The primary Halachic and cultural matters one must deal with when owning a dog, and to a lesser extent, a cat, which may, for many, comprise a barrier to pet ownership, are the following.
1. Muktzah. One Sabbath and Holidays, Rabbinic Law prohibits us from handling objects that do not serve some use for that day. Examples: we cannot handle money; because we cannot engage in commerce on these days, money is of no legitimate use, and is called "muktzah," or "set aside." We cannot handle lumber, because we can't do construction. We cannot handle pebbles, because they have no utility. Many people apply this prohibition to animals, because you can't really "do" anything with animals on the Sabbath or Holidays. You can't have them do work for you or carry your things, and you can't eat them. So animals would be Muktzah. This was certainly true when dogs were working animals. Over the course of the last one hundred and fifty years, however, the function of dogs and cats in the context of human society has changed from provider of service to provider of companionship, from work to sentimentality. (An interesting indicator of this change was the creation of Le Cimetière des Chiens et Autres Animaux Domestiques, the Dog and Domestic Pet Cemetery of Paris. This was founded in 1899, and apparently is the first pet cemetery in the world. To save you the trouble of visiting, here is a series of photos.) There are rabbinic opinions that say that today, pets are not muktzah because they are owned in order to play with them, which, then, becomes a legitimate 'use.' This is, for the moment, the minority opinion. Of course, the balance of opinion is irrelevant to one who has asked the question to his own Rabbi. Because there is a broad spectrum of legitimate opinions on this issue, every Rabbi of good repute can make halachic decisions for his community.
(The muktzeh issue is discussed in the comments which follow this post.)
2. Walking a dog with a leash on the Sabbath. On the Sabbath, and to some extent on religious holidays, we are not allowed to carry anything in a unenclosed public areas. Although we can carry inside a house or an enclosed back yard or a park on the Sabbath, we can not carry outside of such areas unless an eruv was built around the area. No keys, no handkerchiefs, no ID, nothing. Holding an animal's leash while walking it in a public domain can be problematic, because it can be viewed as carrying the leash. Technically, this depends on how the leash is held, but this is a topic for live rabbinic consultation, not the internet.
3. Feeding pets: Jews can only eat kosher food. Our animals, however, are not Jewish. They can eat whatever they want. However: there are certain foods that Jews are not even allowed to own and certainly not to have on their property; one example is leavened grain products on Passover. Similarly, cooked mixtures of milk and meat: not only are we not allowed to eat such mixtures, but we are prohibited from having any benefit, no matter how small, from them. We can't sell them (because receiving the proceeds of the sale is a benefit), we can't even give them away to non-Jewish friends (because the enjoyment of giving a gift is a benefit), and, most importantly for this discussion, we can't feed them to our animals. It can be difficult to find pet food that does not contain a mixture of meat and milk, or grain products on Passover. This has led to the peculiarity of animal foods which are not kosher but which have a Kosher symbol on them to certify that there are no grain products in them (on Passover) and that they have no mixture of milk and meat.
4. Spaying and Neutering pets. The owner of an animal might want to spay or neuter his pet for peace of mind, or for health reasons. Some municipalities require that pets be spayed or neutered. This can generate serious problems in Jewish law, because spaying and neutering of all organisms, from insect to human, is biblically forbidden.
Spaying and Neutering pets, and other issues, are discussed here and here.
5. Animal tags and collars. We are obligated to see to it that our animals do not work on Shabbos for anything but their own benefit. Obviously, they can eat grass, because although eating growing grass would be prohibited to us, they can do whatever they want if it is what they want. Animals that have collars and tags can be said to be carrying them in the street. If these are for their benefit, namely ornamentation or to prevent the government from impounding them or to enable us to retrieve them if they are lost, then it can be argued that they are permitted to carry them, as does Rav Shlomo Zalman Auerbach as brought in the Shmiras Shabbas Kehilchasa. The Aruch Hashulchan is very leery of being permissive. This, too, requires consultation with a live and knowledgeable Rabbi.
6. A Non-Halachic Factor: Among some Orthodox Jews, there is a belief that dogs are 'impure' or 'unholy.' This perception is limited to communities that are oriented toward Hasidism and Kabbala, who discourage even gazing upon animals that are not kosher, and strongly discourage playing with such animals. However, for the many Orthodox Jews that are not Hasidic this is not a factor at all.
7. Frightening away wayfarers and the poor. A dog frightens away people who come to seek help, people whom we should be welcoming into our homes. (Shabbos 63a-b)
8. The language of the Rambam. Maimonides, the Rambam (5 Nizkei Mamon 9) says that it is prohibited to own dogs that are not bound by a strong rope, but one may own such a dog if he lives in a dangerous area and needs the dog for protection. He ends by saying that dogs often cause a great deal of damage, and so the Sages cursed those that own dogs. One of the dangers the Rambam is referring to is mentioned in Bava Kamma in Meruba, where it says that a barking dog can frighten a pregnant woman and cause her to miscarry (Bava Kamma 83a, and the Maharsha in Bava Kamma 15b).
In any case, the Rambam is not cited by the later Halachic authorities. Obviously, the concern about damage depends on the circumstances, and he does say that a dog that is not dangerous is not a problem. These days, such events are vanishingly rare except among the the maladjusted, or criminals, or uneducated people who buy dogs specifically to intimidate and threaten.
