Mother dog and litter at Austin Animal Center, as posted on PetHarbor.com

As a no kill advocate, I am opposed to the spaying of pregnant shelter animals.  While I do not believe in the myth of pet overpopulation, that has nothing to do with my opposition.  Even if I believed pet overpopulation was real (I do not), I would still be opposed to spaying pregnant dogs and cats because doing so means killing unborn puppies and kittens who have the right to live.  As Nathan Winograd wrote in his blog:

When we spay pregnant animals and the unborn kittens and puppies die, the fact that they are not yet born does not relieve our responsibility toward assuring their right to live. When we abort kittens and puppies, we are literally killing puppies and kittens.

If the kittens or puppies are viable, they must be individually killed, usually through an injection of sodium pentobarbital. Even when they are not, however, when a mother is spayed, the kittens or puppies die from anoxia (oxygen deprivation) due to lack of blood supply from the uterus once the vessels are clamped. They suffocate.

I tragically witnessed the spaying of a pregnant dog when I worked in a vet clinic a couple of decades ago.  There were two vets on duty and one was performing the surgery.  She threw the uterus containing the puppies into the trash.  The other vet retrieved the uterus and placed it on a sink table.  The puppies crawled around helplessly while she drew up injections of Fatal Plus for each.  Had she not killed them individually, they would have crawled around in the trash can until they eventually died.  Back then, I did believe that pet overpopulation was real.  But I still knew these killings were wrong.

In a shelter environment, pregnant dogs and cats are either killed or spayed regularly.  There are presumably times when pregnant dogs and cats are killed or spayed and no one knew the animal was pregnant.  While there may be variations among individuals, it is generally impossible to tell if a dog is pregnant just by looking at her during the first 5 weeks of the normal 9 week gestation period.  With some dogs, you can not tell even in the last 4 weeks of pregnancy.  Luckily there are other detection methods which can be performed by an experienced vet but they are limited.  It is possible for vets who specialize in canine reproduction to palpate the uterus at approximately 4 weeks.  The puppies at this time are contained in walnut sized sacs and the window for palpation is brief – about 1 week.  Even if the timing is right and the vet is experienced, there are still some dogs who carry their pups in such a way to make palpation impossible.  Ultrasound is a more reliable method of detecting pregnancy and may be used from about 3 weeks onward.  Radiographs can only be used to detect pregnancy during the final 2 weeks of gestation.  By that point, the dog may be able to diagnosed by simple observational methods such as an enlarged abdomen, development of mammary tissue, and fetal movement.  While I have very little experience with female cats, my understanding is that pregnancy detection methods are similar to those used with dogs and ultrasound is the preferred method for reliability.

What does all this mean for female shelter animals?  I believe we have a moral obligation to protect the lives of all shelter animals, including the unborn.  I would therefore offer guidelines for a certain portion of the shelter population.  That portion includes all female dogs and cats who meet the following criteria:

• Have reached the age of puberty (approximately 6 months).
• Have an unknown medical history and no sign of having been spayed (such as spay scar or tattoo).
• Have not come into heat while in the shelter’s care.  (Pregnant dogs and cats do not come in season.)

For female shelter animals who meet the above criteria, I suggest the following guidelines to protect the lives of any puppies or kittens they may be carrying:

• If the female dog or cat meeting the specified criteria has been at the shelter for less than 9 weeks, the operating assumption must be that the animal is pregnant.  For those animals meeting the criteria who have been at the shelter for less than 3 weeks, an inconclusive veterinary determination must be interpreted as positive for pregnancy until a conclusive determination can be made at a later date.

• Under no circumstances should a female dog or cat meeting the specified criteria be killed unless a veterinarian determines she is irremediably suffering, in which case euthanasia should be performed.

• Once a female is scheduled for sterilization, she should be evaluated for signs of pregnancy by the shelter vet.

• If the shelter vet determines the animal is pregnant, the shelter may release her with reasonable restrictions to ensure that mother and litter are all sterilized prior to permanent adoption.

• If the vet’s determination is inconclusive, the female may be released with a signed agreement to avoid all contact with intact males of her species until 9 weeks have elapsed from date of impound at which time she can be returned to the shelter for spay (or spayed by a private vet of the adopter’s choosing with verifiable documentation to be provided to the shelter).

• Females meeting the specified criteria who have been at the shelter less than 9 weeks (but more than 3 weeks) may be spayed if a veterinarian determines, based upon ultrasound and confirmed by observation, that she is not pregnant.

• Females who have come into heat while in the shelter’s care and who have been prevented from any unsupervised contact with intact males of their species may be assumed not to be pregnant and may be spayed without veterinary consultation regarding possible pregnancy.

• Females meeting the specified criteria who have been at the shelter for more than 9 weeks and who have been prevented from any unsupervised contact with intact males of their species may be assumed not to be pregnant and may be spayed without veterinary consultation regarding possible pregnancy.