Herpes, dog’s virus, and infertility

Herpes, dog’s virus, and infertility

The issue of infertility may be related to several reasons and many of them may also coexist with each other. However, it does happen that sometimes this issue is related to the Canine herpesvirus, even though this virus is not the real cause of the dog's major issue. For years, every time that a dog was suspected to be infertile, or every time a puppy was born dead, the Canine herpesvirus was considered the issue, even if no further examinations were made that could prove its presence or that could prove that it was the main cause of the dog’s pathology.

So, let’s see why the Canine herpesvirus should be considered as the main cause of the dog’s infertility or the central cause of the many issues that may occur during the pregnancy or immediately after. The main reason is that the Canine herpesvirus can interfere during different phases of the dog’s reproductive life and can determine infertility, abortion and puppies that are born dead or that die immediately after the birth. To better understand Canine herpesvirus nature, we must discuss the characteristics of this virus that make it different from other types of viruses that may be dangerous for the dog as well. 

We’re talking about a virus that adapts itself to the animal, so each kind of animal has its own virus, and it can only be transmitted from other dogs or animals. It is covered by an envelope made of lipids and glycoproteins not so resistant to solvents such as ether, chloroform, quaternary ammonium salts e phenolic derivatives. So, it’s perfectly clear that this virus is not so resistant to the external world. 

The first studies which classifies this virus fatal for dogs is from 1965. 

In deceased infants, focal lesions of a generalized and hemorrhagic necrotic type are characteristic, the pathology in adults is subtle or modestly limited to the upper respiratory tract and or external genitalia.

The spread usually happens through saliva, nasal mucosa or by inhalation and this related to the fact that the virus is very sensible to the external world and by the fact that it can die if the temperature is higher than 37 degrees, so it won’t survive within human body, where the temperature goes from 38 degrees to 38,5 degrees. Another way through which this virus goes from an animal to another, is through the mating. This happens through the contact with the genital mucosa where the virus is likely to place itself. 

The main characteristic of this virus is that after the acute stage of the infection, a sort of balance between the virus and the immune system is reached. During this phase, the dog is not likely to be contagious but after that the reactivation of the viral infection can happen at any moment determining the depression of the immune system such as stressful events, pathologies, or in female dogs the giving of birth.

The most common consequence is infertility that is usually associated with temporary rhinitis and little vesicular wounds that are placed on the external genital’s mucocutaneous joints. It’s compatible with the female’s dog quality of the seminal liquid and with her normal and regular periods. The transmission may happen through the licking of a high-infected dog’s genitals. 

After the transmission, that is usually transmitted sexually or when the dog is in heat, different events may happen: 

Absence of pregnancy 

Abortion or reabsorption

Puppies’ death during the 7-15 days after the birth

Fertility that happens thanks to the dog’s antibodies 

The termination of the pregnancy is due to the spread of the virus into the fetus and, most of the times, this is the main cause for abortion, reabsorption, fetus mummification or premature birth. Several years ago, several Japanese researchers studied a transplacental infection and, between 47 and 53 days of pregnancy, 33 puppies were born from 7 female infected dogs and, among them, 28 were infected. 2 puppies were born dead, 26 died after 15 days and only 5 of them were born safe without being infected. The virus placed itself in different fetal tissues: liver, spleen, kidneys, and lungs; also, 14 dogs out of 33 had necrotic wounds: the most famous characteristic of the CHV. 


A more recent study shows that female dogs infected after 30 days of pregnancy had several abortions after 41 or 51 days of pregnancy and they gave birth to a lot of dead or mummified fetus or their puppies dead immediately after the birth. Other two female dogs that were infected at the 40th day of pregnancy, gave birth to 10 puppies prematurely. Also in this case, the virus placed itself in different fetal tissues: liver, spleen, kidneys, and lungs. 


The CHV in male dogs is suspected when several female dogs don’t give birth or when they have an abortion or when their puppies die several days after their birth. Usually, the CHV is not associated with any kind of disorder or there could be several wounds placed on the foreskin or upper side of the penis’s mucocutaneous joint. There may also be several infections on the penis that can negatively interfere with the quality of the seminal liquid. The infected dog can feel libido and there could also be several balanoposthitis which are infections placed in the glans with the presence of ecchymosis and vascular wounds.

(balonopostite con ecchimosi punta del pene)


The CHV in neonatal puppies shows after the third week after the birth of the puppy. The symptoms may include depression, the puppy’s inability of sucking, persistent laments, diarrhea, rhinitis, abdominal pain, incoordination, or death that may occur after 24-48 hours since the beginning of the symptoms. The most recurring wounds provoked by the CHV are hemorrhages or multifocal ecchymosis placed in the kidneys, liver, and lungs that may be observed through the autoptic test that is made after the puppy’s death. During the first three weeks, the puppies are very vulnerable to the CHV because they are not able to maintain their body’s temperature near 38 degrees. Instead, they will assume the temperature according to the environmental conditions: the temperature of the birthing room, the number of puppies that are there and the ability of the female dog to keep her puppies warm. If the puppies are not sufficiently warm, the CHV will attack them and will reproduce itself. There is a slight possibility that a puppy may survive to the virus but will have neurological, renal, or lymphatic tissue permanent damage. 


