If we use the argument that "... whatever action is done out of greed, hatred or delusion ... will ripen wherever the individual is reborn; and wherever the action ripens, there the individual experiences the fruit, be it in this life, or in the next life, or in subsequent future lives. ~ Nidana Sutta (AN 3.34) or that "So, even without any dogs to be born into, the law of kamma will find its way. Right? If there's no available wombs around your area, kamma finds its way elsewhere." to suggest that it is pointless to get animals neutered, then can we also apply this same principle to humans and suggest that drug rehabilitation, treatment of diseases, rescue from natural disasters, prevention of wars, hysterectomies to prevent ovarian cancer, etc. are also futile in the prevention of suffering? Why bother getting a drug addict rehabilitated if his "kamma" is to suffer? Why bother saving the life of a cancer patient if it is his "kamma" to suffer the pain? Cure them now but "kamma will find its way elsewhere", wouldn't it? They are doomed to suffer because "when the action ripens, be it this life, next life or in subsequent future lives, that being, whoever he or she may be, will still bear the fruit of his/her previous action". But we humans don't seem to apply this to fellow humans, so we continue doing charity for humans. We continue helping the poor in the slums of Calcutta, the war victims in Africa, the orphans, the old folks, the mentally depressed, victims of earthquakes and tsunamis. Why? Help them now, but they will still suffer in their next life. So looking at this far-sighted big picture, we are not really alleviating suffering, are we? On this note, I agree with Pilgrim that "The workings of kamma is extremely complex and beyond avoiding evil and doing good, we cannot make policies based on speculation how kamma will come to fruition for the infinite number of beings seeking birth. We can only seek to solve the suffering before us."
And Bhante Kumara, you explained: "My initial response was "I wouldn't want this to be done to me." I wonder: Isn't this inflicting harm on another? Is it right to cause some suffering to existing animals to prevent the potential suffering of those seeking birth (sambhavesi)? As above, is it even possible to prevent their suffering?" Based on your statement above, if I understand you correctly, is it because you are empathetically putting yourself in the place of the animal and you "wouldn't want this to be done" on you? In other words, you do not want to be neutered without your permission? However, for me, personally, if I knew that unless I was spayed, I would be producing offsprings every cycle until the day I die or that I will be hounded by males of my species and subject to an activity which I find painful (according to the university veterinarian) or that I will not be able to take care of the many offsprings that I would produce, I would want a human to get me spayed. That's me speaking, empathetically, ie. putting myself in the place of a female dog or cat. I suppose then, the counter argument to this would be: Wait a minute, if you are a dog or a cat, you won't know all this! Then I might say: How do we know that they don't know? Animals know much more than what we give them credit for. I am speaking from experience since I deal with them on a daily basis. I've had stray cats coming to me, walking straight into the cage only to have me discover that they have a wound that needs to be treated. My most recent experience is this stray cat who came back to me twice a day to be fed his antibiotics...because he knew he needed the bitter medication to get well? I don't know...you tell me.
The benefits of neutering are many. In my opinion, these benefits far outweigh the philosophical arguments put forth against it. If you are directly involved in rescue work, you might see why. For example, (1) We have encountered mother-dogs protecting their newborns, refusing to run when council workers go on their rounds, even when the rest of the colony runs and escapes capture. The mother-dog and her puppies are then captured and brutally killed. (2) We have encountered kittens infected with FIV or FeLV, transmitted from the mother (because she is a stray), dying from these terminal diseases. Now, had the mother-dog in (1) been spayed, she would have run from the council workers as she would not have stayed behind to protect the babies as there would have been no babies. In (2), if the mother-cat had been spayed, she would not have produced the FIV or FeLV-infected babies who later die a slow and agonising death on the street. I could go on, based on the years of rescue work I have done, but as someone rightly pointed out in this forum, our decisions very much depends on what we do and the experiences we have had. It is quite impossible to convince someone to agree with our views when he or she has not seen or experienced what we have and in such case, I would prefer to disagree and go on doing what we think is best for the animals with a clear conscience.
However, one thing disturbs me, though. It is to see that lady crying at the temple, asking me what to do with the 16 puppies her unspayed female dog had given birth to, and telling me that her master (I assume, a spiritual teacher) forbids her to get her pet-dog spayed because it was "wrong" to do so. While we are told to question, investigate and put the teachings to the test, some people prefer to just listen to what their spiritual teachers tell them. I wonder how many puppies the lady has now and I wonder what she has done with those puppies as she refused to let me take her dog to be spayed. I know of others in the same position who would put the puppies in a sack, drive to a far-off place and dump them there (to die). It also disturbs me to have visited this other lady who had rescued more than 100 dogs and had kept them in tiny cages in a "shelter" that she had built. The males are caged separately from the females, because her Buddhist belief forbids her from getting them neutered. We offered to neuter her dogs for free for her, but she declined our offer because she is Buddhist. The male dogs go cranky when the females come on heat and they end up attacking each other. Mating animals will fight to the death and go for blood - that is how strong and vicious this instinct is. Neutered male animals may still fight for territory but they often do not go for blood (based on research findings). So, this lady's dogs are kept in cages all their lives to prevent them from mating. Now, to me, that is suffering, a far greater suffering than living in another shelter that practises neutering where dogs are allowed to roam freely within the shelter grounds, where males do not go cranky and kill each other during the mating season. But of course, that is just my opinion based on what I have seen and what I do to help animals.
Allow me to quote Pilgrim again that "we can only seek to solve the suffering before us". So, if I were to see a child about to be run over by a lorry, I would pull the child away to safety. Someone, quoting the Nidana Sutta, might argue saying that I haven't done the child any good because it is his kamma to suffer that fate in another instance or another life. But I'd still pull the child to safety, anyway.