Canine Heat Cycles

• Irregular flow
• Irregular heat cycle
• Late first heat cycle
• Irregular heat cycle after a litter
• Recommendations to regulate a heat cycle
• Hormonal pack: multiple bitches in one household
• Heat cycle with no swelling

Irregular flow

Q: I have a 5 yr old female boxer. She has a heat cycle about every 8-10 months. She always has an average amount of flow. This time, she has a regular flow at night and spots during the day. The only thing I have done differently this time - I started her on "In Between For Her" about 2 months after her last litter went home. This will be her last litter.

A: It is good that her cycle timing is remaining consistent. I have found with my girls that once they pass the 7-8 year mark their cycle timing can become different. It is not unusual for the blood to puddle up in the uterus overnight, so it looks like it is more, versus the day when the dog is busy and so there is spotting as you describe. The supplement “In Between For Her” appears to be a good all-purpose supplement designed for overall health. I am simply cautious with supplements as if you are using a good food the need for supplements should be minimal, and you do not want to over do it. We can think that if a little of a vitamin is good, then more is better but that is not the case. Good luck on her last litter!

Irregular heat cycle

Q: Hi Susan, I have a female Australian Shepherd that seems to have irregular heat patterns. She has had 2 litters of pups and she is 4 years old. I’m finding that after a litter, she’ll go back into heat around 6 months later. I always skip that heat, but then she goes back into heat again about 3-4 months later. If we breed her with our stud on that heat, they have never tied and only slip mate, and she does not conceive. At that point she may have another heat 6 months later, and they will tie, resulting in a pregnancy. Is there anything I can do to help regulate her? Thank you in advance for whatever advice you can send my way.

A: Science tells us that the uterus goes through the same hormonal cycle regardless of whether your girl is pregnant or not. Knowing this has let the Theriogenologists (canine reproductive specialists) see that doing a back-to-back breeding with a healthy bitch is not a problem. In your specific case it might be worth it to do the back-to-back breeding, providing you and your veterinarian determine that she has rebounded and is healthy from the previous pregnancy.

As far as regulating your girl, you could be running progesterone testing to see when she is ovulating, so that you can do the breeding at the optimum time. Additionally, you describe slip ties without a pregnancy, and it could be that she is having a split-season. If this is the case running the progesterone numbers will let you know that too.

Good luck and I hope this helps!

Late first heat cycle

Q: I have a female that is over 2 now and I have not seen her come into heat. I had the vet check her blood and he said her bloodwork did not show any concerns. My question is how do I know when she is in heat if she doesn't display the normal signs physically?

A: Isn’t it frustrating when you have a girl like this? I feel your pain as my Gordon Setter girl did not come into season until she was 27 months old. If this were my girl I would run complete blood work, including T3 and T4. I would also ask the vet to check for ovarian or uterine cysts via ultrasound, as both of these can cause hormone issues. If everything checked out normally, I would then resign myself to running progesterone every 7-14 days to chart her status. You can always augment that by doing vaginal cytology slides as well to see changes. If you chose to do that I would follow the same 7-14 day schedule. Here is the link from the LSU Vet School on how to do your own vaginal cytology- http://therio.vetmed.lsu.edu/k-9__vaginal_cytology.htm

In the meantime, patience is your best bet if you choose to wait it out. 

If you monitor her progesterone for 6 months and see no change, your other option is to speak to your reproductive veterinarian about the various options available to you that will bring her in season by jump starting her cycle. These include cabergoline (Galostop) and PG600. This article from the Veterinary Information Network (VIN) has a good overview of this -https://www.vin.com/apputil/content/defaultadv1.aspx?id=3854216&pid=11196& 

Additionally, you can try other solutions as outlined in this article by Dr. Marty Greer. https://www.revivalanimal.com/pet-health/how-to-induce-heat-dogs-drug-free/learning-center

There is no magic bullet to fix this situation, and not every treatment will be successful. It is also important to ask your veterinarian if there are any adverse effects to the protocol you choose. Good luck!

Irregular heat cycle after a litter

Q: Hi Susan, first thank you so much for sharing your knowledge with us. My bitch came in season August 2020, she was AI on 8/30 and 31. The pups were born on October 30, 2020; planning to breed her back this next heat. As I figured she should have been back in heat late February, early March. So far nothing, even though she has been coming in every 6 months. Do you often see a bitch's cycle changing after a litter? This will be my first back to back breeding so I feel like I've been waiting forever. Any insight is appreciated!

A: You are very welcome. I think that sharing knowledge and creating a positive community for breeders is so important. Each and every question that people ask matters!

