Spring 2009

This is an excerpt from Breeder’s Handbook on Canine Reproduction from Royal Canin. Providing accurate and useful information on the practicalities of reproduction in breeding kennels is a goal of Royal Canin.

Since 1967, Royal Canin has been at the forefront of developing innovative nutritional responses in the field of dog breeding. Even if nutrition is fundamental in breeding, it cannot give all the keys for success. Application of reproduction techniques is the deciding factor.

Breeder's Handbook: When Breeding Problems Occur

By Bretaigne Jones, DVM

The term infertile is commonly associated with the inability to conceive. It actually applies to any condition that prevents conception, implantation of the embryo, or maintenance of the pregnancy to delivery.

It may be an overused word and applied to a bitch that doesn’t readily get pregnant along the expected time-line of the majority of the canine species. There are certainly conditions that can further restrict an already narrow window of opportunity for conception and, or, implantation, where “subfertile” is more representative.

When a bitch is difficult to get pregnant, or keep pregnant, a logical and thorough review of her history, the breeding management, her overall health, the environmental conditions, and of course, the male’s semen quality and breeding behavior (if natural cover) need to be conducted. Artificial insemination opens a whole new range of potential problems from the skill of the technician to the disinfection of the equipment.

The factors that are to be considered in a subfertility or apparent infertility situation should include first and foremost, the breeding management. Eighty percent of the time, the problem is simply that the bitch isn’t ovulating when we expect her to. So the breeding dates aren’t coinciding with her maximally fertile times, resulting in no pregnancy or consistently small litters.

Days of Estrus
Chart of mating dates resulting in pregnancy (745 bitches monitored at
the center for reproduction at the Alfort veterinary school). It can be seen
that, while 40% of bitches are effectively ready for mating between days
10 and 13 of estrus, 10% were ready before these dates and 50% after.

Luckily there are several diagnostic options that can help determine when the bitch is preparing to ovulate, indicate whether on not she ovulated at all, and pinpoint a window of opportunity to maximize fertility. The breeder needs to decide if the potential litter is worth the expense of the lab work, with no guarantee of success. Like anything else, one must make the most of the information available.

If breeding management is found to be optimal, but not resulting in pregnancy, then other factors need to be investigated. The bitch’s history will help identify if her estrous cycles are normal for her breed. Even though some breeds, such as the German Shepherd, tend to cycle more frequently than others, generally speaking, if a bitch is cycling too frequently she is short-cycling.

There is a reason why dogs have a long interval between heat cycles. During proestrus and estrus, the lining of the uterus is getting thicker with the development of glandular tissue in preparation for pregnancy, and secreting a proteinaceous fluid that will bathe and nourish the free-floating embryo as it comes into the uterus, until it can implant and develop a placenta. When pregnancy doesn’t occur, the uterine tissue must then return to a normal, non-pregnant state. This takes time. If the bitch starts to go into proestrus and estrus again before that tissue has fully resolved, the uterus will not be receptive to the embryos, likely resulting in their death. From the breeder’s perspective the question is whether or not she got pregnant in the first place. Was the problem conception or embryonic? This is important to know in order to focus diagnostic efforts efficiently.

Days of Ovulation
Progesterone monitoring on the same German Shepherd bitch in two different laboratories. This graph illustrates the difficulty in comparing the results from one laboratory to another. There is
no “true” value for progesterone at the moment of ovulation and it is up to each laboratory to interpret its own assays.

A similar condition occurs in bitches that are bred infrequently. More often seen in a hobbyist kennel or home setting, the delay in breeding and pregnancy has a negative effect on the uterine tissues. The repeated cycles of glandular growth followed by atrophy eventually leads to areas of tissue that don’t return to a normal, non-pregnant state. This is called persistent cystic endometrial hyperplasia. The result is areas within the uterus that will not allow an embryo to implant or develop a placenta. With each passing heat cycle, more tissue becomes affected. It might not totally prevent a pregnancy, but it will have a significant negative impact on litter size. Unfortunately, there is not a treatment to turn back the clock, and return the uterus to its earlier state.

While there are some situations that potentially are breeding management issues, others may be more a physiological or behavioral problem with either the bitch or the dog. Failure to achieve a normal mating is one such situation. Sometimes it results from a lack of experience on the part of the stud dog, or a psychological problem from a previous negative experience. The problem might be due to poor receptivity of the bitch to the stud dog’s efforts.

Absence of a breeding tie decreases the likelihood of pregnancy. Deposition of semen into the outer most portion of the vagina can damage the sperm from the more acidic pH of that environment. Is also increases the chance of the bitch squatting and urinating the semen out of the vagina immediately after mating. With a normal mating tie the semen is deposited through the cervix into the uterus. While fertilization is possible if a coital tie isn’t achieved, it will not result in the litter size potentially seen with an optimally timed breeding with a tie.

