L29: Sudden death in ruminants

How do you take a history of sudden death

• Number/groups/fields/ages affected

• Progression of signs (if any)

• Vaccination & worming history

• Management

  • Recent treatments?

  • Changed fields or feed?

  • Unusual weather events?

How do you an environment examination

• Observational skills v v important

• Suspected toxicity- environment examination

What animals do you do an individual clinical exam

• Individuals clearly sick or affected

How much are PMEs for different animals

• On spot diagnosis

• Collect samples for further analysis

When do you do further diagnostic tests

• As appropriate

• Routine part of PM exam within reason

how do you do analyse the data and decision make for sudden death

• Lots of animals at risk

  • Quick and decisive

• Management changes?

  • E.g. feeding/field

• Control programme?

  • E.g. vaccination, worming

• Treatment of individuals?

• discuss actions before leaving farm

• Report lab results and follow up

What are some causes of sudden death in grazing animals

• Infectious

  • Septicaemia/toxaemia

    • Pneumonia

  • Anaemia

    • Liver fluke

    • Haemonchus

• Toxicity – plant or chemical

  • Inadvertant

  • Iatrogenic

• Nutritional

  • Metabolic disease

  • Bloat

  • CCN

  • White muscle …

• Other e.g. climate, trauma

Describe when infectious causes of septicaemia or toxaemia are seen

• Common, usually bacterial

• Often in environment, or commensals

• Predisposed by management factors

  • Good nutrition e.g. clostridial diseases

  • High stocking density e.g. salmonellosis, pneumonia

  • Flooding e.g. leptospirosis

How do you diagnose infectious septicaemia or toxaemia

• History esp vaccination status, management

• Clinical signs noted

• Changes in mucous membranes colour

• PME

What does this show

Clostridial entertoxaemia

•Three unvaccinated yearling dairy-bred bullocks at grass had died in a week. PME confirmed a diagnosis of clostridial enterotoxaemia.

What is the adult ewe clostridial vaccination protocol

• Priming injection then 4-6 weeks later a 2nd injection.

• Booster 4-6 weeks prior to lambing.

• Maximises colostral antibody levels.

What is the young lambs clostridial vaccination protocol

• Maternal antibodies last up to 12 weeks (Clostridial)

• (3 weeks – Mannheimia (P component of some vaccines)

What is the weaned lambs clostridial vaccination protocol

• From 8 weeks in age

• if short time to slaughter is vaccination sensible?

given an overview of infectious anaemia

• E.g. acute fascioliasis, haemonchosis

• Should be obvious premonitory clinical signs BUT infrequent or cursory inspection…

• Diagnosis

  • History esp. parasite control, clinical signs

  • Pale mucous membranes

  • PME more useful than FEC or blood testing

• Prevention – parasitology lectures

Give an example of infectious anaemia in cattle

Two calves, aged 8 weeks and 14 weeks, were found dead. PME confirmed acute fascioliasis. The calves had been moved to a field recently cut for silage so they were grazing the longer grass at the edge of marshy areas. These areas are ideal snail habitat and it is likely that large numbers of metacercariae were present.

How do you diagnose plant toxicity

• History esp. access to toxic plants, all deaths in same field etc

• Search of field

• PME – presence of leaves in rumen. Variety of PME signs

Give an example of plant toxicity in a dairy cow

A dairy heifer was found dead 6 hours after being observed to be alive and well. PM revealed haemorrhages on the heart but little else. Six hours later a further heifer was found dead. Inspection of the field revealed an old house site and a partially grazed oleander tree.

What are some causes of plant toxicity

• Plant e.g. yew, oleander

  • Access to old house site

  • Prunings put into field

  • Storm bringing down boughs

Describe toxicity of minerals and how it is diagnosed

• Mineral e.g. selenium, copper

  • Iatrogenic: Accidental over-supplementation

  • Animals fed wrong type of feed

• Deaths usually very rapid (esp. Se)

• Diagnosis

  • History of supplementation or feed change

  • Se: blood Se levels

  • Cu: Cu levels, PME

What are some other causes of toxicity

• lead, cyanide etc

• Access to random stuff

• Calves in old buildings (lead paint)

• Accidental access to pest poisons

• Medicated feed given to wrong animals

give an example of other (lead, cyanide) toxicity

In a group of 90 calves, 2 were found dead and another 2 were sick with neurological symptoms. Blood lead levels were in the toxic range. The calves had access to a rubbish pile 2 days previously.

What are some metabolic disturbances that can cause sudden death

• Hypocalcaemia

• Ketosis

• Hypomagnesaemia

• obvious in frequently observed animals

Give an example for metabolic disturbances

Hypomagnesaemia was diagnosed as the cause of sudden death of 3 cows in a group of outwintered autumn-calving beef cows in the Borders. The outbreak was notable for the fact that no sign of clinical disease was detected.

How can a nutritional imbalance cause sudden death

• Change in GIT function e.g.

  • Acidosis

  • Bloat

  • Gut torsion

• Deficiency of essential nutrients e.g.

  • Intrinsic due to change in microflora (CCN)

  • Extrinsic (water deprivation)

What can water deprivation lead to

to Salt toxicity

• Abdominal pain and regurgitation

• Nervous signs

  • Ataxia, circling, blindness, seizures, aggression

Give an example of nutritional changes of GIT function

In a herd of 150 cows, 3 died and a further 7 were ill. PME confirmed a diagnosis of acidosis. Enquiry revealed the cows diet was being supplemented with liquid waste from a nearby ice-cream factory. The day before the farm’s water supply had broken down and it is likely the cows overindulged on the liquid ice-cream.

Give an example of nutritional deficiency of an essential nutrient

Four recently weaned calves from a mob of 15 died over a period of 3 days. They had recently had a change in feed. Histopathology of the brain from 1 calf confirmed cerebro-cortical necrosis consistent with thiamine deficiency (Vit B1)

How do you diagnose sudden death

Prevent further cases asap

• Infectious: change husbandry, antibiotics, vaccination, anthelmintic as appropriate

• Toxicity: remove from source, therapy as appropriate

• Metabolic: treat as appropriate, changes to husbandry for remainder of animals

• Nutritional: change diet, therapy as appropriate