Poisonous plants

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Poisonous plants

• ANSC 406

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Livestock

• Most poisonous plants have so unpleasant a flavor
  that neither sheep nor cattle will eat them
  except when they are very hungry and there is
  practically nothing else in the field for them to
  eat
• Most poisoning may be prevented by keeping hungry
  animals and animals in poor condition away from
  pastures populated with known poisonous plants
  and by stocking pastures lightly enough to keep
  the animals constantly provided with other food.
• As the forage on the open public range in Nevada
  has become more and more depleted, losses of
  sheep and cattle from poisonous plants have
  steadily increased

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Cost to producers

• 250 million annually
• Death
• Reduced weight gain
• Reduced reproductive performance
• Management cost
• fencing, riding, veterinary fees
• Control costs
• Reduced land value
• Loss of management land and livestock management
  options
• Loss of useable forage

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Plants Toxic to Livestock

• Abortifacient and Reproductive Toxins 
• Broom Snakeweed (Gutierrezia sarothrae)
• Gastrointestinal Irritants and Toxins 
• Sneezeweed (Helenium hoopesii)
• Neurotoxic and Myotoxic Plants 
• Larkspur (Zigadenus spp.)
• Deathcamus (Delphinium spp.)
• Photosensitizing Plants
• St. Johns Wart (Hypericum perforatum)

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Ponderosa Pine (Pinus Ponerosa)

• Ponderosa pine grows in all of the states west of
  the Great Plains and in western Canada
• Needles cause abortion when grazed by cattle.
• Induced abortions generally occur in late fall to
  early spring, during the last trimester of
  pregnancy.
• Cattle generally graze pine needles during storms
  with increased snow, wind, cold, changes in feed,
  or hunger.
• The toxin that causes abortion is isocupressic
  acid.

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Ponderosa Pine (Pinus Ponerosa)

• Abortions generally occur between 48 hours and 2
  weeks after exposure to pine needles.
• The abortifacient dose is highly variable as some
  cows are highly sensitive and a small amount of
  needles will induce an abortion.
• Cows appear to have no other signs of
  intoxication other than abortion.
• The aborted calves may survive if the abortion
  occurs in late gestation however, they are small
  and weak, may not suckle, and generally require
  extensive care and treatment to survive.
• Nearly all the cows that abort develop
  persistently retained placenta and subsequent
  endometritis (inflammation of the inner uterine
  wall).

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Nitrate Poisoning

• Nitrate is the primary nutrient form of nitrogen
  in most soils and is a normal constituent of
  plants
• In ruminant animals nitrate is converted to
  nitrite by bacteria in the rumen. This nitrite is
  then changed to ammonia. Excess ammonia is
  absorbed by the blood and passed in the urine as
  urea. This occurs when the nitrate breakdown
  system is in balance and no surplus of nitrites
  accumulate.
• In contrast, monogastric animals such as horses
  and pigs, convert nitrate to nitrite in the
  intestine, closer to the end of the digestive
  tract, where there is less opportunity for the
  nitrites to be absorbed by the blood. It is this
  difference in the site of conversion that makes
  nitrate poisoning of much less concern for
  monogastric animals than it is with ruminants.

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Nitrate Poisoning

• Nitrate poisoning occurs when the nitrite level
  in the rumen exceeds the capacity of the microbes
  to convert it to ammonia
• Nitrate and nitrite are absorbed through the
  rumen wall into the bloodstream.
• Nitrite combines with hemoglobin to form
  methemoglobin.
• When enough hemoglobin is converted to
  methemoglobin the animal begins to suffer from
  oxygen starvation
• Nitrate transported into the bloodstream does not
  create
• the initial problem, but it can be recycled back
  into the
• rumen via saliva or intestinal secretions.
• Nitrate that is recycled and returned to the
  rumen can be converted to nitrite and then
  reabsorbed back into the bloodstream, thereby
  intensifying the problem.

