Bovine Heritable Congenital Defects

Question 1

Arthrogryposis multiplex

Answer 1

• Lethal autosomal recessive
• Born dead/die soon after birth
• Small for age
• Dystocia common
  
  • Arthrogryposis, scoliosis, torticollis ± hydramnion
• Fetus fails to move → joints fixed + limbs twisted

NB: Arthrogryposis also caused by akabane/bunyavirus

Question 2

Arachnomelia syndrome (AS)

Answer 2

• Autosomal recessive
  
  • Brown Swiss + Simmental
• Stillborn
• ‘Spidery’ limbs w/ marked thinning diaphysis
• Abnorm shaped skull

Question 3

Bovine citrullinemia

Answer 3

• Autosomal recessive
  
  • Holstein
• Signs:
  
  • Normal at birth
  • 24hrs: depressed, aimless wandering, blind, grinding
  • 4-5 days: ataxia, recumb, convulse, die
• Lesions:
  
  • Mild-mod swelling cerebrocortical grey matter
  • Mild-severe hepatic cell degen
• Cause:
  
  • Mutation in gene coding enzyme involved in urea cycle → extreme ↑ citrulline + ammonia

Question 4

Bovine dwarfism

Answer 4

• Inherited chondrodysplasia
• Diff genes/mutations in diff cases/breeds
• Dexter bulldog dwarfism:
  
  • Autosomal recessive
    
    • Homozygous lethal → abort at 7mths
    • Heterozygous → intermed dwarf phenotype - short legs - favored by breeders! - keeps bulldog lethal allele in breed
• Angus dwarfism:
  
  • Normal at birth - fail to grow
  • Abnormal short legs + thick body
  • ↓endochondral ossif

Question 5

Brachyspina syndrome

Answer 5

• ?Autosomal recessive?
• Holstein
• Lethal - born dead
• Severely shortened vert column + limbs
• Multiple defects int organs
  
  • Renal dysplasia
  • Intestinal atresia

Question 6

Complex vertebral malformation (CVM)

Answer 6

• Autosomal recessive
• Holstein - carrier sires worldwide - high level
  
  • Screening test now avail
• Lethal → ↑EED, abortion, perinatal death
• Signs:
  
  • Mis-shaped vertebra
  • Ankylosis C+T vertebrae + scoliosis
  • Symm arthrogryposis lower limbs
  • Cardiac anomalies

Question 7

Congenital contractural arachnodactyly (CA)

Answer 7

• “Fawn calf syndrome”
• Autosomal recessive
• Non-lethal - born alive - most walk, suckle, survive
• ↓Elasticity conn tissue muscles
  
  • Prox limb contracture
  • Distal limb hyperextension
• Generally improves w/ maturity (may need help to stand + nurse initially)

Question 8

Crooked tail syndrome (CTS)

Answer 8

• Belgian Blue
• Non-lethal
• Signs:
  
  • Deviated tail
  • Growth retard noticed around 1mth
    
    • • abnormal skull shape
    • extreme muscular hypertrophy
• 25% euthanised
• CTS carriers have enhanced muscularity
  
  • 2 x as likely to be selected as elite sires
    
    • Contrib’d to rapid ↑ incid in breed

Question 9

Deficiciency uridine monophosphate synthase (DUMPS)

Answer 9

• Autosomal recessive
• Lethal
• Holstein (2% in US carry gene)
• Growth + devel homozygous embryos arrested → mortality around day 40

Question 10

Developmental duplication (DD)

Answer 10

• Autosomal recessive
• Angus
• Signs:
  
  • Typically FL’s duplicated - orig shoulder/neck
  • May also present as conjoined twins
  • Early DD events may → EED
• Genetic testing avail

Question 11

Inherited congenital myoclonus (ICM)

Answer 11

• Autosomal recessive
• Hereford
• Seizure disorder - incompatble w/ life
  
  • Calves born alive but fail to rise
  • Envir stressors trigger seizures (1min-1hr)

Question 12

Neuropathic hydrocephalus

Answer 12

• “Water head”
• Autosomal recessive
• Lethal
• Angus
• Cranium fluid-filled - no obv brain tissue
  
  • Spinal cord dilated - no obv spinal tissue
• Nearly 10% of Angus AI sires were carriers
  
  • Could explain high embr/fetal loss (50-70%)

Question 13

Osteopetrosis

Answer 13

• “Marble bone”
• Autosomal recessive
• Lethal
• Born 10-30 days early
• Head abnorms + bones shorter + easily broken
• Genetic testing avail

Question 14

Paunch calf syndrome (PCS)

Answer 14

• Outbreak in Italy
  
  • Romagnola cattle
• Stillborn
• Multiorgan dysplasia;
  
  • Craniofacial deforms
  • Enlarged, fluid-filled abd
  • Hepatic fibrosis

Question 15

Pulmonary hypoplasia with anasarca (PHA)

Answer 15

• Autosomal recessive
• Lethal
  
  • High preg wastage
• If gets to term - invariably dystocia
• Signs:
  
  • Anasarca
  • Near absence of lung tissue
  • Lymphatic agenesis
• Genetic testing avail

Question 16

Tibial hemimelia

Answer 16

• Autosomal recessive (deletion)
• Lethal - born dead - or die soon
• Signs:
  
  • Multiple skeletal deforms (esp shortened/absent tibia)
  • Abd hernia
  • Cryptorchidism
  • Failed PMN duct devel
  • Hirsutism
  • Meningocele
• 1st described Scotland - Galloway breed 1950s
  
  • Test breeding + preg termination → elim of disorder
• Later described US in Shorthorns
  
  • Unknown whether deletions orig from Galloway breed