Certainly, if the dog is chained and obviously not a threat, these issues would not apply. (see, e.g., Choshen Mishpat 409:3-4, and שו״ע הרב הל׳ שמירת גוף ונפש ובל תשחית סעיף ג)
9. It is incongruent, perhaps incompatible, with a solemn and contemplative lifestyle. The truth is that classical Jewish culture (see, e.g., Against Apion, paragraph 12), despite the ugly image that often appears in the mass media, has always frowned on frivolousness and wasting of time. Outside of marginal or ignorant Jews, the Jewish People has historically striven to focus their time and their lives on moral and intellectual self-improvement. Owning a dog is a self-indulgence that does not contribute to spiritual growth. Still, this is not a hard and fast concept. People are certainly entitled to a pleasant life, and not everyone is a scholar or a ascetic.
This ends the Halachic and Cultural section of this post.
The craziness that sometimes arises from dog ownership, that also repels some Orthodox Jews, and no doubt others as well, is illustrated here and here.
I don't know how long the links will be active, so I'll tell you that they're about a New York Jew, one David Best, who made a bark-mitzvah for his dog-- and fired his rabbi when he made a mildly negative comment about the appropriateness of the event. Maybe he should have contacted Rabbi Halivni.
There are news articles that make you proud of your fellow Jews. This is not one of them.
Thankfully, this, from the aforementioned pet cemetery in Paris, outdoes Mr. Best.
Now, the conceptual discussion.
In Plutarch's Pericles, written in the year 75, he says
(Translated by John Dryden)
CAESAR once, seeing some wealthy strangers at Rome, carrying up and down with them in their arms and bosoms young puppy-dogs and monkeys, embracing and making much of them, took occasion not unnaturally to ask whether the women in their country were not used to bear children; by that prince-like reprimand gravely reflecting upon persons who spend and lavish upon brute beasts that affection and kindness which nature has implanted in us to be bestowed on those of our own kind.
Plutarch was not the first to make this critical observation. The Haftorah this week (although some people lein it for next week’s parshah), is from Hosheah 13. In passuk 13:2 it says "Zovchei odom agolim yishokun," Those who slaughter men, they kiss their Calf effigies. Rashi brings the Gemora in Sanhedrin (63 or 4) that this is what the idolatrous priests told their followers— if you have sacrificed your child to Moleich, then you will be allowed the great merit of kissing the Calf Effigy. But others (see Ibn Ezra) have said this is a sarcastic reference to those people who have an overdeveloped sense of love for animals but hate people. The Nazis also encouraged love for pets, and the most vile and debased officials often had a pet dog upon whom they lavished their love. O’Henry was aware of this apparent incongruity, and he wrote a story called "The Theory and the Hound" in which a detective exposes a murderer by kicking a dog in the presence of the several suspects and seeing which of them reacts with the most visceral and angry howl of outrage.
Although anecdotal, this seems to be an real phenomenon, and we need to understand why it is true and the underlying mechanism. I suggest that this is a self-esteem compensation mechanism. These people are misanthropes. This trait bothers them, because they want to think of themselves as morally superior and good. So they compensate by saying to themselves, at some deep level, that really they are good people, and they find some absurd way of demonstrating their warmth and sympathy. They are unwilling to love people, so they shower their love on whatever else enters their sphere– cats, dogs, monkeys, anything that does not compete for equivalence, anything that does not infringe on their solipsistic world view--, that is, anything but people. This enables them to feel good about themselves, to have high self-esteem.
We find the same idea expressed in the story of Laban. He cheated Jacob mercilessly, but when the time came to make an accounting, and Jacob took what he was entitled to, Lavan said that Yaakov was a theif. Lavan was the biggest thief, but he thought of himself as the most honest person who was being taken advantage of, and he decided that letting Yakov get away with the sheep showed that he, Lavan, was a sweetheart. He said, the children are mine, the sheep are mine, if only you had let me kiss my daughters goodbye. In fact, no matter what settlement Yakov suggested, he never would have let Yakov go; he would have kept the sheep and his daughters and their children, and he would have killed Yakov in the bargain. But in his own mind, he was a prince of a man.
UPDATE December 2011:
Plutarch was also not the last to make that observation. I just read an article in the New Yorker that contained an ironic group of stories, as follows:
Have you tried SweeTango? Glickberg asked another customer. "If you like a crisp apple, this one is good."
"Too expensive" the woman said......
The next woman began filling a bag with them. "I just like the way they look," she said.
Another woman stopped in front of SweeTango. "Now I read about these new apples on the web, and I think this was one of them."
"What are they like"
"Very crisp and very sweet."
"Oh, good, my dogs will like them."
"Well, we share them," the woman went on. "I have four dogs." She lowered her voice conspiratorially. "I have to peel them for one. He doesn't like the skin."
John Seabrook, Annals of Agriculture, “Crunch,” The New Yorker, November 21, 2011, p. 54
I found a nice little story that is best left untranslated:
מספרים: שפעם א׳ פגש רב אחד את אחד ממכיריו ברחוב שטייל עם כלבו — ואמר לו: מה לך לטפל בדברים
טמאים למה לך הכלב הזהו? א״ל: רבי! זה הקדיש שלי אני אוהב אותו מאד מאד. ממש כבן. כן. אמר לו הרב- צדקת
מאד כי כבר רואה אנכי שאתה תשאיר אחריך קדיש יותר נהמד ונעים ממה שהשאיר אביך המנוח