How often to breed and when to start breeding
Common sense disclaimer: As with everything that I write, it’s critical to seek the advice of a qualified veterinarian, preferably one that is board certified in theriogenology (reproductive science) for reproductive matters. This article and its contents are NOT designed nor intended to replace the need for a qualified veterinarian, but instead to help educate people to to work optimally with their veterinarians. All recommendations should be reviewed with qualified professionals, such as a board certified reproductive veterinarian, prior to implementation in a breeding program. Always seek the advice of your veterinarian.
Back in the day, best practice for breeding was to wait until a dog was at least 2 - 4 years old, had at least 3 heat cycles to breed, and also to skip at least 1 cycle between litters.
Like many other things we used to do, when science is finally applied to our profession and we get information from good data, we realize that we could be doing better.
We were wrong back then, and I (and my dog) paid for it dearly. I thought I was doing the right thing by waiting for my bitch to turn 3 and be titled to have her first litter, going years between litters, and leaving her intact for most of her life. It wasn’t until she developed mammary cancer at 8 or 9 (and died from it at 10) that I discovered my grave error.
Gratefully, her puppies all lived until 14 or 15 with no ill health until very late in life, but losing her so young was hard on me then and I still feel the pain of my mistake. That is one reason I try so hard to stay on top of the science — I owe it to my dogs to do the best I can for them. While it’s too late to help Frieda, maybe I can help my current and future dogs, and yours, too.
This article relates solely to factors involved in breeding frequency and timing, not to whether a bitch is suitable for breeding altogether, so those considerations are not covered here.
So in terms of when to breed and breeding frequency, what is science telling us today?
Back-to-back breeding
Before we discuss this topic I want to clarify that I’m not telling you here to breed your dog at any specific age. I review the information we have available and suggest you review this information with your reproductive vet to make the most appropriate choices for each dog.
There’s no single answer to this question, but let’s look at the biology and the available research to determine where a good starting point is for answering this question for each individual.
Let’s start with back-to-back breeding, or breeding without skipping a heat cycle. Traditionally, we thought that bitches needed a break between litters for their optimum health. That’s no longer considered best practice, for several reasons.
First, when you look at the reproductive and nursing cycle of a dog and their healing needs, it’s fairly comparable to a human having a baby every 2 years. While I emphasize frequently that dogs are not people, I think that as an analogy this can be helpful to some who find initial mental resistance with breeding a bitch as frequently as twice a year.
Next is the effect of progesterone on the uterus. One of the most vocal proponents of breeding back-to-back is well-known reproductive specialist Dr. Robert Hutchinson.
In his seminars, Dr. Hutchinson explains that the progesterone level in the bitch remains elevated for two months after ovulation whether or not she has a pregnancy. This is a critical fact, since progesterone can be inflammatory to the lining of the uterus.
When a bitch cycles and there’s no pregnancy, the uterine lining thickens from the inflammatory effects of progesterone and that can increase the risk of infection (pyometra) and endometriosis. In fact, while most of us think of pyometra as a bacterial disease, Dr. Hutchinson says it’s actually an inflammatory disease, with the bacterial infection being a secondary factor.[1] In Dr. Hutchinson’s own words, the progesterone hammers the uterine lining for 60-plus days.[2]
An additional excerpt from the same seminar:
It's suggested not to skip a season because we have been preserving the uterus from the effects of progesterone; what would be the benefit of exposing her uterus to two months of progesterone? Progesterone's effect on the uterine lining is the reason why bitches six and over have a 33.3 percent less chance of conceiving than bitches under 6 years of age.
(Dr. Hutchinson also says that bitches should be spayed as soon as they no longer will be bred to help avoid future pyometra and other problems. Research shows that spaying also helps prevent mammary cancer, particularly when done by 4 years of age.)
At the risk of repeating myself once again, dogs are not humans, and while human females shed the lining of their uteruses every cycle, dogs only shed their uterine lining when whelping. This little difference is biologically significant. As linings build up, they lose flexibility and elasticity, which can also contribute to fertility problems as that can affect the ability of eggs to attach.
So his advice it to breed your bitches young and breed back-to-back and not to skip cycles unless you have a medical reason to do so.
