One morning you notice a few drops of blood on the floor. You check all of your dogs’ feet — no cuts. So you think nothing of it. Later that day, more drops. Hmmm. Your male dog seems to be sniffing your female puppy quite a bit. She is just 6 months old, but an alarm bell goes off. Maybe she is in heat. A quick check confirms this; her vulva is swollen and there are some blood drops.
Factors That Contribute To The Timing of Heat
Most female dogs have their first “heat” or estrus somewhere between 6 and 15 months of age. Sighthounds are notorious for waiting until they are a bit older, while small and Toy breed females tend to have their first heat on the early side. Large and giant breed dogs may not have a first heat until they are 18 months of age. The range occurs because puberty is related to growth and physical maturity.
The standard pattern for heat cycles in dogs is about every six months, but there is tremendous variation among breeds and individuals. Basenjis tend to have one heat per year. Some bitches will cycle every seven months and some every 13 months. Most are somewhere in between. If you purchased your young female from a breeder, check with him or her to see the “typical” cycle for their females — both the start times and how often.
The primary hints you get if your dog has gone into heat will be the vulvar swelling and the discharge. Now, here are the kickers! Some female dogs are so neat they keep themselves clean and you will never find a single drip on your floor. In those cases, watch for unusual licking behavior. The amount of vulvar swelling can vary dramatically between dogs. Some girls can be identified as “in heat” from 30 feet away. Others have minimal swelling. You will need to learn what is normal for your dog. Of course, if you also own a male dog, he will help to alert you that your female’s perfume has suddenly become very attractive!
Stages Of The Canine Heat Cycle
Your dog will go through four stages in her reproductive cycle.
1. Proestrus: The first stage is proestrus. This stage generally lasts seven to nine days but it could be as short as three days or as long as two weeks. This is when the red discharge occurs and the vulva starts to swell. The female will squash any interest by male dogs at this point.
2. Estus: The next stage is true estrus. This is when your female dog is fertile. Generally, this lasts about a week. During this time, your female will stand and “flag” her tail to the side for a male to mount her. Your young girl should not be bred on her first heat. She is still growing and needs to put her energy into her own development. Female dogs can become pregnant during the first heat, though, so you will need to keep her away from any intact males.
3. Diestrus: The third stage is diestrus. Now your female will rebuff any male advances. In a pregnant female, this will end with whelping a litter. A dog who has not been bred will go through a similar set of hormonal changes and may show signs of a “false pregnancy” — producing milk and nesting, while collecting toys as her “pups.” Diestrus lasts about two months and fades into the fourth stage or anestrus.
4. Anestrus: This is the time when your female dog’s reproductive organs go into quiescence. All organs rest and repair, then lead into the next cycle with proestrus again.
The Hormone Connection
Your dog’s heat cycle is the result of a complicated set of hormonal reactions. First, the pituitary gland produces follicle stimulating hormone, or FSH. As egg follicles develop on the ovaries, estrogen is produced. Estrogen is what causes the vulva to swell and causes the lining of the uterus to shed blood, which is the red discharge. This is all in proestrus.
Right before your female dog goes into full estrus, the estrogen level will start to drop. Luteinizing hormone, or LH, follows a similar pattern but runs about two days behind the estrogen. LH triggers ovulation, which is the release of the eggs. The eggs are now available for fertilization. The empty follicles become corpus luteum cysts and start to produce progesterone. Progesterone levels stay high for the eight to 10 weeks of diestrus when the female would be pregnant. This hormone is responsible for helping to maintain the pregnancy. Progesterone will remain high in a female who is not bred or pregnant as well.
Interesting Facts About Canine Heat
A few female dogs will have a “silent” first heat. There will be minimal swelling, minimal bleeding and minimal attraction of male dogs. Some of these young dogs do go through the full hormonal pattern, however, and could potentially be bred and become pregnant.
There are some important things to keep in mind when your young dog comes into heat. She will attract male dogs (and possibly male coyotes). If you own an intact male dog, they will potentially breed. That includes her sire or a male littermate, which is not what you would want under any circumstances! A young dog should not be bred on her first heat. She is still growing herself and may not be physically or mentally able to raise a litter.
You can lower your dog’s “sweet scent” by feeding chlorophyll capsules. Check with your veterinarian for the correct dose. This will not totally disguise her scent but will help minimize the presence of unwanted suitors. Also consider purchasing a pair of “panties” if she is a female who leaves blood drips around the house. Use disposable pads and wash the panties frequently. Be aware that the panties cannot be counted on to prevent a breeding!
Some suggest that you may want to allow your female dog to have a heat or two before being spayed for health reasons. That puts heavy responsibility on you to be sure you do not have any unplanned litters. Most veterinarians prefer to do a spay surgery once a female is out of heat, so you will need to keep her isolated even if you do plan on a spay.
Good luck with your young female dog!