For most dogs CHV is not thought to cause any significant problem and so for a long time is has largely been ignored by both breeders and vets. However, it is now clear that CHV can be a significant cause of death in young puppies, and also smaller litter size and weight.
The unborn puppy
CHV attacks the placenta of the mother, starving the foetus of nutrients. This can lead to abortion, stillbirth or re-absorption of the foetus (seen by the breeder as infertility).
The newborn puppy
If the puppy is infected before birth and survives, it may be underweight at birth and have a weakened immune system, making it vulnerable to early puppyhood infections.
If the puppy is infected soon after birth, CHV is known to be one of the factors in "fading puppy syndrome", in which the pup fails to suckle, loses weight and fades away despite intensive care.
The adult dog
in the dog, CHV can cause painful lesions on the genitals. In the bitch, there may not be any external signs, but the bitch seems infertile or gives birth to undersize and weak litters. In both males and females, CHV is also known to be a cause of kennel cough.