My standard chuckle when people ask about their girls coming into season “on schedule” is, “you know they are called bitches for a reason, right?” So, the real answer to your question is that every girl is different, every cycle is different, and each girl’s system recovers differently after a litter. Watching for a girl to come into season is kind of like watching paint dry - it feels like it takes forever. I would tell you to be patient, she may be reacting to other girls in your household too. If you are curious, you can always start doing vaginal cytology to see her progress, and of course you can even run a progesterone test too. Good luck with this upcoming breeding and having the patience to wait for your girl to come back into season.

Recommendations to regulate a heat cycle

Q: Hi Susan, what’s the best way to get bitches on a more normal heat cycle? I've heard many suggestions, some of which sound like old wive's (or breeder's) tales and others which sound dangerous (a shot made for pigs?). I have two girls who can't seem to get regular which makes using a stud or AI (or planning any breeding) a real challenge.

A: I think that the first thing we all need to remember is that not every dog cycles the same. If you have a bitch who has a wonky schedule, she can influence the rest of the girls in the home! This is called the “dormitory effect” (reproductive synchrony) and is pretty common. That all being said the first thing to start with is a full blood work panel, this will let you know if there is something going on that is sub-clinical that could be influencing her season. Next you want to work with your veterinarian to have an ultrasound where you look for uterine or ovarian cysts. Cysts disrupt the normal hormone cycle and can also prevent pregnancy.

Finally, working with your reproduction veterinarian you can work on a plan to regulate her cycles. There are different options, and I will list a couple of treatments that you can discuss with your Vet. However you need to remember that using drugs that interfere with the normal cycle of the bitch you might cause more harm than good. Everything we do has a “risk-reward” calculation that we need to do. P.G.600 is a combination of 400IU of pregnant mare serum gonadotrophin and 200IU of human chorionic gonadatrophin. This product was originally formulated for use in pigs. Approximately 50% of bitches treated with this product come into season within a week, but not all heat cycles will be fertile. The use of Ovuplant (deslorelin is generally used in dogs who have had a season. Potential drawbacks include smaller litter sizes and studies show that the cause of smaller litter size is not from a reduction in ovulation rate but instead a reduction in conception rate and possibly a higher early embryonic loss ratio.

My suggestion before you start chemically messing around with your girl’s hormones for your convenience is to try improving her diet, including good carbohydrates and oils. Then, exercise: regular exercise is known to help keep bitches regular and cycling. Another interesting fact is that sometimes bitches raised in an all-female kennel do not cycle the same until they are exposed to male dogs. So perhaps finding a way to have some time in ‘mixed-company’ may be a benefit. And finally, sunshine!! Horse breeders have long used artificial sunlight to help regulate their mare cycles. Use of a full spectrum light with your dogs when they are indoors may make a difference as well. Good luck as you move forward!

Additional reading:

Estrus Induction in Dogs: Approaches, Protocols and Applications  

Induction of Estrus 

Sex Ed for Your Dogs

Hormonal pack: multiple bitches in one household

Q: We had a 3 year old unaltered female returned to us in March. Since that time none of my females have cycled. What could be causing this issue?

A: Female dogs tend to operate in a hormonal pack, and as I am sure that you have noticed, your girls most likely cycle fairly closely together before adding in this new, unaltered girl to your home. Whenever you add in a new “girl,” there is almost always an adjustment period as they figure out the social dynamics of the group. 

While you don’t say how old your other girls are, age also plays into longer times between cycles and fertility. Additionally, I would like to suggest that sunlight may also play a part in this. Hormone cycles are impacted by sunlight, especially photoperiod and day length, so when we keep our dogs inside, we can unintentionally disrupt this. Perhaps using light bulbs that mimic sunlight, such as those used in equine breeding, may be appropriate for this situation. Portions of the below research articles on sunlight might also be of interest to you

Laboratory Animal Management: Dogs

Sources of Stress in Captivity

Heat cycle with no swelling

Q: Why does a female show signs of heat with blood, scents but no swelling is noted, therefore the males cannot enter her? This has happened twice with our females and of course no pregnancy came from this and how often does this occur?

A: This can be a symptom of a number of things. The first thing that I think of is a “split-heat” where there is no ovulation, and thus no eggs to fertilize. When this happens, there is generally a second heat that follows 3-4 months later, at this time there is ovulation and pregnancy is possible. The other situation could be either ovarian or uterine cysts. Cysts can impact the hormonal cycle and your girl will not get pregnant. This is why we need to have the tools to help us know what is going on in order to do a breeding. My first suggestion would be to run progesterone so that we have the right numbers and know exactly when it is the best time to breed our girls. One of the reasons we do this is that there are times that the progesterone (which signals ovulation) and the estrogen (which makes the girls receptive) are not in sync. Additionally, there are times that there is no ovulation, or the progesterone numbers are not high enough to sustain a pregnancy. Once you start running progesterone when your girls come into heat you will have the information to help guide you, and hopefully ensure some successful pregnancies.