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I understand why dogs pant and humans transpire, namely for temperature homeostasis. So why don't cats need to do either, even after expending a lot of energy on a hot day?
Cats are smaller and hotter than dogs and humans, with a temperature between 100.4°F and 102.5°F (38.1°C to 39.2°C).
Smaller animals have a higher surface-to-volume ratio and so radiate excess heat more efficiently.
Being hotter, cats tolerate higher temperatures.
I could not find an accessible ref for this, please insert some if you can find some.
Transpiring and panting are ways to regulate body temperature. When sweat evaporates, it cools the skin, and panting releases heat through the mouth. Horses, humans and even plants transpire for this reason, while dogs and birds pant. But how do cats release heat?
In fact, cats sweat through their paws. It appears that a cat after it has been frightened may leave wet pawprints on the floor. Although it's all over the internet, I couldn't find a convincing picture and as a cat lover, I've never noticed this phenomenon. That aside, cat's paws have little surface area, and cannot provide much cooling power. Instead, felines have other, more effective strategies to adjust their core temperature. Like dogs, they often sprawl out on cool surfaces (Fig. 1), or they seek out the shade on hot days. They also tend to sleep a lot, which reduces core temperature and is preferable of being very active in hot times in terms of body temperature (Fig. 2).
Fig. 1. Sprawling cat. source: Columbian blogs
Fig. 2. Cats in the shade. source: Cat memes
- Indiana Public Media
Why don't cats have to pant? - Biology
People choose to adopt vegan diets for a myriad of personal reasons, some over animal welfare concerns, and some to improve their overall health. And since living a vegan lifestyle is now easier than ever, some vegans may want to extend that aspect of their lifestyle to their pets. But is a vegan, plant-based diet safe for your pets?
The ASPCA Animal Poison Control Center (APCC) says that while it is possible—though challenging—to keep dogs healthy on a plant-based diet, a vegan diet is not appropriate for cats at all.
But, if dogs can do it, why can’t cats?
Well, cats are obligate carnivores, meaning that they need to eat meat to survive. There are a number of reasons why cats don't do well on a vegan diet, but it all essentially comes down to this: they aren't adapted to it. Feeding a cat a plant-based diet is a lot like feeding a cow a meat-based diet—their digestive system isn't geared to handle it, and they will not thrive on it.
What specific components make a vegan diet unhealthy for cats?
Taurine: Taurine is an amino acid (the building blocks of protein) essential for cats. Taurine can only be found in animal sources such as meat, milk, etc. It is not found in plant sources. Taurine can be synthesized in humans and dogs, but cats are unable to do this and require a direct source from an animal product. Cats who are fed a vegan diet will often develop a deficiency of taurine because the diet doesn't provide them with this essential amino acid.
Cats with taurine deficiency can develop a heart issue known as dilated cardiomyopathy or DCM. In cats with DCM, the heart muscle becomes very thin and weak, preventing them from pumping blood and supplying oxygen to the body normally. This is a fatal disease if not corrected early on. A lack of adequate taurine can also cause severe eye problems in cats, including blindness.
Protein: Cats require a diet high in protein. Plants simply don't have high enough levels of high-quality, highly digestible protein to meet a cat's dietary requirements.
Carbohydrates: Cats are not good at digesting carbohydrates. They don't get much energy from them, and a carbohydrate-rich diet is not appropriate for cats. They need calorie dense options that meat provides.
The bottom line is that because cats are obligate carnivores, their gastrointestinal tracts and metabolism have adapted to eating meat. They can't digest plant material well, and they require essential nutrients that only meat can provide to them. They aren't adapted to digesting a plant-based diet, and meat absolutely needs to be on the table when you are feeding a cat. However, you can still improve the lives of farm animals and be mindful of animal welfare by seeking out animal food brands bearing meaningful welfare certification labels, which represent more humane and transparent farming practices. Learn more about how to Shop with Your Heart for not only your food, but for your pets' food as well.
