Fig 1.
Squamous cell carcinoma of the upper digestive tract of cattle associated with chronic poisoning by bracken fern.
Endophytic growth patterns are located in the base of the tongue (A), pharynx (B) and distal esophagus (C; including some small papillomas [arrows]) and exophytic pattern in the rumen (D).
Fig 2.
Histology of squamous cell carcinomas (SCCs) of the upper digestive tract of cattle associated with chronic poisoning by bracken fern.
Well (A), moderately (B), and poorly (C) differentiated SCCs, HE.
Fig 3.
Regional lymph node metastasis of squamous cell carcinoma of the upper digestive tract of cattle associated with chronic poisoning by bracken fern.
The yellow coloration is due to the abundant intratumoral keratinization.
Fig 4.
Papillomas associated with chronic poisoning by bracken fern on cattle.
Multiple oropharyngeal papillomas (A; arrows) and developing papilloma (B), HE.
Fig 5.
Ruminal transforming papillomas associated with chronic poisoning by bracken fern in a cow.
Table 1.
Association between clinical signs and SCCs localization in the upper digestive tract in cattle grazing on bracken fern areas.
Table 2.
Association between histological differentiation grade and tumor localization or presence of metastasis of SCCs of the upper digestive tract in cattle grazing in bracken fern areas.
Fig 6.
Squamous cell carcinomas (SCCs) of the upper digestive tract (UDT) in cattle associated with chronic poisoning by bracken fern.
The average age of cattle according to tumor localization in the UDT. Cattle with oropharyngeal SCCs (7.39 years old) were younger than those with esophageal SCCs (8.6 years, *p = 0.018). Although cattle with oropharyngeal SCCs were, on average, younger than those with ruminal SCCs (7.79 years), the difference was not statistically significant.