The unique nutrient requirements of cats

Cat with bird in a teeth.

It’s no secret that people love their cats. Today, cats are considered the world’s most popular pet. In 2016, the American Pet Products Association (APPA) National Pet Owner Survey estimated 94.2 million cats and 89.7 million dogs in the United States.

However, when compared to dogs, cats have unique nutritional and dietary requirements that require special attention. These requirements stem from the cat’s evolution from its strictly carnivorous ancestors and the nutrients supplied to them through the consumption of animal tissue.

Today, the average house cat lives a much more sedentary lifestyle and can thrive on a variety of diet types. But when it comes to formulating diets for cats, special attention needs to be paid to a few key nutrients that must be included in sufficient amounts to maintain optimal health. The unique nutritional requirements of cats are related to their requirements for protein, taurine, arginine, vitamin A, vitamin D, niacin and arachidonic acid.

Protein and amino acids

From a nutrient perspective, cats do not necessarily require an ultra-high protein diet, but they do have higher requirements for amino acids from dietary protein than dogs. Amino acids are the building blocks of protein, and certain amino acids can be produced by the animal (i.e. nonessential amino acids), while others can only be obtained from the diet (i.e. essential amino acids).

Cats require 10 nonessential amino acids and 11 essential amino acids. They also have a unique requirement for the amino acid taurine as well as a need for significantly increased levels of arginine compared to dogs.

Arginine

Research has shown that cats are sensitive to diets lacking arginine. A diet deficient in arginine has been shown to rapidly result in severe clinical symptoms in cats due to increased levels of blood ammonia.

Arginine is necessary for the detoxification of ammonia by converting it to urea for excretion in the urine. During a deficiency of dietary arginine, ammonia builds up and results in ammonia toxicity within the cat. Cats are unable to synthesize the precursors ornithine and citrulline, both needed for the production of arginine.

However, arginine is abundantly available in animal protein, and cats have evolved to be reliant on it from a dietary source.

Taurine

Similar to arginine, taurine is an amino acid that is readily found in meat protein. Dogs and other mammals are able to produce taurine through the oxidation of sulphur amino acids, cysteine and methionine. For cats, the enzymes necessary for these pathways have low activity levels, and as such, cats are limited in their production of taurine.

Dietary taurine is necessary in the diet for cardiovascular health, bile formation, retinal health, as well as proper growth and development in kittens. Symptoms of taurine deficiency include retinal degeneration and/or an enlarged heart, also known as dilated cardiomyopathy.
Vitamins

Vitamins are organic compounds necessary in minute amounts for proper regulatory function and health maintenance. Vitamins can be classified into one of two groups: fat-soluble or water-soluble. Fat-soluble vitamins can be stored in fatty tissues, whereas water-soluble vitamins cannot be stored and are excreted in the urine if consumed in excess.

Vitamin D

Vitamin D is a fat-soluble vitamin necessary for bone health and development. Humans can produce vitamin D from exposure to sunlight or obtain the vitamin through food sources. Cats, however, are unable to synthesize vitamin D and depend solely on dietary sources.

A study investigating the exposure of both hairless and nonhairless kittens to direct sunlight demonstrated this lack of endogenous production. When the kittens were placed on a diet deficient in vitamin D they showed the same rate of vitamin D decline as kittens receiving the same diet but housed indoors.

Research has since concluded that cats’ skin has a low concentration of the precursor 7-dehydrocholesterol, necessary for the synthesis of vitamin D. Additionally, synthesis is prevented by the high activity of the enzyme responsible for breaking down this precursor substrate and converting it into cholesterol.

Historically, cats obtained their vitamin D from the liver of prey, such as birds and rodents. Commercial cat diets are typically supplemented with vitamin D to ensure adequate intake.

Vitamin A

Just like vitamin D, vitamin A is also a fat-soluble vitamin. Vitamin A is necessary for maintaining normal vision, immune function, as well as growth and development. As vitamin A is naturally abundant in animal tissue, cats have not evolved to synthesize vitamin A in the same way as herbivores and omnivores.

