Thomas P. Mullaney

Proposal of a 2-Tier Histologic Grading System for Canine Cutaneous Mast Cell Tumors to More Accurately Predict Biological Behavior

Currently, prognostic and therapeutic determinations for canine cutaneous mast cell tumors (MCTs) are primarily based on histologic grade. However, the use of different grading systems by veterinary pathologists and institutional modifications make the prognostic value of histologic grading highly questionable. To evaluate the consistency of microscopic grading among veterinary pathologists and the prognostic significance of the Patnaik grading system, 95 cutaneous MCTs from 95 dogs were graded in a blinded study by 28 veterinary pathologists from 16 institutions. Concordance among veterinary pathologists was 75% for the diagnosis of grade 3 MCTs and less than 64% for the diagnosis of grade 1 and 2 MCTs. To improve concordance among pathologists and to provide better prognostic significance, a 2-tier histologic grading system was devised. The diagnosis of high-grade MCTs is based on the presence of any one of the following criteria: at least 7 mitotic figures in 10 high-power fields (hpf); at least 3 multinucleated (3 or more nuclei) cells in 10 hpf; at least 3 bizarre nuclei in 10 hpf; karyomegaly (ie, nuclear diameters of at least 10% of neoplastic cells vary by at least two-fold). Fields with the highest mitotic activity or with the highest degree of anisokaryosis were selected to assess the different parameters. According to the novel grading system, high-grade MCTs were significantly associated with shorter time to metastasis or new tumor development, and with shorter survival time. The median survival time was less than 4 months for high-grade MCTs but more than 2 years for low-grade MCTs.

Otitis Media in Preweaned Holstein Dairy Calves in Michigan Due to Mycoplasma Bovis

Mycoplasma bovis was isolated from the tympanic bullae of dairy calves with an exudative otitis media. The history, clinical signs, gross and histologic lesions, and bacteriologic findings are described for 5 preweaned Holstein calves with otitis media from a 600-cow dairy in Michigan. Clinical findings consisted of unilateral or bilateral ear droop, epiphora, head tilt, and recumbency in severely affected calves. Postmortem examination revealed unilateral or bilateral fibrinosuppurative to caseous exudate in the tympanic bullae. Histologically, a marked fibrinosuppurative to caseous exudate filled the tympanic air spaces. The partially ulcerated tympanic mucosa was markedly thickened with mononuclear cell infiltration and proliferation of fibrous connective tissue. Bone remodeling and periosteal hyperostosis were present in some osseous septa. Mycoplasma bovis was isolated from the tympanic bullae of all 5 calves and from the lungs of 2 calves and the frontal sinus of 1 calf. Mycoplasma bovis was isolated at > 100,000 colony forming units/ml from the bulk milk tank of the farm of origin. The isolation of M. bovis from the bulk milk tank, indicating subclinical mycoplasmal mastitis coupled with the feeding of waste milk from mastitic cows to calves is suggestive of a possible source of the infection resulting in otitis media in preweaned dairy calves.

Biopsy Mineral Analysis by Inductively Coupled Plasma—Atomic Emission Spectroscopy with Ultrasonic Nebulization

Liver copper concentration is generally considered the best measure of copper nutritional status in cattle. Ultrasonic nebulization in conjunction with inductively coupled plasma-atomic emission spectroscopy (ICP—AES) was investigated as a method to provide adequate sensitivity to allow accurate simultaneous measurement of copper and 14 additional elements from needle biopsy samples. The element concentration frequency distribution profile of 12 elements routinely present in liver was compared to profiles of the elements in fat, muscle, vena cava, kidney, and clotted blood. The profiles could be used to confirm the authenticity of the liver biopsy sample. Element concentrations in biopsy samples taken in triplicate from the five lobes of a bovine liver were compared to those from triplicate wedge sections taken adjacent to the biopsies and analyzed by conventional ICP—AES. Precision between biopsies was equal to or better than precision between wedge samples. Some element concentrations determined by the biopsy procedure differed statistically from those determined by the wedge procedure, but differences were not sufficient to influence clinical interpretation of data.

Novel calicivirus identified in rabbits, Michigan, USA.

This virus is distinct from rabbit hemorrhagic disease virus.

