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  • Author or Editor: Robert B. Duncan x
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Abstract

Objective—To quantitatively evaluate expression of vascular endothelial growth factor (VEGF) in intracranial tumors in dogs and determine whether relationships exist between circulating and intratumoral VEGF concentrations and tumor type and grade.

Animals—27 dogs with primary intracranial neoplasms and 4 unaffected control dogs.

Procedures—Plasma and brain tumor samples were obtained from each dog, and plasma and intratumoral concentrations of VEGF were measured by use of an ELISA.

Results—Dogs with meningiomas (n = 11) were significantly older than dogs with oligodendrogliomas (7) or astrocytomas (9). Measurable VEGF was detected in all tumors, and a significant negative correlation between age and intratumoral VEGF concentration was detected. Age-adjusted comparisons identified significant differences in intratumoral VEGF concentrations among all tumor types; the highest VEGF concentrations were associated with astrocytomas. Within each tumor type, increasing tumor grade was significantly associated with increasing VEGF expression. Plasma VEGF concentrations were detectable in 9 of 27 dogs; the proportion of dogs with astrocytomas and a detectable circulating VEGF concentration (7/9 dogs) was significantly higher than the proportion of dogs with meningiomas (1/11 dogs) or oligodendrogliomas (1/7 dogs) with a detectable circulating VEGF concentration.

Conclusions and Clinical Relevance—Overexpression of VEGF appears common in canine astrocytomas, oligodendrogliomas, and meningiomas. In the neoplasms examined, intratumoral VEGF concentrations correlated well with tumor malignancy. The VEGF expression patterns paralleled those of analogous human tumors, providing evidence that dogs are a suitable species in which to study angiogenesis and intracranial neoplasia for human application.

Full access
in American Journal of Veterinary Research

Abstract

Case Description—An 8-year-old male Golden Retriever was evaluated because of an 8-week history of intermittent diarrhea with melena and hematochezia that were not responsive to medical treatment and resulted in severe anemia.

Clinical Findings—Exploratory celiotomy with intestinal and colonic biopsy revealed mild enterocolitis but did not result in diagnosis of the cause of melena and hematochezia. Endoscopy of the upper portion of the gastrointestinal tract and colonoscopy were performed. Multifocal areas of coalescing, tortuous mucosal blood vessels were observed in the cecum and all regions of the colon. A diagnosis of vascular ectasia (VE) was made on the basis of the endoscopic and histologic appearance of the lesions.

Treatment and Outcome—An ileorectal anastamosis was performed. Melena and hematochezia resolved within 3 days after surgery, and the anemia resolved within 6 weeks after surgery. Surgical resection of the cecum and colon and feeding of a highly digestible diet resulted in long-term (22 months) resolution of clinical signs.

Clinical Relevance—Initial exploratory celiotomy with intestinal and colonic biopsy failed to reveal the VE lesions responsible for the melena, hematochezia, and anemia. Endoscopic evaluation was necessary for detection of the colonic VE lesions. Surgical resection of the cecum and colon and feeding of a highly digestible diet may result in a favorable outcome in affected dogs.

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in Journal of the American Veterinary Medical Association

Abstract

Case Description—1 dog evaluated because of inappetence and lameness of the left hind limb of 1 day's duration and 1 dog evaluated because of inappetence, fever, and lymphadenopathy of 2 weeks' duration.

Clinical Findings—Histologic examination of excisional biopsy specimens from lymph nodes revealed pyogranulomatous lymphadenitis in both dogs. Quantitative real-time PCR assays detected Bartonella henselae DNA in blood samples and affected lymph node specimens from both dogs. Antibodies against B henselae were not detected via immunofluorescent antibody testing during active disease in either dog.

Treatment and Outcome—1 dog recovered after 6 weeks of treatment with doxycycline (5 mg/kg [2.3 mg/lb], PO, q 12 h), whereas the other dog recovered after receiving a combination of azithromycin (14.5 mg/kg [6.6 mg/lb], PO, q 24 h for 21 days), doxycycline (17.3 mg/kg [7.9 mg/lb], PO, q 24 h for 4 weeks), and immunosuppressive corticosteroid (prednisone [3 mg/kg {1.4 mg/lb}, PO, q 24 h], tapered by decreasing the daily dose by 25% every 2 weeks) treatment.

Clinical RelevanceB henselae is implicated as a possible cause or a cofactor in the development of pyogranulomatous lymphadenitis in dogs. In dogs with pyogranulomatous lymphadenitis, immunofluorescent assays may not detect antibodies against B henselae. Molecular testing, including PCR assay of affected tissues, may provide an alternative diagnostic method for detection of B henselae DNA in pyogranulomatous lymph nodes.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To study the effects of experimentally induced hypothyroidism on skeletal muscle and characterize any observed myopathic abnormalities in dogs.

