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Veterinary Toxicology > Reproductive Toxicology > Flashcards

Reproductive Toxicology Flashcards

1
Q

What are the 6 steps to the reproductive process?

A
  1. gametogenesis
  2. release of gametes
  3. formation of zygote
  4. embryonic fetal development during incubation or gestation
  5. birth/parturition
  6. lactation
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2
Q

What are the 2 general mechanisms of reproductive toxicity?

A
  1. alteration in endocrine function
  2. alteration in non-endocrine function, like gametogenesis
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3
Q

What are some general clinical signs of reproductive toxicosis?

A
  • abortion
  • dystocia
  • retained placenta
  • reduced fertility
  • edema of prepuce and atrophy of testis
  • enlargement of mammary glands in males
  • vaginal discharge
  • anestrous
  • agalactia
  • teratogenesis
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4
Q

What are the main 2 sources of zearalenone? What does it cause?

A
  1. mycotoxin produces by Fusarium graminearum commonly found in corn*, wheat, barley, oats, and forages (heat-stable and withstands pelleting)
  2. Zeranol (Ralgro), a growth-promoting implant for beef, cattle, and sheep

vulvavaginitis

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5
Q

What species are most susceptible to zearalenone toxicity? Why?

A

swine, especially pre-pubertal gilts

slower metabolism and enhanced enterohepatic recirculation

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6
Q

How is zearalenone metabolized? Excreted? What happens in the rumen?

A

in the liver to zeranol (α-zearalanol) and taleranol (β-zearalanol)

undergoes glucuronidation and sulfation and excreting mainly via bile and feces (enterohepatic recirculation!)

rumen microbes degrade about 30%

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7
Q

What swine are most sensitive to zearalenone toxicity? What species is least sensitive?

A
  • prepubertal swine and cycling females
  • females > young males > older males

poultry

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8
Q

How does zearalenone cause toxicity? What is its mechanism?

A

acts as an estrogen

binds to cytoplasmic receptor for estradiol-17β, whch causes translocation to the nucleus, and stimulation of estrogenism genes —> ovarian follicle matures and ovulation is inhibited due to reduced plasma FSH

(+ immunosuppression due to thymus atrophy and inhibition of macrophage activation)

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9
Q

What are the clinical signs of zearalenone toxicity in gilts and boards?

A

HYPERESTROGENISM:

  • gilts: swelling and hyperemia of the vulva, mammary glands, and uterus, ovarian atrophy, vaginal discharge, vaginal and rectal prolapse
  • boards: edema of prepuce, atophy of testis, reduced libido and sperm quality
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10
Q

What are the clinical signs of zearalenone toxicity in castrated/prepubertal male pigs and sows?

A

HYPERSTROGENISM:

  • castrated/perpubertal males: enlargement of mammary glands, edema of prepuce, difficulty urinating
  • sows: anestrous, nymphomania, pseudopregnancy, reduced litter size due to fetal resorption, weak or stillborn piglets
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11
Q

What are the clinical signs of zearalenone toxicity in sheep and heifers?

A

HYPERESTROGENISM:

  • sheep: decreased ovulation rate and low lambing percentage
  • heifers: enlargement of mammary glands, estrous behavior, turbid vaginal discharge
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12
Q

What clinical pathology is associated with zearalenone toxicity?

A

elevated serum progesterone and decreased prolactin and LH

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13
Q

How is zearalenone toxicity diagnosed?

A
  • reproductive performance of herd/flock
  • occurrence of reproductive problems while excluding other relevant causes of infertility
  • PM reproductive lesions
  • zearalenone analysis in feeds
  • virgin prepubertal mice bioassay
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14
Q

What treatment is recommended for zearalenone toxicity? What is recommended for anestrous in sows?

A
  • prompt discontinuation of suspect feed (reproductive functions should recover/regress in 1-4 weeks)
  • treat vaginal or rectal prolapse and physical damage to external genitalia
  • no adsorbent has been proven efficacious

PG2α - caused by retained corpora lutea

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15
Q

Where are broom/threadleaf snakeweed (Gutierrezia spp.) most commonly found? What species are most affected by toxicosis?

A
  • BROOM = ubiquitous across North America
  • THREADLEAF = southwestern US and northern Mexico in dry, desert habitats with sandy soil

sheep, cattle, goats

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16
Q

What causes variable toxicity of broomweed? What are the 3 toxic principles?

A

growing conditions, stage of growth, soil type (sandy > hard)

  1. monoterpenes/diterpenes
  2. saponins
  3. oxygenated flavonol methyl esters
17
Q

What causes broomweed toxicosis? What reproductive signs are most common? What exacerbates these signs?

A

overgrazing forces animals to eat broomweed

  • vulvar swelling and premature udder development
  • abortion, retain placenta, stringy mucoid vaginal discharge
  • stillbirth or premature birth or underweight calves

poor nutrition

18
Q

What is seen in acute broomweed toxicosis? What clinical signs are observed?

