Opinions on Breeding
by Kate Schoeffel BSc(Hons), BVSc
Reproduced with permission.
NOTE : See link below to updated post 'Revisiting back to back breeding', Feb. 5,2011
I'd like to make some comments on the various points raised in this and a previous thread.
Firstly I'd like to endorse what Nicole has said about your relationship with your vet. Vets are expert in animal disease - they are not necessarily expert in animal management outside of their area. Like any undertaking (including veterinary practice) breeding dogs requires practical experience as well as theoretical knowledge. You will have more practical knowledge of breeding than your vet in only a couple of years and if you read widely your theoretical knowledge will soon challenge most practitioners.
The other thing I would like to comment on it the issues of breeding age and how often to breed.
At university - in our animal reproduction course - I was told in no uncertain terms that, contrary to "breeders ethics" there is no scientific reason for not breeding a dog on its first and subsequent heats. "As long as the bitch is fed well they will continue to grow normally through pregnancy" was Dr Wright's advice. Admittedly this was 25 years ago but when I started breeding I assumed this advice was valid and that I could, safely and without causing harm to my dogs, breed them on their first cycle.
I'm happy to report that theory held up! I have never had a "dystocia" (difficult whelping) in any of my Labradors, they are all fit healthy dogs and to date I have never had any health problems associated with reproduction.
I think that I have an advantage by breeding small poodles to large Labradors - the puppies are much smaller than purebred Labs and being F1 are very vigorous puppies - so it may be that I have just been lucky and that the theory that I was taught at vet school is not universally valid.
I'd be interested to know what health problems you are finding to be reported as likely problems in dogs bred earlier than 2 years - what were your vet's concerns Karen B? It may be that they are concerned about weight on growing joints perhaps? I suspect that many breeding problems are a result of "inbreeding depression" - the "opposite", if you like, of hybrid vigour - which results in fertility and reproductive problems in many purebred dogs.
The argument that 2 years is required before one can be sure that dogs are HD free is valid - Juliane knows more about this than I do and might like to comment on this (an example of an educated breeder doing the research). Certainly if I was planning to breed on from my dogs I would be screening my bitches and taking this into consideration when deciding on the choice of breeding age.
In my little poodles I wait for at least one heat - the little girls are so tiny and mature so early that I "feel sorry for them" - this is anthropomorphic and is a different thing to actually being concerned about the health of the dogs. A couple of times when accidents have occurred (as inevitably they do if a pup comes on heat a bit earlier and with less fanfare than expected and there is a quick dog around!) these tiny bitches have whelped naturally and without complications - although I do find that my pure poodle puppies are much less vigorous than the labradoodles and they do throw the occasional birth defect.
It is probably an appropriate place to question on your question about "regular breeding" Rochelle. Yes I was being a bit euphemistic - the condemnation of breeding on every heat is so universal that even I am a little reluctant to "come out" on this issue. But the fact remains that breeding on every heat is what dogs are designed to do by nature and that the "unnatural" practice of preventing regular pregnancies is actually bad for bitches!
Radical stuff I know but if you don't believe this then ask your vet the following:
1. Does pregnancy postpone the onset of Cystic Endometrial Hyperplasia and reduce the incidence of mammary tumours in entire bitches
2. What are the adverse health consequences for a normal healthy bitch from breeding on every heat?
My approach and my advice to clients who want to breed their dog - mostly backyard pet owners wanting to breed a litter or two for fun - is to breed early and breed regularly until you have bred the puppies you want - then desex your dog. IMNVHO this is the approach that is in the best interest of the bitch with regard to diseases associated with reproduction.
I believe that the current 'breeder ethics' which limit the breeding age and frequency of litters are designed to limit the puppy population (not a bad thing) or are based on 'feeling sorry for the bitch' rather than on science.
Since this is already a ridiculously long post I may as well add a bit of theory to back up what I'm saying:
When a bitch comes on heat she will go through a series of hormonal changes - rising oestrogen, drop in oestrogen then rising progesterone and high levels of progesterone for about 2 months. The unusual thing about dogs compared with the other species we deal with is that these hormonal changes are the same whether the animal is pregnant or not. The long “luteal phase” with high progesterone is what produces “pseudopregnancies” and rather than being abnormal or unusual and needing treatment pseudopregnancy is what happens when a bitch is not mated.
In a pseudopregnancy the uterine lining thickens as it does in pregnancy but in pregnancy the lining does not get “hyperplastic” - it doesn't thicken or secrete abnormally. In each successive pseudopregnancy this thickening is exacerbated. Pregnancy therefore protects against Cystic Endometrial Hyperplasia.
I am not sure why pregnancy is regarded as being protective against mammary tumours. In humans my understanding is that it is because the predisposing factor is the increase in breast tissue with the influence of oestrogen every month but in dogs the hormones don't change much whether the dog is pregnant or pseudopregnant. I assume it is actually lactation which is protective.
I'll stop now …. Sighs of relief all round!
