Unit 2 - Toxic Plants in Large Animals II Flashcards
What plants cause respiratory effects in large animals?
Perilla mint and moldy sweet potatoes
What species are susceptible to perilla mint toxicosis?
Cattle and horses
When do problems with perilla mint typically occur?
In late summer with lack of other forage
What is the toxic principle of perilla mint?
Perilla ketone
What does perilla ketone do?
It damages endothelial cells and type I pneumocytes
What does perilla mint toxicosis result in?
Atypical interstitial pneumonia
When do clinical signs associated with perilla mint toxicosis occur?
1-2 days after consumption
What clinical signs are associated with perilla mint toxicosis?
Acute onset of dyspnea, extension of head and neck
Froth around the mouth and nose
What clinical signs are associated with severe cases of perilla mint toxicosis?
Collapse and death during handling/restraint
How is perilla mint toxicosis treated?
Corticosteroids, diuretics, and NSAIDs
What lesions does perilla mint toxicosis cause?
Non-collapsing lungs, rib impressions on lung surface, and emphysema
What is the prognosis for perilla mint toxicosis?
Good if animals survive past 2-3 days
What is the toxic principle of moldy sweet potatoes?
4-ipomeanol
What does 4-ipomeanol do?
Damages endothelial cells and type I pneumocytes
T/F: The mechanism, clinical signs, and lesions of Perilla mint and moldy sweet potatoes are the same.
True
What is the prognosis of moldy sweet potato toxicosis?
Guarded to poor
What are the teratogenic species in sheep that result in cyclopsia?
Veratrum californicum, Veratrum viridae, and Veratrum japonicum
What do Veratrum species look like?
Coarse erect herb 1-2 meters tall Stems are unbranched, leafy throughout Long leaves Numerous flowers
What parts of the Veratrum plants are toxic?
All of them - especially the roots
What are the two toxic components of Veratrum species and what effects are they responsible for?
Cevanine alkaloids - neurotoxic
Jervanine alkaloids - teratogenic
What is the MOA of cevanine alkaloids?
Bind open voltage-selective Na channels
What is believed to be the most important jervanine alkaloid in Veratrum toxicosis and what is its MOA?
Cyclopamine - interferes with intercellular signalling and patterning during embryogenesis and organogenesis
What clinical signs are associated with acute cases of Veratrum poisoning?
Onset 2-3 hours post ingestion
Excessive salivation
Ataxia, collapse
Death in severe cases
Teratogenesis occurs when ewes are exposed to Veratrum species from day ___ to ____ of gestation. Cyclops occurs if consumption is on day ____ and limb and tracheal defects occur when consumption is from day ___ to ___. _____ lip and _______, as well as syndactyly are possible.
12-30 14 28-33 cleft palate
What plants are commonly associated with pyrrolizidine alkaloids?
Ragwort, rattlepod, and hound’s tongue
What species are commonly affected by pyrrolizidine alkaloids? More resistant?
Cattle and horses - young are more susceptible
More resistant
When are pyrrolizidine alkaloids generally consumed?
In drought conditions
Where are pyrrolizidine alkaloids located in the plant?
In all parts of the plant - highest in flowers
What is the MOA of pyrrolizidine alkaloids?
They are converted by mixed function oxidases to toxic pyrroles that are detoxified and rapidly excreted
Others are activated and remain in th eliver where they inhibit mitosis
What acute gross lesions are associated with pyrrolizidine alkaloids?
Signs of liver failure - icterus and edema
What chronic gross lesions are associated with pyrrolizidine alkaloids?
Firm nodular liver, cirrhosis, icterus, +/- photosensitivity
What microscopic lesions are associated with pyrrolizidine alkaloid toxicosis?
Heopatocytomegaly
Bridging periportal fibrosis
Bile duct proliferation
How is pyrrolizidine alkaloid toxicosis treated?
Supportive care for liver failure
What clinical signs are associated with acute high doses of pyrrolizidine alkaloids?
Hepatic insufficiency
Icterus
Anorexia
Depression
What clinical signs are associated with chronic low doses of pyrrolizidine alkaloids?
Chronic hepatopathy - weight loss, emaciation, +/- icterus
Hepatic encephalopathy - aimless walking, head pressing, coma
Photosensitivity
T/F: Pyrrolizidine alkaloids cannot cross the placenta but can pass into milk.
False - it can do both
What species are the most often affected by Cocklebur toxicosis? Other species?
Swine are the most often affected
Cattle and sheep are also susceptible
What is the toxic principle of Cocklebur toxicosis?
Carboxyatractyloside
Where is carboxyatractyloside located in Cocklebur plants?
In seeds and cotyledons
What is the MOA of carboxyatractyloside?
- Competitively inhibits oxidative phosphorylation in mitochondria
- Block ATP production
- Cellular damage
- Hepatocytes and PCTs highly susceptible to damage
What clinical signs are associated with cocklebur toxicosis?
Depression, abdominal pain
Convulsions/seizures
Opisthotonus
Apparent blindness
What laboratory findings are associated with cocklebur toxicosis?
Elevated liver enzyems
hypoglycemia
What gross lesions are associated with cocklebur toxicosis?