Scratch 'n Sniff: A Guide to Cats and Dogs
The inner eyelid of cats--more properly called the palpebra tertia but also known as the nictitating membrane, third eyelid or "haw"--has been regarded by some as a biological curiosity much like the human appendix or wisdom teeth. In fact, some veterinary articles in the early 1900s describe methods for removing this supposedly irrelevant structure so as to facilitate examination of the eye. Despite these perceptions, the third eyelid of cats plays an important role in maintaining the health of their eye surface. In fact, it is so important that among mammals and birds the norm is for a species to have a third eyelid and those lacking one--such as humans and some of our fellow primates--are the true oddities in nature.
The anatomy of the third eyelid is complex. It is a fold of tissue covered by a specialized mucous membrane (the conjunctiva) that faces the inner surface of the eyelids (palpebral surface) on one side and the cornea on the other side (bulbar surface). Embedded in the bulbar surface is a dense population of lymphoid follicles that are in contact with the surface of the eye and the tear film, a thin layer of liquid. These structures function as the lymph nodes of the eye, trapping unwanted dirt and detritus.
Between the two layers of conjunctiva is a dense T-shaped cartilage plate. The crossbar of this T cartilage stiffens the free edge of the third eyelid and is also curved so as to conform to the corneal surface. The stem of the T cartilage is surrounded by an accessory lacrimal gland, which produces a substantial portion of the tear film. The tiny ducts through which tears leave the gland of the third eyelid exit between the lymphoid follicles on the surface of the third eyelid, allowing these cells to dump their contents into the tear film and be widely distributed over the surface of the eye.
In cats, as in most species, the third eyelid is large enough to completely cover the cornea and acts much like a windshield wiper blade by removing debris from the surface and redistributing tears over the cornea. When the cat is alert, the bulk of the third eyelid is hidden within the eye socket and only a small portion is visible in the inner corner of the eye. When relaxed, during sleep or during blinking, however, retraction of the eyeball by a set of skeletal muscles causes the third eyelid to passively move across the ocular surface from the inner, lower corner of the eye to the upper, outer corner. Movement of the third eyelid in cats is also partially regulated by the sympathetic nervous system as well as by smooth muscle cells within the third eyelid. The former fact has been used extensively in the study of how certain drugs affect the sympathetic nervous system.
The exact function of the third eyelid in cats is not completely known but it is believed to help protect a very large cornea from injury as cats move through tall grass or capture prey. Additionally the presence of an accessory tear gland allows for even greater tear production and rinsing of the ocular surface than is found in primates. As this portion of the tear film flows over the lymphoid follicles covering the surface of the third eyelid, a variety of immunologic mediators, including secretory IgA and lactoferrin, are dumped into the tear film to bathe and immunologically protect the ocular surface from the stew of bacteria and fungi that inhabit the surface of even a normal eye.
The third eyelid is also believed to help keep the surface of the eye moister by holding the tear film against the cornea better than the eyelids do by themselves. Loss of the third eyelid through trauma or in the treatment of neoplasia frequently results in chronic irritation of the cornea and remaining conjunctiva. In view of this, the real question is not "Why do cats have a third eyelid?" but "Why don't people have a third eyelid?" In humans, the third eyelid has been reduced to a rudimentary fleshy bump in the inner corner of the eye. Although the exact reason why we lack a third eyelid is unknown, it may be related to the fact that humans do not typically capture prey by biting (as would a cat) or by rooting through vegetation (as would a horse). Thus, there may be no advantage for us in having this extra measure of protection for the surface of the eye.
You probably know that cats purr. An interesting fact that you might not know is that cats also have a “cry” which they use to manipulate humans. This cry is strikingly similar to the cry of a baby or a small child, and humans are programmed to respond to this and try to help. If anything, this proves that even cats know they are evil creatures, and they have to impersonate our children to try and manipulate us into doing their bidding.
