Prevent a litter, fix your critter!
March 13, 2014
From the desk of Dr. Voorheis
I’m sitting here contemplating at 5:00 am and recalling my wife’s recommendation, “Write about what you see”. I’m thinking this is the best time of day, surrounded by 4 dogs in various stages of repose and two cats sharing the table with me (literally the cats are sharing the table with me – my cat clients know exactly what that means. The cats have seen fit to allow me to garner a small bit of space on this table for my laptop). More musings and sharing thoughts with clients and Mozart’s 527 Overture playing in the background. Well that is something most of you didn’t know and wouldn’t have guessed. Dr. Voorheis is a classic rocker who also likes classical music. And in the midst of all this, here is what presents itself to me for this week’s blog – spay and neuter et all.
“Really Doc, you’re going to write on spay and neuter? Hasn’t that topic been done a million times?” The answer is obviously yes but new information is abreast! Remember my first blog when I shared that I am awake at 4:45am every morning reading veterinary journals, research papers and the like? All in an effort to bring the most current knowledge to my clients and their critters? Well, of late I have come upon some very interesting findings that absolutely need to be shared with all of you. This will be different than what you have always understood to be true with regard to the topic of spay and neuter. New information tells us that we need to continue discussion and interpret new information in an appropriate light and pass that information on to clients. In addition, you will get my take on ovariohysterectomies and castrations as surgeries learning what is actually involved and when they should be done. But first, let’s start with what we have always known to be true.
Traditionally, my recommendation has been to spay and neuter at approximately six months of age. I have two main reasons for this recommendation. The first reason is to prevent unwanted litters. The second reason is to prevent mammary cancer.
Mammary gland cancers are the second most common cancers outside of skin cancers. If a dog is spayed before her first heat, there is almost no chance of her developing breast cancer. If she is spayed before her second heat there is a 90% reduction in the incidence of breast cancer. If she is spayed after her second heat, there is no reduction in the incidence of breast cancer as compared to the unspayed female. There are several different types of breast cancer in dogs, just as there are with people. Some of these can be fatal. That is important to keep in mind as we discuss the new information below.
There is a third reason that I have recommended ovariohysterectomies and that is to reduce the incidence of pyometra which is an infection of the uterus. This infection is common in older female dogs. We have seen an unusual number of cases of pyometra at WBAH recently.
Traditionally, I have also recommended castration for male dogs at about six months of age. It reduces marking and roaming behavior as well as reducing the size of the prostate. This is important because benign prostatic hypertrophy (BPH) is common in dogs. Castration also removes the possibility of testicular cancer which is also seen in dogs.
My traditional “con” when I talk about spaying a female dog is the tendency towards obesity. Metabolic requirements change as dogs age. Without the sex hormones such as estrogen, progesterone and testosterone, those metabolic requirements really change. One of the best ways to counteract that change is to feed less, almost from the moment the dog is spayed or neutered. Usually about 10% less will do it. In some dogs even less, and in some dogs no change is necessary. The second “con” to be aware of is that in a small percentage of spayed female dogs, they develop urinary incontinence with age. This is easily corrected with medication and in no way should be taken as a reason to not spay the female dog.
Without going in to too much graphic detail, I do want to briefly discuss the actual surgical procedure for a spay as well as a neuter. I believe that ovariohysterectomies are one of the more difficult abdominal surgeries that veterinarians perform. Surprised? It is a difficult surgery that is made to look easy by veterinarians. This is done through experience and practice. Removing a spleen or an intestinal foreign body or a bladder surgery is probably technically easier. The lifting and stretching of an ovary in order to position it for removal is actually a procedure that is difficult and requires a true “feel” for the technique. As with any surgery, things can go wrong. But because we do them so often, veterinarians and clients often dismiss the difficulty of the surgery.
A castration surgery in the dog is a technically easier surgery to perform as the testicles are removed through a prescrotal incision and an abdominal incision is not used. Tissue handling is key with this surgery as prescrotal and scrotal skin is very sensitive. Many male dogs require an “E-collar” following surgery to prevent excessive licking which may traumatize the skin.
