It is a highly friable disease of neonatal puppies. Death usually occurs within 24-48 hours of onset of clinical signs.
Distribution
The disease is widely prevalent through out the world in domestic and wild dogs. It was first reported by Charmchael in 1965. In some Kennels prevalence rate of 100% have been recorded without clinical signs.
Susceptible Host
Both wild and domestic canidae are worst victim.
Adult may suffer but there is collosal mortality in pups.
Aetiology
It is an alpha herpes virus having close antigenic relationship with human herpes simpex virus. The virus remains stable at temperature from -70 C to 40 C and a pH of 5 to 8. Virus gets inactivated at on exposure to common disinfectants. The virus has got the affinity to invade canine host cells. Virus can be grown in canine kidney or testicular cells where they produce severe cytopathic effect.
Virus used to produce type A inclusion bodies in affected cells. Plaque and giant cell formation may be the feature. Closest genomic relationship is seen with feline herpes virus, equine herpes virus-1, pseudorabies virus and varicella zoster virus. CHV becomes latent following primary infection and shared periodically. The virus is poorly immunogenic, neutralizing antibodies disappear with a few months after infection. Virus may be isolated from vesicular lesions of external genitalia.
Mode of Transmission
- Pup get the infection from genitalia of infected dams during intra-uterine life they get the infection.
- Contact with oro-nasal secretion of bitch following birth.
- Infected bitch of the Kennel birches.
- Infected neighbouring dogs/bitches discharging the virus.
- Infected littermates discharging the virus.
- Carrier asymptomatic dogs shred the virus and act as a source of infection.
- Concurrent distemper infection.
Lesions
- Diffuse multifocal haemorrhage and grey discolouration in parenchymatous organs in dead neonates.
- Serous or haemorrhagic fluid in the peritoneal cavities.
- Enlarged lungs with form texture and adematous in certain points along with enlarged bronchial lymph nodes.
- Petechial on the sera of intestine.
- Kidney shows circumscribed areas of haemorrhage on pale gray cortex. It is having a ‘Speckled’ appearance.
- Signs of meningo encephalitis, suppurative ganglio neuritis.
- Cerebellar and retinal dysplasia.
- Necrosis of placenta in female.
- Genital infection is characterised by enlargement of submucosal lymphoid follicle with a variable degree of vaginal hyperaemia and petechial or ecchymotic haemorrhage.
- Multifocal necrotizing lesions are seen in pups that acquire an in utero infection.
Diagnosis
It is based on
- History
- Physical examination
- Pathological changes on affected pups.
- Haematological and biochemical parameters.
- Increased ALT level due to hepatic necrosis
- CHV can be isolated from organs like adrenals, kidney, lungs, spleen and liver.
- Serology – Virus neutralization test, plaque formation test, tissue culture, antibody may persist following infection up to 2 years.
- Fluroscent antibody test
- Electron microscopy
- ELISA
- PCR – nasal, vaginal sample
Treatment
- Treatment can be hardly be attempted due to rapid course of the disease.
- 2 ml of hyper immune serum intraperitoneally has been suggested
- Elevation of environmental temperature and subsequently rectal temperature has been recommended with benefit.
- Antiviral drugs like vidarabine and acyclovir is showing some result.
- The serum is not commercially available but can ne had from bitches that have lost litters previously due to CHV infection.
Control
- One should try to gather information about the entry of the virus. Maternal antibody can afford protection of pups from fatal CHV but can not prevent the inapparent infection and shedding of virus.
- Inactivated sub unit vaccine is available in Europe that can be used during pregnancy.
- Maintainance of environmental temperature is one of the important tool of disease prevention.
- Isolation of the bitch as well as affected pups would be a logical proposal to prevent further spread.
- Finally, least contact with aerosol or through fomites of the carrier cause risk of acquiring infection low or minimum.
