The original London production received mostly rave reviews, with critics hailing it as a watershed moment in British musical theatre.[295] Michael Billington of The Guardian lauded Cats as "an exhilarating piece of total theatre". Billington praised the show's "strong framework" and the ease in which the poems were integrated. He was also very impressed by Lloyd Webber's fitting compositions, Napier's environmental set, Lynne's effective and at times brilliant choreography, and Nunn's "dazzling staging" that makes use of the entire auditorium.[296] The show received similarly glowing reviews from The Sunday Times' Derek Jewell and The Stage's Peter Hepple. Jewell proclaimed it to be "among the most exhilarating and innovative musicals ever staged",[295] while Hepple declared that with Cats, "the British musical has taken a giant leap forward, surpassing in ingenuity and invention anything Broadway has sent us".[297]
Vitamin A is required in kitten diets because cats cannot convert carotenes to retinol in the intestinal mucosa because they lack the enzyme so this vitamin must be supplement in the diet.[24][42] Vitamin E is another required vitamin in kitten diets seeing as deficiency leads to steatitis, causing the depot fat to become firm and yellow-orange in colour, which is painful and leads to death.[42] Also, vitamin D is an essential vitamin because cats cannot convert it from precursors in the skin.[24]

Cats conserve heat by reducing the flow of blood to their skin and lose heat by evaporation through their mouths. Cats have minimal ability to sweat, with glands located primarily in their paw pads,[105] and pant for heat relief only at very high temperatures[106] (but may also pant when stressed). A cat's body temperature does not vary throughout the day; this is part of cats' general lack of circadian rhythms and may reflect their tendency to be active both during the day and at night.[107]:1
Additionally, Cats was the first Broadway and West End show to capitalise on merchandising as a major revenue stream. Stalls were set up in the theatre lobbies to sell souvenirs ranging from toys and watches to coffee mugs, all of which were emblazoned with the cat's-eyes logo. The official Cats t-shirt became the second-best-selling t-shirt in the world in the 1980s, second only to the Hard Rock Cafe t-shirt. Merchandising has since become an important source of income for the industry.[313][323]
Despite moderate hits with Jesus Christ Superstar and Evita, Lloyd Webber was still relatively unknown to the general public before Cats, especially in the US. With Cats, he became a big celebrity in his own right.[318] The musical also established the theatrical careers of the original creative and production team. Following Cats, they collaborated on other global blockbusters including Starlight Express (composed by Lloyd Webber, directed by Nunn and designed by Napier), Les Misérables (directed by Nunn, designed by Napier and produced by Mackintosh), and The Phantom of the Opera (composed by Lloyd Webber, choreographed by Lynne and produced by Mackintosh).[1][335]
An event called the Jellicle Ball was referenced by Eliot in the poem "The Song of the Jellicles", while a cat version of heaven known as the Heaviside Layer was mentioned in one of his unpublished poems. Nunn expanded on these concepts by conceiving the Jellicle Ball as an annual ritual in which the cats vie to be chosen to ascend to the Heaviside Layer, thus giving the characters a reason to gather and sing about themselves in the musical. He also added the element of rebirth as a play on the idea that cats have nine lives.[1]
The musical was scheduled to open on 30 April 1981, with previews starting on 22 April. Shortly before tickets went on sale in mid-February, Nunn revealed to the alarmed producers that he was struggling to write the script for the musical. Despite still having no established book or score, rehearsals began on 9 March 1981 in a church hall in Chiswick, London. The original music director, Chris Walker, became so frustrated with the unfinished score that he quit by lunchtime and was replaced by the film conductor Harry Rabinowitz.[20] The situation improved later that day when Lloyd Webber, Mackintosh and Nunn met with Stilgoe, a musician known for his ability to improvise lyrics on the spot, in hopes that Stilgoe could write an opening song for the musical. By the next evening, Stilgoe had produced a draft for "Jellicle Songs for Jellicle Cats".[21] However, "Memory", an 11 o'clock number for Grizabella that Nunn insisted the show needed as its "emotional centre",[22] still had no lyrics at this point. Lloyd Webber's former writing partner Tim Rice was brought in to write a lyric for the song, but his version was rejected by Nunn for being too depressing. The lyrics for "Memory" were not completed by Nunn until well into the previews.[23]
About 250 heritable genetic disorders have been identified in cats, many similar to human inborn errors.[286] The high level of similarity among the metabolism of mammals allows many of these feline diseases to be diagnosed using genetic tests that were originally developed for use in humans, as well as the use of cats as animal models in the study of the human diseases.[287][288]

