Chemical and Plant Poisoning in Cattle

Approach to Chemical and Plant Poisoning in Cattle

1. Demonstrate a logical problem-solving approach to suspect poisoning events in cattle
2. Recognise the common presentations for which poisoning would be a differential diagnosis in cattle
3. Understand the clinical signs, diagnosis and treatment of the more common poisonings of cattle
4. Give examples of common plant and chemical poisonings grouped by presenting signs and consider their differential diagnoses
5. Apply general principles of treatment of poisonings in cattle

Demonstrate a logical problem-solving approach to suspect poisoning events in cattle

Approach to suspect poisoning:

• Hx taking
• CE
• PM

Clinical Exam

• Initially observation from distance
• Observe surroundings
• PE:
• Is first aid required
• Predominant clinical signs
• Common poisons in these circumstances
• Can a non-toxic cause be identified

History

• May be on phone - helps triage and decide course of action
• Topics to cover:
• Signs - onset and duration
• Location of livestock
• Nutrition of livestock
• Access to poisons
• Does hx suggest non-toxic cause?

Post Mortem

• Useful to diagnose cause:
• Anthrax investigation if sudden death with no explained cause
• Done on farm or PM facility:
• Full external examination
• Need to consider economics and value of PM to farmer

Recognise the common presentations for which poisoning would be a differential diagnosis in cattleUnderstand the clinical signs, diagnosis and treatment of the more common poisonings of cattle Givee examples of common plant and chemical poisonings grouped by presenting signs and consider their differential diagnoses

Plants

Presenting Signs

Chemicals

• Sudden death
• Neurological
• Gastrointestinal
• Respiratory
• Cardiovascular
• Dermatological
• Urine discolouration
• Abortion

• Yew
• Ragwort

• Braken

• Acorn / oak
• Rhododendron
• Water dropwort
• Ergot
• Hemlock
• Brassica
• Foxglove

• Blue-green algae

• Laburnum
• Fungal alflatoxins
• Cyanogenic glycosides
• Nitrates

• Lead
• Fog Fever
• Photosensitisation
• Molybdenum - geographical
• Copper
• Organophosphates
• Urea
• Warfarin

Blue - Common Red - Uncommon Bold - Important

Bracken

Common and Important Plant Posions

• Principal sign - urine discolouration
• Other clinical signs:
• Haemorrhagic syndrome
• Laryngitis in calves
• Neoplasia
• Cumulative over several weeks before clinical signs appear

• Ubiquitous in Britain
• Grazed or in hay
• Cattle > sheep

• Treatment - symptomatic:
• Remove source
• Blood transfusions
• Clotting agents [vit K]
• Abx for 2ndry infectons
• Control:
• Remove animals from pasture
• Provide good forages in areas of minimal grazing

Ragwort

• Principal sign - neurological:
• Bilateral central blindness
• Head pressing
• Weakness
• Coma
• Other clinical signs:
• GIT - constipation and tenesmus
• Dermatological - jaundice, photosensitisation

• Diagnosis:
• Nutritional hx
• Clinical signs
• Liver biopsy
• PM
• Horses > cattle

• Live and dead plant both poisonous:
• Control - pull or burn plant
• Aetiology of poison - pyrrolizidine alkaloids:
• Hepatotoxic
• Acute exposure - acute liver failure
• Chronic exposure - progressive liver damage and chronic liver failure

Yew

• Principal sign - sudden death

• Diagnosis:
• Yew leaves present in mouth
• Yew leaves present in stomach
• Mouthful of leaves kill cattle in minutes
• Leaves more poisonous cf berries

Acorn

Uncommon and Important Plant Posions

• Principal sign - GIT:
• Indigestion
• Cessation of rumination
• Inappetance
• Constipation
• Tenesmus
• Blood-tinged faeces
• Other clinical signs:
• Renal - proteinuria and azotaemia

• All oak species toxic
• Poison from tannins:
• Can lead to chroic renal failure in animals recovered from acute stages
• Tx - symptomatic:
• Purgative
• IVFT

Ergot

• Principal sign - neurological:
• Weakness
• Ataxia
• Paralysis

• Other clinical signs:
• CVS - Dry gangrene of extremities [arterial constriction]

• Dark fungus growns amoung grasses
• No tx

Water dropwort

Rhododendron

• Principal sign - sudden death
• Other clinical signs:
• Neurological - ataxia
• Respiratory - Dyspnoea
• GIT - Salivation

