Canine Herpes (CHV) infection manifests in pregnancy as resorption of the embryos, abortion of the fetuses, stillbirth, or death of puppies within a few weeks of life. Transmission occurs by direct contact (sexual contact will do it but the usual route is simply normal nosing, licking, and sniffing) between the infected and uninfected dogs. For this reason, it is recommended that a pregnant female dog be isolated from other dogs for the last three weeks of pregnancy and the first three weeks after birth.
Fortunately, herpes viruses do not readily live in the environment (they dies at 68º F and are readily killed by common disinfectants); direct contact with an infected host or fresh secretions is needed for transmission. Still, once a dog is infected, it will be infected for life. Shedding virus is increased by stress. One more time: all mother dogs should be isolated from the final 3 weeks of pregnancy through the first 3 weeks after birth.
In Europe, a vaccine is available for use during canine pregnancy (one dose at the time of breeding and a second 6-7 weeks later, to be repeated with each pregnancy). Herpes is only a danger to the puppies when the mother is infected during pregnancy or shortly after delivery. Once the mother has been infected, subsequent pregnancies should be unaffected as she will have made enough antibodies to keep the virus in check.
CHV has also been known as "Fading Puppy Syndrome". Young puppies born to bitches who are infected by the canine herpes virus that do survive are highly susceptible to infection by the virus either in utero or by contact with urogenital secretions as they pass through the birth canal. You will typically notice some or all of the following symptoms in infected puppies:
- Acute onset of persistent crying
- Difficulty breathing (dyspnea; rapid shallow breathing; shortness of breath)
- Nasal discharge (coming from the nose)
- Ocular discharge (coming from the eyes)
- Pale, odorless, soft stool
- Lack of appetite; failure to nurse
- Lethargy
- Weight loss
- Abdominal tenderness
- Loss of consciousness; coma
- Death
Many adult dogs that are infected with CHV do not display any noticeable signs. When they do, both males and females tend to show signs of respiratory distress, and or 'sores' just like people do.
The following is from Ron Bell published in the ILD.
CANINE HERPES
Ron Bell, DVM - The Labradors of Borador
This article appeared in the first issue of the ILD - WRITTEN PRIOR TO THE EUROPEAN VACCINE BEING DEVELOPED AND MADE AVAILABLE IN THE EU.
Herpes virus infections can be found in virtually all species of animals. Generally speaking, the viruses are host-specific, that is to say they will not spread across species. However, some exceptions are noted where in the herpes viruses can be fatal to species which are no the primary host.
One of the most common herpes virus is Herpes Simplex which can cause oral lesions in humans (cold sores), but can be fatal in certain species of monkeys. The opposite is true for a virus called Herpes B also known as Herpes virus simiae, whose natural hosts are Macaca species of monkeys, but highly fatal to man. Thus, the complexity of this virus continues to baffle all members of the scientific community.
There are many herpes viruses which affect animals. However, there is one major herpes virus which is definitely known to cause problems in puppies, primarily those under three weeks of age. The major reason for this age bracket is that the body's heat regulatory system is not fully developed until after the third week of life. There is some indication that the herpes virus is also involved in the common "kennel" cough syndrome. Exactly what link, if any, exists between these two canine diseases, is unknown.
Anyone who raises puppies has the potential of experiencing this dreaded disease. Generally speaking, by the time a positive diagnosis is made, it is too late to save the affected puppies. It is not uncommon for an entire litter to die within 24 hours post clinical signs.
Unfortunately, this diseases is not clearly understood, thus there are many unanswered questions such as transmission, susceptibility, immunity, potential vaccination, and particularly, treatment. Because of the relative infrequency of this disease, it has not attracted major funding for research.
Some features of the disease that are generally accepted as facts are as follows:
- It primarily affects puppies 1-3 weeks of age, at least clinically.
- The major modes of transmissions are in utero, or from oral or vaginal secretions during the birth.
- Older dogs are usually unaffected clinically or may show signs of a mild upper respiratory disease.
- It generally only affects one litter from a given bitch. All subsequent litters appear to be protected by the immunity developed in the bitch.
Some questions that still remain unanswered are:
- Does the bitch truly develop a lifetime immunity post affected litter?
- Do other animals in the same kennel or environment develop and immunity?
