L2: Sudden Death II

major cardio toxicants:

chronic heart failure

-irritant diterpenoids of Pimelea spp

-Gossypol (in cotton seed)

-Persin (in avocado)

major cardio toxicants:

peripheral vascular dysfunction

ergot alkaloids

irritant diterpenoids:

Pimelea spp

-Simplexin

-Huratoxin

irritant diterpenoids:

Pimelea spp - syndrome names

-Pimelea poisoning of cattle

-St George disease

-Marree disease

irritant diterpenoids:

Pimelea spp - major sources

Pimelea spp. (rice flowers, flax weeds)

• Family Thymeleaceae

• 90 spp in Australia, all endemic

-winter-growing annual herbs; inland Qld, NSW, SA

Pimelea trichostachya

Pimelea simplex ssp. simplex (desert rice flower)

Pimelea simplex ssp. continua (elongata)

types;

Pimelea trichostachya (4)

-flax weed

-rice flower

-broom bush

-Borgia’s bouquet

irritant diterpenoids:

Pimelea spp - minor sources

Small perennial shrubs; coastal or near-coastal Qld

-Pimelea latifolia ssp.

-altior Pimelea, neoanglica

-Pimelea strigosa

-Pimelea linifolia

toxicity:

irritant diterpenoids (Pimelea)

-v unpalatable

-dosing with simplexin reproduces the disease

-inhalation, ingestion of dry dead plants

• trapped in mucus and swallowed

moa:

irritant diterpenoids (Pimelea)

-potent activators of protein kinase C

which species is affected by Pimelea?

-cattle

-other spp only get diarrhea

-full syndrome rare in horses

toxicicosis symptoms:

cattle - Pimelea

-persistent constriction of pulmonary venules → chronic right-sided heart failure

-irritation of alimentary tract → persistent diarrhoea

-expansion of the plasma volume without stimulating erythropoiesis → anaemia

Pimelea:

why are horses and sheep less susceptible to chronic RHS HF?

-have less sm mm in pulmonary venule walls → constriction

symptom progession:

Pimelea - cattle

Pulmonary venules constricted → back-pressure causes right ventricular dilation?edema fluid leakage into thorax → jugular pulse & distension → sq edema swelling

Pimelea:

poisoning conditions

-annual herbaceous spp boosted by grazing pressures

• overstocking

• poor pasture condition

• bad soil

Pimelea:

incidence

-above-average winter rain promotes growth

-below average summer rain or drought prevents removal of dry Pimelea particles from pastures by rain and biodegradation by soil microbes

Pimelia:

clinical signs

-diarrhoea (absent in some cases)

-weight loss → emaciation

-distended jugular vv

-subcutaneous oedema of brisket & submandibular space → massive anasarca

-anaemia

-↓ exercise tolerance

pimelea:

path

-dilation of right ventricle

-hydrothorax

-sq edema of brisket and submandibular space liver: peliosis

-hepatis = swollen blue-black liver engorged with blood in massively dilated sinusoids

-capillary dilation in adrenal glands and kidney

Pimelea:

tx, control

-no specific therapy

-remove from toxic pastures

• diarrhoea will decrease

• HF and anaemia will persist for months → recovery or death from circulatory collapse

-only return cattle to pasture after significant rainfall

-control with fire regimes, herbicides

-reduce grazing pressures

gossypol

sources

-pigment glands in seeds of Gossypium spp (cotton)

• some strains do not have glands in seeds

tox:

gossypol

-free gossypol is toxic

-protein-bound gossypol is non-toxic

-effects usually from chronic intake

-occur after weeks or months

-monogastric and pre-ruminant animals more susceptible,

• some ruminants

which sp is not affected by gossypol?

