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Ethical Back to Back Breeding: A Biological Breeding Strategy for Feline Welfare

Back to Back breeding, what a hot and very taboo topic. Often this type of breeding is what we associate with backyard breeders, unethical breeders and breeders just wanting to profit as much as possible off of an animal with little regard for the health and welfare of the animals in their care. But what if ETHICAL back to back breeding IS for the health and welfare of the animals in our care? Let's get a few things straight before you bite my head off. 1. I don’t practice Ethical Back to Back Breeding at this time. 2. The animals in our care are still respected, taken care of, loved and regarded not just as part of our breeding programs but are our companions and part of our family. 2. ETHICAL Back to Back breeding is not about breeding on every single heat as many times as you can, nor does it NOT mean allowing your female to have rest between litters.

3. ETHICAL Back to Back breeding is supported by reproductive veterinarian professionals There are many reasons a breeder would never even consider breeding a cat back to back 1. Societal Taboos

2. Suggestions made by registering bodies (which are not based on biological research, and should rather consider a limit to total number of litters or specific age they should be retired)

3. Pressures from animal rights activists, adopt don’t shop advocates, shelters and rescues.

3. Humanizing the cat 4. Taking advantage of the show season The Science Behind Ethical Back to Back Breeding

First and foremost, you can not dictate biology. While these beautiful companions are in your care and responsibility, you can’t sit them down and tell them when they should and can breed.

As breeders, many of our cats are in ARTIFICIAL environments. In the wild cats tend to breed whenever they are in heat as well as seasonally, dictated by many factors primarily influenced by the day/night light cycles (1, 2), also known as the Circadian rhythm. This rhythm affects physical, mental, and behavioral changes. Of course this varies depending on geographical location. For example, in Alaska there can be 24-hour daylight during the summer months and 24-hour darkness during the winter whereas in North Carolina there is about 13 hours of daylight in the summer months and 10 hours of daylight in the winter months.


Cats are not people, so while we may think they are too young to breed and get pregnant, most females are able to breed at 6-11 months, depending on the breed (3).

As with any species, youth is reproduction's best friend. No, this does not mean we are breeding females when they are only a few months old but this is a factor that should be considered. As age increases we see a reduction in litter size, frequency of litters, health of kittens etc (4, 5).

In addition progesterone ages and thickens the uterine lining. The repercussions of this, unfortunately, include a less friendly environment for the cluster of cells, or blastocyst, to implant into the uterine wall eventually resulting in an embryo or a developing kitten. The possibility of pregnancy complications, some fatal, also increase as a cat ages.

Concern for Cystic Endometrial Hyperplasia

Another concern with cats is the risk of Cystic Endometrial Hyperplasia, a potentially fatal

uterine infection that occurs in unbred females (6). It is known especially in the dog world, that pregnancy maintains proper uterine health. There is a much lower incidence of Cystic Endometrial Hyperplasia in those bred more consecutively than those left to skip heat cycles (7, 8).

Unlike humans and canines, cats don’t have a “period” where they shed the lining of the uterus, this only clears out when delivering kittens. Because the lining is not shed during a heat, another tissue layer grows on top meant to prepare the uterus for pregnancy . If this continues to happen for several cycles, cysts can develop that release secretions creating the perfect environment for bacterial growth and infection. In addition, progesterone prevents the contraction of the uterine muscles (9) therefore no fluids, or bacteria can be expelled.

Cats are more at risk for uterine infections than dogs as they have heat cycles much more frequently. Whereas dogs may have 1-2 a year (on average) depending on your location, temperature in your area and other related factors, your female can go in heat every 2 weeks or never even come out of a heat until they are bred. Some females have consistent heats while many are more unpredictable and can change duration and periods between heats over time. Unlike dogs and many other species, Cats are induced ovulators which means they must be

bred to ovulate. Methods such as a neutered male, the Q-tip method, the glass rod method, even pressure points around the vagina to knock a female out of heat are still stimulating ways to make a female ovulate (10). If a female does not get pregnant they can remain out of heat for 40-50 days. While primarily induced ovulators, studies have shown that female cats CAN spontaneously ovulate (11, 12). In one study 87% of queens over a 4.5 month study, had high levels of progesterone and spontaneously ovulated at least once. In the same study when a male was placed in a cage nearby (no physical contact) the occurrence of ovulation occurred at an increased rate of 33% to 57% versus 0-22% with no separated male present. This means that before the male entered the picture 67% spontaneously ovulated (13)! In another study, while cats had no physical contact with a male or other females, 37% of the queens spontaneously ovulated 1-3 times during the study (14). When females are induced to ovulate their progesterone levels drastically increase.

