A syndrome known as steatitis, also called yellow fat disease, is uncommon, but it can affect young horses. Generalized inflammation of adipose tissue might be related to a deficiency of antioxidants and/or an increased intake of polyunsaturated fatty acids.
Clinicians at Ghent University in Belgium examining medical records from 2008 through 2015 identified 20 cases of steatitis. [Paulussen, E.; Lefere, L.; Bauwens, C.; Broux, B.; De Clercq, D.; and van Loon, G. Yellow fat disease (steatitis) in 20 equids: Description of clinical and ultrasonographic findings. Equine Veterinary Education, 2017].
Of the 20 cases, six were foals, and the other 14 ranged between one and three years of age.
Clinical signs are somewhat non-specific, but some signs to look for include dullness, low-grade fever, recumbency, decreased appetite and weight loss, ventral edema, stiff or painful gait and a painful neck. One significant laboratory finding was low vitamin E and selenium along with moderately elevated CPK (creatinine phosphokinase) and markedly elevated LDH (lactate dehydrogenase).
Cases tended to occur in winter months, peaking in December and January. Ultrasound was useful in diagnosing increased echogenicity of abdominal and thoracic fat along with surrounding edema and fluid. Biopsy of affected fatty lesions showed the accumulation of ceroid, a yellow to brown pigment that is similar in composition to lipid-containing residues called lipofuscin; the presence of ceroid is pathognomonic.
With treatment—vitamin E, selenium, and corticosteroids—75% of the affected horses survived and recovered over a two- to six-month period.