CANINE HERPESVIRUS INFECTION

Introduction It is an acute rapidly fatal disease that is associated with hepatic necrosis. Puppies are especially susceptible because of their inadequate thermoregulation.

Aetiology:- Canine herpesvirus, A DNA virus. It is ether sensitive, acid and heat labile. Replicates solely in canine cells and produces CPE (Cytopathic effect). Intranuclear inclusions are found occasionally. Optimum temperature for viral replication is 370C.

Pathogenesis and Pathology Routes of infection Mainly by inhalation of the virus. During passage through the vaginal canal Contact with infected litter mates Contact with oronasal secretion of the dam Intrauterine infection can take place

Pathogenesis and Pathology (contd.) Following inhalation acute necrotizing rhinitis develops by the second day. On successive days similar necrotizing lesions may in other regions of the body. The virus enters the blood stream through nasal lesion to produce viraemia and subsequent dissemination of virus throughout the body causing necrotizing lesions by the 3rd day of infection. But no initial multiplication of the virus on the tonsil and regional lymph nodes. Necrosis of the wall of small blood vessels and capillaries – acute vasculitis through which red blood cell leak out resulting in generalized haemorrhages especially in the kidney, liver, intestine and lungs. Necrosis of parenchymal tissues of the liver, kidneys, brain, lung, retina, adrenal glands, intestine and gastric mucosa.

Clinical signs A distinct feature is the absence of fever. In puppies:- It may be difficult to distinguish neonatal herpesvirus infection from other neonatal diseases clinically. But in herpesvirus infection the following are observed Progressive weakness, persistent crying and anorexia but no fever A distinct feature is the absence of fever. Depression, diminished suckling response, persistent crying, yellow-green diarrhea, rhinitis, abdominal pain and incordination. Notable petechial haemorrhages on the mucous membranes. Death frequently occurs within 24-48 hours after the onset of clinical signs in infected puppies. Puppies older than 3-5 weeks at the initial infection may develop only mild or inapparent infection. Clinical signs

In older dogs: Cutaneous lesions include and erythematous rash, with red papules progressing to vesicles. Papular and vesicular lesions may develop in the vulvovaginal orifice, prepuce, and/or oral cavity. Recurrence of lesion happens in bitches with the onset of oestrus but not in dogs. Lesions in affected animal is associated with infertility, abortion and still birth. Subcutaneous oedema of the ventral abdominal and inguinal area has been observed in some cases. Neurologic signs may precede the terminal stages of the disease. Clinical signs

Diagnosis – history, clinical signs, Presence of eosinophilic intranuclear inclusion bodies P.M. findings – histopathology Virus isolation on dog kidney tissue culture Increase in ALT and AST

Prophylaxis – No vaccine yet Keep the neonates warm using infra-red lamp or similar source of heat.