The main culprit of Cystic Endometrial Hyperplasia is due to progesterone. Progesterone plays a role in many parts of reproduction. While it's important to help maintain pregnancy it can also cause problems such as terrible inflammation of the uterine lining. Progesterone levels are not consistent from female to female. There are several stages of the feline estrous cycle which we address in our article on feline reproduction Most do not involve progesterone however the Luteal phase does. This period occurs after ovulation (15). This is when Cystic endometrial hyperplasia develops, typically within 4-8 weeks of the heat. This is why a cat can develop Cystic endometrial hyperplasia DESPITE being bred considering pregnancy is approximately 9 weeks long (16). It's not so much the heat cycles themselves but the hormones produced after ovulation that creates the hostile environment in the uterus with bacterial infection being secondary (17).

Many breeders choose feline commercial birth control (which is covered in more detail in our article concerning feline birth control). The primary ingredient is a Progestin which is a source of artificial progesterone and meant to act like the natural hormone in the body (18). Megestrol acetate (MA) also is used to prevent heats in females. This too is an artificial progesterone (19). In addition the adrenal glands and placenta can produce progesterone but this tends to be in small amounts (20). To make matters worse, during the estrous cycle white blood cells are prohibited from entering the uterus to prevent the damage and destruction of sperm (21, 22). White blood cells are important for fighting infections (23). As you can see this all causes quite the storm of problems for the female cat if not properly understood.

So should you be skipping heat cycles for the health of your cat?

Frankly it's not 100% your decision to make. Again nature and biology often can’t be dictated by human made law and desires. It is dependent on your female and her heat cycles.

So we have to ask even if we as humans decide to NOT breed this female, by “skipping a heat” are we truly giving the female the biological rest. Sure she isn’t growing kittens but is it causing other serious problems that may result in the decline of their personal welfare and health. So whether you have an unbred 2 year old cat that had 4 heats or a 2 year old who has had 4 litters the uterus is still generally experiencing the same hormonal stressors and damage from the actions of the progesterone. Again, in no way shape or form are we recommending or advocating for the

  • Over breeding of cats

  • Not allowing cats to have breaks

  • Breeding a cat at just a fews month age

  • Not ensuring all health testing has been done at the right age etc. Read that again!

We are advocating for the educated, ethical and responsible breeder, to ethically breed back to back should it be in the best interest of their female for their welfare and health.

A female is appropriate for breeding that

  • Is an appropriate age

  • Has been health tested

  • In good condition

  • Is healthy

  • Is at a good weight and size

  • Is mentally and emotionally mature

If they had a litter before

  • Produces healthy kittens

  • Enjoys being a mother

  • Is a good mother

  • Free of previous pregnancy/birth complications

Pregnancy can be very taxing to the body and it does take a lot of energy and resources, there are absolutely times in which heats should be skipped for the health of your females.

Holding off is beneficial as well for

  • Showing

  • Waiting to see development from a pairing

  • Choosing a better male for the next pairing

  • Health reasons

Some females can be very “difficult” when it comes to spacing out heats. I say difficult only because it's more of an inconvenience for us or we feel the social pressures, but it's completely normal and natural for them and their biology. Females can go into heat while still nursing kittens. Others will wait until the kittens are done weaning. Generally this first heat is a light heat and it's easier to knock them out.

While this may be the case, kittens naturally are cared for by mom not until 8 weeks but typically til 12 weeks and remain with mom between 4-10 months (3). At the end of the day this breeding strategy is NOT to make money, it does NOT replace quality over quantity. It is a natural biological approach to not only understanding feline reproduction but for the ultimate health, wellbeing and welfare of our companion animals and success of our breeding programs. Choosing to breed back to back or skipping heats come with numerous considerations and take in many factors. Understandably breeding styles should be evaluated on a case by case basis.

REFERENCES: Dawson AB (1941) Early estrus in cat following increased illumination. Endocrinology 28,907-910

  1. Michel C. Induction of oestrus in cats by photoperiodic manipulations and social stimuli. Lab Anim. 1993 Jul;27(3):278-80. doi: 10.1258/002367793780745381. PMID: 8366675.

  2. IUCN Cat Specialist Group, 1996a; IUCN Cat Specialist Group, 1996b; IUCN Cat Specialist Group, 1996c; Nowak, 1997

  3. Root MV, Johnston SD, Olson PN. Estrous length, pregnancy rate, gestation and parturition lengths, litter size, and juvenile mortality in the domestic cat. J Am Anim Hosp Assoc. 1995;31:429.

  4. Sparkes AH, Rogers K, Henley WE. A questionnaire-based study of gestation, parturition and neonatal mortality in pedigree breeding cats in the UK. J Feline Med Surg. 2006;8:145.

