gallbladder or bile duct are sudden loss of appetite, lethargy, vomiting, and abdominal pain. Mild to moderate jaundice with concurrent fever is commonly associated with conditions of the bile duct. Look for yellow eyes and yellowing of the gums. Shock due to infection and reduction in blood volume can also occur. Signs of shock include shallow breathing, hypothermia, pale or gray gums, and a weak but rapid pulse. Inflammation and adhesions involving the gallbladder and adjacent tissues can lead to swelled tissue; a palpable mass of tissue will be felt in the upper right abdomen, especially in smaller sized cats. The causes for an inflamed gallbladder or bile duct can result from one or more conditions that will lead up to it. Muscles in the gall bladder may be malfunctioning, which can lead to impaired bile flow in the cystic duct or gall bladder, irritating the walls of the gallbladder. Or the blood supply to the gallbladder wall is being restricted, in which case the cause for the restriction must be isolated and treated to improve the blood flow. Irritants in the bile can cause the bile duct to be overly sensitive and reactive; a backward flow of pancreatic enzymes may trigger and intensify inflammation. Previous abdominal surgery, or trauma to the abdomen, can directly lead to internal sensitivity, affecting one or more of the internal organs, including the liver and gallbladder. Gallbladders are essential in carnivores, but not so much in herbivores as the horse doesn’t even have one. All of the components of the digestive system work in tandem, and if one fails to function properly, the result is that most of the body will suffer ill effects.
To see what a gallbladder looks like, click here to watch my video.
English: Macro photo of a cat cleaning itself, showing the hooked papilla on the tongue. (Photo credit: Wikipedia)
The tongue is a muscular organ that has several functions, the main ones being the guiding of food and water into the mouth and for the taste sensation. The tongue assists in the chewing and swallowing of the food as well. The tongue also plays a role in reducing body temperature in the cat. Dogs are well known for panting, but when the ambient temperature is particularly hot cats will also pant. As air passes over the tongue, the air is cooled. Saliva augments this process as it evaporates. The tongue of a cat differs from that of a dog in several ways. In the center of the tongue are papillae – small hair-like projections that act as small hooks. They are responsible for that “sandpaper” feel when a cat licks our skin. These papillae are made of keratin, the same material found in human hair and fingernails. The papillae serve several purposes. They are important in grooming the fur. And also assisting in gathering and holding food inside the mouth. Specialized papillae at the tip and the sides of the tongue play an important role in taste sensation. Studies have shown that the feline tongue can sense texture as well as flavor. This may explain why some cats prefer dry foods based on their shape. The feline tongue is very sensitive to temperature, and studies have shown that cats prefer food served at room temperature over chilled or warmed food. Which is part of the reason that cats are so picky.
To see papillae under a microscope, click here to watch my video.
Now it is time to focus on a carnivore’s stomach. Namely, the cat stomach. Obviously, a carnivore’s stomach is different then say, a goat or horse stomach. The esophagus transports food to the stomach where it enters a valve-like structure titled the cardiac sphincter. From there, it enters the stomach. A cat’s stomach is a sac-like structure designed to store large amounts of food and continue the digestive process. Cats usually swallow large lumps of food, rarely chewing for very long. So meat and bones make their way to the stomach and are ground up there. The interior of the stomach is made up of a series of folds called “gastric folds”. Their function is to grind the food into small pieces and digest it. The inner stomach lining also secretes acids and enzymes to break down food. Once the initial stomach digestive process is complete, the partially digested food exits the stomach through the pyloric sphincter area and then enters the duodenum. Once eaten, most food leaves the stomach within twelve hours after entering. The cat stomach was designed very well for what it is meant to do, although, modern cats that are fed cat food out of containers may need some supplementing. What is better for my cat? You may ask, wet food or dry food? Well, this is sort of a trick question because truthfully, (depending on the quality) the most ideal diet is a mixture of both. You see, wet food is usually more nutritious, although if a cat never chews anything other than soft food their teeth can get weak. Hearts and brains are the best things you can supplement into your cat’s diet. As they contain the taurine cats need to thwart health problems and death. Egg yolks are also a good idea as they are nutritious and good for your cat’s fur. Conclusively, cats are carnivores and need lots of protein and saturated fats as well as access to greenery such as cat grass or catnip for other nutrients. Assuredly, if you give your cat this diet, it will live long and prosper.
About 10% of Americans have pet allergies, the most common being cats. Contrary to popular belief, it is not cats’ fur/hair that people are allergic to but the dander (dead skin), saliva, and urine. An interesting fact about pet allergies is that they are caused by an oversensitive immune system. What happens is that the body mistakes something harmless like pet dander for some dangerous invader and attacks it like it is a bacteria or virus. And the person gets the wonderful symptoms and side-effects that go along with it. Although sometimes the person might not be allergic to cats or dogs. Outside animals can carry pollen, mold, or other allergens in their fur. And then there are the “hypoallergenic” or hairless breeds like the sphinx or the chinese crested. Now don’t get me wrong, these breeds may cause less of a reaction but if someone in your family is allergic to cats or dogs it is just not a good idea to adopt that kind of pet. Now for all of you that are not allergic to cats or dogs, pet your cat or play fetch with your dog and think about the poor lonely souls who have never held a kitten or got licked by puppies. Now go give your cat a bath and brush your dog’s teeth.
Did you know that cats are not the only creatures that purr? Mongooses, hyenas, racoons, civets*, and even Guinea pigs have been known to purr. Another interesting fact is that while mountain lions and bobcats can purr, they cannot roar. And creatures that can roar (like lions and tigers) cannot purr. The reason for this is that most big cat’s laranxes are not stiff enough to purr and cats which do purr have the opposite problem. While most people think that cats only purr when they are happy or content, that might not always be the case. Sometimes cats purr when they are in distress such as going to the vet or recovering from a wound or illness. Also, Queens with kittens tend to purr more than usual. All cats tend to purr more when in contact with humans. So pet your cat and especially kittens in order that they can be happy and sociable. Plus you get to hear them purr.
(*A lithe-bodied, mostly nocturnal mammal native to tropical Asia and Africa,)
English: Young male tabby cat (Photo credit: Wikipedia)
The Domestication of Cats
When where cats first domesticated? Apparently most people think it happened in the Middle East. Ancient Egyptians (who also worshipped cats) kept cats to keep the gluttonous mice from devouring their grain stores. Around that time traders brought cats to Italy where they were lovingly accepted. Soon all of Europe wanted cats and they even made their way to America via ships. People who own cats are very lucky, because cats are usually good natured and long living.