Evidence of cerebellar abiotrophy (CA) was found in a six-month-old Arabian filly with signs of incoordination, head tremor, wobbling, loss of balance and falling over, consistent with a cerebellar lesion. Normal hematology profile blood test and cerebrospinal fluid analysis excluded infectious encephalitis, and serological testing for Sarcocystis neurona was negative. The filly was euthanized. Postmortem X-ray radiography of the cervical cephalic region identified not abnormalities, discounting spinal trauma. The histopathological analysis of serial transverse cerebellar sections by electron microscopy revealed morphological characteristics of apoptotic cells with pyknotic nuclei and degenerate mitochondria, cytoplasmic condensation and areas with absence of Purkinje cells, matching with CA histopathological characteristics. The indirect DNA test for CA was positive in the filly, and DNA test confirmed the CA carrier state in the parents and the recessive inheritance of the disease. To our knowledge this is the first report of a CA case in Argentina.

Genetic diversity of the major histocompatibility complex (MHC) is essential for the antigen recognition and presentation during the immune response. Indirect MHC typing by microsatellites (STR) provides data on genetic diversity and population structure, and provides knowledge of selective and evolutionary processes. In order to characterize a sample of Arab horses, we identified MHC haplotypes based on three STRs (UM011, DRB2-STR2 and COR112) covering a region of ~1Mpb. Genomic DNA was extracted from blood and hair of 30 horses from five farms of the province of Buenos Aires. STRs were amplified with fluorescent primers and typed in an automated sequencer. Population and diversity parameters were estimated. Haplotype detection was performed by segregation analysis and with the PHASE program for reconstructing haplotypes. Of the 24 haplotypes identified, 12 were verified by segregation in the Stud Book pedigree records. Our results showed linkage with known equine leukocyte antigen (ELA) class II alleles. The number of haplotypes identified allowed to expand the estimates of diversity in the equine MHC. This methodology is a useful tool and an alternative approach to type MHC in horse lineages and immune-related population studies.