Nutrition and GI: Toxicology Flashcards
What is the name for a disease state that results from exposure to a poison?
Toxicosis
What samples can be used for clinical pathology of toxins?
- Urine
- Liver
- Kidney
- Blood
- Stomach contents
- Feed
- Bone/hair
What is the general treatment for toxicosis?
- Remove source
- Limit absorption/hasten elimination
- Symptomatic and supportive
What are common mineral poisoinings?
- Lead
- Copper
- Selenium
What is the role of the APHA in toxicoloty?
- Screening programmes
- Wildlife incident investigation scheme
- Emergency response- fire/flooding
- Animal disease outbreaks
What are the acute and subacute clinical signs of lead poisoning?
Acute
* young calves- typically
* found dead within 24hr
* Neurological signs- tremors, twitching, hyperthermia, salivation, rolling etes, blindness
Subacute
* Adults cattle and sheep
* Live for several days
* Neurological- dullness, anorexia, blindness, incoordination
* Staggerining, circling, muscle tremors
- When does chronic lead poisoning occur?
- How is lead poisoning diagnosed?
- Typical in lambs with high lead in soil- nephrosis is common, ill thrift, gait abnormalities, lameness
- Dx
* Clinical signs
* Heparin levels in blood
* Kidney lead levels gold standard, liver can also be used
How is lead poisoning treated and prevented?
Treatment
* Chelation therapy
* Thiamine hydrochloride
* Supportive therapy
* Rumenotomy
Prevention/Control Measures
* Remove animals from source
* Good waste managment on farm
* Check old buildings for paint, flashings etc
Following lead poisoning case what must farmers do?
- Farmers are obliged to take measures to avoid contamination of the food chain- 16 weeks
- If emergency slaughter in 16 weeks FCI saying offal discarded
- If animals close to finishing- blood lead analysis < 0.15 ok
- When does copper poisoning in cattle occur?
- What are the clinical signs?
- Access to pig feed or pasture grazed with pig manure
- Sudden onset, depressed, anaemia, jaundice and haemoglobinuria, ataxia, recumbency
What does PM or copper poisoning show?
How is it diagnosed?
PM
* Carcase- pale or jaundiced
* dehydrated
* liver pale tan or bronze
* Kidneys dark red or gun metal grey
* Urine dark red/black
* Secondary lung consolidation
Diagnosis
* History, clinical signs and PM
* Kidney copper concentrations to confirm
How is copper poisoning treated?
How is it prevented?
Tx
* Supportive therapy
* Copper antagonism
Prevention/Control
* Remember poisoning id due to efficiency or absorption and dietary availability
* Care with copper foot baths
- When does selenium posisoning occur?
- What are the clinical signs?
- Acute toxicosis occurs due to excessive supplementation
- Toxic CV, resp and urinary damage- staggering, dyspnoea, colic, diarrhoea, cyanosis, death
- What does PM show for selenium poisoning?
- How is it diagnosed?
- Sub cut haemorrhage, straw coloured fluid in pericardium, pulmonary oedema, abomastitis, intestinal and hepatic congestion, brain stem haemorrhage
- Elevated selenium in the liver, heart and kidneys
What are the clinical signs of anticoagulant rodenticides?
What is the implication for humans?
Anaemic, non-pyrexic, haemorrhages
Residues can remain in tissues for a long time, affected livestock may never enter food chain
Fertiliser
What is the aetiology of nitrate and nitrite poisoning?
Therefore what are the clinical signs?
- Excess intake
- Rumen bacteria convert to bacterial protein
- But if large quantities nitrate to nitrite which is absorbed into blood
- Converts haemoglobin to methemoglobin
Lack of O2
* Anoxia
* Cyanotic mucosae
* Tachypnoea
* Weak/rapid pulse
How is nitrate/nitrite poisoning diagnosed, treated and prevented?
Diagnosis
* Clincial signs/ history
* Blood- plasma bound nitrite
* Chocolcate brown blood
Tx
* Methylene blue IV
Prevention/Control
* Accidentally
* Can also be in docks and fat hen plants
- What can cause botulism?
- What are the clinical signs?
- How is it diagnosed?
- Use of broiler litter as fertiliser
- Often dead, if alive, recumbent with flaccid paralysis
- Clinical signs/history, PME- botulusm toxin test
No treatment
What is the aetiology of mycotoxins?