A

non-reproductive signs

  • anorexia, weakness
  • mucopurulent nasal discharge, nasal pad crusting
  • icterus, diarrhea, constipation
19
Q

What treatment is recommended for cows with retained fetal membranes following broomweed toxicosis? How can toxicosis be prevented?

A

antibiotic therapy

  • prevent grazing by ensuring adequate feed is available
  • control broomweed with rangeland herbicides, like Tordon or Escort
20
Q

What are the 3 most common plant sources of isocupressic acid?

A
  1. pines (Pinus ponderosa/contorta)
  2. junipers (Juniperus communis)
  3. cypress (Cupressus macrocarpa)

widely distributed in US and Canada

21
Q

What is isocupressic acid? What does it commonly cause?

A

labdane diterpene found in green and dried needles, bark, and new growth tips of branches of pine trees

“pine needle abortion” - succinyl ICA and acetyl ICA also contribute to abortion after converted into ICA in the rumen

22
Q

What species are most affected by isocupressic acid toxicity?

A

cattle and buffalos —> last trimester most sensitive

23
Q

What is the mechanism of toxicity of isocupressic acid?

A

profound constriction of caruncular vascular bed decreases blood flow to fetus

  • likely due to activation α2-adrenoreceptors that increase vascular tone and decreased uterine blood flow and delivery of nutrients and oxygen to the fetus = release of fetal cortisol and abortion/premature parturition
24
Q

What are the most common clinical signs of isocupressic acid toxicity?

A
  • last trimester* abortions typically in late fall, winter, and early spring
  • premature udder development with milk production and vulvar swelling
  • depression, dullness, udder and edema signal impending abortion
  • premature birth of small and weak calves
  • retained placenta* (removal = excessive bleeding, septic metritis)
  • mucoid/hemorrhagic vaginal discharge
25
Q

What actions have slight changes of success for treating retained placenta due to isocupressic acid toxicity? How can toxicity be prevented?

A
  • uterine infusions
  • prostaglandins
  • oxytocin
  • collagenases

avoid grazing pregnant cows around pine trees, especially in the third trimester

26
Q

What plant contains quinolizidine alkaloids that have reproductive effects? What is the main clinical sign?

A

lupine

TERATOGENESIS due to anagyrine - arthrogryposis (crooked calf disease) resulting from reduced fetal movement due to neuromuscular blockade at critical stages in gestation

(WESTERN US)

27
Q

What plant contains indolizidine alkaloids that have reproductive effects? What are the most common clinical signs?

A

locoweeds

  • TERATOGENESIS - brachygnathia, contracture or overextension of joints, limb rotations
  • infertility, abortions
  • ovarian and testicular abnormalities
28
Q

What plant contains piperidine alkaloids that have reproductive effects? What is the most common clinical sign?

A

poison hemlock

TERATOGENESIS due to γ-coniceine and coniine - neuromuscular blockade decreases intrauterine fetal movement = joint contractures, cleft palate, skeletal malformations

29
Q

What reproductive effect does the tobacco plant have? How?

A

teratogenesis (arthrogryposis) especially in pigs

ababisine and anatabine caused decreased fetal movement

30
Q

What reproductive signs are associated with ergotism and fescue? What is the mechanism of reproductive toxicity?

A

agalactia, abortion, dystocia, retained placenta, prolonged gestation, reduced conception and calving rates

  • STIMULATION of D2 receptors = decreased prolactin = impaired lactogenesis and steroidgenesis due to low progesterone and high estradiol)
  • STIMULATION of α1-adrenergic/serotonergic receptors and INHIBITION of D1 receptors = vasoconstriction with impaired circulation to placenta and abdominal/pelvic fat, uterine contraction causes abortion
  • necrotic fat in abdominal and pelvic cavities obstructs genitourinary tract = dystocia
31
Q

How does gossypol affect male and female reproductive tracts?

A

MALE = decreased spermatogenesis, spermatozoa abnormalities (aplastic midpiece)

FEMALE = decreased progesterone estradiol

32
Q

How do selenium and onion affect the reproductive system?

A

SELENIUM = teratogenesis due to inhibition of DNA and RNA polymerases

ONION = abortion

33
Q

How do nitrate/nitrite, moldy sweet clover, and red maple affect the reproductive system?

A

N/N = crosses placenta and induces fetal methemoglobinemia and hypoxia, abortion, stillbirth, infertility, reduced milk production

MOLDY SWEET CLOVER = dicoumarol crosses placenta, causing hemorrhage and fetal hypoxia = abortion in catle

RED MAPLE = abortion in mares

34
Q

How do carbon monoxide and aflatoxins affect the reproductive system?

A

CO = crosses the placental barrier, causing fetal hypoxia (abortion)

AFLATOXINS = impair reproductive performance

Veterinary Toxicology (29 decks)

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