Plants produce β-carotene, a precursor for the synthesis of vitamin A by the body. Unlike omnivores and herbivores, cats appear to lack the enzyme necessary to convert β-carotene into retinal. It is assumed that cats have not evolved to synthesize vitamin A as meat proteins are low in carotenoids and the liver of prey is rich in vitamin A, so the conversion pathway would not be considered metabolically necessary or beneficial in terms of energy efficiency.

Niacin

Niacin is a water-soluble vitamin that is essential for energy metabolism. Cats possess all the necessary enzymes and pathways for the production of niacin from the amino acid tryptophan.

Tryptophan can be metabolized to produce acetyl coenzyme A (acetyl CoA) and carbon dioxide or nicotinamide adenine dinucleotide (NAD; the active form of niacin). In cats, the enzyme responsible for catalyzing the conversion of tryptophan to acetyl CoA and carbon dioxide has a high activity, so niacin is broken down faster than it is produced.

However, cats are well supplied with niacin from the NAD and NADP found in abundant concentrations in animal tissues. On average, cats require about 2.4 times the amount of niacin than dogs.

Arachidonic acid

Cats cannot make arachidonic acid and require a dietary source of the omega-6 fatty acid, especially during the demanding life stages of growth, gestation and lactation.

Arachidonic acid is found in abundant supply in animal tissues, especially organs. It is not present in plants, however omnivores and herbivores are able to synthesize arachidonic acid from linoleic acid, another type of omega-6 fatty acid. Arachidonic acid is a necessary component of cell membranes, and plays roles in cell signaling and inflammation. Read more…

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Major misperceptions in how supplements are tested before being launched for sale

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Many horse owners are quick to try new horse supplements to remedy any number of health issues. But just how well do people understand the equine supplement industry? Recent study results from Ireland suggest there’s room for improvement.

While several studies have focused on identifying types of supplements fed according to riding discipline, Jo-Anne Murray, PhD, PgDip, PgCert, BSc(Hons), BHSII, RNutr, FHEA, a professor at the University of Glasgow’s School of Veterinary Medicine, in Scotland, and colleagues sought to learn about the use and perceptions of dietary supplements among Irish equestrians. They defined a supplement as “any additional feed ingredient that is a nutritional or health supplement.”

The researchers distributed an online survey to collect information on user demographics, types of horse supplements fed, reasons for use, factors influencing supplement choice, where respondents sought advice, and perceptions of equine supplement testing and regulation.

The researchers collected responses from 134 equestrians identified as equine industry professionals (30%) or nonprofessionals/amateurs (70%).

Most participants (98% of professionals and 86% of nonprofessionals) reported feeding at least one supplement. Joint and calming supplements were the most common, fed by 22% and 13% of all participants, respectively. Respondents fed digestive, vitamin/mineral, and electrolyte supplements least frequently.

Further, the researchers found that:

  • 12% of participants reported giving horses more than the recommended feeding rate, anywhere from 1.5 to two times the manufacturer’s suggested amount;
  • 53% of respondents sought nutritional advice from their feed merchants while 46% sought advice from their veterinarians;
  • 90% of respondents said veterinary recommendation was the most influential factor when choosing a supplement, followed by cost (69%);
  • Many respondents believed horse supplements were regulated better than current law requires; more than 93% said they believe supplements must meet legal standards, 73% believe each supplement batch is analyzed for quality, and 92% believe supplements are tested on horses before being marketed; and
  • 89% of participants reported being dissatisfied with the availability of unbiased nutritional advice for their horses.

“This study has identified the main types of supplements used in the Irish equestrian industry along with the reasons for their use,” the researchers noted. “However, it has also highlighted major misperceptions in how supplements are tested before being launched for sale and further work on this aspect of the findings would be beneficial.”

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