All the best
Kate Schoeffel BSc(Hons)
Nyora, Condobolin NSW
Phone: 068 95 2511
A/H: 02 6896 2935
Fax: 02 6895 3851
* UPDATE 2011
New post by Dr. Kate Schoeffel - 'Revisiting back to back breeding', Feb. 5,2011
Revisiting back to back breeding
February 5, 2011 By Dr Kate Schoeffel
It is frequently claimed that breeding dogs on every heat or “back to back breeding” is bad for a bitch’s long term health and well being. However the research in canine reproduction shows that not breeding a dog when it comes into heat can in fact be bad for its health.
Scientist have shown that pseudopregnancy ['phantom pregnancy'] increases the risk of mammary cancers which are the second most common cancer in dogs after skin tumours and are 3-5 times more common than breast cancers in women1:
Pseudopregnancy often occurs when a bitch is not bred. She will show signs such as nesting, weight gain, mammary enlargement and lactation – usually about 6 to 12 weeks after oestrus. Pseudopregnancy represents the extreme of the changes which normally occur during the oestrus cycle and it is suggested that it is a hang over from dogs evolution from wolves. Subordinate non breeding pseudopregnant female wolves in a pack can help to raise pups by nursing the litters of other females” 2
In 1994 Donnay and his associates showed that there is a relationship between the number of pseudopregnancies a bitch goes through and the development of mammary cancer – see Table 1 below3. Verstegen and Onclin (2006)1 have also studied canine mammary cancer and found that a large number of bitches presented for mammary tumours also show pseudopregnancy, that a large percentage of these females had had frequent pseudopregnancies and that the bitches with recurring pseudopregnancy at each cycle tended to develop mammary tumours significantly earlier than other animals.
Both of these authors say that there is need for more research but clearly bitches which don’t breed are likely to become pseudopregnant and pseudopregnancy increases the risk of cancer.
Pregnancy protects against life threatening uterine diseases. The most common uterine disease in the bitch is cystic endometrial hyperplasia. It is linked to several serious uterine diseases including the potentially life threatening disease “pyometra” (literally – a uterus full of pus) which affects nearly one quarter of dogs under 10 years old which are not desexed4 . According to canine reproduction specialist Dr S. Romagnoli “bitches whelping regularly throughout their reproductive life almost never develop pyometra, while those who whelp rarely or never in their lives have a greater chance of developing this condition”. Furthermore a standard textbook of veterinary internal medicine notes that uterine diseases are less common in kennels where bitches are bred and conceive regularly indicating that pregnancy has a protective effect on the lining of the uterus or “endometrium”5,6
Given that artificially restricting bitches, which haven’t been desexed, from breeding is bad for their health, it is not surprising that many breeding dogs bred have reproductive problems. If they are show dogs they often don’t start breeding until they are three years old, and have finished their show career, and then kennel club rules and even government regulations require that the bitch is only bred on every second season. Frequently older bitches need veterinary intervention to reproduce, and good bitches may end up being bred well beyond 6 years of age when their fertility is beginning to decline.
No responsible breeder who cares about their dogs would breed their bitches until they are exhausted, and rules certainly need to be in place to ensure that irresponsible breeders don’t exploit their dogs, however the current regulations in place in some states do not take into account the biology of the bitch. Breeding should be regulated by limiting the number of litters a bitch can breed or the age at which they should be desexed and retired.
Breeding dogs regularly while they are young, followed by desexing and rehoming them early is in the best interest of the bitch and a good pet breeder can use this knowledge to work with the natural biology of their animals.
Breeders must be aware of and comply with any government regulations regarding dog breeding in their state and unfortunately in Victoria, NSW and QLD current regulations do not permit this approach to dog breeding.
Table No 1: Odds ratio for the risk of mammary tumours development related to the frequency of pseudopregnancies. (from Donnay et al. 1994). In this study, bitches with > 3 episodes of pseudopregnancy in their lifetime had a higher risk of developing mammary tumours.
1. J.P. Verstegen III and K. Onclin. Prolactin and Anti-Prolactinic Agents in the Pathophysiology and Treatment of Mammary Tumors in the Dog. NAVC Proceedings 2006, North American Veterinary Conference (Eds).
2. Canine Pseudopregnancy: A Review (Last Updated: 23-Aug-2001)
C. Gobello1, P. W. Concannon2 and J. Verstegen III3, Recent Advances in Small Animal Reproduction, Concannon P.W., England G., Verstegen III J. and Linde-Forsberg C. (Eds.)
3. Donnay I, Rauis J & Verstegen J – Influence des antécédents hormonaux sur l’apparition clinique des tumeurs mammaires chez la chienne. Etude épidémiologique. Ann. Med. Vet. 1994, 138, 109-117
4. 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 Conference Oct. 17-19, 2008 – Barcelona, Spain
5 Davidson AP, Feldman EC. Ovarian and estrous cycle abnormalities. In:
Ettinger SW, Feldman EC (eds) Textbook of Veterinary Internal Medicine.
WB Saunders, 2004
6 Johnson CA. Cystic endometrial hyperplasia, pyometra, and infertility. In:
Ettinger SW, Feldman EC (eds). Textbook of Veterinary Internal Medicine
WB Saunders, 1992, pp. 954.