Cats have excellent night vision and can see at only one-sixth the light level required for human vision.[66]:43 This is partly the result of cat eyes having a tapetum lucidum, which reflects any light that passes through the retina back into the eye, thereby increasing the eye's sensitivity to dim light.[75] Another adaptation to dim light is the large pupils of cats' eyes. Unlike some big cats, such as tigers, domestic cats have slit pupils.[76] These slit pupils can focus bright light without chromatic aberration, and are needed since the domestic cat's pupils are much larger, relative to their eyes, than the pupils of the big cats.[76] At low light levels, a cat's pupils will expand to cover most of the exposed surface of its eyes.[77] However, domestic cats have rather poor color vision and (like most nonprimate mammals) have only two types of cones, optimized for sensitivity to blue and yellowish green; they have limited ability to distinguish between red and green.[78] A 1993 paper reported a response to middle wavelengths from a system other than the rods which might be due to a third type of cone. However, this appears to be an adaptation to low light levels rather than representing true trichromatic vision.[79]
Despite mixed reviews when Cats opened in New York in 1982, critics agreed that it was innovative and visually spectacular in ways that Broadway had never seen before.[304] The musical became a cultural phenomenon and has had a profound influence on the medium.[312] Cats established musical theatre as a global commodity,[313][314] marking the beginning of a new era in the industry that is characterised by huge global stakes for potentially even huger global profits.[313] It led the shift in the Broadway market towards big-budget blockbusters and shows that appeal to families and tourists,[88][315] which in turn left smaller productions struggling to compete.[314] Cats also ushered in a "golden age of British musicals" which saw West End exports dominate the industry for nearly two decades.[316][317] Musical theatre historian Vagelis Siropoulos asserted that its "seminal Broadway opening" was "comparable only to Rodgers and Hammerstein's Oklahoma! thirty nine years ago."[313]
Cats have excellent hearing and can detect an extremely broad range of frequencies. They can hear higher-pitched sounds than either dogs or humans, detecting frequencies from 55 Hz to 79,000 Hz, a range of 10.5 octaves, while humans and dogs both have ranges of about 9 octaves.[80][81] Cats can hear ultrasound, which is important in hunting[82] because many species of rodents make ultrasonic calls.[83] However, they do not communicate using ultrasound like rodents do. Cats' hearing is also sensitive and among the best of any mammal,[80] being most acute in the range of 500 Hz to 32 kHz.[84] This sensitivity is further enhanced by the cat's large movable outer ears (their pinnae), which both amplify sounds and help detect the direction of a noise.[82]

After the fight, Rum Tum Tugger calls upon the magician Mr. Mistoffelees for help ("Magical Mr. Mistoffelees"). Known as the "original conjuring cat", Mr. Mistoffelees can perform feats of magic that no other cat can do. He displays his magical powers in a dance solo and uses them to restore the lights and bring back Old Deuteronomy. Now, the Jellicle Choice can be made.
The fourth national company, Cats National IV, toured the United States for 13 years from March 1987 to December 1999.[117] It overtook the first national tour of Oklahoma! in November 1997 to become the longest-running tour in theatre history, and played its 5,000th performance in July 1999.[118] Notable performers in the fourth tour included Amelia Marshall as Sillabub (1988), Jan Horvath as Grizabella (1990), Bryan Batt as Munkustrap (1991–1992), Jennifer Cody as Rumpleteazer (1992), David Hibbard as Rum Tum Tugger (1992–1993), Natalie Toro as Grizabella (1992, 1997), Christopher Gattelli as Mistoffelees (1993), John Treacy Egan as Old Deuteronomy (1993–1994), J. Robert Spencer as Rum Tum Tugger (1995), Bart Shatto as Bustopher Jones/Gus/Growltiger (1996), Linda Balgord as Grizabella (1998), Andy Karl as Rum Tum Tugger (1998), and Lena Hall as Demeter (1998).[117] By June 1997, the North American touring companies had grossed over $400 million.[88]
Felines are carnivores and have adapted to animal-based diets and low carbohydrate inclusion. Kittens are categorized in a growth life stage, and have high energy and protein requirements.[23] When feeding a kitten, it is often recommended to use highly digestible ingredients and various components to aid in development in order to produce a healthy adult.[24] In North America, diets certified by the Association of American Feed Control Officials (AAFCO) are accepted as adequate nutrition, thus kitten diets should be AAFCO approved to ensure full supplementation.[25] Key components of the diet are high fat content to meet caloric requirements of growth, high protein to meet requirements for muscle growth as well as supplementation of certain nutrients such as docosahexaenoic acid to benefit the development of the brain and optimization of cognition.[26]
Though it’s not something you have any control over, your kitten’s age is more than just a number. In fact, it’s crucial that you learn it. Kittens have very specific developmental needs for the first 10 weeks of their lives in terms of nourishment, warmth, socialization, and excretion. For this reason, most breeders and shelters typically wait until their kittens are of age before they’re put up for adoption. If you, by chance, find yourself in a situation where you need to care for an orphaned kitten under 10 weeks old, consult your vet for special instructions.

For the first several weeks, kittens cannot urinate or defecate without being stimulated by their mother.[6] They also cannot regulate their body temperature for the first three weeks, so kittens born in temperatures less than 27 °C (81 °F) can die from hypothermia if their mother does not keep them warm.[7] The mother's milk is very important for the kittens' nutrition and proper growth. This milk transfers antibodies to the kittens, which helps protect them against infectious disease.[8] Newborn kittens are unable to produce concentrated urine, and so have a very high requirement for fluids.[9] Kittens open their eyes about seven to ten days after birth. At first, the retina is poorly developed and vision is poor. Kittens cannot see as well as adult cats until about ten weeks after birth.[10]

Cats are naturally carnivores and require high amounts of protein in the diet. Kittens are undergoing growth and require high amounts of protein to provide essential amino acids that enable the growth of tissues and muscles.[30] It is recommended that kittens consume a diet containing approximately 30% protein on a dry matter basis for proper growth.[35]
Meanwhile, Mackintosh engaged the advertising agency Dewynters to design a poster for the musical. After much back-and-forth, the agency presented a minimalist poster consisting of a pair of yellow feline eyes (with dancing silhouettes for the pupils) set against a black backdrop. The producers and the creative team loved the design but felt that the title — Practical Cats — looked out of place when paired with the image of the cat's eyes. The musical's title was thus shortened to just Cats.[19]
Female domestic cats can have kittens from spring to late autumn, with litter sizes ranging from two to five kittens.[9] Domestic cats can be bred and shown as registered pedigreed cats, a hobby known as cat fancy. Failure to control the breeding of pet cats by spaying and neutering, as well as abandonment of pets, has resulted in large numbers of feral cats worldwide, contributing to the extinction of entire bird species, and evoking population control.[10]