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Systematic Assessment of Mammalian Skull Specimens for Dental and Temporomandibular Joint Pathology

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Ochronosis-like condition in a cat.

Laura K Bryan¹, Brad R Weeks¹, Harold Ross Payne¹

¹Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, 4467 TAMU, College Station, TX, 77843-4467, USA.

Veterinary Dermatology

|May 27, 2016

Summary

This study describes a cat with ochronosis-like symptoms, including skin plaques and brown urine. Postmortem analysis revealed pigment similar to ochronosis, but no HGD gene mutations were found.

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Area of Science:

Veterinary Pathology
Comparative Pathology
Biochemistry

Background:

Endogenous ochronosis is a rare metabolic disorder caused by homogentisate 1,2-dioxygenase (HGD) deficiency.
It leads to abnormal pigment deposition in tissues and urine, primarily documented in humans.
Histological and ultrastructural descriptions of ochronosis in domestic animals are lacking.

Observation:

A 5-year-old domestic cat presented with facial black cutaneous plaques, lethargy, and brown urine upon air exposure.
The cat's medical history was unknown.
Postmortem examination revealed septic peritonitis and pigment deposition in multiple organs.

Findings:

Histopathological, ultrastructural, and spectroscopic analyses confirmed the pigment's similarity to human ochronotic pigment.
The pigment was identified as an organic compound.
No mutations were identified in key exons (3, 6, 8, 13) of the HGD gene in the affected cat.

Implications:

This case represents the first histological and ultrastructural description of an ochronosis-like condition in a domestic animal.
It expands the differential diagnosis for aberrant pigmentation in cats.
Further research into the genetic basis of this condition in animals is warranted.