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]

Encouraged by the reception to the first West End revival, producers began looking to bring Cats back to Broadway in early 2015.[108] The Broadway revival opened on 31 July 2016 at the Neil Simon Theatre.[109] It featured new choreography by Andy Blankenbuehler, with Nunn and Napier from the original creative team returning to direct and design respectively.[110] Scherzinger, who played Grizabella in the 2014 West End revival, had originally agreed to reprise the role on Broadway but later withdrew.[111] Leona Lewis was cast as Grizabella instead and was ultimately succeeded by Mamie Parris in October 2016.[64] The Broadway revival closed on 30 December 2017 after 16 previews and 593 performances.[109]
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.
Before Old Deuteronomy can announce his decision, Grizabella returns to the junkyard and he allows her to address the gathering. Her faded appearance and lonely disposition have little effect on her song ("Memory"). With acceptance and encouragement from Jemima and Victoria, her appeal succeeds and she is chosen to be the one to go to the Heaviside Layer and be reborn into a new Jellicle life ("Journey to the Heaviside Layer"). A tyre rises from the piles of junk, carrying Grizabella and Old Deuteronomy partway toward the sky; Grizabella then completes the journey on her own.[i] Finally, Old Deuteronomy gives his closing speech to the audience ("The Ad-dressing of Cats") and the show comes to a close.
Cats are unusually dependent on a constant supply of the amino acid arginine, and a diet lacking arginine causes marked weight loss and can be rapidly fatal.[115] Arginine is an essential additive in cat food because cats have low levels of the enzymes aminotransferase and pyrroline-5-carboxylate which are responsible for the synthesis of ornithine and citrulline in the small intestine. Citrulline would typically go on to the kidneys to make arginine, but because cats have a deficiency in the enzymes that make it, citrulline is not produced in adequate quantities to make arginine. Arginine is essential in the urea cycle in order to convert the toxic component ammonia into urea that can then be excreted in the urine. Because of its essential role, deficiency in arginine results in a buildup of toxic ammonia and leads to hyperammonemia.[116] The symptoms of hyperammonemia include lethargy, vomiting, ataxia, hyperesthesia and can be serious enough to induce death and coma in a matter of days if a cat is being fed an arginine-free diet. The quick onset of these symptoms is due to the fact that diets devoid in arginine will typically still contain all of the other amino acids, which will continue to be catabolized by the body, producing mass amounts of ammonia that very quickly build up with no way of being excreted.[citation needed]
English-language touring companies have also toured the European region extensively. International tours in the early to late 2000s included stops in Sweden, Norway,[219] Finland,[220] Greece,[188] Portugal,[221] Germany,[222] and Italy.[223] The 2013–2014 UK tour visited cities in Belgium,[214][224] Greece, Italy,[225] Monaco, and Portugal.[153] Most recently, a UK production played in numerous European cities from 2016 to 2019, with tour stops in Switzerland, Croatia, Belgium, Poland, Bulgaria, Germany, Norway, Sweden, Finland, Denmark, Netherlands, and Luxembourg.[226] These European tours have featured several notable performers in the role of Grizabella, including Pernilla Wahlgren (Sweden; 2003),[227] Katarína Hasprová (Slovakia; 2016)[228] and Jenna Lee-James (Netherlands; 2018–2019).[229]
After the Jellicle Ball, Old Deuteronomy contemplates "what happiness is", referring to Grizabella. However, the cats do not understand him, so he has Jemima (or Sillabub, depending on the production), the youngest of all Jellicles, sing it in simpler terms ("The Moments of Happiness"). Gus – short for Asparagus – shuffles forward as the next cat to be introduced ("Gus: The Theatre Cat"). He was once a famous actor but is now old and "suffers from palsy which makes his paws shake". He is accompanied by Jellylorum, his caretaker, who tells of his exploits. Gus then remembers how he once played the infamous pirate captain, Growltiger a.k.a. the Terror of the Thames ("Growltiger's Last Stand"). Gus tells the story about the pirate captain's romance with Lady Griddlebone, and how Growltiger was overtaken by the Siamese and forced to walk the plank to his death.
Cats are known for spending considerable amounts of time licking their coats to keep them clean.[147] The cat's tongue has backwards-facing spines about 500 μm long, which are called papillae. These contain keratin which makes them rigid[148] so the papillae act like a hairbrush. Some cats, particularly longhaired cats, occasionally regurgitate hairballs of fur that have collected in their stomachs from grooming. These clumps of fur are usually sausage-shaped and about 2–3 cm (0.8–1.2 in) long. Hairballs can be prevented with remedies that ease elimination of the hair through the gut, as well as regular grooming of the coat with a comb or stiff brush.[147]

Domestic kittens in developed societies are usually vaccinated against common illnesses from two to three months of age. The usual combination vaccination protects against feline viral rhinotracheitis (FVR), feline calicivirus (C), and feline panleukopenia (P). This FVRCP inoculation is usually given at eight, twelve, and sixteen weeks, and an inoculation against rabies may be given at sixteen weeks. Kittens are usually spayed or neutered at seven months of age, but kittens may be neutered as young as seven weeks (if large enough), especially in animal shelters.[20] Such early neutering does not appear to have any long-term health risks to cats, and may even be beneficial in male cats.[21] Kittens are commonly wormed against roundworms from about four weeks.[22]

The Late Latin word is generally thought to originate from an Afro-Asiatic language, but every proposed source word has presented problems. Many references refer to "Berber" (Kabyle) kaddîska, 'wildcat', and Nubian kadīs as possible sources or cognates, but M. Lionel Bender suggests the Nubian term is a loan from Arabic قِطَّة qiṭṭa.[25] Jean-Paul Savignac suggests the Latin word is from an Ancient Egyptian precursor of Coptic ϣⲁⲩ šau, 'tomcat', or its feminine form suffixed with -t,[26] but John Huehnergard says "the source [...] was clearly not Egyptian itself, where no analogous form is attested."[25] Huehnergard opines it is "equally likely that the forms might derive from an ancient Germanic word, imported into Latin and thence to Greek and to Syriac and Arabic". Guus Kroonen also considers the word to be native to Germanic (due to morphological alternations) and Northern Europe, and suggests that it might ultimately be borrowed from Uralic, cf. Northern Sami gáđfi, 'female stoat', and Hungarian hölgy, 'stoat'; from Proto-Uralic *käďwä, 'female (of a furred animal)'.[27] In any case, cat is a classic example of a word that has spread as a loanword among numerous languages and cultures: a Wanderwort.