Environmental issues encompass a wide range of factors. Infectious processes are included in this category and involve bacteria, viruses and parasitic pathogens. Exposure to drugs and biological compounds (vaccines) are also potential environmental problems. Nutrition, both before breeding and during pregnancy, can impact reproductive performance. Housing and population concentration can also have a marked affect on the success of breeding attempts.

Infectious agents can cause problems on a multitude of levels. A pathogen (disease-causing organism) can affect the uterus making it inhospitable to the embryos. It can directly attack the placenta killing the embryo or fetus through starvation or lack of oxygen. The pathogen may also attack the embryo or fetus itself. Sometimes there are multiple tissues involved, affecting all three classifications.

Typical appearance of the uterus in cystic
endometrial hyperplasia after spaying.
Without treatment, this condition develops into pyometra, which can become lifethreatening.

The first bacterial pathogen that needs to be considered is Brucella canis. Brucellosis can be a ghost showing no outward signs of infection until the death of embryos or fetuses, or failure of the bitch to get pregnant. If the pregnancy is far enough along, the dead fetuses are aborted and the bitch will show a persistent vagina discharge. Early in the pregnancy, the disease may cause the death and resorption of the embryos with no outward signs, just no puppies. The type of problem exhibited by Brucellosis is largely determined by the timing of the exposure and subsequent infection. If the bitch is already infected, she may be difficult to get pregnant, not get pregnant at all, or result in the death and resorption of the embryos. If she is exposed and infected at the time of breeding, it is more typical to see late term abortion with the persistent vagina discharge.

This is a disease that demands constant surveillance by breeders. Once it invades a kennel, it is very difficult to clean out. Infected bitches and dogs need to be removed from the facility entirely, as soon as feasible, and spayed or neutered at the very least. There remains a small chance of humans getting infected from contact with infected animals, so the breeder must be very careful if trying to place these retired breeders (spayed or neutered) into homes.

Other bacteria known to cause problems such as abortion or infertility include Leptospira species (disease is known as leptospirosis), Salmonella species, streptococci, and E.coli. Diagnostics such as culture, gram stained tissue imprint slides, and histopathology are necessary to detect the definitive cause, which is necessary to institute appropriate treatment and preventive measures.

Pathogenic viruses that target the reproductive tract, also may affect the dam’s uterus, the placenta, the embryo, or all three. Canine Herpes Virus is a well-known cause of late term abortion, stillbirths and early neonatal death.

The most vulnerable time for this virus to affect breeding is during the last three weeks of gestation and the first three weeks after birth. Biosecurity is the best tool to contain this pathogen. Isolation areas for quarantine of new animals, and for animals returning from the show circuit, can protect the breeding population as long as proper cleaning and disinfection techniques are used. Close monitoring of kennel inhabitants, and rapid isolation of any showing respiratory signs can minimize losses from herpes virus.

Other viruses identified for causing reproductive disease are the distemper virus, parvovirus type II (the one readily recognized as “Parvo” with hemorrhagic gastroenteritis), and parvovirus type I (also referred to as the Minute virus).

A good vaccination protocol and biosecurity can keep distemper and parvovirus type II at bay, but parvovirus type I is more complicated. There is no vaccine against the canine parvovirus type I, and the type II vaccine is not cross-protective. It can be very difficult to diagnose because special reagents are needed for testing. Really the only option to protect against this viral invader is vigilant and consist biosecurity.

Parasites that can cause abortion or infertility include Toxoplasma gondii, an organism that completes its lifecycle in cats, and Neospora caninum, for which the dog is the definitive host.

Nutritionally, extensive research has demonstrated several nutrients that directly and indirectly impact reproduction. While a bitch doesn’t have a substantially increased need for energy or protein until the last three to four weeks of pregnancy, there are micronutrients that play a pivotal role before she even goes into heat, and throughout gestation.

Folic acid is recognized for helping to prevent cleft palates, but it also plays an integral part in the bitch’s behavior in estrus attracting the male’s attention and impacting her receptivity to the stud dog. Optimal growth of the follicles on the ovary, and fertilization of the eggs are also influenced by the presence of folic acid.

β-carotene is critical for healthy reproduction, promoting the formation of estrogen and progesterone. Estrogen not only functions for the synthesis of sexual pheromones, but the development of the uterine lining in preparation for pregnancy. Progesterone helps the uterus prepare for the implantation of the embryos, and maintains gestation.

Tyrosine, an amino acid, affects sexual behavior, follicular growth, and ovulation.

These are just a few examples, with several more nutrients involved.

Determining the reason for reproductive failure can be complex and frustrating. However, to minimize ongoing difficulties, possibly involving other dogs, fast action and thorough evaluation are needed. Diligent recordkeeping and a ready plan in case of abortion, can simplify the problem-solving process.

For more information on Royal Canin and its nutritional solutions, visit www.royalcanin.us/akc.

Ronald N. Rella, Director, Breeder Services
Email: AKCbreeder@akc.org
Customer Service | Phone: 919-233-9767 | Email: info@akc.org

© The American Kennel Club 2008