An epidemiological French study observed that 75-80% of the holdings are infected even if infertility or neonatal mortality were not detected previously. There isn't official data about CHV cases in Italy, but after observing fertile and infertile dogs, I believe that the situation is completely comparable. Another important thing that we must consider is that even if the holding is 100% infected, the cause may not be represented just by the CHV, there could be other causes too that may provoke infertility. 


There are several diagnoses that can be divided into two groups: on blood and on tissues that are considered infected. Two are the diagnostic tests made on blood: the first and most reliable one is the serum neutralization test, the second one is called the ELISA technique. The serum neutralization test is done by isolating the virus, later the dog’s serum will be put on it. The test is effectuated on the cellular substrate where the dog’s serum is placed, then the CHV is added and if antibodies are generated the cytopathic effect is not executed. On the other hand, if the dog won’t produce antibodies then its cells will be attacked by the virus. The presence of antibodies is effective evidence that confirms that the dog met the virus. The higher the antibodies are, the more active the infection is. However, it won’t be possible to distinguish a severe infection (the virus has encountered the dog’s body just recently) from an infection that just reactivated and that was already into the dog’s body. Another diagnostic technique is PCR that must be conducted on tissues that are considered infected; whether they are vesicular lesions affecting the genitals or whether they are fetuses or fetal adnexa.

The technique is reliable because it consists in isolating the viral particles; the tissues that will be examined must be sent to zooprophylactic institutes. If the exam must be conducted on wounds while the patient is still alive, then they must be sent to the swab institutes with the material that will be examined, with terrain used for virology and unusual materials that will be requested from the laboratory that will conduct the test. 


The isolation during the most vulnerable period of pregnancy is the only measure that can protect the dog from infection or from a reactivation of an infection already placed in her organism. The isolation should be done between three weeks before the birth and three weeks after the birth. Another correct measure to avoid damages is to make the puppies meet the adult dogs as soon as possible. The adult dogs should have already been found positive to the serum neutralization test. Probably the puppies will already have contracted the CHV but staying in contact with the virus will help them to reach a balance between the presence of the virus and the latency period. Another helpful measure is to take care of the birth room conditions. The virus will die at a temperature of 37 degrees and since the puppies will not have the capacity to control their internal temperature, the birth room temperature must be around 28 and 30 degrees during the first week. Then, the temperature must be around 24-26 degrees during the second week and around 21 degrees during the third week. The moisture content must be around 55 and 60% so that the puppies’ bodies temperature will be under control. It is also important to bear in mind that the most efficient way to keep the puppies warm is contact and not radiant warmth. For this reason, a warm platform on the childbirth box’s pavement would be the best way to keep the puppy’s temperature regular.


There Does not exist any kind of specific medicine for the CHV; several medicines were tested without being successful. The serum collected from dogs that were previously exposed to the CHV is then administered by subcutaneous or intraperitoneal administration to other dogs . This should be helpful to provide antibodies that can fight off the infection. Another way that experts tried out, was to supply medicines that can stimulate the puppy’s immunity and female dog’s immunity that are part of various categories. All those attempts failed. 


The main characteristic of CHV virus is that it is scarcely immunogenic, this means that the virus produces a humoral response with serum antibodies that will remain active for little time. There is a treatment to help immunize the female dog that will protect the puppies from the most common CHV which is the main cause of the puppy’s death. This treatment is very different from other vaccines, because the CHV main characteristics are very different from other types of canine viruses. Two treatments should be done: the first one from the heat dog phase to 15 days from the mating; the second one should be done one or two weeks before the birth. This procedure has the aim to inject enough antibodies through the colostrum. The puppies will still be infected, but they won’t get sick thanks to the mother’s antibodies. Merial’s Eurican Herpes 205 is to be considered the only vaccine that can fight off the CHV, together with the treatments done during pregnancy in birth rooms. This treatment must be done again during every pregnancy because the antibodies are enough just for a few weeks. This is also the reason why the vaccine isn’t done on male dogs. 


100 dogs were monitored. Among them 15 were males and 85 females and all of them were part of different breeds [the 80% of them had previously infertility issues]. They were tested through the serum neutralized test for the CHV: 7 of them were negative [6%], 93 of them were positive [94%]. 72 vaccinated female dogs that were positive, had the first treatment 10 days after the mating; they had the second treatment 10 days before the birth. 51 of them gave birth to litters that were considered regular for their breeds [70,8%]. 21 female dogs out of 72 didn’t give birth. Despite a correct ‘’breeding management’’, through artificial seeding or natural birth after an accurate monitoring during the ovulation through the usage of vaginal smears and through the progesterone dosage, 10 of them [60%] already had infertility issues and it wasn’t possible to identify the real cause of infertility. 


The CHV is not the only cause of infertility, so it will be necessary to investigate all the probable causes of infertility or all the causes that provoked the puppy’s death, to avoid false expectations about the immunizing treatment for those issues the CHV is not the main or the only reason for. I believe that vaccination is a good treatment to protect female dogs from the reactivation of the CHV or from a new infection. I believe also that the vaccine during pregnancy is recommended for those female dogs that already had the virus or were part of a holding in which the virus was already detected, and for female dogs that aren’t affected by it, to avoid a new infection or a reactivation during pregnancy. 

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