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Nitrate Poisoning

• Crops such as oat hay, sorghum, corn, sudangrass,
  Johnsongrass, beets, and weeds such as
  carelessweed, kochia, pigweed, Russian thistle,
  and nightshade
• Accumulation usually is triggered by some
  environmental stress where plant growth is
  restricted but absorption of nitrate from soil
  continues.
• The most common stress of summer annuals is
  drought. Lack of moisture, together with
  excessive soil nitrogen for existing growing
  conditions, is a frequent cause of toxic levels
  of nitrate.
• Other stress factors that favor buildup are
  reduced sunlight from cloudiness or shading,
  frost, certain herbicides including 2,4-D, acid
  soils, low growing temperatures, and deficiencies
  of essential nutrients like phosphorus, sulfur
  and molybdenum.

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Nitrate Poisoning - Symptoms

• Acute poisoning
• Blue coloration of membranes of mouth, eyes, and
  other mucous membranes (cyanosis)
• Shortness of breath
• Staggering gait
• Death
• Chocolate brown blood
• Muddy, cyanotic mucus membranes
• Congestion of rumen and abomasum
• Subacute poisoning
• Watering eyes
• Unthrifty appearance
• Reduced milk flow
• Reduced weight gain
• Abortion and infertility

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Nitrate Poisoning - Prevention

• Nitrate accumulation can be minimized by
  analyzing soil and using a balanced fertility
  program consistent with plant needs and moisture
  conditions.
• High nitrate forage should be diluted with low
  nitrate forage to decrease nitrate intake
• Occasionally forage that is questionable as hay
  can be grazed safely when forage is abundant,
  because animals tend to select leaves and refuse
  stalks
• Never turn animals out hungry in a high nitrate
  pasture

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Sheep - Lupin

• Grows on foothills and mountain ranges in
  sagebrush and aspen areas
• During years with a wet spring, lupine
  populations explode and may be especially
  troublesome
• Poisonous species of lupine are dangerous from
  the time they start growth in the spring until
  seed pods shatter in late summer or fall
• Younger plants are more toxic than older plants
  however, plants in the seed stage in late summer
  are especially dangerous because of the high
  alkaloid content of the seeds and enhanced
  palatability in preference to dried senescent
  grasses

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Lupine - Symptoms

• Nervousness
• Excessive salivation frothing at the mouth
• Depression
• Reluctance to move about
• Lethargy,
• inappetence
• Difficulty in breathing
• Twitching leg muscles
• Loss of all muscular control
• Convulsions
• Coma
• Death
• Cleft palate and skeletal defects in fetus

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Lupine

• A sheep that is getting good forage may not be
  affected by occasionally eating a small amount of
  lupine (0.1 kg) even if the lupine includes seed
  pods
• A sheep generally develops clinical signs of
  poisoning if it eats that dose for 3 or 4 days

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Lupine

• Losses can be reduced by keeping hungry animals
  away from lupine patches in the early growth
  stage and in late summer when the plant is in the
  highly toxic seed stage, and from dense plant
  stands at all times.
• Supplemental feeding is beneficial, especially
  when animals are trailed through lupine ranges.
  If sheep are poisoned on lupines, do not try to
  move them until they show signs of recovery

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Selenium Accumulators

• Selenium is accumulated by a number of plants in
  sufficient amounts to be toxic if consumed by
  livestock
• Plants that accumulate high amounts of selenium
  and may require selenium for growth are often
  found in selenium rich areas
• Considered indicator species
• Certain species of Astragalus, prince's plume,
  and some woody asters
• Plants may accumulate up to 3000 parts per
  million (ppm) selenium. 5 ppm potentially toxic
  in cattle

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Facultative Selenium Absorbers

• Plants that will accumulate selenium but do not
  have a requirement for it are called facultative
  or secondary selenium absorbers
• These plants can accumulate up to 50 ppm.
• Some native range plants, and crop plants such as
  western wheatgrass, barley, wheat, and alfalfa

