C5: . Most important porcine genetic diseases (PSS, MHS, PSE; general and specific stress factors)

Question 1

genetic diseases of swine: muscles

Answer 1

– Porcine stress syndrome (PSE, PSS, DFD, MHS, Ha blood group association): autosomal, RECESSIVE, incomplete penetrance, ryanoid receptor mutation (RYR1 gene, localization chrom. 6).

– Progressive myopathy (lameness of piglets).

– Tremor type III (XL, myoclonia, highly frequent muscle tremor of piglets).

– resistance to oedema disease = neonatal diarrhoea

Question 2

what is PSS?
what are its causes?
what are the affected pig breeds?
what are the clinical signs?
what is the diagnosis and control?

Answer 2

what is PSS?
-> Also known as Malignant Hyperthermia Syndrome (MHS), Pale Soft Exudative Pork/Musculature (PSE), Transport Myopathy, Back Muscle Necrosis.

causes?
-> POINT MUTATION in ryanodine receptor, congenital, autosomal RECESSIVE, closure of calcium channels in muscles.
-> Intolerance of stress, increase in metabolism and intense production of heat, carbon dioxide and lactic acid and contraction of skeletal musculature.

affected breeds?
-> landrace
-> poland-china
-> pietrain

clinical signs?
– SUDDEN DEATH, usually during transport. Before death hyperthermia, tachycardia, arrhythmia, trembling, the skin often becomes blotchy, erythematous and cyanotic.
– Pale, soft and exudative (PSE)POOR QUALITY MEAT (fall in muscle pH, denaturation of muscular proteins) or dark, firm and dry meat (DFD).
– HALOTHANE SENSITIVITY: manifested as malignant hyperthermia during anaesthesia.

diagnosis and control?
– In homozygote: halothane challenge (historical method, susceptible pigs become rigid within 5 minutes).
– DNA test (PCR) is available to detect and to eliminate the heterozygous carriers. (To date: Largely eliminated in developed countries).

Question 3

genetic diseases of swine affecting metabolism

Answer 3

• Porphyria -> Rare, congenital, AR
• Hemophilia A
• Pseudo-hemophilia/Von Willebrand
• Obesity genes
  -> Leptin → obesity, hyperphagia
  -> Myogenia → adipocyte fatty acid binding protein (A- FABP4)
  -> H-FABP → heart fatty acid binding protein
  -> Hypercholesterolemia
• Gangliosidosis II

Question 4

genetic diseases of swine affecting bones and other organs

Answer 4

• Vitamin D resistant rickets (rachitis, hydroxylase-enzyme
  deficiency and receptor types).
• Arthrogiposis, apodia (lack on homeobox-proteins, homeosis-genes-mutations).
• Atresia, agenesia (atresia ani).
• Foramen ovale persistens.
• Intersexes (XX males).
• Dwarfism: proportional, mutations of GH receptors.