General Veterinary Pathology

EXOGENOUS PIGMENTS - 2

Tattoo

• Tattooing is a method of identification of animals in which the carbon pigments used are deposited in the dermis.
• The carbon pigments may be found as phagocytised by macrophages or remains free in tissue.
• It evokes no inflammatory reaction.

Carotenoid pigments

Lipochrome pigments, not lipofuscin pigments.

Sources: β-carotene and fat soluble phyto-pigments

Grossly , the pigments are normally found in the cells like adrenal cortex, corpus luteum, Kupffer and testicular cells and in plasma/serum and fat of horses and Jersey cattle. The fat is discoloured to yellow to orange-yellow. Holstein cattle, sheep, goat and cats store little or no carotenoids in which fat is white and serum is clear. In starvation fat atrophy, the adipocytes become dark yellowish brown due to concentration of carotenoids.

Microscopically , pigments are not seen due to dissolution of pigments by alcohol and clearing agents (Fat soluble nature).

Tetracyclines

Deciduous teeth or developing teeth and bone may show yellow or brown deposits if the animals are treated with tetracycline antibiotics.

Plumbism

Plumbism is deposition of lead in the body in chronic poisoning.

Sources : Ingestion of lead containing grains, water, fodder, lead containing batteries, lead water pipes, etc.,

The lead sulphide (PbS) formed by hydrogen sulphide (H₂S) and lead imparts “blue line” in the gum, along the edges of teeth and gray colour to faeces. Hydrogen sulphide is derived from the putrefaction of food particles.

Argyria

• Argyria is deposition of silver as finely granular albuminate in tissue. There is grayish blue discolouration of skin and conjunctiva and internal organs.
• The pigment is extracellular and deposited in the cementic substances like dermis, arterioles and venules. This is a permanent blemish and not harmful.

Asbestosis

• Inhalation of asbestos particles leads to asbestosis and results in to interstitial fibrosis
• Asbestosis leads to mesothelioma in human beings
• Microscopicallly, ferruginous bodies were seen in the parenchyma.Ferruginous bodies are believed to be formed by macrophages that have phagocytized and attempted to digest the fibers

Siderosis

• Inhalation of oiron dust materilas can leads to siderosis and occurs commonly in horses, mules and dogs.
• Macroscopically, brown or rusty red pigemtation can be seen
• Microscopically, brown or black coloured irregularly shaped granules as spherical masses with in the macrophages