Bob Paddle (2000), when referring to the epizootic disease in his book
Last Tasmanian Tiger", states:
"In the wild it was
anecdotally described as 'distemper' or 'mange' and distressed individuals,
exhibiting significant hair loss or scabs over the head or body, were easily
killed, and when snared, frequently made little attempt to free themselves,
and often died as a result of the additional trauma of capture".
Paddle's research on
captive thylacines suggests the disease was episodic and debilitating,
with symptoms varying depending on severity, rather than always having
a fatal outcome. Bleeding skin lesions, together with hair loss to
the body, limbs and tail were the outward manifestations found in both
the mild and severe forms, with the extent varying according to severity.
In the worst affected cases, loss of appetite and diarrhoea were also present.
Paddle (2012) notes:
"These symptoms could persist for up to four days. On occasions when
a captive animal survived a first bout of illness, it reoccurred at two
to three month intervals".
With reference to the possible cause of the disease,
Sleightholme & Campbell (2015) state: "The canine distemper virus
(CDV) is an enveloped, single stranded, negative RNA virus of the family
Paramyxoviridae, genus Morbillivirus that is closely related to the measles
virus. There is no evidence to suggest that marsupials can contract
CDV. Feline panleukopenia virus (FPV) or feline distemper is an entirely
different disease to canine distemper, and is not transmissible to dogs
or marsupials. Distemper in either its canine or feline form can
therefore be eliminated as a cause of the epizootic disease. From
Paddle's description of the symptoms, certain outward manifestations of
the disease are those one would commonly associate with sarcoptic mange,
a highly contagious infestation of Sarcoptes scabiei canis, a burrowing
mite. The canine sarcoptic mite can also infest cats, pigs, horses,
sheep and various other species. Marsupials known to be prone to infection
include the Common wombat (Vombatus ursinus), Southern Hairy-nosed wombat
(Lasiorhinus latifrons), koala (Phascolarctos cinereus), Agile wallaby
(Macropus agilis) and Common Ringtail possum (Pseudocheirus peregrinus).
The incubation period for clinical signs to develop is around 14 days,
but can be as short as 24 hours in cases of re-infection. The mites
burrow into the skin, causing intense itching which results in scratching
and biting. Scab formation and hair loss frequently appear first
on the elbows and ears. Secondary skin infection is common.
Animals infected with sarcoptic mange are often emaciated and in poor condition.
In advanced stages, sarcoptic mange has a devastating effect on internal
organs, including the heart, liver, kidneys, lungs and reproductive organs.
Mange can also have a negative impact on the reproductive capacity of infected
animals - e.g., absence of lactation, reduced litter size and weight, and
reduced pup viability and growth rates. Heavy infestations can also
result in anaemia in the young".