If your dog in heat stopped bleeding and then started again, you may be wondering what is going on. The normal reproductive cycle in dogs is a repetitive rhythm of hormonal changes that trigger release of eggs and prepare the uterus and mammary glands for pregnancy. Most females dogs have heat cycles twice a year on average, except the Basenji, wolf hybrids, and some Greyhounds, which cycle once yearly.
Understanding a Dog's Heat Cycle
There are several signs that announce the female dog’s heat. Attentive dog owners may notice the following signs:
Bloody discharge – this is the most common and easily observable sign. Drops of blood can be found on the dog’s fur, on the floor or in the dogs' bedding.
Swollen vulva – the vulva becomes bigger and easily visible.
Swollen nipples – the nipples become bigger, harder and firmer.
Tail flagging – the female dog’s tail will usually be held straight up even under random circumstances.
Male interest – male dogs will be attracted and they will sniff her and even try to jump her.
Mood swings – some females become cuddlier while others become more isolated.
It should be noted that not all female dogs in heat show all of the above listed signs. In some females only one or two sign will be visible. You just need to be attentive and observe her carefully.
The Dog's Heat Cycle
The female dog’s reproductive cycle follows a pattern of four clearly defined stages, each with accompanying activity in the female’s reproductive tract and sexual behavior. The four phases are:
Proestrus – it lasts between 4 and 15 days and during this phase the vulva swells and shows first clear and then bloody discharge. Additionally, the dog exhibits moods swings.
Estrus – it lasts between 4 and 8 days and during this phase the bleeding stops and the ovulation begins. At this point, the bitch will accept mating by dogs.
Diestrus – it lasts between 6 and 10 weeks and during this phase the walls of the uterus become thicker and hormonal changes occur but there are no visible signs.
Anestrus – it lasts for 15 weeks and during this phase the female dog’s reproductive tract rests and prepares itself for the next heat.
The proestrus and estrus phase are popularly known as heat or season.
Simply stated, the heat cycle usually lasts between 2 to 3 weeks. Generally speaking, as a rule of a thumb, it takes a bitch one week to come in heat, then one week to actually be in heat and ultimately one week to come out of heat.
More precisely speaking, the heat lasts for around 18 days. However, in certain cases it can last for as little as 12 days or for as long as 28 days. Every dog is different and therefore, every heat cycle is different.
Help, My Dog in Heat Stopped Bleeding and Then Started Again
If your dog in heat stopped bleeding and then started again, this can be indicative of pyometra. The term pyometra indicates a life-threatening uterine infection. It may occur at any time in the days, weeks, or months after an estrous cycle and requires immediate veterinary attention.
Pyometra is one of the most common life-threatening conditions in intact females. While it is most likely to occur in females over six years of age, a pyometra may develop at any age, even after the very first cycle. It can develop as early as immediately after ovulating or as late as three months after ovulating.
The disease is almost invariably associated with metoestrous, the phase of the cycle that is dominated by progesterone. Progesterone drugs may also predispose to pyometra. What happens is not fully understood, but it seems that the lining of the uterus over-responds to the progesterone, creating an environment in which bacteria multiply.
The earliest sign of an impending uterine infection is a discharge of mucus after the estrus stage of the cycle. To all intents and purposes, the female is clinically fine, yet inside the womb mucus-producing cells have multiplied and created a condition called cystic endometrial hyperplasia. This may not cause a clinical problem, but mucus is an ideal breeding ground for bacteria. Either in that estrus, or in the next, bacteria do multiply, turning the mucus into pus.
If the cervix remains open, pus escapes from the uterus and dribbles through the vagina and out of the vulva. This is "open pyometra" and it can be diagnosed relatively easy. If the cervix has clamped shut, then pus builds up inside the uterus. This is a "closed pyometra" and its clinical signs develop faster. They include increased thirst, decreased appetite, more frequent urination and lethargy. If left untreated, a closed pyometra is fatal.
Females with pyometra often have a normal body temperature, and if the cervix is open, a pale green, creamy to bloody discharge from the vagina may be seen. Later in the course of infection, the presence of considerable amounts of pus accompanies signs of shock. These include vomiting, rapid breathing, racing pulse, fever and collapse.
Open pyometra is usually diagnosed from the symptoms. In the early stages, with little or no discharge, a blood sample can reveal the presence of a bacterial infection in the body. Diagnosis of closed pyometra is confirmed by x-ray or ultrasound, both of which will show an enlarged uterus. The womb can swell to an enormous size, even larger than it does for a full litter of pups. Ultrasound will safely be able to distinguish between pyometra and pregnancy.
If either an open or closed pyometra is diagnosed by the vet, an immediate ovariohysterectomy, or spaying, needs to be performed. Intravenous fluids and antibiotics are routinely given. If the cervix is open so that the pus can drain freely, it is possible to use drugs to induce the womb to contract and squeeze out the pus. However, the likelihood of future womb infections in extremely high and the female should be bred at the next season if recurrence is to be avoided.
Prevention. To prevent pyometra just make sure your female dog is spayed. If she is not, watch out for the signs – vaginal discharge, usually four to eight weeks after estrus, lethargy, increased thirst and decreased appetite.
About the Author
Dr. Ivana Crnec is a graduate of the University Sv. Kliment Ohridski’s Faculty of Veterinary Medicine in Bitola, Republic of Macedonia.
She currently practices as a veterinarian in Bitola and is completing her postgraduate studies in the Pathology of Domestic Carnivores at the Faculty of Veterinary Medicine in Zagreb, Croatia.
Ivana’s research has been published in international journals, and she regularly attends international veterinary conferences.