NOTICE: United Vaccine no longer offers ADV
testing
January 25,
2006, United Vaccines ceased accepting blood samples
for their CEP test for the Aleutian disease virus.
Blue Cross Animal Hospital now offers CEP testing. See right sidebar for info.
Introduction
Formally considered a disease of mink,
the parvovirus that causes Aleutian disease is becoming
increasingly prevalent in ferrets. A fulminant lethal infection
in mink, the Aleutian disease virus appears to be a chronic
latent infection in ferrets (often referred to as "hypergammaglobulinemia"
of ferrets), which causes clinical disease over a period
of one to two years. While the parvovirus itself causes
little or no harm to the ferret host, the marked inflammatory
response generated by the ferret may cause life-threatening
hematopoietic and urinary derangement. The large number
of antigen-antibody complexes associated with the humoral
response to the presence of the virus results in a systemic
vasculitis (with the most prominent lesions being in the
glomerular capillaries, resulting in eventual renal failure
and death). The marked lymphoplasmacytic response interferes
with bone marrow hematopoiesis, and local accumulations
of plasma cells may result in organ derangement.
In 1997,
a rescue facility in San Antonio,
Texas experienced an epizootic of AD which was unlike any
previously documented. In contrast to the 40% or less morbidity
seen in other facilities, 61/65 animals tested positive
on CIEP testing for AD virus antibodies. Early signs of
infection noted in a number of animals were an ascending
paralysis and respiratory signs such as sneezing or coughing.
Post-mortem on one of these animals showed characteristic
plasmacytic infiltrates in the spinal cord and other organs.
Similarly affected animals who received supporting treatment
recovered from the paralysis, but have since gone on to
succumb two years later of more characteristic disease (glomerulonephritis,
hypergammaglobulinemia, etc.) Similar facility outbreaks
have been reported in Wisconsin, Alabama, Maryland, and
Virginia.
Clinical Signs
Most infected ferrets remain asymptomatic
until shortly before death. Non-specific signs include lethargy,
anorexia. Ataxia and paraparesis may be seen classically
in chronic cases (but occasionally in very acute cases as
a premonitory sign) due to accumulations of inflammatory
cells within the spinal cord.. Anemia, thrombocytopenia,
and/or leukopenia, cutaneous hemorrhages, and secondary
infections may be seen in various combinations in end stage
disease.
Diagnosis
An elevated globulin (defined as >20%
of the total protein) is strongly indicative of this disease.
Ferrets with total proteins over 7.5, especially those with
mildly decreased albumins should be immediately suspect.
Additionally, a CIEP test is commercially available from
United Vaccines, and may be run on a hematocrit tube of
blood. Biopsy or necropsy specimens from infected ferrets
(particularly kidney, spleen, and liver) often yield a presumptive
diagnosis.
Gross Lesions
Gross lesions are seen only late in the
course of disease. Splenomegaly and lymphadenopathy are
the most common gross lesions with this disease; splenic
infarction as a result of marked splenomegaly may complicate
the clinical and pathologic picture.. Enlarged, brown-tan
kidneys may be present. In terminal cases, clotting abnormalities
resulting from vasculitis and the marked hypergammaglobulinemia
may result in petechial hemorrhage and hematuria.
Microscopic Lesions
Several characteristic microscopic findings
are seen in ferret AD as well as in the mink disease. Prominent
plasmacytic infiltrates are seen in numerous organs, most
prominently in the renal interstitium, hepatic portal areas,
and in the splenic red pulp, where an almost pure population
of plasma cells expands the red pulp. Additionally, there
may be marked plasmacytosis of numerous lymph nodes and
the bone marrow. In most cases, there will be marked membranous
glomerulonephritis and numerous ectatic protein-filled tubules
as a result. (Note: Glomerulosclerosis is commonly seen
in chronic interstitial nephritis in this species - but
there is little evidence of tubular protein casts or plasmacytic
infiltrate in uncomplicated CIN). Vasculitis may be seen
in almost any organ.
Treatment
There is no current treatment for Aleutian
disease in the ferret, nor is there a vaccine for this disease.
Supportive therapy may prolong life; however most cases
are not diagnosed until late in the course of disease, and
infected animals may serve as a source of infection for
other ferrets.
References
Alexandersen S et al. Acute interstitial pneumonia
in mink kits inoculated with defined isolates of Aleutian
mink disease parvovirus. Vet Pathol 31:216-228, 1994.
Daoust PY, Hunter DB. Spontaneous Aleutian disease
in ferrets. Can Vet J 19:133-135, 1978.
Ohshima K et al. Comparison of the lesions of Aleutian
disease in mink and hypergammaglobulinemia in ferrets. Am
J Vet Res 39:653-657, 1978.
Oxenham M. Aleutian disease in the ferret. Vet Rec
126:585, 1990.
Palley LS et al. Parvovirus-associated syndrome (Aleutian
disease) in two ferrets. JAVMA 201:100-106, 1992.
Porter HG et al. Aleutian disease in ferrets. Infect
Immun 36:379-386, 1982.
Welchman E, et al. Aleutian disease in domestic ferrets:
diagnostic findings and survey results. Vet Rec 132:479-484,
1993.
Une Y et al. Spontaneous Aleutian diseases in a ferret.
J Vet Med Sci 62(5): 553-555, 2000.