Characterization of eae+Escherichia coli isolated from healthy and diarrheic calves

n Abstractn n Strains of Escherichia coli from 101 healthy and 114 diarrheic calves were screened by PCR for the eae (intimin) gene and Shiga toxin genes (stx). Each eaen + and eae/stxn + strain was examined for antimicrobial susceptibility, enterohemolysin activity, and the somatic O antigen was determined. An immunoassay was used to detect Shiga toxin antigens for the eae/stxn + n E. coli. Significantly more (pn =0.005) of the healthy calves carried eaen + and eae/stxn + n E. coli in their feces when compared to strains from diarrheic calves. Moreover, Shiga toxin antigens were detected significantly more (pn =0.001) often among the eae/stxn + strains from healthy calves when compared to eae/stxn + strains from diarrheic calves. However, significantly more (pn =0.001) of the eaen + and eae/stxn + strains from diarrheic calves were resistant to at least one of the antimicrobials tested, and the strains from diarrheic calves had a significantly (pn =0.05) higher rate of antimicrobial resistance to at least two different antimicrobial classes. No significant difference (pn ≥0.05) was detected among the eaen + and eae/stxn + strains from healthy and diarrheic calves for enterohemolysin production. Serogroups O-negative, O5, O26, and O111 were predominate among both healthy and diarrheic calves.n n

Association of perianal fistula and colitis in the German shepherd dog: response to high-dose prednisone and dietary therapy.

Twenty-seven German shepherd dogs with perianal fistulas and histological evidence of colitis were entered in a prospective clinical study to investigate the association between perianal fistula and colitis. Additionally, the response of perianal fistula disease to immunosuppressive doses of prednisone and an alternative protein diet was evaluated. All 27 cases completed the treatment protocol, and perianal fistulas completely resolved in nine (33.3%) cases, improved in nine cases, and remained unchanged in nine cases.

Copper-Associated Hepatitis in Labrador Retrievers

Labrador Retrievers with elevated hepatic copper levels have been reported; however, it is unclear whether primary copper-associated hepatitis occurs in this breed. The objective of this study was to determine whether copper-associated hepatitis could be identified in Labradors by reviewing cases from the Diagnostic Center for Population and Animal Health, Michigan State University. Sixteen Labrador Retrievers (3 male, 12 female, and 1 of undetermined sex) between 4 and 11 years old, had multifocal and coalescing, centrilobular hepatitis characterized by macrophages with abundant intracytoplasmic copper and hemosiderin. Other lesions included multifocal, centrilobular and random, pigmented granulomas, hepatocellular necrosis, intrahepatic cholestasis, centrilobular or bridging fibrosis, and occasionally, pseudolobule formation. In rhodanine-stained sections, copper was concentrated in the cytoplasm of centrilobular and midzonal hepatocytes and in macrophages, which is consistent with copper-associated hepatitis. In 12 of the dogs, quantitative liver copper levels were available, and in all but 2 dogs the levels were greater than 2,000 parts per million dry weight (ppm dw). One dog had a liver copper level of 1,990 ppm dw and one dog with advanced hepatic cirrhosis had a level of 1,490 ppm dw. The findings suggest that primary copper-associated hepatitis likely occurs in Labrador Retrievers.

Distinguishing Intestinal Lymphoma From Inflammatory Bowel Disease in Canine Duodenal Endoscopic Biopsy Samples

Inflammatory bowel disease (IBD) and intestinal lymphoma are intestinal disorders in dogs, both causing similar chronic digestive signs, although with a different prognosis and different treatment requirements. Differentiation between these 2 conditions is based on histopathologic evaluation of intestinal biopsies. However, an accurate diagnosis is often difficult based on histology alone, especially when only endoscopic biopsies are available to differentiate IBD from enteropathy-associated T-cell lymphoma (EATL) type 2, a small cell lymphoma. The purpose of this study was to evaluate the utility of histopathology; immunohistochemistry (IHC) for CD3, CD20, and Ki-67; and polymerase chain reaction (PCR) for antigen receptor rearrangement (T-cell clonality) in the differential diagnosis of severe IBD vs intestinal lymphoma. Endoscopic biopsies from 32 dogs with severe IBD or intestinal lymphoma were evaluated. The original diagnosis was based on microscopic examination of hematoxylin and eosin (HE)–stained sections alone followed by a second evaluation using morphology in association with IHC for CD3 and CD20 and a third evaluation using PCR for clonality. Our results show that, in contrast to feline intestinal lymphomas, 6 of 8 canine small intestinal lymphomas were EATL type 1 (large cell) lymphomas. EATL type 2 was uncommon. Regardless, in dogs, intraepithelial lymphocytes were not an important diagnostic feature to differentiate IBD from EATL as confirmed by PCR. EATL type 1 had a significantly higher Ki-67 index than did EATL type 2 or IBD cases. Based on the results of this study, a stepwise diagnostic approach using histology as the first step, followed by immunophenotyping and determining the Ki67 index and finally PCR for clonality, improves the accuracy of distinguishing intestinal lymphoma from IBD in dogs.

