Prevalence Of Dirofilaria Immitis In Cats And Dogs - Journal of ...

Journal of Veterinary Diagnostic
Investigation
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Prevalence of Dirofilaria Immitis in Cats and Dogs in Eastern Tennessee
Sharon Patton and Malcolm D. McCracken
J VET Diagn Invest 1991 3: 79
DOI: 10.1177/104063879100300118
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Examination of raccoon feces from haylofts in Ontario has
usually revealed large numbers of B. procyonis eggs (Lautenslager
P, personal communication). Treatment of infected
animals with various anthelminthics including thiabendazole,
fenbendazole, levamisole, and ivermectin has not been
effective. 2
Brief communications 79
References
1. Fox AS, Kazacos RR, Gould NS, et al.: 1985, Fatal eosinophilic
meninogoencephalitis and visceral larva migrans caused by the
raccoon ascarid Baylisascaris procyonis. N Engl J Med 312:1619-
1623.
2. Kazacos RR, Boyce WM: 1989, Baylisascaris larva migrans. J
Outbreaks similar to the 1 reported here will continue to Am Vet Med Assoc 195:894-903.
occur as raccoons become more common as pets and coexist 3. Kazacos RR, Reed WM, Kazacos EA, Thacker HL: 1983, Fatal
with human beings in urban and rural areas. It is important cerebrospinal disease caused by Baylisascaris procyonis in dothat
physicians, public health officials, veterinarians, and the mestic rabbits. J Am Vet Med Assoc 183:967-971.
general public be made aware of the Zoonotic potential and
take necessary precautions when handling or harboring raccoons.
4. Richter CB, Kradel DC: 1964, Cerebrospinal nematodosis in
Pennsylvania groundhogs (Marmota monax). Am J Vet Res 25:
1230-1235.
J Vet Diagn Invest 3:79-80 (1991)
Prevalence of Dirofilaria immitis in cats and dogs in eastern Tennessee
Sharon Patton, Malcolm D. McCracken
The heartworm, DiroJilaria immitis, is enzootic in dogs in
the United States. Diagnostic tests for heartworm disease are
usually included in the evaluation of dogs presented with
respiratory insufficiency, chronic cough, and exercise intolerance.
Heartworm disease in cats is not as common as it is
in dogs, but an increasing number of cases are reported each
year. Currently, infection with D. immitis is usually included
in the differential diagnosis of cats with coughing, dyspnea,
or intermittent vomition. 2,4-8,14
The frequency of heartworm
infection in cats in a particular location correlates with that
in the dog population but at a lower incidence. 13
The objective
of this study was to determine the prevalence of heartworms
in dogs and cats in eastern Tennessee based on the
Knott’s concentration technique for microfilariae and the
enzyme-linked immunosorbent assay (ELISA) for antigen of
adult heartworms.
Two populations were examined: (1) dogs and cats brought
to the small animal clinic at the University of Tennessee,
College of Veterinary Medicine (VTCVM) and (2) stray dogs
and cats from random sources. Blood was collected from the
dogs in the clinic as part of the routine physical examination
and from both dogs and cats with signs of heartworm disease.
All samples were collected and examined between November
1985 and February 1990. The diagnosis of heartworms was
based on the presence of D. immitis microfilariae in blood
examined by Knott’s concentration technique or by the presence
of antigen of adult heartworms detected in the serum
with a commercial ELISA kit. a
tests. The results of the Knott’s tests and the ELISA tests for
D. immitis antigen for both dogs and cats are shown in Table
1. From the clinic population, 1/23 cats (4.35%) and 135/
2,658 dogs (5.08%) had circulating D. immitis microfilariae;
93/673 dogs (13.82%) and 9/95 cats (9.47%) were positive
for heartworm antigen. In the stray dog population, 78/950
(8.2 1%) were positive for D. immitis. No D. immitis microfilariae
were found in 122 stray cats examined, although 3
(2.5%) of the cats had 1 adult female worm in the right
ventricle. One of the cats with an immature female worm in
the heart was positive for D. immitis antigen. All the other
stray cats, including the 2 with adult D. immitis, were negative
for D. immitis antigen.
Other reports have indicated that ELISA tests for D. immitis
antigen in cats are more likely to give a false negative
than a false positive result.
When the stray cats in the
study were euthanitized by an animal shelter, they were necropsied
and examined for D. immitis in the heart or other
areas of the body to validate the usefulness of the diagnostic
From the Department of Pathobiology, College of Veterinary
Medicine, University of Tennessee, Knoxville, TN 37901- 1071.
Received for publication April 2, 1990.
1,3,11
As in our study, when

80 Brief communications
Table 1. Prevalence of Dirofilaria immitis in dogs and cats in
eastern Tennessee based on the presence of microfilariae and D.
immitis antigen.
