Multifactoral Flashcards
What is a multifactoral disorder
many genes and environmental triggers
accounts for the vast majority if late onset inherited diseases
sporadic occurance in pedigree
incidence not equal between sexes
difficult to eradicate
what is canine malignant lymphoma
triggered by 2,4-D herbicide (weed and feed)
exposure 3-5 days after application, via grooming
cancer
diabetes in dogs
2-5 females and 1 male
gender imbalance
exacerbated by pregnancy
what does multifactoral cause in hereford cattle?
cancer eye
lack of pigmentation and is worse from sunlight
Osteochondrosis
effects dogs, pigs, horses - more males then females
pitted ball joint - femur/humerus
exacerbated by rapid weight gain (gender imbalance)
Hip Dysplasia
shallow acetabulum
more severe cases shown in younger ages
occurs in most large dog breeds
increased age increase arthritis increasing pain
what are possible environmental triggers for hip dysplasia?
rapid growth (overfeeding)
dietary imbalance
over exxercise
what is epilepsy
multifactoral seizure disorder
more common in certain breeds, such as belgian shepards
polygenid trait caused by stress and sex hormones
indicatorars of multifactoral inheritance
late onset
sporatic occurance in pedigree
incidence not equal between sexes
how do you calculate risks
its the sqaure root of incidence
this risk rises every first relative parent, sibling and offspring
5% 1 parent or sib or offspring
10% 1 parent and 1 sib
20% 1 parent and 2 siblings
how does risk of reoccurance increase
more severe the case or the earliier the onset
mating is consanguineous
trigger is common
multiple family memebers affected
what is the burden of disease
- severity of symptoms
- cost of treatment
- pain or discomfort
how do you make breeding decisions
client must weigh risk and burden
5% risk of eye cancer … but about 50% of the carcass is then condemned
5% risk of hip dysplasia
What is the genetic advice for breeding decisions
avoid repeat matings that produce multifactorial diseased offspring
suggest healthy lifestyle changes in breeds known to be susceptable
what are the goals of future breeding programs
- fewer antibiotics used, especially in meat producing animals
- greater longevity
- increased quality of life/health
- increased milk production (peaks at 4-5 years of age in dairy cattle)
what is teratogenesis ?
abnormal development influenced by drugs, viruses, chemicals, radiation - in utero = mammalian phenomenon
examples of teratogenesis?
twisted legs(cattle)
cyclopean(lambs)
cleft palate(cattle, dogs)
heart defects (sheep)
what is the biological threshold?
developmental processes occur on a fixed schedule
at a fixed period in gestation, disruptions or delays cause that organ to be incompletely developed
what are spina bifida risks?
maternal folic acid deficiency
exposure to high temperature in early pregnancy (prolonged fever or hot tub use)
maternal insulin-dependednt diabetes
medications (anti-seizure)
what is a cleft lip and palate
in utero development of face at 7-9 weeks (cattle)
fixed time period for facial development
delay (fever, virus)
face not finished (failt fusion of nasal processes )
what is important in tereatogenesis?
genetic backgroun (predisposition to the tetratogen, predisposition to the malformation)
exposure (time and length, dose)
generalizations of teratogens
- animal pregnant or lactating at time of exposure (rarely through male)
- few effects last prior to conception
- most effects have a two week delay
preimplantation a safe period or embryo dies - primarily congenital defects
What is the development stage at time of exposure
stage = effect
blastocyst = lethality
organogenesis = structureal defects
histogenesis = microscopic changes
growth = stunting
what are types of direct acess for teratogens
radiation, microwaves, ultrasound
indirect teratogens
maternal blood via the placenta (alters absorption and dose
what are physical teratogens
temperature - fever, overheating, hypothermia
Ultrasound
electromagnetic fields - power towers
what are biological teratogens
malnutrition - general (low birth weight offspring)
specific dietary deficiencies
twisted legs (arthrogryposis)
manganese deficiency
what specific foods are teratogens
locoweed - abortions and malformations in sheep and cattle
lupine (in cypress hills region) crooked calf disease, high concentration of alkaloids
vetratrum - grows in foothills, cyclopia in lambs if ewes ingest about day 14 of gestation
sudan grass- arthrogryposis in horses
tobacco stalks - byproduct of the cigarette industry - piglets develop stiff and swollen joints
what is BVD?
bovine viral diarrhea
abortion
central nervous damage
persistently infecte calves
weak and small
twin mortality
premature birth - low birth weight, respiratory problems
postion effects - limb deformities
freemartinism
chemical teratogens in food
ethoxyquin (dog food perservative)
skin problems
abortion
animal feed additive
reduction of use - several countries do not allow use
what kind of pollutants can be teratogens?
sour gas - increased sulfure and decreased selenium, white muscle disease in calves
what drugs can be teratogens
albendazole
angry- agenesis of the tail anus and CNS in cattle and sheep
rumatel - lactating sheep
ivermectin - cattle
what is chloramphenicol
- can not be used in food-producing aniamls
- aplastic anemia in humans (bone marrow damage from milk
- regulations are made to protect humans not aniamls
what is phenibarbital?
prescribed for seizures
can cause a broad spectrum of major defects (5/77 human pregnancies)
mildly depressed cognitive and language abilities
frequent seizures can cause hypoxia fetal distress and or defects
