THE LIGHT MICROSCOPIC APPEARANCE OF DYSPLASIC ZONULAR LIGAMENT PROTEIN IN BREED RELATED LENS LUXATION Dick Dubielzig Rebecca Morris Class of 2006

Lens displacements particularly common in terrier breeds Lens displacements particularly common in terrier breeds Abnormal zonular ligament morphology SEM, PAS in Tibetan Terriers, Curtis et.al. J.Comp.Path., 1983 Abnormal zonular ligament morphology SEM, PAS in Tibetan Terriers, Curtis et.al. J.Comp.Path., 1983 Lack of description of nature of abnormality using standard histopathlogy Lack of description of nature of abnormality using standard histopathlogy Lens displacement is a common cause of secondary glaucoma in the dog

Hypothesis: determine whether LM can detect abnormal patterns in zonular ligament protein, any breed correlation Hypothesis: determine whether LM can detect abnormal patterns in zonular ligament protein, any breed correlation Search of COPLOW database for glaucoma caused by lens displacement Search of COPLOW database for glaucoma caused by lens displacement  Selection criteria  Exclusions Evaluation Evaluation  From records: signalment and laterality  Histopathology: zonular ligament morphology, other morphological features Study Design

The normal make-up of the zonule Fibrillin 1 & Fibrillin2 Fibrillin 1 & Fibrillin2  Glycoprotein sub-units  Strung together as a “string of beads”  Surrounded by microfibril associated glycoprotein  Fibrillin also found as a component of elastin

Zonular protein classification Normal Normal Abnormal Abnormal  Zonular ligament dysplasia  Thick lamellar protein sheet tightly adherent to nonpigmented ciliary body epithelium  Collagenization  Filamentous, not tightly adherent

Normal zonular protein Zonular ligament dysplasia Collagenization PASTrichromeElastin Stain Staining Characteristics

Normal Zonular ligament dysplasia Collagenization Mixed (2) Brittany Spaniel (1) Poodle (1) Cocker Spaniel (3) German Shepherd cross (1) Pekingese (1) Shih Tzu (2) Boston Terrier (1) Terrier mix (1) Peekapoo (1) American Eskimo Hound (1) Mixed (2) English Springer Spaniel (1) Welsh Terrier (1) Jack Russell Terrier (6) German Hunting Terrier (1) Rat Terrier (3) Fox Terrier (2) Mini Bull Terrier (2) Terrier Mix (1) Chinese Crested Terrier (2) Australian Blue Heeler (2) Shar-Pei (4) Shar-Pei cross (1) Laborador Retriever (1) Mixed (1) English Springer Spaniel (1) Spaniel (1) Toy poodle (1) Miniature poodle (1) Mixed mini poodle (1) Pekingese (1) Pekingese mix (1) Boston Terrier (3) Terrier mix (3) Chinese Crested Terrier (1) Shar-Pei (1) Dachshund (1) Labrador Retriever (1) Beagle (1) German Shorthaired Pointer (1) Pointer (1) Breeds Represented

ResultsNormal Zonular ligament dysplasia Collagen- ization Terrier2(7.4%)18(66.7%)7(25.9%) Non-terrier13(36.1%)11*(30.6%)12(33.3%) Ave age of lens luxation 10.7 yrs 5.2 yrs 8.9 yrs *includes 4 Shar-Peis

Average Age Normal Zonule Profile: 10.7 years Normal Zonule Profile: 10.7 years Collagenization: 8.9 years Collagenization: 8.9 years Zonular Ligament Dysplasia: 5.2 years Zonular Ligament Dysplasia: 5.2 years

Laterality OS: 39 OS: 39 OD: 28 OD: 28 Unknown: 5 Unknown: 5 9 dogs had both globes involved and 8 of these had zonular ligament dysplasia 9 dogs had both globes involved and 8 of these had zonular ligament dysplasia

Conclusions LM is useful in detecting abnormal patterns in zonular ligament protein LM is useful in detecting abnormal patterns in zonular ligament protein “Normal” zonular ligament with glaucoma “Normal” zonular ligament with glaucoma  Secondary to trauma or other disease process? Zonular ligament dysplasia Zonular ligament dysplasia  Terriers and Shar-Peis, young, bilateral, distinct morphology Collagenization Collagenization  No breed predilection, older, possibly secondary to disease process