Animals—9 female, adult mixed-breed dogs; 6 with hypothyroidism induced with irradiation with 131 iodine and 3 untreated control dogs.

Procedures—Clinical examinations were performed monthly. Electromyographic examinations; measurement of plasma creatine kinase, alanine aminotransferase, aspartate aminotransferase, lactate, and lactate dehydrogenase isoenzyme activities; and skeletal muscle morphologic-morphometric examinations were performed prior to and every 6 months for 18 months after induction of hypothyroidism. Baseline, 6-month, and 18-month assessments of plasma, urine, and skeletal muscle carnitine concentrations were also performed.

Results—Hypothyroid dogs developed electromyographic and morphologic evidence of myopathy by 6 months after treatment, which persisted throughout the study, although these changes were subclinical at all times. Hypothyroid myopathy was associated with significant increases in plasma creatine kinase, aspartate aminotransferase, and lactate dehydrogenase 5 isoenzyme activities and was characterized by nemaline rod inclusions, substantial and progressive predominance of type I myofibers, decrease in mean type II fiber area, subsarcolemmal accumulations of abnormal mitochondria, and myofiber degeneration. Chronic hypothyroidism was associated with substantial depletion in skeletal muscle free carnitine.

Conclusions and Clinical Relevance—Chronic, experimentally induced hypothyroidism resulted in substantial but subclinical phenotypic myopathic changes indicative of altered muscle energy metabolism and depletion of skeletal muscle carnitine. These abnormalities may contribute to nonspecific clinical signs, such as lethargy and exercise intolerance, often reported in hypothyroid dogs.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine effects of cyclophotocoagulation via administration of 100 J with a neodymium: yttrium aluminum garnet (Nd:YAG) laser on corneal touch threshold (CTT), intraocular pressure (IOP), aqueous tear production, and corneal nerve morphology in eyes of dogs.

Animals—15 dogs.

Procedure—Noncontact Nd:YAG laser was transsclerally applied (10 applications; 25 W for 0.1 seconds for each application to each of 4 quadrants) to the ciliary body of the left eye of 15 dogs; the right eye was the control eye. Corneal integrity, CTT, tear production as measured by the Schirmer tear test (STT), and IOP were evaluated for 14 days following laser treatment. On day 14, dogs were euthanatized, eyes harvested, and corneas stained with gold chloride. Major nerve bundles were analyzed by use of a drawing tube attached to a light microscope, and maximum diameters were measured by use of image analysis software.

Results—All laser-treated eyes had significantly higher CTT values, compared with control eyes. Six of 15 laser-treated eyes developed ulcerative keratitis. On most days, IOP was significantly lower in laser-treated eyes in both morning and evening. Laser-treated eyes had a significant decrease of approximately 1 nerve bundle/corneal quadrant. Values for STT or nerve bundle diameters did not differ significantly.

Conclusion and Clinical Relevance—Administration of 100 J with a Nd:YAG laser effectively reduced IOP while increasing CTT and caused a significant decrease in number, but not diameter, of major corneal nerve bundles. Nerve damage and corneal hypoesthesia are etiologic factors in ulcerative keratitis following Nd:YAG cyclophotocoagulation. (Am J Vet Res 2002;63:906–915)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether substantial interobserver variation exists among diagnostic pathologists for descriptions of intestinal mucosal cell populations and whether histopathologic descriptions accurately predict when a patient does not have clinically evident intestinal disease.

Design—Comparative survey.

Sample Population—14 histologic slides of duodenal, ileal, or colonic tissue from 10 dogs and 3 cats.

Procedure—Each histologic slide was evaluated independently by 5 pathologists at 4 institutions. Pathologists, who had no knowledge of the tissues' origin, indicated whether slides were adequate for histologic evaluation and whether the tissue was normal or abnormal. They also identified the main infiltrating cell type in specimens that were considered abnormal, and whether infiltrates were mild, moderate, severe, or neoplastic.

Results—Quality of all slides was considered adequate or superior by at least 4 of the 5 pathologists. For intensity of mucosal cellular infiltrates, there was uniformity of opinion for 1 slide, near-uniformity for 6 slides, and nonuniformity for 7 slides. Five dogs did not have clinical evidence of intestinal disease, yet the pathologists' descriptions indicated that their intestinal tissue specimens were abnormal.

Conclusions and Clinical Relevance—Substantial interobserver variation was detected. Standardization of pathologic descriptions of intestinal tissue is necessary for meaningful comparisons with published articles. Clinicians must be cautious about correlating clinical signs and histopathologic descriptions of intestinal biopsy specimens. (J Am Vet Med Assoc 2002;220:1177–1182)

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in Journal of the American Veterinary Medical Association