  5. “Dr. Hutchinson’s Reproductive Seminar,” Doberman Pincher Club of America. accessed 28 January 2020.

  6. 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.

  7. Schoeffel, K. “Revisiting back to back breeding.” The Australian Journal of Professional Dog Breeders. 05 Feb 2011.

  8. Zakar T, Mesiano S. How does progesterone relax the uterus in pregnancy? N Engl J Med. 2011;364:972–3.

  9. Johnston S, Root Kustritz M, Olson P. Prevention and termination of feline pregnancy. In: Johnston S, Root Kustritz M, Olson P, editors. Canine and feline theriogenology. Saunders; Philadelphia: 2001. p. 447.

  10. Binder C, Aurich C, Reifinger M, Aurich J. Spontaneous ovulation in cats-Uterine findings and correlations with animal weight and age. Anim Reprod Sci. 2019 Oct;209:106167. doi: 10.1016/j.anireprosci.2019.106167. Epub 2019 Aug 16. PMID: 31514917.

  11. Lawler D, Evans R, Reimers T. Histopathologic features, environmental factors, and serum estrogen, progesterone, and prolactin values associated with ovarian phase and inflammatory uterine disease in cats. Am J Vet Res. 1991;52:1747

  12. Gudermuth DF, Newton L, Daels P, Concannon P. Incidence of spontaneous ovulation in young, group-housed cats based on serum and faecal concentrations of progesterone. J Reprod Fertil Suppl. 1997;51:177-84. PMID: 9404283.

  13. Lawler DF, Johnston SD, Hegstad RL, Keltner DG, Owens SF. Ovulation without cervical stimulation in domestic cats. J Reprod Fertil Suppl. 1993;47:57-61. PMID: 8229985.

  14. Schmidt, P.M. et al: Ovarian activity, circulating hormones and sexual behavior in the cat. II. Relationships during pregnancy, parturition, lactation and the postpartum estrus. Biol. Reprod. 28:657-671; 1983.

  15. Johnson CA. Progesterone and prolactin-related disorders; adrenal dysfunction and sex hormones. In: Rand J, Behrend EN, Gunn-Moore D, Campbell-Ward ML, eds. Clinical Endocrinology of Companion Animals. Wiley-Blackwell; 2013:487–503.

  16. Memon, Mushtaq A. “Pyometra in Small Animals - Reproductive System.” Merck Veterinary Manual, Merck Veterinary Manual, Nov. 2013,

  17. Romagnoli S. Progestins to control feline reproduction: Historical abuse of high doses and potentially safe use of low doses. Journal of Feline Medicine and Surgery. 2015;17(9):743-752. doi:10.1177/1098612X15594987

  18. Greenberg M, Lawler D, Zawistowski S, Jöchle W. Low-dose megestrol acetate revisited: a viable adjunct to surgical sterilization in free roaming cats? Vet J. 2013 Jun;196(3):304-8. doi: 10.1016/j.tvjl.2013.01.038. Epub 2013 Mar 14. PMID: 23499239.

  19. de Sousa Oliveira, Kellen. “The Role of Progesterone in the Development of Pyometra in Dogs and Feline Mammary Hyperplasia - WSAVA 2016 Congress - Vin.” Powered By VIN, World Small Animal Veterinary Association Congress Proceedings, 2016, 2016,

  20. Zalata AA, Christophe AB, Depuydt CE, Schoonjans F, Comhaire FH. White blood cells cause oxidative damage to the fatty acid composition of phospholipids of human spermatozoa. Int J Androl. 1998;21:154–62.

  21. Lackner JE, Agarwal A, Mahfouz R, du Plessis SS, Schatzl G. The association between leukocytes and sperm quality is concentration dependent. Reprod Biol Endocrinol. 2010 Feb 5;8:12. doi: 10.1186/1477-7827-8-12. PMID: 20137070; PMCID: PMC2830972.

  22. Maton D, Hopkins J, McLaughlin CW, Johnson S, Warner MQ, LaHart D, Wright JD, Kulkarni DV (1997). Human Biology and Health. Englewood Cliffs, New Jersey, US: Prentice Hall. ISBN 0-13-981176-1.

a. Verstegen, J.P.: Physiology and endocrinology of reproduction in female cats. Manual of Small Animal Reproduction and Neonatology (Simpson, G.; England, G; Harvey, M. eds). British Small Animal Veterinary Assoc., Cheltenham, U.K., 1998; pp 11-16.

b. Verstegen, J.P. et al.: Regulation of progesterone during pregnancy in the cat: studies on the roles of corpora lutea, placenta and prolactin secretion. J. Reprod. Fert., Supp. 47:165-173; 1993.


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