What are the financial impacts to the farm?
Aetiology
* produced by fungi
* Occur in feed routinely but usually at concentrations that do not impact health and performance
Financial impact
* Reduce crop yields
* Product rejection
* Reduced animal performance
* Increased health issues
How is mycotoxicosis controlled?
- Reduce exposure to mycotoxin
- Prevent production of mycotoxins- temp, CO2, water
- Ensure grain dried to correct moisture content
- Prevent exposure of silage to O2
- Big bale- avoid damage
- Keep straw dry
- Avoid feed, forage or bedding with visual mould
- Clen crop storage between batches
- Consider mycotoxin binder
- What causes aflatoxins?
- What are the clinical signs
- How is it treated?
- Aspergillus fungi, occur in field prior to harvest or post harvest if drying delayed/insect
- Primarily hepatic disease, decreased feed intake, decreased milk yields, recurrent infection
- None- remove source
- What causes zearalenone
- What are the clinical signs?
- Fusarium fungi- high temps, pigs more affected
- Signs of hyperoestrogenism, hyperaemia and swelling of the vulva, mammary glands, nymphomania
What mycotoxin causes facial eczema?
- Ingestion og sporidesmin, produced by the fungus
- Occurs in humid, warm wather
- Toxin concentrated in the liver causing epithelial necrosis of the bile ducts
- Ill thrify, reduced fertility
- Severly affected animals develop photosensitisation
Prevention/Control
* Oral administration of zinc salts
* Feed hay or brassica crops
* Remove stock from high risk areas
* Breed for resistance
- What causes ryegrass staggers?
- What are the clinical signs?
- Ingestion of the mycotoxin lolittrem produced by acremonium loliae found on perennial ryegrass
- Neurological signs 1-2 weeks after- fine tremors head and neck, head nodding, alteration in stance, severely affected animals
What does ingestion of ergoy alkaloids produced by claviceps purpurea
Ergotism
What are the clinical signs of ergotism?
- Capillary damage with extremities of animal appearing painful
- Inflamed then cold
- Dry gangrenous lesions
What are common plant poisonings associated with?
- Poor pasture availability
- Overgrazing
- Incorporation into conserved forages
- Use of herbicides
- Increased accessibility
- Transportation- hungry on arrival
- What plant is this?
- What does it cause?
- What are the clinical signs?
- How is it diagnosed?
- Ragwort
- Hepatotocixity- pyrrolizidine alkaloids
- Weight loss, oedema, straining diarrhoea, photosensitisation
- Liver biopsy- fibrosis, vein occlusion, bile duct proliferation
What do brassica crops (rape and kale) cause?
What are the clinical signs?
- Contin S-methly cysteine sulfoxide (SMCO)
- Nitrites
- Goitrogens
- Oxalates
SCMO- haemolysis, anaemia, pallor, jaundice
Hypothyroidism, goitre, hypocalcaemia
What can the following feed associated plants cause?
1. Clover
2. Linseed
3. Potatoes
- Oestrogens, cyanogenic, glycosides- frothy bloat
- Cyanogenic glycosides- death, salivation, sleepiness, staggering, convulsions
- Glycoalkaloids, phenolic compounds
- What is this plant?
- What does it cause?
- St Johns wort
- Photosensitisation
- What is this?
- What does it cause?
- What are the clinical signs?
- Rhododendron
- Grayanotoxinc bind Na channels- nervous, CV, muscles
- Abdominal pain, vomiting, tremors, staggering, recumbency, padding
What do acors/oak cause?
- Alimentary signs- colic, anorexia, weight loss, ascites, oedema
- PME- GI ulceration, haemorrhage, nephritis, liver degeneration
- What does braken ingestion lead to?
- What are the clinical signs?
- Cyanogenic glycoside, thiaminases
- Vary- Different toxins affect species differently, enzootic haematuria in cattle, depression, weakness, anorexia, tumours of bladder wall
What does yew ingestion cause?
Contains taxicatoside
Sudden death
Cardiac depression, dyspnoea, abdominal pain, muscle tremour
- What is this?
- What does it cause?
Hemlock water dropwort- oenathotoxin
Sudden death
Nervous signs
Diarrhoea with sublethal exposures