My goal with starting this blog was to educate both my clients as well as our entire community of clients here at WBAH. So, at this point I’d like to go over the reasons for recommending spays and neuters in the first place and we’ll also discuss the pros and cons. In addition, there were two journal articles published last year that started new conversations about ovariohysterectomy and castration. I will also give a response to those conversations that I deem appropriate.
The first and most “well known” reason to spay and neuter is of course to save lives by preventing unwanted pregnancies and thus unwanted litters. To quote Dr. Janet Scarlett, Professor of Epidemiology at the College of Veterinary Medicine, Cornell University; “There is no disease or condition of companion animals that takes more of their lives than euthanasia.” In fact, no other disease even comes close. If any infectious disease caused the death of as many animals every year as euthanasia does, the veterinary profession would be in overdrive trying to find a solution to the problem. Yet euthanasia in shelters gets little attention outside of the shelter and rescue community. Every year in the United States, 13% to 20% of owned dogs and cats have litters. Of those, 50% are “accidents”. The vast majority of those animals who have accidental litters are spayed later. The ideal situation is to spay them before they have a litter. Ten million dogs and cats are in shelters every year. Ten million. Of that ten million, 3 to 4 million are killed and most of those are healthy, adoptable animals. If we can reduce the incidence of delayed spay by 25%, we can reduce the number of unplanned puppies and kittens by 3 or 4 million, which turns out to be the number of animals euthanized in shelters every year. Interesting isn’t it?
I think we can agree that spaying and neutering is important. I also think that early spay and neuter is still an important concept that needs to be discussed. We’ll get to that in a moment. But first, let’s look at this new information I keep talking about.
In 2013, two articles about two different studies were published by separate groups that set the “when to spay and neuter world” on its ear. These articles were presented by the University of California, Davis and at the University of Georgia, Athens.
The University of Georgia study looked at over 40,000 dogs of all different breeds. The study showed that sterilization was associated with an increase in lifespan which was 13.8% longer in males and 26.3% in females. The study also showed decreased death from infectious disease but an increased risk of death from some cancers such as lymphoma, osteosarcoma and hemangiosarcoma.
The UCD study looked exclusively at Golden Retrievers. It was a much smaller study, looking at only 759 dogs. There was an increased risk of hip dysplasia from 5% to 10% and an increased risk of cruciate rupture which was 5% in males and 8% in females compared to 0% in intact dogs. It is postulated that this may be due to changes in how the growth plates of these joints close in an intact dog vs. a dog with absent gonadal hormones. Interpreting the portion of the study on cancer is more difficult. Female dogs who had undergone an early ovariohysterectomy had a higher incidence of lymphoma as well as splenic and liver cancers. Intact females have a higher incidence of breast cancer than spayed females. Interpreting these studies across all breeds of dogs will require more work but we think there is enough evidence to make changes in our recommendations for ovariohysterectomy and castration in dogs. This is especially true with large and giant breed dogs.
According to Julie Bulman-Fleming, DVM and Diplomate ACVIM (Oncology) of the Veterinary Cancer Group, allowing female dogs to have one heat is reasonable except for breeds that have high incidence of breast cancer. The report from UCD is actually challenged by the oncologists in light of the comments about MCT (mast cell tumors). They said that if dogs were spayed after the first heat but before the third or fourth heat, those dogs had higher incidence of MCT than the dogs spayed after or spayed before the first heat. Rottweiler breed male dogs kept intact for 2 to 2.5 years lowers incidence of bone cancer and orthopedic disease but increases incidence of dog to people biting.
Those in the field of Osteo-Oncology have been heard to say that they would prefer the growth plates to be completely closed prior to a spay or neuter taking place. If you spay or neuter your dog before the growth plates close, it prevents the growth plates from closing properly. For this reason, dogs that are spayed and neutered at a young age are often more prone to osteosarcoma (bone cancer), hip dysplasia, and other health problems.
The Bottom Line
For years, the veterinary medical profession has promoted spay and neuter. We have even promoted early spay and neuter. For WBAH that has meant recommending spay and neuter at about six months of age. Ovariohysterectomy and castration is still recommended. No question about it. But there is a question about “when?” This should be an individual discussion between client and veterinarian and specific for each breed and dog’s circumstances. We do not want to get into a situation where this information is misinterpreted and clients forego spay and neuter.
