CASE NOTES

A Case of Pimelia Poisoning

Kylie Greentree, Veterinary Officer (Bourke), Industry and Investment NSW

Posted Flock & Herd August 2010

CASE HISTORY

A producer from the Louth area rang with regards to a 3 month old male Santa Gertrudis calf presented with pronounced ventral oedema extending from under the jaw along the entire ventral midline and prepuce. This calf was the second affected calf in one week in a herd of 47 cows and calves. The cows and calves were on agistment and had been grazing in the paddock for 12 months. Both calves that were affected were standing but in respiratory distress.

Image of bovine with swollen jaw and protruding tongue

Clinical findings

The calf presented with very pronounced ventral oedema under the jaw, down the neck and brisket and extending under the belly to the prepuce, and was in respiratory distress. The calf had rapidly lost a lot of condition and had foul smelling diarrhoea. The calf was depressed, was reluctant to move and had pale mucus membranes. The remainder of the mob were in good condition, condition score 3-4. A post-mortem was performed on one of the sick calves.

Image of bovine post-mortem showing discoloured fluid accumulation

Post-mortem findings

Post-mortem revealed extensive subcutaneous oedema and generalised pale tissues. The Thoracic cavity was filled with large volumes of fluid that was brown/ red in colour. The lungs appeared pale pink with a 10cm section at the bottom of the left caudal lung lobe that appeared depressed and a darker pink, and the pleural surface of the lung had a diffuse roughened dark red to yellow areas with strands of friable yellow material. The liver was enlarged, paler red in colour and irregular in shape with rounder margins of the liver lobes.

DIFFERENTIAL DIAGNOSIS

Pimelea toxicity(or other toxicity that alters vascular permeability)
Pleuropneumonia
Congenital defect (anomalies of the thoracic duct or RHS heart failure)
Hypoproteinemia in liver disease
Obstruction of Lymphatics (ie neoplasia)
Parasitic worm burdens
Urinary calculi
Lumpy jaw
Hardware Disease

CLINICAL TESTS PERFORMED

Faecal egg count; worm eggs negative
Urinalysis; no calculi detected
Haematology; marked hypoproteinaemia. Moderate anaemia without reticulocyte response, mild leucopaemia.
Biochemistry; Liver enzymes, mild elevation of GGT, no biochemical evidence of active hepatocellular damage
Pericardium; Fibrinohaemorrhagic exudate on surface facing epicardium. Reactive mesothelial cells. In some areas of the loose connective tissue layer there is fibroblast proliferation and infiltration with lymphocytes and occasional neutrophil and macrophage. In some areas connective tissue is proliferating into the exudate in the process of organisation
Liver; Distrubtion of architecture. Severe dilation of sinusoids creating extensive empty spaces in the liver parenchyma. Extensive whirl of fibrous tissue, sometimes surrounding central veins, and thick cords of fibrous tissue transversing parenchyma. Some central veins and many veins in portal triads thickened and dilated. Scattered replacement haemorrhages. Mild bile ductule proliferation in portal triads. Moderate fatty change
Lungs; Atelectasis in one section, other areas of parenchyma appears normal. Fibrinohaemorrhagic exudate on the pleural surface, which in some areas gets organised by connective tissue proliferating from the pleura

MORPHOLOGICAL DIAGNOSIS

Severe Chronic Diffuse Hepatic Phlebectatic Peliosis (Blood filled spaces in the liver, sinusoidal dilation; which occurs in pimelea poisoning in cattle).

With a Chronic-active severe Haemorrhagic Hydropleuritis.

Diagnosis

Pimelea Toxicity.

Discussion

Pimelea Toxicity occurs in the drier regions of NSW, QLD and Northern South Australia.

The four most toxic plants include;

Pimelea simplex sub species simplex (desert rice-flower)
Pimelea simplex subspecies continua (gibber rice-flower)
Pimelea trichostrchya (flax weed)
Pimelea elongate (lakebed pimelea)

Simplexin toxin is the principal toxin found in the above Pimelea species. Simplexin toxin activates the enzyme protein kinase C. This enzyme acts on cell proteins particularly myosin, resulting in the contraction of thick muscled vessel walls. The constriction of these vessels takes blood away from the heart and lungs. Constriction causes a build up of pressure, which leads to fluid leakage into the chest, right sided heart dilation and subcutaneous oedema.

Reference

Fletcher,M. Silcock,R. Ossedryver,S. Milson, J. &Chow, S. (2009) Understanding Pimelea Poisoning of Cattle.