To add to this, skipping a pregnancy puts your bitch at risk for a phantom, or pseudo pregnancy—a false pregnancy.[3] False pregnancies look just like regular pregnancies, except there are no puppies. Your bitch, however, will gain weight, nest, have enlarged teats, and lactate.[4] But she won’t shed her uterine lining. There’s a relationship between the number of false pregnancies and an increase risk of mammary cancers in dogs.[12]
False pregnancies are common in dogs because they provided an evolutionary advantage to wild canid packs—wolves, coyotes, and wild dogs. If a bitch in a pack has a false pregnancy, that means she will lactate and can help nurse the pups of other females.[5]
When not to breed back to back
Gestation and nursing use a lot of energy and require increased calories. Sometimes, the physiological burden of carrying and nursing a litter can deplete the fat and nutrient stores of a dam. Depending on her recovery, you might want to consider skipping a cycle. I talk a little about caloric needs in this article[JK1] .
It’s often thought that because bitches blow their coats that means they need more recovery time. Most often blown coats have less to do with recovery and more to do with lack of adequate calories and other nutrients during gestation and nursing, as explained in the article I just mentioned.
I always stress the importance of consulting a qualified reproductive veterinarian, and this is absolutely no exception. The opinion of a good repro vet should be your number one consideration for whether to breed back-to-back or skip a cycle. You should have your bitch evaluated by your repro vet before every breeding.
Like humans, dogs are individuals and should be evaluated individually. Some breeders will weigh other factors in this decision, such as whether the dog is titled, how mentally and emotionally mature the dog is, waiting to see if certain health conditions are present for conditions that can’t be tested for and don’t appear until dogs are older, and other factors relating to the breed or individual.
There’s no one right answer. Those factors should all be discussed with a qualified reproductive vet.
Other people also feel a bitch may need a break after a C-section. Usually, they recover quickly and this isn’t an issue. But, again, talk to your vet. She can examine your dog and give a veterinary opinion on whether she should be bred or rested.
When faced with additional costs, it might seem “fine” to cut corners like this and just breed if your bitch seems fine to you, but the cost of a visit is well worth it as the health and lives of my bitch and her puppies depend so much on how suitable she is for breeding at a given time.
How old does a dog have to be to breed?
Besides breeding back-to-back, Dr. Hutchinson also advises to breed for the first time at a young age.[2] While I can’t find any reference where Dr. Hutchinson gives a specific age to start, there are a couple of studies on the subject that suggest breeding your female dog between 1 and 2 years of age.
A Cornell University study presented at a Theriogenology conference in 2016 studied dystocia (difficult birth) in almost 700 litters. The study showed that bitches having their first litter after 2 years of age were 2.4 times more likely to experience dystocia compared to those having their first litter between 1 and 2 years of age.[6] Dystocia risk decreased with age and successive litters. Dr Cornelius had a journal paper in 2019 on dystocia risk, however the 2019 paper did not include age of first litter data.[7]
(While not related to this post topic, I think it’s important to note that in the 2019 study, litter size was also highly correlated to dystocia, and dystocia is highly correlated to having stillborn puppies. According to this study, we’re looking for the goldilocks zone with litters—between 5 and 9 puppies—if we want to reduce risk of dystocia and stillbirth.)
When to start breeding later
There are also good reasons to wait until later to breed. Sometimes, these reasons have nothing to do with the health of the bitch, although some do.
Examples for reasons to consider breeding later include:
Health concerns for diseases or conditions that only appear later in life and cannot be cleared through other means of testing (such as Addison's disease, some seizure disorders, some eye disorder, some heart disorders). If you have a breed or line prone to some of these disorders, you might wait to breed until your dogs are past a certain age to help reduce the breeding of dogs with these conditions.
Dogs bred for conformation competition will need to be evaluated at 2 years of age or older. This is not a health concern for either parents or puppies, but it is a goal for some breeders.
Working dogs rarely are bred until titled. Again, this is not a health issue but is important to some breeders.
When should you stop breeding your bitch?
There is no one set age recommendation for when to stop breeding I have ever known. It’s different for each bitch. Consult your repro vet at each breeding to determine with her whether it’s advisable to keep breeding your bitch or if it may be time for retirement.
