Veterinary Preventive Medicine-II

CLINICAL MANIFESTATIONS

• In enzootic areas, where most animals could have been exposed to the virus and develop a certain degree of immunity, it may be longer.
• It is an acute febrile disease with morbidity in susceptible populations reaching 100% and mortality 90-100%.
• The normal route of infection is through nasopharyngeal mucosa.
• The course of the disease comprises of 4 stages.

I stage : Incubation period

• 2-9 days. It depends according to the strain and dose of the virus.
• The virus multiplies rapidly in the lymphoid tissue, lungs, bone marrow and intestines.
• Active proliferation of the virus in the tissue results in fever.

II stage : Prodromal phase

•  There is first rise in temperature - 105-107°C (41-42°C) and lasts for about 3-5 days until the appearance of lesions in the mouth.
• Animal shows depression, restlessness and anorexia.
• Muzzle is dry, starry coat and initial constipation noticed, Leucopenia with onset of fever and persists till death.

III stage : Mucosal phase

•  Mouth lesions on the inner lips and adjacent gums. Visible mucous membranes are congested.
• The mouth lesions are greyish foci with necrotic centers and shallow erosions with bleeding.
• Ulcers with bran like deposits noticed. Smacking as in FMD is not common. Animal is restless and shows excess thirst.
• Temperature is high and recedes after that diarrhoea begins.
• Rapid dehydration, marked weakness and severe progressive emaciation leads to death.

IV stage : Diarrhoeic phase

• About three days after the appearance of the mucosal ulcers fever regresses and profuse diarrhoea develops.
• The dark fluid faeces often contain mucus, necrotic debris and blood. Dehydration and wasting soon become evident.
• Severely affected animals may collapse and die within 12 days of the onset of clinical signs.
• In surviving animals convalescence lasts several weeks.

V stage : Convalescent phase

• Mouth lesions start healing. Rapid regeneration of the affected epithelium noticed.
• Slow recuperation of general health. Mortality in cattle, sheep and goats and pigs is 90%.

TO VIEW THE PHOTOS CLICK HERE