Susceptibility to Pug Dog Encephalitis
(PDE)
Introduction
Approximately 1.2% of Pug dogs die of necrotizing
meningoencephalitis (NME), also known as Pug dog encephalitis (PDE).
NME is an inflammatory disease of the central nervous system that is
usually progressive and fatal. Symptoms of NME include seizures,
depression, ataxia, abnormal gait and blindness (1). Female,
fawn-colored Pug Dogs younger than 7 years of age are more apt to
develop NME than older, male and non-fawn colored individuals (2).
Recent research has revealed that susceptibility to NME is associated
with the dog leukocyte antigen (DLA) region of dog chromosome 12 (3).
The association is at or near the region containing the DLA class II
genes. Dogs that have two identical copies of the NME associated
markers in this region, have an observed risk (OR) of 12.75 for NME in
their lifetime over Pugs that have only one or no copies of these
markers (OR 0-1.08).
Results reported as:
N/N - No copies of the NME associated markers (homozygous for normal). These dogs have a low risk of developing NME.
N/S - One copy of the NME associated markers (heterozygous for susceptibility). These dogs have a low risk of developing NME.
S/S - Two copies of the NME susceptibility
associated markers. These dogs are 12.75 times more likely to develop
NME in their lifetime.
Outcomes of matings based on NME test results:
Detailed Information
1. N/N x N/N = all puppies will have two copies of the low NME
risk markers (N/N) and will have a significantly reduced risk of
developing NME during their lifetime.
2. N/N x N/S = One half of the puppies will have two copies of
the low NME risk markers (N/N), and have a significantly reduced risk
of developing NME during their lifetimes. One half of the puppies will
carry one copy of the susceptibility markers (N/S), but will also be at
low risk for developing NME.
3. N/S x N/S = One fourth of puppies will be
N/N and at low risk for NME; one half will be N/S, carry the
susceptibility marker, but will also be at low risk for NME; one
fourth will be S/S and will be at high risk for NME.
4. N/S x S/S = One half of the puppies will carry the
susceptibility marker (N/S), but will not be at increased risk of NME;
one half of the puppies will have two copies (S/S) of the susceptibility
marker and be at high risk of NME.
5. N/N x S/S = All of the puppies will carry one copy of the
susceptibility markers (N/S), and be at low risk for developing NME.
6. S/S x S/S = All of the puppies will carry two copies of the susceptibility marker (S/S) and be at high risk for NME.
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Notes: This is not a diagnostic test for NME in Pug Dogs or for NME disease or risk in other breeds.
The test is only to determine risk for developing NME in Pug Dogs and
for selecting matings that will produce puppies that are at decreased
risk (N/N, N/S).
Although a significant proportion (11%) of Pug Dogs
is S/S, only about 1 in 8 of this group will develop NME during their
lifetime. Also, breeders are advised against breeding out the S genotype,
because 40% of Pug Dogs have the S genotype in a heterozygous (N/S =
29%) or homozygous state (S/S = 11%). Eliminating the S genotype will
lead to a considerable loss of genetic diversity. Therefore, breeders
should carefully select matings that do not produce S/S puppies. The NME report includes DNA types for a panel of 8 markers
selected from the International Society of Animal Genetics (ISAG)
canine parentage panel. These markers provide individual
identification for each sample tested.
References:
1. Talarico LR, Schatzberg SJ. Idiopathic granulomatous and
necrotising inflammatory disorders of the canine central nervous
system: a review and future perspectives. J Small Anim Pract 2010: 51: 138–149.
2. Levine JM, Fosgate GT, Porter B et al. Epidemiology of necrotizing meningoencephalitis in Pug dogs. J Vet Intern Med 2008: 22: 961–968.
3. Greer KA, AK Wong, H Liu, TR Famula, NC Pedersen, A Ruhe, M
Wallace and MW Neff. Necrotizing meningoencephalitis of Pug Dogs
associates with dog leukocyte antigen class II and resembles acute
variant forms of multiple sclerosis. Tissue Antigens 2010: 76:110-118.
