Green’s Dictionary of Slang

1. very tall, very high.

1833		S. Smith Major Downing (1834) 200: Cutting up capers as high as a cat’s back.
1896		J.F. Lillard Poker Stories 196: Soon his checks were piled ‘higher than a cat’s back’.
1912		DN.
1931		D. Runyon ‘Blood Pressure’ in Runyon on Broadway (1954) 73: My blood pressure is higher than a cat’s back.
1942		Berrey & Van den Bark Amer. Thes. of Sl. 39.7: Tall; high...higher than a cat’s back .
1984		R. Wilder You All Spoken Here 72: As high as a cat’s back: ’Way up.

2. very expensive; priced very high.

1882		Breeder’s Gaz 1 505/2: SHEEP— ‘Higher than a cat's back!’ is the expressive and frequently very emphatic answer to the question ‘How is the sheep market?’.
1906		DN III 140: High as a cat’s back [...] Very high-priced.
1927		Ruppenthal Collection n.p.: High as a cat’s back —very high, esp. as to price, cost, etc [DARE].
1934		Smiley Gloss. New Paltz n.p.: High as a cat’s back—Speaking of the price of maple syrup: ‘Syrup is going to be as high as a cat’s back’ [DARE].
1965–68		in DARE.
1971		Today Show Letters n.p.: That store is as high as the hair on a cat’s back [DARE].

3. in fig. use, of money or a limit in gambling.

1887		G. Devol Forty Years a Gambler 18: I began [...] to play the bank higher than a cat’s back, as the old keno game was a great producer.
1903		A. Adams Log of a Cowboy 269: The dealer has lowered the limit from a hundred to fifty, for old Paul is playing them as high as a cat’s back.
1903		A.H. Lewis Boss 195: You’re setting into a game of commerce where the limit’s higher than a cat’s back.

4. drunk [pun on SE high/high adj.¹ (1)].

1969–70

in DARE.