What about small breed dogs? It turns out that the cancers discussed in this blog are fairly uncommon with smaller breed dogs. For the vast majority of the small breed dogs including the spaniel breeds, neutering before they have a heat is just fine. With male dogs, we are recommending neutering at the same time. With giant breed male dogs, waiting until the dogs have all the effects of the sex hormones is preferable. In other words, secondary sex characteristics reduce the risk of bone cancer. Any negatives on that type of decision? The owners of these animals must be truly ready to handle a giant breed dog who is a fully mature male. It won’t matter much if we have prevented a future cancer, if we are euthanizing the dog because it bit someone in the neighborhood.
In general, large breed dogs should be allowed to mature and have one estrous cycle. If we wait past two cycles, we will see increased breast cancer. If we go too early, we may increase the chance of cruciate injury. This calculates out to anytime after the first birthday, maybe approximately 14 to 16 months of age for large breed dogs and 18 to 20 months of age for giant breed dogs. My bet is that this information will result in a “more will be revealed” type statement. I have heard some clients say they will never spay their female dogs because they have heard some of this data. My opinion is that this is a huge mistake. Huge. One word – pyometra.
I alluded to this earlier. This disease is the reason for this week’s blog more so than any discussion on timing of spaying a female dog. Over the last two weeks, we have diagnosed and treated 5 cases of pyometra. What the heck is pyometra? Stay with me….here comes more medical vocabulary.
In intact (non spayed) females, the lining of the uterus changes with exposure to estrogen and progesterone. This change in the lining of the uterus is called cystic endometrial hyperplasia which you can think of as the uterine wall thickening over time. Pyometra develops secondarily to cystic endometrial hyperplasia. It develops when there is a bacterial invasion of the abnormal endometrium (uterine lining) which leads to intraluminal accumulation of purulent exudate. Where do the bacteria come from? They ascend from the vagina through the partially open cervix during the phase of the reproductive cycle called proestrus and estrus. This is what we commonly call “heat”. The most common bacteria that invades the uterus is E.coli. Most commonly affected are intact females greater than 6 years of age, although I have seen it in dogs as young as 3. Cats are more variable, and it is less common in cats. The most common presenting signs are lethargy, increased thirst and in general not feeling well. It is so common that IF your dog is middle aged and is not spayed and she is presented as “sick” in my office, pyometra must first be ruled out over almost any other illness.
Pyometras can be both open and closed. Closed means the cervix is closed and there is no vaginal discharge. Open means the cervix is open and there is a vaginal discharge. The diagnosis is made through history, physical exam, lab work, radiographs and ultrasound. These dogs can develop marked derangements in their CBC’s including markedly elevated white blood cell counts. They can also become anemic if their disease is chronic. The E.coli bacteria elaborate a toxin which impairs kidney function so they often present with signs of kidney failure as well. Pyometra is a life threatening condition. The treatment is fluid support, antibiotics and surgical removal of the uterus. There are cases in which medical (non surgical treatment) can be used, but many of these treatments do not result in cure and the animal ends up needing to go to surgery in the long run. In my opinion this is best treated surgically. The prevention to pyometra is to spay your dog before the 18th month of life or second heat of her life. By doing so, you will also gain the benefits of breast cancer prevention and all other things discussed in this blog above.
It is clear that there are benefits to spaying and neutering our pets. The only controversy at this point is when the ideal time is for your dog or cat. Again, for small dogs we can recommend what we have been recommending for years. For medium and large dogs we can wait a little longer. For giant breed dogs we wait a little longer still. For our kitties, there is no evidence to my knowledge that the six month old spay/neuter causes health problems in cats. Honestly, if a decision must be made between spaying at 6 months and forgetting about it because it wasn’t on your mind, then go with the early spay. The benefits tend to out way the risks.
I realize this might be something new to your ears, but I hope that I have been able to provide the most up to date, valuable information possible so that you are all able to make the most informed and educated decisions for your critters.
Until next week…………..