Page 519 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

494 CHAPTER 2

VetBooks.ir cease until all the lesions have healed. Mares can early on there is a mucoid or purulent urethral and/
or preputial discharge. Later there is scrotal and pre-
usually be mated on the next oestrous period.
Prognosis putial oedema, which may extend cranially towards
the ventral abdomen and chest. In the mare, in the
There is no effect on fertility, except in the short early stages, there is a mucoid or purulent vaginal
term because of delays in breeding or reluctance discharge. Later there is perineal and vulval oedema,
to breed. Once the lesions are healed they present which may extend cranially towards the mammary
no further problems, since it is considered that the gland and ventral abdomen.
affected animal is now immune, although it is not
known if this herpesvirus can be latent. No vaccine Diagnosis
is available for prevention. Diagnosis is based on history, clinical presentation
and identification of the organism from discharges,
DOURINE fine-needle aspirates from skin lesions, blood and
cerebrospinal fluid. Control of spread of the disease
Definition/overview internationally depends on serological testing to
Dourine is a venereally transmitted, protozoal dis- detect previous disease exposure and possible carrier
ease present in certain parts of the world and sub- status.
ject to international controls. Carrier animals are an
important factor in the spread of the disease, along Management
with a very long potential incubation period and It is possible to treat this condition, but in most
slow onset of clinical signs. Clinical signs include countries there are control and eradication measures
fever, characteristic skin lesions, weight loss and dis- in force, including slaughter policies, and these need
charges from, and swelling of, the external genitalia to be checked before any action is taken.
of the mare and stallion. The organism is identifiable
from discharges, blood and fine-needle aspirates of Prognosis
skin lesions. Cases are rarely treated and many coun- The prognosis is poor to grave, with most affected
tries have a slaughter eradication policy. animals being humanely euthanased.

Aetiology/pathophysiology TUMOURS OF THE FEMALE
Dourine is caused by a protozoal organism REPRODUCTIVE TRACT
Trypanosoma equiperdum, which is transmitted vene- EXCLUDING THE OVARY
really. It is present in the Middle East, certain areas
of Africa, Central and South America and parts of Definition/overview
Asia. The condition is subject to national and inter- Tumours of the uterus are very rare and the only
national control measures to stop the spread of the significant occurrence is leiomyoma. Tumours of
disease, which is complicated by the existence of the vestibule and vulval area are more common and
clinically unaffected carriers. Epidemics have been include polyps, squamous cell carcinoma (SCC), mel-
reported where carrier or early infected animals are anoma in grey animals and, rarely, hamartoma. All
introduced. The course of the disease is slow, but it is occur mainly in older mares. Biopsy for histopatho-
progressive and leads to a high mortality rate. logical diagnosis is essential for differential diagnosis.
Many tumours can be surgically removed, with a fair
Clinical presentation to guarded prognosis for survival and fertility.
The disease is very slow in onset, with an incuba-
tion period of up to 26 weeks. Clinical signs include Aetiology/pathophysiology
a chronic mild fever, urticarial-like plaques of Leiomyomas have an unknown cause. Polyps/papil-
oedema, particularly on the flank skin, muscle wast- lomas are thought to be caused by an unidentified
ing and weight loss and, in the later stages, neuro- papillomavirus unrelated to the cutaneous form.
logical signs, collapse and death. In the stallion, Both leiomyomas and polyps are benign.