-eq

moa:

gossypol

-myocardial necrosis (via hypokalaemia)

poisoning conditions:

gossypol

-whole cotton seed or cottonseed meal fed to livestock

-when cotton seed a large proportion of diet

clinical signs - gossypol:

pigs

-HF

-ill-thrift

-weakness

-dyspnoea

-cyanosis

-death

± haemolysis

reproductive effects - gossypol:

ruminants

-infertility

reproductive effects - gossypol:

pigs

-premature birth

-poor piglet survival

reproductive effects - gossypol:

poultry

-ill thrift

-reduced hatchibility

-discoloration of yolks (red-brown)

clinical signs - gossypol:

cattle

-HF

-weakness

-dyspnoea

-brisket oedema

-distended jugular vv

-depression

-death

± haemolysis

path:

gossypol

-myocardial necrosis (→ fibrosis)

-cardiac dilation pulmonary oedema

-fluid in thorax and abdomen

-periacinar hepatic congestion

-necrosis

-mild nephrosis

-both sides of heart affected

-stops spermatogenesis

tx control:

gossypol

-remove excess gossypol from the diet

• <0.01% gossypol (100mg/kg)

-supportive therapy

-high quality diet supplemented with lysine, methionine and fat-soluble vitamins

-dietary iron and calcium bind free gossypol

-supplement diet with iron (ferrous sulphate) or lime

what supplements needed for gossypol tx?

-lysine

-methionine

-fat soluble vits

-iron or lime

sources:

persin

-Persea americana (avocado)

-Guatemalan

-Mexican

-W Indian

-Guatemalan cultivars and their hybrids are toxic (eg Hass, Fuerte)

-Mexican cultivars are non-toxic

-major varieties grown in Australia are hybrids

• b/t Guatemalan and Mexican cultivars

tox - sp affected:

Persin

-eq

-goats

-ostriches

-caged birds

-dogs

-alpacas

moa:

Persin

-pathogenesis of cardiotoxic syndrome is undetermined (possibly similar to polyether ionophore antibiotics)

-sterile mastitis

-agalactia results from primary effect on vasculature of mammary gland NOT on secretory epithelium

poisoning conditions:

Persin

-consumption of any plant part (usually leaves)

-absent from mature seeds

-ripe fruit is toxic to caged birds (budgerigars, canaries) and dogs

CSx:

Persin

-cardiotoxic syndrome:

• sudden death ± dyspnoea (budgerigars, canaries)

• anasarca of head and neck (particularly neck in ostriches, head in horses)

• fluid line detected on chest wall brisket oedema

-dyspnoea

-coughing

CSx - other:

Persin

Mammary gland syndrome:

• sterile mastitis → agalactia (horse, goat)

± swollen masseter muscles,

-tongue paresis (horse)

-colic (foals)

path - cardiac syndrome:

Persin

-cardiac muscle necrosis

-hydrothorax pulmonary oedema

path - mammary gland syndrome:

Persin

-sterile mastitis

-necrosis of the acinar epithelium of the mammary gland

-masseter muscle necrosis (horses)

tx, control:

persin

-remove access

-no specific therapy

-antiinflammatory and diuretic drugs used

eq: prognosis fair to good if no masseter or tongue involvement

sources:

ergot alkaloids

(mycotoxin)

-Sclerotia (ergot bodies) of Claviceps purpurea (‘ergot of rye’)

-infecting seedheads of Lolium rigidum (annual ryegrass)

-grain crops (rye, barley, wheat, triticale, maize, rice)

-grasses

-C. purpurea (Aus)

term:

ergot

-fungal species (eg Cl purpurea: ergot of rye)

the body (sclerotium - a dark, horn-like mass of fungal hyphae) the source of ergot alkaloids

tox:

ergot alkaloids - cattle

-gangrenous ergotism

-only the sclerotial (ergot) stage of the Claviceps spp life cycle produces clinically-significant amounts of ergot alkaloids

-fescue foot (fescue toxicosis)

-St Anthony’s fire (humans)

-hyperthermia

-repro issues (pigs & eq)

moa:

ergot alkaloids

-gangrenous ergotism

-peripheral vasoconstriction → peripheral gangrene (limbs, tail, ears) under cold weather conditions

-in vitro experimentation suggests ergot alkaloids promote growth of vascular smooth muscle cells → restriction of peripheral blood flow

path:

ergot alkaloids

-gangrenous ergotism:

• gangrene of extremities (cattle)

• ulcers of mouth, pharynx, rumen (sheep)

poisoning conditions:

ergot alkaloids

-ambient low T

low air T → inc severity

-grain contaminated with sclerotia during winter

-tall fescue or ergotised L. rigidum pasture grazing

CSx:

ergot alkaloids

-lameness recumbency

± diarrhoea

-abortion (very rare)