Test 3- Developmental Abnormalities Flashcards
Developmental Anomalies may manifest as either…
Anatomic Malformations
– Failure to fuse
– Failure to canalize/separate
– Cysts
– Failure of a structure to develop
– Abnormal development of a structure
– Ectopic development
Biochemical Defects
- Involve an inability to synthesise adequate amounts of a particular enzyme or other protein
- Usually due to a genetic mutation
• Usually no grossly visible malformations
• Examples
– Haemophilia
– Lysosomal storage diseases
– Dermatosporaxis
– Albinism
Aborted calf
MDx: Arthrogryposis(abnormally fixed limbs)
Limb are fixed in abnormal(flexed or extended)
Pathogenesis of arthrogryposis:
Limbs do not move during development/ leads tomuscles don’t develop correctly leads to connective tissue matures leads to limbs fixed in place
The animal hasn’t been able to move limbs in utero
Pathogenesis of Anatomical Developmental Anomalies Occur due to injury of cells during embryogenesis.
The nature of the anatomical defect that results depends on:
- Timing
- Tissue injured
Zygote
Cow 10-12 days following fertilization
Death and resorption leads to early returns to breeding / infertility
Embryo (organogenesis)
Cow 15-45 days
Ewe 11-34 days
Mare 12-60 days
Depends on extent of injury:
Developmental anomaly carried to term- THIS IS THE TIME, WHERE YOU GET MALFORMATION
Death of embryo and abortion
Fetus (growth)
Cow 45 days to term Cow 45-125 days Mare 55 days to term Ewe 34 days to term
Illness/ death of foetus resulting in:
Abortion
Mummification
Stillbirths
Weak neonates
Persistent viremia immunotolerance
What tissue would need to be injured to result in arthrogryposis?
- muscle injury
- nerve injury
calf spinal cord in early gestation
MDx: Severe nonsuppurative myelitis
How can we determine the cause of the arthrogryposis and hydranencephaly?
SEROLOGY ON THE CALVES- because if they are positive then they have been exposed, but you can’t do it on a calf that suckled( can have false positives due to colostrum)
Final Disease Dx = Akabane (Bunyavirius)
All calves infected with akabane virus at the same time, but they are at different stages of gestation
(some conceived earlier than others)
Infected 120-180 days – AG (see 1st)
Infected 80-100 days – HA (see 2nd)
DEPENDING ON TIMING OF INFECTION, THE LESIONS CAN BE DIFFERENT
Causes of developmental anomalies
Causes of developmental anomalies
Things that injure cells at a critical stage of development.
The defect depends on tissue tropism and timing.
1. Genetic defect( can happen in outbreaks)
2. In utero infection – BVD, bluetongue, border disease, akabane, panleukopenia, classical swine fever
3. In utero exposure to teratogens – toxic plants, griseofulvin in cats
4. In utero nutritional deficiencies
Cat brain
MDx: Cerebellar hypoplasia
Etiology: Feline panleukopenia virus (parvovirus)
parvovirus in any species- also bovine diarrhea virus
Cat oral cavity
MDx: Palatoschisis(clef palate)
Etiology: Griseofulvin
when given griseofulvin while preganant- clef palate
Lamb
MDx: Synophthalmia
Etiology: Veratrum californicum day 14 gestation
orbits and eyes are fused
toxic plant grazed on day 14
Foal intestines
MDx: Colonic hypoplasia
Disease: Lethal white syndrome
Etiology: inherited genetic defect
no melanin- albino
more than 1 abnormalitiy- gene affected has more than 1 protein that it codes fo
neurocrest cells are responsbile for both large intestine cells and melanin
Genetic Etiology of Developmental Anomalies
Inherited genes – often autosomal recessive
Spontaneous somatic genetic defect
Chromosomal anomalies
Breed predispositions
Dog MDx: hydrocephalus
ventricles are expanded with CSF, causes atrophy of surrounding tissues
chicuwawas
Developmental anomalies of Persian cats
polycystic kidney disorder (PKD)
cardiomyopathy
cataracts
cleft palates & cleft lips
mega-oesophagus
portosystemic shunt (liver)
patent ductus arteriosus (PDA)
entropion
amyloidosis
mucopolysaccharidosis
Anatomic Malformations
• Types
– Failure to fuse
– Failure to canalize/separate
– Cysts
– Failure of a structure to develop
– Abnormal development of a structure
– Ectopic development
Type of anatomical defect: failure to develop
Dog pancreas
MDx: pancreatic aplasia
Disease name: Exocrine pancreatic insufficiency
