Test 3- Developmental Abnormalities Flashcards by Magenta Kline

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

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Aborted calf
MDx: Arthrogryposis(abnormally fixed limbs)

Limb are fixed in abnormal(flexed or extended)

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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

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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

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Zygote

Cow 10-12 days following fertilization

Death and resorption leads to early returns to breeding / infertility

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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

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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

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What tissue would need to be injured to result in arthrogryposis?

muscle injury
nerve injury

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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)

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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

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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

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Cat brain
MDx: Cerebellar hypoplasia
Etiology: Feline panleukopenia virus (parvovirus)

parvovirus in any species- also bovine diarrhea virus

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Cat oral cavity
MDx: Palatoschisis(clef palate)

Etiology: Griseofulvin

when given griseofulvin while preganant- clef palate

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Lamb
MDx: Synophthalmia
Etiology: Veratrum californicum day 14 gestation

orbits and eyes are fused

toxic plant grazed on day 14

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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

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Genetic Etiology of Developmental Anomalies

Inherited genes – often autosomal recessive

Spontaneous somatic genetic defect

Chromosomal anomalies

Breed predispositions

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Dog MDx: hydrocephalus

ventricles are expanded with CSF, causes atrophy of surrounding tissues

chicuwawas

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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

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Anatomic Malformations

• Types

– Failure to fuse

– Failure to canalize/separate

– Cysts

– Failure of a structure to develop

– Abnormal development of a structure

– Ectopic development

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Type of anatomical defect: failure to develop

Dog pancreas

MDx: pancreatic aplasia
Disease name: Exocrine pancreatic insufficiency

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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 ## Footnote growth-hormone receptor

GM1 gangliosidiosis

IN: cat, cow, sheep, dog ## Footnote Β-galactosidase

Goitre

In: cow, goat thyroglobulin

Malignant hyperthermia

In; pig ## Footnote ryanodine receptor

Myotonia congenita

In: dog, goat, horse ## Footnote chloride channel

X-linked muscular dystrophy

In; cat, dog ## Footnote 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