Okay, it’s not cats themselves that make you more stupid. It’s the cat videos. The average person has probably spent 7,638 hours watching cat videos. And by spent, I mean wasted. What do you have to show for those hours? Maybe a shortcut to the cutest cat video on the internet, but nothing of real value. You could have read 300 life-changing books in that time, gone on 47 enlightening walks through nature, had countless deep and meaningful conversations with friends and family. It’s not the internet that is ruining our brains, it’s cat videos. Mindless, dull, repetitive and completely devoid of any value, these are the bane of my life and I can’t understand why anyone wants to waste their time watching them.
Obligate Carnivores: Nature’s True Carnivores
Very simply, carnivores are animals whose diet consists mainly or entirely of animal tissue. Because animals evolved to eat the diet which is healthiest for them, and carnivores are no different. Over millions of years, carnivores have developed traits which optimize their ability to find and consume meat.
So what makes a carnivore, a carnivore?
Some specific traits include:
- Short, simple digestive tract: not equipped to break down the tough cell walls of plants.
- Eyes on the front of their head: increased depth perception for hunting.
- Strong, wide-opening jaws which cannot move side to side: to capture prey and tear flesh.
- Pointed teeth that do not line up with each other: to rip meat. Little to no ability to grind plant-material.
- Lack of amylase in saliva: an enzyme found in the mouths of herbivores and omnivores to begin the breakdown of plant cells while chewing.
The many kinds of Carnivores
Not all carnivores are created equal. Aside from a requirement of meat in the diet, there are many specific requirements which are often unique to their species. Dogs and wolves are known as facultative carnivores. A facultative carnivore does best on a carnivorous diet, but can survive, not thrive on a non-carnivorous one. An omnivore really doesn’t care much either way. It eats what’s available, vegetable or meat. All members of the Felidae family: lions, tigers, leopards etc., and the domestic housecat (who shares 95% of their DNA with the Siberian Tiger!), are known as obligate carnivores.
Obligate Carnivores in-depth
An obligate carnivore (or true carnivore ) is an animal that must eat meat in order to survive. Cats meet their blood sugar requirements by breaking down protein, rather than carbohydrates in their diet. They are so dependent on protein that if their diet is lacking enough protein to supply their energy needs, they will break down their own body muscle and organs. True carnivores lack the digestive system features required for the efficient digestion of plant material. In fact, some carnivorous mammals will eat vegetation specifically to vomit.
Cat’s digestion and nutritional needs
Domestic cats evolved from a desert-dwelling species found in Northern Africa and the Arabian Peninsula. This region would not have allowed wild cats much access to vegetation. This explains why their bodies adapted to have little-to-no requirement for plant material. They evolved to get all of their nutrient and water requirements solely from the animals they could catch in their environment: small rodents and birds, and even sometimes bugs!
Because eating a meat-only diet provides some essential vitamins and fatty acids in their natural state, cats have lost the ability to make these amino acids and vitamins the way omnivores and herbivores do. They don’t need to make these nutrients, since the animals they are eating have already done it for them. For example, they have a high requirement for taurine, which is found almost exclusively in animal flesh. Arginine, also found in animal flesh, is so critical to the cat that a meal without it can lead to death. Fortunately, all meat sources have plenty. Simply put, cats must eat meat to live.
The digestive systems of cats have also become specifically adapted to eating raw flesh. They have the shortest digestive tract compared to body size of almost any mammal. Raw prey is highly digestible and there is no need for a long gut and the fermenting bacteria that animals that eat plants need. After all, you don’t need to be efficient at breaking down carbohydrates when your diet contains practically none.