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Selenium

• It has been suggested that even though selenium
  accumulating plants are not readily eaten, they
  contribute to selenium toxicosis by making
  selenium in the soil available  to neighboring,
  palatable, secondary selenium-accumulating plants

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• Selenium is required in the diet of most animals.
  Concentrations of 0.3 ppm are recommended for
  most food producing livestock
• Acute selenosis has been associated with
  ingesting large amounts of selenium such as would
  happen if animals eat indicator plants (400
  ppm).
• Oral selenium doses of between 1 and 5 mg/kg body
  weight are considered toxic.
• Lower doses of between 5 and 40 ppm in the diet
  for several weeks or months result in chronic
  poisoning, oftentimes called alkali disease.
• The mechanism of toxicity is not completely
  understood, but the clinical and morphologic
  lesions suggest glutathione depletion and
  secondary lipid peroxidation are important in
  pathogenesis.

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Selenium - Acute Symptoms

• Lethargy, nonresponsiveness
• Dyspnea with abnormal posture
• Unsteady gait
• Diarrhea
• Abdominal pain (teeth grinding)
• Increased pulse, respiration rate and body
  temperature.
• Prostration
• Death (Sheep may not show signs and are found
  dead)
• Necropsy and histologic lesions include pulmonary
  edema, hydrothorax, and pale myocardium.
  Additionally there may be mild enteritis and
  passive congestion of the liver

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Selenium Chronic Symptoms

• Dullness
• Rough hair coat
• Emaciation
• Lack of vitality, anemia
• Lameness, joint stiffness
• Hooves may become overgrown or deformed (circular
  bumps or breaks below coronary band)
• Loss of long hair (horses commonly lose their
  mane and tail)
• Histologic lesions variable but often include
  cardiomyopathy and liver cirrhosis
• Reproductive losses in cattle

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Selenium

• The only practical method of reducing losses in
  livestock is to prevent animals from eating
  excessive amounts of selenium-containing plants.
• Affected animals that are removed from
  seleniferous forages may recover without apparent
  permanent effects.
• The rate of recovery is dependent upon the
  severity of intoxication.

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Horses - Alsike Clover

• The most common symptom of alsike clover
  poisoning is photosensitization or a reaction to
  light
• Actually a secondary symptom to liver damage
• Alsike clovers may contain some compound,
  possibly an alkaloid, which causes liver
  dysfunction. If this cirrhosis of the liver is
  allowed to continue, death may result.

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Photosensitivity

• The plant material that the horse eats contains
  chlorophyll. Bacteria in the intestinal tract
  change the chlorophyll into another substance,
  phylloerythrin.
• In an animal with a healthy liver, the
  phylloerythrin is removed from the blood by the
  liver, and excreted in the bile.
• However, in an animal where the liver has been
  damaged, it cannot pick up the phylloerythrin. It
  then is carried by the blood and deposited in the
  skin cells.

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Photosensitivity

• When light of a certain wavelength is absorbed by
  the skin it reacts with the compound, damaging
  the cell and causing inflammation and redness.
• This occurs only on areas unprotected by thick
  skin, hair covering or pigmentation, such as in
  black skin. Therefore, liver damage may be
  present without any signs of photosensitization.
• Some horses may die within 24 hours of alsike
  consumption.

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Alsike Clover

• Symptoms of Photosensitization
• Lining of eyelids, or conjunctiva, become red and
  swollen
• Inflammation and lesions of the muzzle, mouth,
  tongue, eyes, eyelids, and ears, with discharge
  from the lesions
• Jaundice
• Nervousness
• Digestive disorders "off feed"
• Brownish urine
• Clay-colored feces
• These are all possible symptoms animals may show
  all or none of these

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Poisonous Plants - Dogs

• Dogs are very inquisitive. Sniffing, smelling,
  and usually tasting almost anything in sight are
  natural behaviors for a dog.
• For that reason, we commonly see dogs ingest
  items that are not their food and at times can be
  very dangerous poisons
• There are two major areas where such danger may
  occur inside the house, and outside of it. These
  areas are different in terms of what types of
  poisons the dog may be exposed to. In the house,
  dogs usually get themselves in trouble when they
  are bored. Outside it's usually the dogs'
  curiosity that endangers them

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Poisonous Plants - Cats

• Cats like to chew green things.
• Be sure to provide something safe for your cat to
  chew on
• You can prevent your cat from chewing on plants
  by misting the leaves then sprinkling them with
  cayenne pepper.
• If your cats are digging in your pots, go buy a
  few pieces of plastic needlepoint canvas to cover
  soil

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Grayanotoxins Rhododendron sp.