Type of anatomical defect: failure to develop
Dog pancreas
MDx: pancreatic hypoplasia
Disease name: Exocrine
just a little bit of pancreas
Calf/Puppy
Type of anatomical defect: failure to fuse
MDx: spina bifida
neural tube defect
Calf brain
MDx: meningoencephalocele
Type of anatomical defect: failure to fuse
meninges and brain protude out - because bones of the skull have not fused
head equalivate of spina bufida
Fusion Defects (Failure to close/fuse)
Spina bifida – cleft in the dorsal tissues of the spine
Palatoschisis (cleft palate) – cleft in the hard palate
Cheiloschisis – cleft lip
Hypospadias – cleft in the penis, exposes the urethra
exposing the urethra
Coloboma – cleft in the internal structures of the eye
Interventricular cardiac septal defect – a hole communicating between the ventricles of the heart- causes two ventricle to communicate
Schistosomus reflexus
Pig MDx: umbilica hernia
Fusion Defects (Failure to close/fuse)
Calf brain
Type of anatomical defect: failure to fuse
MDx: maxillary brachygnathia and palatoschisis
(cleft palate)
Calf Type of anatomical defect: failure to fuse
MDx: schistosomas reflexus
sternal cleft, dorsal reflection of ribs, eventration of viscera, non-union of pelvic symphysis
Lamb
Type of anatomical defect: failure to canalize
MDx: atresia ani
FAILS TO OPEN
Cat kidneys
MDx: Renal cysts
Disease: Polycystic kidney disease
Etiology: Inherited genetic defect
Type of anatomical defect: Cyst
Cat kidneys
MDx: Pituitary cyst (Raphke’s pouch cyst)
Disease: Pituitary dwarfism
Type of anatomical defect: Cyst
Because they don’t have the Anterior pituary- no GROWTH HORMONE
Calf feet Type of anatomical defect:
MDx: polydactyly
Abnormal development of a structure
Sheep thoracic limbs Type of anatomical defect:
MDx: polymelia
Abnormal development of a structure
too many limbs
“Vets believe his condition is a result of an error during embryo formation, which meant he was born a polydactyl - or with many legs.
It is a condition that occurs once in several million sheep.
Veterinarian Steve Williams at Canterbury Vets Clinic in Methven said the animal is also a hermaphrodite and missing some of its bowel which means he will probably have to be destroyed.”
Correct: polymelia
Dog coxofemoral joints
MDx: coxofemoral malformation Disease name: Hip dysplasia
Type of anatomical defect:
Abnormal development of a structure, which manifests as arthrisitis later in live
- flat heads of both femurs
- flat acetabular rims
- one head luxated out of joint
Calf heart
MDx: Ectopia cordis
Type of anatomical defect:
Ectopic development
heart forms outside of body
Calf with worsening neurological signs, otherwise looks ok. Was normal at birth.
Does this rule out a developmental anomaly?
NO- not all developmental anomaley have something anatomically wrong
Calf brain
MDx: Vacuolar neuronal degeneration
Disease name: Mannosidosis
Etiology: genetic defect for mannosidase
neurons filled with vacoules lysosomal storage disease
Lysosomal Storage Diseases
Genetic deficiency of particular lysosomal enzymes
Histo: vacuoles filled with the accumulated substrate of the deficient enzyme
Post-mitotic (long-lived) cells most susceptible, accumulate more substrate
– Neurons
– Skeletal and cardiac muscle
Raccoon Cerebellum
MDx: Vacuolar neuronal degeneration
Disease name: Neiman Pick Disease
Etiology: genetic defect for sphingomyelinase
Congeital
ANIMAL IS BORN WITH THIS DISORDER
DIFFERENT FROM GENTETIC OR INHERITED
Calf brain
MDx: Hydranencephaly
brain hemispheres are missing
THE TIMING OF INJURY AFFECTS
WHAT KIND OF INJURY AND TO WHAT TISSUE
Albinism
In: cat, cow, chicken, dog, sheep
tyrosinase
Dwarfism
IN: chicken
growth-hormone receptor
GM1 gangliosidiosis
IN: cat, cow, sheep, dog
Β-galactosidase
Goitre
In: cow, goat
thyroglobulin
Malignant hyperthermia
In; pig
ryanodine receptor
Myotonia congenita
In: dog, goat, horse
chloride channel
X-linked muscular dystrophy
In; cat, dog
dystrophin
What is a congeital lesion?
A congeital lesion are defeats of growth or developement of a tissue or organ that are present, but not nessarily obvious at birth.
Calf brain
MDx: Hydranencephaly
Injuries to tissue that result in a malformation usually occur during which stages of gestation?
Early to middle
