| Varicellovirus canidalpha1 | |
|---|---|
Virus classification | |
| (unranked): | Virus |
| Realm: | Duplodnaviria |
| Kingdom: | Heunggongvirae |
| Phylum: | Peploviricota |
| Class: | Herviviricetes |
| Order: | Herpesvirales |
| Family: | Orthoherpesviridae |
| Genus: | Varicellovirus |
| Species: | Varicellovirus canidalpha1 |
| Synonyms[1] | |
| |
Canid alphaherpesvirus 1 (CaHV-1), also calledCanine herpesvirus (CHV), is a virus of the familyHerpesviridae which most importantly causes a fatal hemorrhagic disease inpuppies (and in wildCanidae) less than two to three weeks old. It is known to exist in theUnited States,Canada,Australia,Japan,England andGermany.[2] CHV was first recognized in the mid-1960s from a fatal disease in puppies.[3]
Theincubation period of CHV is six to ten days.[4] CHV is transmitted to puppies in the birth canal and by contact with infected oral and nasal secretions from the mother or other infected dogs, but it is not spread through the air.[2] The virus replicates in the surface cells of the nasalmucosa,tonsils, andpharynx. Low body temperature allows the virus to spread and infect the rest of the body.[5] Symptoms include crying, weakness, depression, discharge from the nose, soft, yellowfeces, and a loss of thesucking reflex. CHV also causes a necrotizingvasculitis that results inhemorrhage around the blood vessels.[6] Bruising of the belly may occur. Eye lesions includekeratitis,uveitis,optic neuritis,retinitis, andretinal dysplasia.[7] There is a high mortality rate, approaching 80 percent in puppies less than one week old,[8] and death usually occurs in one to two days.[9]
In puppies three to five weeks old, the disease is less severe due to their ability to properly maintain body temperature and mount afebrile response.[8] More puppies survive, but they can develop alatent infection, they can also develop petechial hemorrhages in the kidney[10] due to vasculitis. Some later getneurologic disease and have symptoms like difficulty walking and blindness. Reactivation of a latent infection may be caused by stress or immunosuppressive drugs such ascorticosteroids.[7] The site of latency has been shown to be thetrigeminal ganglion and possibly thelumbosacral ganglion.[11]
In adultdogs, the virus infects the reproductive tract, which allows it to be sexually transmitted or passed to puppies during birth. The disease can causeabortion,stillbirths, andinfertility. It is also an infrequent cause ofkennel cough. However, sexual contact is not the primary cause of transmission. Most adult dogs become infected by inhaling the virus via airborne particles spread by coughs or sneezes. It can also be contracted by drinking from a contaminated water bowl, or even just by sniffing or licking another dog that is shedding the virus.
Like other types of herpesvirus, previously infected dogs can from time to time release the virus invaginal secretions,penile secretions, and discharge from the nose. Raised sores in the vagina or on thepenis may be seen during these times. Spread of the disease is controlled by not breeding dogs known to have it.Serology can show which dogs have been exposed (although not all of them will be releasing the virus at that time). Serological studies of various dog populations have revealed a seroprevalence of 40 to 93 percent.[7] Bitches who have a negative serology for CHV should be isolated from other dogs from three weeks before to three weeks after giving birth.[9] Bitches that have lost puppies to the disease may have future litters that survive due to transfer ofantibodies in the milk.
Diagnosis of the disease in puppies is best accomplished bynecropsy. Findings include hemorrhages in thekidneys,liver,lungs, andgastrointestinal tract. Treatment of affected puppies is difficult, although injecting antibodies to CHV into the abdomen may help some to survive. Keeping the puppies warm is also important. The virus does not survive well outside of the body and is easily destroyed by mostdetergents.[5] A vaccine in Europe known as Eurican Herpes 205 (ATCvet code:QI07AA06) has been available since 2003. It is given to the dam (mother) twice: during heat or early pregnancy and one to two weeks before whelping.[4]
Dog pox is an infection of canines which may be caused by thecanine herpes virus, and can result in symptoms ranging from no symptoms to inflammation of therespiratory ordigestive tract toskin inflammation andlesions. Over 60% of adult male dogs exhibit lesions as a result of this infection.[12] It can result in reduction ofepithelial function in the intestine.[13]
Studies of using CHV as aviral vector forgene therapy in dogs and as a basis forrecombinant vaccines are ongoing.[14] Its use as a vector in bait-delivered oral vaccines in wildfoxes is also being investigated.[15]
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