• Grayanotoxin is a polyhydroxylated cyclic
  diterpene.
• It binds to specific sodium ion channels in cell
  membranes, the receptor sites involved in
  activation and inactivation.
• The grayanotoxin prevents inactivation, leaving
  excitable cells depolarized.
• Empirically the toxin is C22H36O7.

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Grayanotoxin - Symptoms

• vomiting
• drooling
• diarrhea
• weakness and depression of the central nervous
  system in animals
• Severe azalea poisoning could ultimately lead to
  coma and death from cardiovascular collapse

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Cardiac Glycosides Oleaner Nerium oleander

• Cardiac glycosides are drugs used in the
  treatment of congestive heart failure and cardiac
  arrhythmia.
• These glycosides are found as secondary
  metabolites in several plants
• Cardiac glycosides work by inhibiting the Na/K
  pump
• This inhibition increases the amount of Ca2 ions
  available for contraction of the heart muscle,
  improves cardiac output and reduces distention of
  the heart

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Cardiac Glycosides - Symptoms

• gastrointestinal tract irritation
• abnormal heart function
• hypothermia
• death

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Ricin Castor Bean (Ricinus communis)

• Ricin is poisonous if inhaled or ingested, acting
  as a toxin by the inhibition of protein synthesis
  
• Classified as a ribosome inactivating protein
  (RIP)
• Mediates entry of the A-B protein complex into
  the cytosol
• Severe abdominal pain, drooling, vomiting,
  diarrhea, excessive thirst, weakness and loss of
  appetite.

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Ricin - Symtoms

• Severe abdominal pain,
• drooling
• vomiting
• diarrhea
• excessive thirst
• weakness
• loss of appetite
• muscle twitching
• seizures
• coma
• death

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Pyrethrins Chrysanthemum (Compositae)

• Grown commercially to supply insecticide
• Pyrethrins are neurotoxins that attack the
  nervous systems of all insects
• One study suggested a link between maternal
  pyrethrin use and autism in children.
• The study indicated that mothers of autistic
  children were twice as likely to have washed a
  pet dog with a flea shampoo containing pyrethrin
  while they were pregnant.

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Pyrethrins

• Gastrointestinal upset
• Drooling
• Vomiting
• Diarrhea
• depression
• loss of coordination

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Be prepared

• Invest in an emergency first-aid kit for your
  pet.
• A fresh bottle of hydrogen peroxide, 3 percent
  USP (to induce vomiting)
• a turkey baster, bulb syringe or large medicine
  syringe (to administer peroxide)
• saline eye solution
• artificial tear gel (to lubricate eyes after
  flushing)
• mild grease-cutting dishwashing liquid (for
  bathing an animal after skin contamination)
• forceps (to remove stingers)
• a muzzle (to protect against fear- or
  excitement-induced biting)
• a can of your pets favorite wet food
• a  pet carrier

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What to do

• Call the ASPCA Animal Poison Control Center
• Be ready with the following information
• the species, breed, age, sex, weight and number
  of animals involved
• the animals symptoms
• information regarding the exposure, including
  the agent (if known), the amount of the agent
  involved and the time elapsed since the time of
  exposure.
• Have the product container/packaging available
  for reference.
• If your animal is having seizures, losing
  consciousness, is unconscious or is having
  difficulty breathing, telephone ahead and bring
  your pet immediately to your local veterinarian
  or emergency veterinary clinic.