• Diagnosis:
• Gnawed roots in stomach
• Along banks and streams
• Tuberous roots v palatable to cattle

• Principal sign - GIT:
• Projectile v+
• Abdominal pain
• Bloat
• D+
• Other clinical signs:
• Neurological - ataxia
• Sudden death

• Tx - symptomatic:
• Rumenotomy
• IVFT
• Diurestics
• Unpalatable unless food scarce / inquisitive animals

Common and Important Chemical Posions

Lead

• Principal sign - neurological [acute]:
• Convulsions
• Blindness
• Head pressing
• Excitability
• Collapse
• Other clinical signs [chronic]:
• Ill thrift
• Weight loss
• Scour
• Fertility issues
• Diagnosis:
• Clinical signs
• PM - lead levels in blood, kidneys, faeces

• Tx - symptomatic:
• Calcium EDTA - binds lead
• Need to inform APHA - human health risk in meat / milk
• Calves susceptible - inquisitive
• Lead sources:
• Paint
• Batteries
• Ground deposits

Photosensitisation

• Principal sign - dermatological:
• Pruritus
• Cutaneous oedema
• Blistering and ulceration
• Toxicity - circulating chemicals that absorb harmful sun rays and damage tissue
• Aetiology:
• 1ry - direct action ingested toxin [St John's wort]
• 2ry - damaged liver fail to break down toxic chlorophyll metabolites [Ragwort]
• Congential - rare
• Tx:
• Move cattle
• NSAIDs

Fog Fever

• Principal sign - respiratory:
• Dyspnoea
• Crackles lung ausc
• Other clinical signs:
• Non pyrexic
• Pale mm
• Tx:
• Diruetics
• Anti-infl. - NSAIDs
• Abx

• From L-tryptophan:
• Converts to Tri-methyl indole in rumen
• Cytotoxic to lung tissue

Molybdenum

• Principal sign - dermatological:
• Depigmentation - poor, rusty coat
• Other clinical signs:
• GIT - green / black D+, poor BCS
• Poor milk yield, poor calf growth rate

• Diagnosis - challenging:
• Copper levels - blood and liver
• Soil analysis
• Teart pastures - high molybdenum levels
• Toxicity comes from copper antagonism

Uncommon and Important Chemical Posions

• Principal sign - sudden death
• Other clinical signs:
• Haemolysis
• Anaemia
• Haemoglobinurea
• Jaundice
• Diagnosis - PM:
• Yellow carcase
• Bronze Liver
• Black kidneys

• Essential for maintaining health - small quantatities:
• Pigs > cattle > sheep
• Toxicity - winter housing:
• In concentrate feed
• Levels can build in liver

• Acute poisoning - iatrogenic:
• Overdose when treating deficiency
• Chronic poisoning - nutrition:
• Supplementation in feed
• Leads to acute haemolytic crisis
• Tx - withdraw concentrates

Copper

Apply general principles of treatment of poisonings in cattle

Reduce toxin absorption

• Absorbents - activated charcoal
• Oral fluid therapy
• Purgatives - laxatives [paraffin]
• Rumenotomy and lavage

Expedite toxin elimination

• Forced diuresis:
• IVFT
• Diuretics

Symptomatic treatment

• Of clinical signs

Toxin antagonist

• Rarely available
• Calcium disodium EDTA for lead poisoning

• Evidence of seizuring - churned soil, lacerations
• Check pharynx, oesophagus and rumen - presence of yew
• Check rumen - presence posionous plants or chemicals
• Identify main body system involved
• Collect samples - blood, liver and kidney:
• frozen and formalin fixed
• Does PME suggest non-toxic cause [clostridium]?

First Aid

Posions

Signs

• Sudden death
• Neurological
• GIT
• Respiratory
• CVS
• Dermatological
• Urine discolouration
• Abortion

• Seizuring
• Hyperaesthetic
• Pain

• Account for clinical signs
• Accessible in area

Sedate with Xylazine

Access

Onset and Duration

Nutrition

Location

• Forages
• Grazing
• Feed shortages
• Contamination
• Ration formulation errors
• Pasture management

• Housed

• Grazing / at pasture

• Recent movement

• Lead paint in buildings
• Fly tipping

• Acute onsent:
• Yew

• Chronic / delayed onset:
• Braken

Food shortages - resort to eating unpalatable [toxic] food