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Lantana Poisoning In Yearling Heifers

 Unusual presentation: Acute illness and buccal erosions in young heifers.

Above: Lesions under the tongue are sometimes the only signs of photosensitisation in cattle with pigmented skin as this area is exposed to sunlight when they lick their nostrils.

Time and location: April 2020, northern Queensland.

Case definition: Heifers with lethargy and pyrexia, some developing erosions in the mouth and cracked, peeling skin on nose and ears. Their condition progressively worsens and does not respond to treatment.

Disease mapping: An assortment of breeds – including Brahman/Murray Grey/Friesian crosses from multiple properties – were grazed on a house paddock for months, moved to a new paddock between November and March, and then back to the house paddock at the end of March 2020 (see timeline). Five cases occurred in the last two weeks of April from a mob of 25 cattle.

At the end of April post-mortems were conducted on two Murray Grey heifers that had moderate to marked photosensitisation. The heifers had ulcers on the nose tongue and mouth, yellow discolouration of fatty tissue, rumens distended with a large quantity of partially digested grass and fluid, hepatomegaly, distension and bruising of the gallbladder and gallstones, and discolouration of the renal cortex.

Gross findings:The first two heifers examined in mid-April were pyrexic. The Emergency Animal Disease Hotline was notified of the suspect erosions. Blood and tissue samples were sent for vesicular disease diagnostic testing. The heifers deteriorated over the next fortnight during which time another three cases occurred.

Laboratory findings: Histological findings were suggestive of lantana poisoning, especially the hepatopathy, myocardial necrosis and severe, subacute nephrosis.

Animal / management / environment risk factors:  Interestingly there was no shortage of feed with abundant reasonable quality dry matter available in the paddock. While initial examination of the house paddock was unremarkable, a more thorough examination revealed lantana plants that had been eaten.

Recommendations to the producer: Move all cattle from the house paddock. Spray lantana and check there is none present before introducing cattle.

Above: Fatty tissues yellow, liver large and gall bladder distended.