Histiocytic ulcerative colitis in three non-boxer dogs.

Histiocytic ulcerative colitis (HUC) is described in three non-boxer dogs. Clinical signs were typical of large-bowel diarrhea and included soft stool, hematochezia, tenesmus, and an increased frequency of defecation. Diagnosis in each case was made by light microscopic evaluation of endoscopically obtained colonic biopsy specimens. Treatment regimes varied, but included immunosuppressive agents, anti-inflammatory drugs, antimicrobials, and dietary modification. Clinical response was substantial in two patients, while the third patient was euthanized due to treatment failure. The authors observations indicate that HUC may be encountered in non-boxer dogs.

A 12-year retrospective study of equine abortion in Michigan.

for Brucella abortus strain RB5. Vet Pathol 33:615. [Abstr.] 4. Chitwood MB, Lichtenfels JR: 1972, Identification of parasitic metazoa in tissue sections. Exp Parasitol 32:461-464. 5. Ewalt DR: 1989, Comparison of three culture techniques for the isolation of Brucella abortus from bovine supramammary lymph nodes. J Vet Diagn Invest 1:227-230. 6. Ewalt DR, Payeur JP, Martin MB, et al.: 1994, Characteristics of a Brucella species from a bottlenose dolphin (Tursiops truncatus). J Vet Diagn Invest 6:448-452. 7. Farrell ID: 1974, The development of a new selective medium for the isolation of Brucella abortus from contaminated sources. Res Vet Sci 16:280-286. 8. Fleischman RW, Squire RA: 1970, Verminous pneumonia in the California sea lion (Zalophus californianus). Pathol Vet 7:89101. 9. Foster G, Jahans KL, Reid RJ, et al.: 1996, Isolation of Brucella species from cetaceans, seals, and an otter. Vet Rec 138:583586. 10. Howard EB, Britt JO, Matsumoto G: 1983, Parasitic diseases. In: Pathobiology of marine mammal diseases, ed. Howard EB, pp. 128-213. CRC Press, Boca Raton, FL. 11. Kennedy PC, Miller RB: 1993, Brucellosis. In: Pathology of domestic animals, ed. Jubb KVF, Kennedy PC, Palmer N, 4th ed., pp. 396-402. Academic Press, San Diego, CA. 12. Lambourn DM, Jeffries SJ, Hall PB, et al.: 1996, Evidence of brucellosis in Pacific harbor seals (Phoca vitulina richardsi) and California sea lions (Zalophus californianus) from Puget Sound, Washington. Annu Conf Wildl Dis Assoc 45:000. [Abstr.] 13. Luna LG: 1960, Manual of histologic and special staining technics, 2nd ed. McGraw-Hill, New York, NY. 14. Migaki G, Van Dyke D, Hubbard RC: 1971, Some histopathological lesions caused by helminths in marine mammals. J Wildl Dis 2:281-289. 15. Morales GA, Helmboldt CF: 1970, Verminous pneumonia in the California sea lion (Zalophus californianus). J Wildl Dis 7:22-27. 16. Morgan WJB, Corbel MJ: 1976, Recommendation for the description of a species and biotypes of the genus Brucella. Dev Biol Stand 31:27-37. 17. Palmer MV, Cheville NF, Tatum FM: 1996, Morphometric and histopathologic analysis of lymphoid depletion in murine spleens following infection with Brucella abortus strains 2308, RB51, or an htrA deletion mutant. Vet Pathol 33:282-289. 18. Ross HM, Foster G, Reid RJ, et al.: 1994, Brucella species infection in sea-mammals. Vet Rec 134:359. 19. Ross HM, Jahans IU, MacMillan AP, et al.: 1996, Brucella species infection in North Sea and cetacean populations. Vet Rec 138:647-648. 20. Rhyan JC, Wilson ISL, Burgess DE, et al.: 1995, Immunohistochemical detection of Tritrichomonas foetus in formalin-fixed, paraffin-embedded sections of bovine placenta and fetal lung. J Vet Diagn Invest 7:98-101.