Malignant melanomas in farm animals.

This research article describes the occurrence and characteristics of malignant melanomas in various farm animals including horses, a calf, a cow, and pigs.

Overview of the Study

The researchers studied nine cases of malignant melanomas in farm animals: five horses, one calf, one cow, and two pigs. These animals belonged to different breeds and had different colors. The aim of the study was to examine and describe the characteristics and behavior of the tumours.

Findings in Horses

• In horses, the cancer was found on the skin and had spread to organs within the abdominal cavity, particularly in white or gray horses.
• Under microscopic analysis, different types of cells were identified: dendritic cells, fusiform pigment cells, and multinucleated cells. Dendritic cells have a role in the immune system, fusiform cells are spindle-shaped and multinucleated cells have more than one nucleus. This diversity of cells shows the complexity of the tumours.
• The researchers also found microcysts in the pituitary gland (hypophysis), and in one case, a pituitary adenoma, which is typically a benign tumor.

Electron Microscopy Analysis

• With the aid of electron microscopy, the researchers also identified differentiated melanophores (cells that produce and contain pigment) and melanophages (cells that ingest melanin) in the horses.
• The mature melanosomes (organelles that synthesize melanin) were intensely black and the elementary granules were concentrically and lamellarly arranged, indicating a high level of melanin production.

Findings in Cattle and Swine

• In the calf and cow, the cancer had spread to the visceral organs, which are the internal organs within the main cavities of the body. The cow also presented cerebral localizations, suggesting the melanoma had spread to the brain.
• In the pigs, one Duroc displayed a spread of the cancer to visceral organs, whereas a Bazna pig had the cancer localized on the skin.

Conclusions

The research provides a comprehensive description of malignant melanomas in different farm animals including their characteristics, appearance, and spread in the body. These findings contribute to the understanding of the disease in animals, which might have implications in future research and treatment efforts.