Page 705 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

680 CHAPTER 3

VetBooks.ir 3.134 The severity of clinical signs varies considerably.
In the peracute disease form there is sudden death
due to pulmonary oedema. In the acute disease form
there is death from pulmonary oedema and myo-
cardial failure. In the subacute disease form there is
myocarditis with accompanying signs of heart failure
and death in around 50% of cases. The least severe
Fig. 3.134 form of the disease (‘horse sickness fever’) occurs
A veterinarian dressing in horses with some immunity to the virus or in
up to enter a stable with resistant species (zebras and donkeys). In this form
a horse that is suspected there is transient URT disease and low mortality.
to suffer from Hendra Vaccination can be used to control the disease.
virus. The personal
protective equipment Hendra virus
for a suspected Hendra Hendra virus (formally known as equine morbil-
case consists of a single livirus) is a zoonotic henipavirus of the family
use, full body coverage Paramyxoviridae. Hendra virus infections in horses
including a waterproof and humans have been recognised since 1994 in
suit with head cover, Australia in Queensland and the north of New
shoe covers, gloves, South Wales. Hendra virus has a fruit bat reser-
mask and glasses. voir and transmission appears to require very close
contact with bat uterine secretions or body fluid
The rhinoviruses are shed through nasal secretions. exposure from infected horses. Hendra virus infec-
In addition, ERAV also sheds in faeces and urine. tions can cause fatal pneumonia and encephalitis.
ERAV causes viraemia, ERBV does not. Viral infec- However, there are no pathognomic clinical signs, a
tion can be confirmed with serology and PCR. wide range of potential presenting clinical signs and
not all horses develop respiratory or neurological
African horse sickness signs. This poses a significant challenge for attend-
African horse sickness (AHS) is endemic in southern ing veterinarians (Fig. 3.134). In the limited num-
Africa and causes high morbidity and mortality in ber of equine outbreaks that have occurred there has
susceptible horses. It is a notifiable disease in many been high morbidity and mortality, yet not all horses
countries and is OIE listed. AHS is caused by an die from the infection. Fatal infections of Australian
orbivirus related to blue-tongue virus of sheep. The equine veterinarians have occurred. Hendra virus
virus requires an insect vector, Culicoides imicola, for infection is a notifiable disease in Australia and
transmission. The geographical distribution of the is OIE listed. Vaccination can be used to prevent
vector extends into Europe and it is possible that cli- the disease, and many equine referral hospitals in
mate change may eventually extend its range further. Queensland refuse unvaccinated horses.

BACTERIAL DISEASE

STRANGLES draining the URT and a variety of other, potentially
fatal, sequelae including disseminated abscessation
Definition/overview and purpura haemorrhagica. An alternative mani-
Strangles is a highly contagious bacterial infection of festation is a mild, transient URT disease without
the URT, characterised in its most severe form (‘clas- abscesses referred to as ‘atypical strangles’. In most
sical strangles’) by abscessation of the lymph nodes outbreaks the number of mild ‘atypical’ cases is