Developmental Disorders

Question 1

Defects in neurulation/neural tube

Answer 1

• Anencephaly- parts of the brain and skull are missing
• Spinal bifida- improper formation of the spinal cord

Question 2

Hydrops

Answer 2

• Excessive accumulation of fetal fluids in either amnion or allantois in cattle
• Includes both hydrallantois and hydramnion

Question 3

Hydraallantois

Answer 3

• Present ~6-9 months gestation with up to 40x excess fluid
• Clinically present as progressive distention of the right abdominal wall and thought to be a result of placental abnormalities

Question 4

Hydramnion

Answer 4

• In cows 8-10x normal fluid level associated with malformation of the digestive system
• Rare in sheep, pigs, dogs, cats and not reported in horses

Question 5

Patent or persistent umbilical urachus

Answer 5

• Umbilical cord ruptures as the fetus passes through the birth canal. Ruptured umbilical arteries retract within the abdomen and the elastic fibers in their walls seals their lumina to prevent haemorrhage. Urachus should close around the same time
• If urachus fails to close properly, there will be a leakage of urine at the umbilicus which can cause infection
• Can be surgically corrected

Question 6

Congenital Diaphragmatic hernia

Answer 6

When fusion fails and results in an opening between the thoracic and abdominal cavities which allows for the abdominal vicera to pass through into the thoracic cavity

Two types in domestic animals:
1. Pleuro-peritoneal herniation
2. Peritoneal-pericardial herniation

Question 7

Pleuro-peritoneal herniation

Answer 7

• Failure of one or both pleuro-peritoneal folds to develop or fuse with mesoesophagus and septum transversum
• Usually occurs on left side
• Most common in humans resulting in viscera such as stomach and intestines being present in the pleural cavity

Question 8

Peritoneal-pericardial herniation

Answer 8

• Domestic animals (particularly dogs and cats)
• Result of defect in development of septum transversum leading to improper communication between peritoneal and pericardial cavities
• Herniation of viscera such as the liver, pyloric region of stomach and the intestines into the pericardial cavity

Question 9

Gastroschisis

Answer 9

Failure of ventral body wall to close in the abdominal region can lead to movement of abdominal contents (such as the intestines) outside the body cavity through a fissure between the umbilicus and sternum

Question 10

Congenital umbilical hernias

Answer 10

• Associated with abdominal ventral body wall defect
• Protrusion of viscera occurs around the umbilicus due to lack of muscular body wall in the region and can be found in small animals, pigs, cattle

Common developmental defects in pigs, calves (especially Holstein friesian cattle 4-15% frequency)

Question 11

Schistosomus reflexus

Answer 11

• Congenital fetal anomaly
• Primarily observed during embryonic development in ruminants
• Leads to significant dystocia that is less difficult in large ruminants compared to smaller ones
• Presents as head, limbs, and tail in close proximity, displaying ventral convex curvature (acute angulations of spinal column), limb fusion/stiffness (ankylosis), failure of the closure of all or part of the ventral wall of the fetal body resulting in exteriorized viscera
• Unable to pass through birth canal, removed by C-section or fetotomy. Cow recovers and can be used for later breeding