[Ocular and non-ocular squamous cell carcinomas in the Haflinger: Eight cases at the Institut Suisse de Médecine...

This case series describes the clinical course of ocular and non-ocular squamous cell carinoma (SCC) in the Haflinger horse and is intended to raise awareness of the high recurrence rate and tendency to metastasize. Eight Haflingers with histologically confirmed SCC were included, five ocular and three non-ocular, who were presented at the Institut Suisse de Médecine Équine (ISME) Bern between July 2015 and January 2022. The ocular SCC cases were all presented because of an apparent mass, which in most cases was post-treatment recurrence. The occurrence of recurrences was observed between 3 weeks and 16 years after initial therapy. Four of five Haflingers with ocular SCC had an enucleation, three of which were clinically normal at the time of the completion of this study, one case was euthanized due to confirmed metastases and one due to lameness. The result of enucleations for therapy of ocular SCC was good if no metastases occurred. Of the three non-ocular SCC cases, only one case, a penile SCC, had an apparent mass. Therapy was initiated in this case, while the other two cases were euthanized shortly after diagnosis due to the poor prognosis of SCC in the appropriate locations (maxillary sinus, mandible). Metastases occurred three and two years after removal of the primary tumor in ocular SCC in the scapula, liver and lungs and in non-ocular SCC from the penis to the nostrils. Since a postmortem pathological examination was not carried out on all Haflingers, further metastases cannot be ruled out. Haflingers with SCC should be monitored by a veterinarian over the long term, as recurrences and/or metastases can still occur years later.