This study shows that the frequency of infection with D.
immitis in cats in eastern Tennessee is similar to the frequency
of infection in dogs. However, the sick cats studied
are not representative of the general cat population. The data
from the dogs may be more representative because dogs examined
at the UTCVM are routinely screened for heartworms
rather than only when disease is obvious. Immunodiagnostic
tests that detect adult D. immitis antigen are
valuable adjuncts in heartworm diagnosis, particularly in cats
where the infection is usually amicrofilaremic. 2,9,10,15
However,
these tests lack sensitivity and false negatives occur.
For an accurate diagnosis, the results of the antigen test should
be considered with the evaluation of clinical signs, physical
examinations, fecal examinations, tracheal washes, complete
blood counts, electrocardiograms, and radiologic findings.
Sources and manufacturers
a. ClinEase/Dirochek Canine Heartworm Antigen Test Kit, Synbiotics
Corp., San Diego, CA.
References
1. Brunner CJ, Hendrix CM, Blagbum BL, Hanrahan LA: 1988,
Comparison of serologic tests for detection of antigen in canine
heartworm infections. J Am Vet Med Assoc 192:1423-1427.
J Vet Diagn Invest 3:80-81 (199 1)
2. Calvert CA, Mandrel1 CP: 1982, Diagnosis and management
of feline heartworm disease. J Am Vet Med Assoc 180:550-
552.
3. Courtney CH: 1986, Comparison of tests for immunodiagnosis
of canine dirofilariasis. In: Proc Heartworm Symp, ed. Otto GF,
pp. 77-82. American Heartworm Society, Washington, DC.
4. Dillon R: 1983, Feline heartworm disease: clinical evaluation.
In: Proc Heartworm Symp, ed. Otto GF, pp. 31-33. VM Publishing,
Bonner Springs, KS.
5. Dillon R: 1986, Feline heartworm disease. In: Proc Heartworm
Symp, ed. Otto GF, pp. 149-154. American Heartworm Society,
Washington, DC.
6. Dillon R: 1988, Feline heartworm disease. In: Dirofilariasis,
ed. Boreham PFL, Atwell RB, pp. 205-215. CRC Press, Boca
Raton, FL.
7. Dillon R: 1989, Clinical presentation and diagnosis of feline
heartworm disease. Calif Vet 43(special ed.):33-3 5, 38.
8. Dillon R: 1989, Clinical management of feline heartworm disease.
Calif Vet 43(special ed.):36-37.
9. Donahoe JMR: 1974, Clinical aspects of feline dirofilariasis.
In: Proc Heartworm Symp, ed. Morgan HC, pp. 59-65. VM
Publishing, Bonner Springs, KS.
10. Donahoe JMR: 1975, Experimental infection of cats with Dirofilaria
immitis. J Parasitol 61:599-605.
11. Dzimiznski MT, McCall JW, McCall CA: 1986, Evaluation of
heartworm immunodiagnostic test kits using well defined cat
sera. In: Proc Heartworm Symp, ed. Otto GF, pp. 159-161.
American Heartworm Society, Washington, DC.
12. Lok JB: 1988, Dirofilaria sp. Taxonomy and distribution. In:
Dirofilariasis, ed. Boreham PFL, Atwell RB, pp. l-28. CRC
Press, Boca Raton, FL.
13. Otto GF: 1975, Occurrence of the heartworm in unusual locations.
In: Proc Heartworm Symp, ed. Morgan HC, pp. 6-l 3.
VM Publishing, Bonner Springs, KS.
14. Rawlings CA: 1986, Heartworm disease in cats. In: Heartworm
disease in dogs and cats, ed. Rawlings CA, pp. 295-310. W. B.
Saunders Co., Philadelphia, PA.
15. Wong MM: 1982, Dirofilariasis in cats. J Am Anim Hosp Assoc
19:855-864.
Pancreatic fibrosis associated with zinc toxicosis in a dog
Daniel P. Shaw, James E. Collins, Michael J. Murphy
A 13-year-old mixed breed female dog of unknown vaccination
status was found dead in the kennel after 5 days of
lethargy, poor appetite, and weight loss. Antemortem clinical
examination had not been attempted.
During necropsy, marked icterus was found. The pancreas
From the Department of Veterinary Diagnostic Investigation, College
of Veterinary Medicine, University of Minnesota, 1943 Carter
Avenue, St. Paul, MN 55108.
Received for publication July 18, 1990.
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was firm and coarsely nodular. A partially dissolved penny
was lodged in the pyloric antrum of the stomach. The spleen
was moderately enlarged and dark red. No other gross changes
were identified.
Microscopically, there was severe interstitial fibrosis in the
pancreas, which caused accentuation of the lobular pattern
(Fig. 1). There was infiltration of the fibrotic interstitium by
moderate numbers of lymphocytes and macrophages. Many
of the acini of the exocrine pancreas were distorted due to
periacinar fibroplasia. The nuclei of the acinar cells were