Atlanto-axial malformation and instability in dogs with pituitary dwarfism due to an LHX3 mutation.

BACKGROUND: Canine pituitary dwarfism or combined pituitary hormone deficiency (CPHD) in shepherd dogs is associated with an LHX3 mutation and can lead to a wide range of clinical manifestations. Some dogs with CPHD have neurological signs that are localized to the cervical spine. In human CPHD, caused by an LHX3 mutation, anatomical abnormalities in the atlanto-axial (C1-C2) joint have been described. OBJECTIVES: To evaluate the presence of atlanto-axial malformations in dogs with pituitary dwarfism associated with an LHX3 mutation and to investigate the degree of similarity between the atlanto-axial anomalies found in canine and human CPHD patients with an LHX3 mutation. ANIMALS: Three client-owned Czechoslovakian wolfdogs and 1 client-owned German shepherd dog, previously diagnosed with pituitary dwarfism caused by an LHX3 mutation, with neurological signs indicating a cervical spinal disorder. METHODS: Radiography, computed tomography, and magnetic resonance imaging of the cranial neck and skull, necropsy, and histology. RESULTS: Diagnostic imaging identified abnormal positioning of the dens axis and incomplete ossification of the suture lines between the ossification centers of the atlas with concurrent atlanto-axial instability and dynamic compression of the spinal cord by the dens axis. The malformations and aberrant motion at C1-C2 were confirmed at necropsy and histology. CONCLUSIONS AND CLINICAL IMPORTANCE: The atlanto-axial abnormalities of the dwarf dogs resemble those encountered in human CPHD patients with an LHX3 mutation. These findings suggest an association between the LHX3 mutation in dogs with CPHD and atlanto-axial malformations. Consequently, pituitary dwarfs should be monitored closely for neurological signs.

Pituitary dwarfism in Saarloos and Czechoslovakian wolfdogs is associated with a mutation in LHX3.

BACKGROUND: Pituitary dwarfism in German Shepherd Dogs is associated with autosomal recessive inheritance and a mutation in LHX3, resulting in combined pituitary hormone deficiency. Congenital dwarfism also is encountered in breeds related to German Shepherd Dogs, such as Saarloos and Czechoslovakian wolfdogs. OBJECTIVES: To investigate whether Saarloos and Czechoslovakian wolfdog dwarfs have the same LHX3 mutation as do Germans Shepherd Dog dwarfs. A specific aim was to determine the carrier frequency among Saarloos and Czechoslovakian wolfdogs used for breeding. ANIMALS: Two client-owned Saarloos wolfdogs and 4 client-owned Czechoslovakian wolfdogs with pituitary dwarfism, 239 clinically healthy client-owned Saarloos wolfdogs, and 200 client-owned clinically healthy Czechoslovakian wolfdogs. METHODS: Genomic DNA was amplified using polymerase chain reaction (PCR). In the Saarloos and Czechoslovakian wolfdog dwarfs, PCR products were analyzed by sequencing. DNA fragment length analysis was performed on the samples from the clinically healthy dogs. RESULTS: Saarloos and Czechoslovakian wolfdog dwarfs have the same 7 bp deletion in intron 5 of LHX3 as do German Shepherd Dog dwarfs. The frequency of carriers of this mutation among clinically healthy Saarloos and Czechoslovakian wolfdogs used for breeding was 31% and 21%, respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: An LHX3 mutation is associated with pituitary dwarfism in Saarloos and Czechoslovakian wolfdogs. The rather high frequency of carriers of the mutated gene in the 2 breeds emphasizes the need for screening before breeding. If all breeding animals were genetically tested for the presence of the LHX3 mutation and a correct breeding policy would be implemented, this disease could be eradicated completely.