(a) Describe the etiology, pathogenesis, symptoms, diagnosis and control of lumpy skin disease in cattle. (20 marks) (b) Write…

(a) Lumpy skin disease in cattle: etiology, pathogenesis, symptoms, diagnosis and control

Etiology: lumpy skin disease virus (LSDV), a Capripoxvirus of the family Poxviridae, closely related to sheep pox and goat pox viruses. It is spread mainly by blood-sucking arthropods (Stomoxys calcitrans, Aedes aegypti, Culicoides and ticks), and by direct contact, contaminated feed and semen. In India it was first reported in 2019 (Odisha), with large multi-state losses in 2022.

Pathogenesis: the virus multiplies at the bite site, spreads to regional lymph nodes and causes viraemia. It localises in skin and mucosae, infecting endothelium and pericytes, which leads to vasculitis, thrombosis, oedema and necrosis of the nodules.

Symptoms: after 4–14 days, fever (40–41°C), lachrymation, salivation and nasal discharge, enlarged superficial lymph nodes, and firm round skin nodules 2–5 cm across, from head, neck and udder to the body. The nodules may ulcerate and form deep necrotic plugs ("sit-fast"); oedema of limbs and brisket, lameness, mastitis, keratitis, abortion and infertility follow. Morbidity is high and mortality low, about 1–5%.

Diagnosis: clinical picture; PCR on skin nodules, scabs or blood is the test of choice; virus isolation in lamb-testis cells; electron microscopy; histopathology showing intracytoplasmic inclusion bodies; ELISA or virus neutralisation for antibodies. Differentials are pseudo-lumpy skin disease (bovine herpes mammillitis), dermatophilosis, insect bites, demodicosis and urticaria.

Control: no specific treatment, so supportive care with antibiotics for secondary infection, NSAIDs and fluids. Control relies on vaccination (the homologous live-attenuated vaccine or the goat pox vaccine), isolation and quarantine, movement restriction, vector control with repellents and insecticides, and disposal of dead animals, with notification.

(b) Rumenotomy in buffaloes: indications, anaesthetic regimen, procedure and post-operative care

Indications: traumatic reticuloperitonitis or foreign bodies in the reticulorumen (polythene, metal), rumen impaction and acute grain overload, and recurrent or vagal-indigestion bloat that has not responded to treatment.

Anaesthetic regimen: local infiltration (inverted-L or line block) or a paravertebral block of T13, L1 and L2 with 2% lignocaine in the standing animal. Buffaloes are more sensitive to xylazine than cattle, so only a reduced dose (about 0.01–0.02 mg/kg IM) is used when sedation is needed. Fluids correct dehydration and acidosis.

Procedure: the animal is restrained standing with the left flank clipped and prepared aseptically. A 20–25 cm left paralumbar fossa incision is made through skin, muscles and peritoneum. The rumen is pulled to the wound and sutured to the skin, or held by a rumenotomy frame, to prevent peritoneal contamination. It is incised and emptied of gas and contents, the reticulum and foreign bodies are felt, and they are removed by hand. The rumen is washed, closed with a two-layer inverting pattern (Cushing or Lembert), and returned after the wound is cleaned; the abdominal wall is closed in layers and the skin closed with interrupted sutures.

Post-operative care: antibiotics (penicillin-streptomycin) for 5–7 days, NSAIDs, fluids, withholding of feed for 24–48 hours then gradual refeeding, rumen liquor transfaunation, and wound dressing with suture removal at 10–14 days.

(c) Collection and despatch of materials for disease diagnosis in poultry

Collection:

• Send live, typically sick birds or fresh carcasses kept chilled, not frozen.
• Blood for serology is taken from the wing (brachial) vein, and serum is separated.
• Tracheal or choanal and cloacal swabs go in viral transport medium.
• Liver, spleen, kidney, lung and brain are taken for virology and bacteriology; small pieces about 3 mm thick are placed in 10% formalin (about 1 part tissue to 10 parts formalin) for histopathology.
• Feed, water and litter are sampled for toxicology.

Despatch: samples are triple-packed (leak-proof primary container, absorbent, and outer box) and labelled, kept at 4°C with gel packs, sent by the fastest transport, following biosafety and IATA rules. A history form states the flock size, age, vaccination, mortality and signs, so that Newcastle disease and avian influenza can be distinguished.