A species-appropriate diet for your True CarnivoreThe African wildcat (Felis silvestris lybica), the ancestor of today’s domestic cats
Though our cats today are long removed from their desert ancestors, their dietary requirements haven’t changed much from their days of roaming the African desert! The most appropriate diet for your cat is one which is high in moisture, contains quality sources of muscle meat, and has little-to-no carbohydrates. A raw diet is fantastic for your cat as it covers all these requirements, on top of being biologically-appropriate, highly-digestible and minimally processed. “Traditional” diets of dry kibble are very low in moisture, often high in rendered meat meals, and full of grains or other starches in order to hold kibble together and increase profit margins. This inappropriate diet has been one of the root causes of many common illnesses plaguing domestic cats today, such as:
- Kidney disease
- Urinary tract infections
- Urinary crystal formation and blockages
- Dental disease
Simply switching your cat to a species-appropriate diet can have remarkable effects on the improvement or reversal of these diseases, as well as prevention of their occurrence. Want to know how to start? Check out our detailed guide full of tips and tricks.
Dogs will also greatly benefit from a raw meat diet! Read about making the switch here.
Onions contain a substance (N-propyl disulfide) that destroys red blood cells in the cat, causing a form of anemia called Heinz body anemia. Garlic contains a similar substance in a lesser amount. It's not likely that a small amount of garlic or onion cooked into a sauce will cause problems for your cat. It can be dangerous for them to consume a full clove of garlic or any large pieces of raw onion and will likely cause an upset stomach.
There are a number of foods that are not toxic to cats, but they should be avoided. Meat trimmings, raw eggs, and caffeinated beverages should not be consumed by pet cats. Although milk is not toxic to cats, it may have adverse effects. Adult cats that are fed a nutritious diet don't need milk. Also, many cats are lactose-intolerant, which means that the lactose in milk and milk products produces stomach upset, cramps, and gassiness. If your cat loves milk and begs for it, a small amount of cream may be okay, two or three times a week. (The more fat in the milk, the less lactose it contains.) Another compromise is CatSip, a product made from skim milk with an enzyme added that helps the digestion of lactose. CatSip is available in supermarkets, pet stores, or online retailers. Xylitol, a sweetener, is deadly to dogs and can cause hypoglycemia and potential liver failure. The Pet Poison Helpline has not indicated its toxicity to cats, but it does not seem worth the risk. If you see this ingredient in any food items, make sure to avoid sharing with your cat.
Tips if you must bathe a cat
Bathing is rarely needed for cats either. If your cat does need to be bathed for medical reasons, or if they became overly dirty for some reason, there are some ways to make it a little less stressful.
Fill the tub first, the sound and splashing of running water will make things worse. Line the tub with a folded towel (which will of course become wet) so they feel like they have something to grip onto. A slippery tub floor will also cause more stress for the cat. Use a container to carefully pour water over, versus using a faucet. Lastly, be really careful around the face and eyes!
How to Keep Cats Out of Houseplants
You can also cat-proof houseplants by making them smell bad. Sprinkle cayenne pepper around the leaves of houseplants and your cat will back away pretty quickly. Cats also hate the smell of citrus. Put orange and lemon peels in your pots along with the plants to help deter them. Another option is spraying the leaves directly with diluted lemon juice or orange oil. NOTE: Citrus oil extracts like those found in insecticidal sprays, dips, shampoos, insect repellents, food additives, and fragrances are toxic to cats and should be avoided.
Many people who have trouble with their cats using plants as a litter box will purchase plants with offensive textures that will make cats think twice about their bathroom habits.
You can also cover the soil with some large pebbles or stones around the base of the plants to prevent digging. Pinecones or aluminum foil, for instance, placed around the planter may help to keep cats away. Another option is covering the base of the plant with chicken wire, mesh, or another breathable fabric.
If you still can’t keep your cats away from your plants, don’t give up. There are still a few more options.
Only half of a dolphin's brain sleeps at a time.
The dolphin was also considered a special case because dolphins have the ability to put only half their brains to sleep at a time. The half-asleep brain made it difficult to measure response time and made scientists start to question their initial definition of sleep. Remember, part of being asleep means being still, and since dolphins still swam around it seemed that they did not fit into that category. However, when scientists measured dolphins’ brain waves they saw that the patterns were similar to brains that were asleep, at least in half of the brain.
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