Types
Horses can be infected by at least four different papilloma
viruses
At least 2 different Equine specific
papilloma viruses (EPV), it is presumed that the different types of
papilloma virus cause the
various presentations of warts in horses. (5,11)
bovine papilloma virus 1 (BPV-1)*
bovine papilloma virus 2 (BPV-2)*
*Associated with the development of Equine Sarcoids
CONGENITAL PAPILLOMATOSIS
Common Name: Baby warts
General Information: The wart is present on the foal at birth (congenital). While pregnant, if a
mare is infected
with EPV, the virus can cross the placenta and infect the foal in utero.This does not mean that the warts
are inherited, warts are an infectious disease and may affect any breed
or sex.(10)
What do they look like?
Most of the time the foal will have a single wart, sizes can vary
from very small ( a few mm in diameter) to quite large (up to 20cm!).
They are usually grey or greyish pink in colour and may be flat or look
like flattened cauliflower.(10, 13)
Unlike other equine warts, these do
not usually go away on their own and will need treatment
by a qualified veterinarian.
PAPILLOMATOSIS
Common Name: Grass warts
General Information: Usually affect young horses less than three years
old , most commonly in horses between 6 months and a year old.
Occaisonally they will infect very old horses (in their twenties) as
well.(10, Any breed and both males and females may be affected(13) The
EPV responsible for these warts is highly contagious and horses become
infected either through direct contact with each other or via fomites.
Usually multiple warts found singly and in clumps, often the clumps may
come to look like one big wart. They may be smooth round bumps or
appear cauliflower like. They are pink to grey in colour,
often depending on the horse's skin pigmentation in the area ( darker
warts on darker skin). Warts are most common around the muzzle,
lips and eyes, and may also develop on tthe lower legs and around the
genitals.(14)
Prevetnion: Because the EPV is so highly contagious, prevention is very
difficult if one horse in the herd is infected. You can try to
prevent spread of warts by keeping a closed herd (no new horses enter
the herd), isolating infected animals and not sharing equipment between
horses, however this is not realistic at most boarding stables!
Treatment is usually not required as most warts clear up on their own
in a few months. If the warts are in an awkward area that cause
the animal discomfort or interfere with training, your veterinarian may
try one of a few treatment
options.
AURAL PLAQUES (Pinnal papilloma, Papillary acanthosis)
Common name: Ear Fungus
General Information: Can occur in horses of any age, breed or
sex, usually both ears are affected and the lesions may be worse in the
summer.
What do they look like?
Can be a single wart or clumps of warts found in the horse's inner
ear. They are often grey in colour or non-pigmented. Some
are flattened others are raised, a
cauliflower like appearnace is typical as for other warts.(10,14)
Importance: Often blamed for head shaking, head shyness and difficulty
in bridling however these warts rarely cause a problem and other
reasons for these behavioural problems should be investigated. During
the summer months, they may attract flies resulting in irritation and
potential for infection.(10,11)
Treatment: Leave them alone! Aural plaques don't usually bother the
horse and picking at them may result in irritation and soreness which
may make head shyness or bridling issues worse. In severe cases, the
warts may have to be treated by your
veterinarian, but this is often unsuccesful.
SARCOIDS
General Information: Sarcoids are the most common tumor found in
horses, they can occur in any breed sex or age. Often horses will
have more than one. They are most frequently found on the legs but can
occur pretty much anywhere on the body
Why sarcoids occur is unknown, many factors are involved and a link has
been established between sarcoids and infection of horses with bovine
papilloma viruses 1 and 2 however this link is not well understood and
investigation continues in this area.
What do they look like? Sarcoids can have the typical cauliflower
like appearance of warts, they can be flattented or a
combination. Many sarcoids will ulcerate and bleed causing discomfort
and attracting flies.(11, 12,14)
Treatment: Sarcoids
may disapear on their own
but many veterianrians opt to treat them as they can be fairly invasive.