It’s been my experience that reproductive advice about when to stop breeding has been relatively consistent over the last 20 years: Stop breeding when litter size decreases or problems arise. Personally, I prefer to stop breeding BEFORE problems arise. I would rather miss out on having one last litter than risking dystocia or other problems. Adding to this the information from Dr. Hutchinson about trying to start early, breed back-to-back, then retire early, I try to retire my bitches by 4. I’ve had occasion to go a little past that, but that’s the exception not the norm and it was done under the close guidance of my reproductive veterinarian.
I hope there’s enough information in here for you to go talk to your repro vet and decide where your own limits lie.
Summary
To summarize, current research is telling us to consider:
Starting early (before 2 years old)—reduces dystocia risk by almost 60%[6]
Breeding back-to-back—reduces pyometra, mammary cancer, and endometriosis risks[1-3,5]
Retiring early (ideally by 4, but not always)— reduces pyometra, mammary cancer, and endometriosis risks[1-3]
These are generalizations, not specific recommendations for you and your program. These generalizations are all subject to advice of your repro vet on the condition of each individual dog, they are not hard and fast rules, and as responsible breeders we must always consider the welfare of the bitch above all else.
References
[1] Dr. Hutchinson’s Reproductive Seminar, Doberman Pincher Club of America. https://dpca.org/BreedEd/dr-hutchisons-reproductive-seminar/Last accessed 28 January 2020.
[2] Hutchinson, R. Reproduction Seminar about Dogs (Transcript). 08 Jan 2002. https://veterinarypartner.vin.com/default.aspx?pid=19239&id=6048084Last accessed 28 January 2020
[3] Verstegen, JP and K. Onclin. Prolactin and anti-prolactic agents in the pathophysiology and treatment of mammary tumors in the dog. NAVC Proceedings, 2006. North American Veterinary Conference. https://www.cabi.org/isc/FullTextPDF/2006/20063121210.pdf
[4] Gobello, C., PW Concannon, and JP Verstegen. Canine pseudopregnancy: A review. In Recent Advances in Small Animal Reproduction. International Veterinary Information Service (www.ivis.org), Ithaca, New York, USA: 2001.
[5] Schoeffel, K. Revisiting back to back breeding. The Australian Journal of Professional Dog Breeders. 05 Feb 2011. http://www.rutlandmanor.com/uploads/5/6/3/1/5631556/dr_kate_schoeffel_back_to_back_breeding.pdf
[6] Cornelius and SH Cheong. Risk factors for canine dystocia and stillbirth. Clinical Theriogenology. 8(3), 312.Sept 201. Conference Proceedings.
[7] Cornelius, AJ, R Moxon, J Russenberger, B Havlena, and SH Cheong. Identifying risk factors for canine dystocia and stillbirth. Theriogenology. 128 (2019) 201-206. https://www.sciencedirect.com/science/article/pii/S0093691X18307003?via%3Dihub
[8] Johnson CA. Cystic endometrial hyperplasia, pyometra, and infertility. In: Ettinger SW, Feldman EC (eds).Textbook of Veterinary Internal Medicine WB Saunders, 1992, pp. 954.
[9] Davidson AP, Feldman EC. Ovarian and estrous cycle abnormalities. In: EttingerSW, Feldman EC (eds) Textbook of Veterinary Internal Medicine. WB Saunders,2004
[10] Canine Pseudopregnancy: A Review (Last Updated: 23-Aug-2001). C.Gobello1, P. W. Concannon2 and J. Verstegen III3, Recent Advances in SmallAnimal Reproduction, Concannon P.W., England G., Verstegen III J. andLinde-Forsberg C. (Eds.)
[11] Simón Martí Angulo Clinical aspects of uterine disease in the bitch and queen.Proceeding of the Southern European Veterinary Conference Oct. 2-4, 2009. S.Romagnoli, How I Treat… Pyometra. Proceeding of the SEVC. Southern European Veterinary ConferenceOct. 17-19, 2008 – Barcelona, Spain
[12] Donnay I, Rauis J & Verstegen J – Influence des antécédents hormonaux surl’apparition clinique des tumeurs mammaires chez la chienne. Etudeépidémiologique. Ann. Med. Vet. 1994, 138, 109-117"
