What’s New in Old Horses? Postmortem Diagnoses in Mature and Aged Equids

Abstract

Postmortem findings in 241 equids admitted to a teaching hospital that were at least 15 years old at autopsy were reviewed (1) to determine disease prevalence, (2) to compare the cause of death (or euthanasia) in equids 15 to 19 years of age (n ¼ 116) with that in equids 20 years of age (n ¼ 125), and (3) to catalog coexisting lesions in equids with pituitary pars intermedia dysfunction (PPID). Breed and sex were evenly distributed between the age groups. Death or euthanasia was attributed to disease of the digestive system (41.5%), pituitary gland (12.9%), locomotor system (10.0%), nervous system (7.9%), cardiovascular system (4.6%), urinary system (4.6%), reproductive system (4.2%), respiratory system (4.2%), integumentary system (4.2%), lymphoid system (2.5%), liver (2.5%), or systemic neoplasia (1.2%). Nervous system disease was more common in the 15-to 19-year group; urinary tract disease was more common in the 20-year group. Neoplastic disease, regardless of systemic location, was the basis for death or euthanasia in 18.7% of all equids. Squamous cell carcinoma, lymphoma, and melanoma were the most common malignant neoplasms. PPID was the most common specific diagnosis, based on the postmortem presence of hyperplasia or adenoma, and was the reason for euthanasia in 47.7% of 65 equids with PPID. The most common nonpituitary causes for death or euthanasia in equids with PPID were colic, lameness, cancer, and spinal cord disease. Coexisting conditions in equids with PPID that were not considered the basis for euthanasia included neoplasms, infections, lameness, and recurrent airway obstruction.

Glucose-independent Acetate Metabolism Promotes Melanoma Cell Survival and Tumor Growth

“…Interestingly, genome analysis of thoroughbred horses revealed a positive selection for ACSS1 locus (50), and a polymorphism in ACSS1 was associated with elite racecourse performance of horses (51). These observations in the context of our data may explain why melanoma is more commonly seen in horses than any other domesticated animals (52,53). However, we show that depletion of ACSS1 or ACSS2 reduced the growth of melanoma xenografts.…”

Integumentary Disorders Including Cutaneous Neoplasia in Older Horses

“…PPID was the most common specific diagnosis, based on the postmortem presence of hyperplasia or adenoma, and was the reason for euthanasia in 47.7% of 65 equids with PPID. 2 Coexisting conditions in equids with PPID that were identified in this study but were not considered the basis for euthanasia included skin and other neoplasms, skin and other infections, lameness, and chronic airway diseases.…”

Endocrine tumours in equids

“…) and reported to be the second most prevalent neoplasia in horses at necropsy, with 7.1% of animals affected (Miller et al . ). However, in horses aged >20 years, a prevalence of 75% was documented (Ueki et al .…”

“…; Miller et al . ). Pheochromocytomas are more commonly reported in older equids (average age 23 years) (Germann et al .…”