Coined on various occasions by different persons, independently from each other, the noun bark mitzvah denotes a (thirteenth-birthday) party held for a dog.

This noun is a blend of:
– bark, denoting the sharp explosive cry of a dog,
and
– bar mitzvah, denoting the initiation ceremony of a Jewish boy who has reached the age of thirteen and is regarded as ready to observe religious precepts and eligible to take part in public worship,
or
– bat mitzvah, denoting a religious initiation ceremony for a Jewish girl aged twelve years and one day, regarded as the age of religious maturity.

In most cases, the noun bark mitzvah is used jocularly, the events having generally little, if any, religious aspects.

The earliest occurrences of this noun that I have found are as follows, in chronological order:

1-: From Maury White’s column, published in The Des Moines Register (Des Moines, Iowa) of Thursday 22^nd September 1966—here, bark mitzvah does not denote a party held for a dog, but football-field running as an initiation ceremony for a dog:

Next to pretty girls in bands and cheering corps, dogs rank as the most welcome intruders on football fields. […]
[…]
Are dogs one-shot performers, like bulls in a bull fight, or do they show up at later games for encores? Is football-field running a status symbol or mark of maturity, possibly a canine Bark Mitzvah?

2-: From Marriage Without Children (New York: Harper & Row, 1982), by Diana Burgwyn:

Another childless couple had a beloved dog named “Son” who had his own room and a closetful of clothes; when Son reached thirteen, his “parents” told friends, they would be invited to a “Bark-Mitzvah.”

3-: From Herb Caen’s column, published in the San Francisco Chronicle (San Francisco, California) of Thursday 3^rd June 1982:

Awwww: Jim Joyce’s dog, Beowolf, having reached 13, will be honored at a “Bark-Mitzvah” tomorrow at Jim’s place on Potomac, but what does a dog need with a fountain pen?

4-: From The Scranton Times (Scranton, Pennsylvania) of Tuesday 7^th September 1982:

‘Bark Mitzvah’ Cheered, Jeered

Hewlett, N.Y. (AP)—Profanity on a crude level? Or a hilarious and fun idea?
Either way, Joan Taylor’s “Bark Mitzvah” marking her pet dog’s 13^th birthday has attracted plenty of attention.
“I had no idea it was going to take off,” said Mrs. Taylor, an interior decorator, of the celebration of her dog Lump Lump’s 13^th. “I planned on having a small little thing in my office” to raise money for a local animal society.
But word got around and the event grew to the point where on Sunday, Mrs. Taylor was preparing to entertain at least 500 people at the Sept. 15 Bark Mitzvah with hopes of presenting more than $10,000 to the North Shore Animal League.
Betty Rosenzweig, spokeswoman for the league, joked the party has grown so large “we’ll have to have everybody on a leash.”
But Rabbi Ephraim R. Wolf of the Great Neck Synagogue was not amused.
“Why use that kind of phraseology?” he asked. “I’m sure she thought it was a cute idea. However, I think she’ll find this is going to make some people upset. I think it will boomerang on her. It’s profanity on a crude level.”
Mrs. Taylor also received an anonymous call on her answering service which accused her of being “a disgrace to the Jewish faith.”

The event that Joan Taylor organised for her dog’s thirteenth birthday may have popularised the noun bark mitzvah, as this event was talked about in various newspapers and provoked many reactions—cf., below, quotation 6.

5-: From ‘Tons’ of easy hors d’oeuvres, about Rania Harris, a caterer and cooking teacher, by Woodene Merriman, published in the Pittsburgh Post-Gazette (Pittsburgh, Pennsylvania) of Wednesday 8^th December 1982:

When she caters, she does some most unusual parties. This weekend, she’s preparing all the food for what she describes as a very elegant bark mitzvah for 90. That’s right, a bark mitzvah. “The dog is 13.”

6-: From Low points are high on Esquire * reading list, by Dave Larsen, published in the Corpus Christi Times (Corpus Christi, Texas) of Thursday 23^rd December 1982—the following is about the Dubious Achievement Awards, Esquire’s fixture honouring the most preposterous, egomaniacal and monstrous behaviour of the past year:

For the time being […], all eyes are on the dubious achievements, past and present.
[…]
1982: “Four hundred pets in Hewlett, Long Island, were invited to a ‘bark mitzvah’ for a 13-year-old female mutt named Greggie (Lump Lump) Taylor.”

* Esquire is a U.S. men’s magazine.

The earliest occurrence of the synonymous noun dog mitzvah that I have found is from an Associated-Press story by Murray Coleman, published in several U.S. newspapers on Sunday 12^th January 1997—for example in The Atlanta Journal The Atlanta Constitution (Atlanta, Georgia):

Durham, N.C.
Three years ago, Andrew and Barbara Burg were a normal couple living happily in Florida—he an engineer, she a housewife.
Now the pair flies around the country, paid by well-to-do pet lovers to throw dog mitzvahs and weddings for poodles.
“People think we’ve gone bonkers,” Barbara Burg says. “But we love dogs, and there are a lot of people who share our feelings.”

There also exists the noun cat mitzvah, denoting a (thirteenth-birthday) party held for a cat—as in the following from Pet supply industry betting you like to fuss over Fido, by Chris Bynum, published in the Austin American-Statesman (Austin, Texas) of Sunday 18^th April 2004:

In the vegan category, there are vegan dog treats and kosher dog biscuits, not to mention Cat-Mitzvah treats for felines.

The rare noun car mitzvah occurs in the following from The Atlanta Journal and The Atlanta Constitution (Atlanta, Georgia) of Thursday 25^th November 1976:

Rolls-Royce Comes of Age In Florida

Lauderhill, Fla. (AP)—The invitation says, “Mr. and Mrs. B. Bregman cordially invite you to our Car Mitzvah.”
About 250 guests will dance to live music, nibble birthday cake and hear speeches at a local country club Friday night. The centerpiece of the $2,000 affair will be a Rolls Royce Silver Cloud III, built 13 years ago.
“I always liked to give parties,” said Bregman, 59, a paper company executive. “If you just give one, it’s nice. But if you think of something special, the party will be even more successful.”
Bregman said he bought the used car for $15,000 three years ago.
Despite its name, the “Car Mitzvah” will be a secular affair, Bregman said. Unlike the Jewish bar mitsvah—the coming-of-age ceremony for a 13-year-old boy—no rabbi will be there.