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Thesis (M.S.)—University of Nebraska—Lincoln, 1950. Department of Animal Pathology.


Copyright 1950, the author. Used by permission.


Equine cutaneous papillomatosis was studied with reference to infectiveness, filtrability of the causative agent, resistance to heat, and infectiveness after varying lengths and conditions of storage.

Susceptible horses could readily be infected with suspensions of ground wart tissue and with bacteriologically sterile filtrates made from these suspensions.

The virus remained infectious after being held at a temperature of 45⁰C for thirty minutes but was rendered non-infectious when held at 55⁰C for the same length of time.

Supernatant fluid from suspensions made by grinding wart tissue in physiological saline remained infectious for 73 days when stored in an equal part of glycerol at 4⁰C, but it was non-infectious after 112 days of storage.When stored at -35⁰C supernatant fluid remained infectious for 185 days but not for 224 days.

A degree of immunity is apparently produced by experimental infection, but it does not always protect against spontaneous infections.On the other hand, spontaneous infections seem to induce solid immunity.

Histologically the principal difference between sections of normal skin and that of equine papillomatosis appears to be hyperkeratosis and parakeratosis of the stratum corneum, acanthosis with an increase of mitotic figures, and a proliferation of the corneal papillae in cases of papillomatosis.

Advisor: Carl Olson, Jr.