- Do puppies which survive an affected litter have future problems?
- Can a vaccine be manufactured to prevent the disease?
The answers to these four questions are not clear. However, it is generally believed that a bitch with an infected litter will develop an immunity, but for how long is not known. There is more indication that the hormonal changes during pregnancy affect this immune response, thus causing the immune status to fluctuate. It is also suggested by some, that the exposure of the entire adult kennel to affected puppies or bitches will serve to protect all animals in the kennel. This sounds good in theory, but awaits an absolute answer.
Some puppies that survive an outbreak of Herpes Canis are know to have kidney problems later in life, but not all. This apparently depends on many factors such as the age when affected , severity per given puppy, and many unknowns. To say, carte blanche that all surviving puppies will have future health problems related to this disease, is simply not known.
The development of a vaccine may be possible but if this comes about, it will most likely be from the field of human medicine, as economics make it impractical in animal due to the infrequency of the disease. Exposure of non-infected to infected animals may indeed offer the development of the desired immunity. However, that means you must experience a disease outbreak prior to gaining any potential protection.
The clinical signs of this disease have a very rapid onset. One moment the puppies appear perfectly normal and the next moment you will them crying in severe pain. Your first thought is that the puppies have a severe bellyache. Most will have what is called abdominal breathing rather than normal chest breathing. They stop nursing and usually die within several hours. Due to the short time span from the first clinical signs to death, a person must act rapidly to have any chance of saving these puppies. The fact that it appears initially as a severe digestive problem usually delays a positive diagnosis, which further shortens the response time. Those who have experienced the disease are better equipped to recognize the difference between the two conditions. The crying and apparent pain associated with herpes is much greater than that demonstrated by an upset stomach.
The current mode of treatment is to immediately place the affected puppies in an incubator type apparatus at temperatures of 100F for about three hours and then reduce the temperature to 95F for another 21-24 hours. The relative humidity should be around 60%. Of critical importance, the puppies must be well hydrated with fluids, water and or 5% glucose solution, throughout this time span. This treatment is very tough to perform as the puppies cry constantly and one feels they are doing more harm than good. The higher temperatures do indeed either kills or arrest the infective virus, the sooner the treatment is started, the better chance one has of saving the puppies.
Another possible treatment, which motivated the writing of this article is a relatively new human anti herpes/antiviral drug called Zovirax (Burroughs Wellcome Company). This drug is commonly referred to as Acyclovir and comes in 200mg capsules. This report is based on experience using this drug. However, the positive affects were dramatic and they were worth sharing. Within hours following an oral administration of this drug, the affected puppies were moving around, ceased crying and started nursing. No further deaths occurred and the surviving puppies progressed normally post treatment. Up to that time, several puppies had died and a positive diagnosis was made of Herpes Canis via very typical kidney lesions found on necropsy.
As Acyclovir is a human drug, no dosage levels are available for puppies. The dosage used in this case was extrapolated from humans to puppies as not acute overdoses have been reported in humans. The puppies involved weighed around 2-3 pounds and were administered 10 mg. of the drug orally every six hours until they were 3-31/2 weeks old. It appears that 10mg every six hours would be safe for any size puppy, at least until further investigation dictates other wise.
The method of administration was very simple in that the capsules were separated and the 200 mg of Acyclovir powder was place in a cup and mixed with 10 cc of warm water. The powder does not fully dissolve, however, it is suspended adequately to be drawn into an ordinary syringe. The puppies were then given 1/2 cc (10mg) of this suspension orally every six hours.
While this treatment of this disease with this drug has not been reported, at least to my knowledge, the results of this single incident were remarkable. It is possible that this approach can benefit others who have experienced Herpes Cani in their breeding program.
In conclusion, it should be reemphasized that this formation is based on a single case with limited knowledge using a new drug. When dealing with this particular herpes virus in puppies one is dealing with a life and death situation. It may be more realistic to try the combination of the high temperature incubator environment plus the new drug until further data is generated. It should be pointed out that the drug Acyclovir is relatively expensive but we would all agree that with respect to the life of even one puppy it is insignificant.
Over the years I have shared this with other breeders who have used Acyclovir SUCCESSFULLY on their CHV litters. Just keeping your puppies warm does not guarantee success, the drug Acyclovir appears to be a miracle with CHV puppies/litters.
