Mannosidosis in Galloway calves

Area of Science:

• Veterinary Pathology
• Biochemistry
• Genetics

Background:

• Mannosidosis is a rare lysosomal storage disease affecting glycoprotein metabolism.
• It is caused by an inherited deficiency of the enzyme alpha-mannosidase.
• This condition affects humans, cattle (including Angus breeds), and cats, typically inherited in an autosomal recessive manner.

Purpose of the Study:

• To detail the histological and biochemical findings in Galloway calves with congenital mannosidosis.
• To confirm the diagnosis of mannosidosis in stillborn and aborted fetuses from experimental matings.

Main Methods:

• Gross and histological examination of affected fetuses.
• Biochemical analysis of lysosomal enzyme activities (alpha-mannosidase and others) in brain, liver, and kidney tissues.
• Comparison of enzyme activities between affected calves and normal controls.

Main Results:

• Four stillborn and one autolyzed Galloway fetus diagnosed with mannosidosis.
• Gross lesions included hydrocephalus, enlarged liver and kidneys, and arthrogryposis.
• Histopathology revealed neuronal cytoplasmic vacuolation, spheroids in the brain, and vacuolated renal tubular and hepatic cells.
• Affected tissues showed a profound deficiency in alpha-mannosidase activity (up to 99% in liver, 98% in brain).
• Activities of other lysosomal enzymes were elevated in affected tissues.

Conclusions:

• Congenital mannosidosis in Galloway calves presents with specific gross, histological, and biochemical abnormalities.
• The findings confirm the genetic basis and enzyme deficiency characteristic of this lysosomal storage disease.
• This study provides a detailed account of a naturally occurring animal model for mannosidosis research.