Pale liver with enhanced lobular pattern and centrilobular hemorrhages
Presence of burs in the stomach/rumen
What histologic lesions are associated with cocklebur toxicosis?
Hepatic necrosis and hemorrhage centrilobular to midzonal
Renal tubular degeneration and necrosis
How is cocklebur toxicosis diagnosed?
Detection in stomach content
How is cocklebur toxicosis treated?
Supportive care and oral detoxification
What species are most commonly affected by oak tree toxicosis?
Cattle mainly - spring calves are often poisoned in the fall by acorns
There are a few reports in horses
What is the toxic principle for oak tree toxicosis?
Metabolites of tannic acid
What percentage of a cows diet needs to be oak in order to be toxic?
> 50%
What are the 3 mechanisms of oak tree toxicosis?
Direct toxicity to GI epithelium
Hydrolyzed tannins are absorbed and damage endothelium
Metabolites of ingested tannins are toxic to proximal tubular epithelium
What clinical signs are associated with early oak tree toxicosis (2 days)?
Anorexia, dullness, rumen atony, constipation, melena
What clinical signs are associated with early oak tree toxicosis 3-7 days post exposure?
Weak, prostrate, icterus, hematuria, and dehydration
What serum chemistry findings are associated with oak tree toxicosis?
Increased BUN, creatinine, phosphorus
What urinalysis findings are associated with oak tree toxicosis?
Hematuria, proteinuria, protein casts
What gross lesions are associated with oak tree toxicosis?
Ascites, hydrothorax
Perirenal blood tinged edema
Hemorrhagic and ulcerative gastroenteritis
Acorns in rumen
What microscopic lesions are associated with oak tree toxicosis?
Coagulation necrosis of proximal convoluted tubules
Regeneration
How is oak tree toxicosis treated?
Remove from access to oak
Activated charcoal or mineral oil
Fluids to correct dehydration/acidosis
What species does redroot pigweed primarily affect?
Pigs
Cattle, sheep, and goats are also susceptible
What season is Redroot pigweed toxicosis common in?
Mid june to late summer
What is the toxic principle and MOA for Redroot pigweed?
Unknown toxic principle
causes acute renal tubular necrosis
What clinical signs are associated with Redroot pigweed toxicosis?
Posterior weakness, incoordination, and sternal recumbency (5-10 days post ingestion)
Death
What gross lesions are associated with Redroot pigweed toxicosis?
Perirenal edema +/- hemorrhage
Ascites
What histologic lesions are associated with Redroot pigweed toxicosis?
Acute tubular necrosis affecting both proximal and distal tubules
What plants are commonly associated with soluble oxalates?
Halogeton, greasewood, beets, dock, pigweed, lamb’s quarters, and rhubarb
What species are commonly associated with soluble oxalate toxicosis?
Sheep > cattle
All species are susceptible
What are soluble oexalates?
Sodium and potassium
What is the MOA of soluble oxalates?
- Soluble oxalates are rapidly absorbed
- Complex with serum calcium to form calcium oxalate
- Excreted in the kidney and crystalize
What clinical signs are associated with soluble oxalate toxicosis?
Onset: 2-6 hours Dullness, depression Abdominal pain, rumen atony Twitching bruxism Ataxia, prostration, coma
What gross lesions are associated with soluble oxalate toxicosis?
Ascites, hydrothorax
What microscopic lesions are associated with soluble oxalate toxicosis?
Oxalate nephrosis
Crystals within vessel walls
What species are affected by black walnut toxicosis?
Primarily horses
What is the pathogenesis of black walnut toxicosis?
It is suspected that the wood has a vasoactive effect with ischemia, reperfusion, and reperfusion injury
What clinical signs are associated with black walnut toxicosis?
Reluctance to move w/in 24 hours of exposure
Depression
Increased temperature, heart and respiratory rate, digital pulses and hoof temperature
Lower limb edema
Severe laminitis with continued exposure
How is black walnut toxicosis diagnosed?
History of recent exposure acute clinical disease
How is black walnut toxicosis treated?
Nonfatal disease
Remove animal from offensive breeding immediately
Oral detox
Treat limb edema and laminitis
What factors are necessary for photosensitization to occur?
- presence of photodynamic pigment in the skin
- Exposure to sunlight
- Areas of susceptible skin
What are the two major forms of photosensitization?
Primary - performed photodynamic agent is ingested
Secondary - a photodynamic secondary metabolite is not cleared by the liver
What clinical signs are associated with photosensitization?
Photosensitization - photophobia
Pruritus and erythema - non pigmented areas are affected most commonly
Blindness
Sloughing of damaged skin
How is photosensitization treated?
Removal from the source
Keep animals out of sunlight
Antibiotics for secondary bacterial infections
Ointments, anti-inflammatories prn for tissue swelling
What toxins are involved in the pathogenesis of photosensitization?
Quinones
Phylloerythrin
What species are at a higher risk for St. Johns wort toxicosis?
Herbivores > all other species
What is the toxic principle of St. Johns wort?
Hypericin - photodynamic pigment
What species are affected by buckwheat toxicosis?
All species, but herbivores are at a greater risk
What is toxic principle of St. John’s wort?
Fagopyrin
T/F: The toxic agents of St. John’s wort and buckwheat are both slowly eliminated from the body and have cumulative effects
TRUE