Evaluation of Weight Change During Carboplatin Therapy in Dogs With Appendicular Osteosarcoma.

BACKGROUND: The prevalence of cancer cachexia in veterinary medicine has not been studied widely, and as of yet, no definitive diagnostic criteria effectively assess this syndrome in veterinary patients. OBJECTIVES: (1) To determine the patterns of weight change in dogs with appendicular osteosarcoma treated with amputation and single-agent carboplatin during the course of adjuvant chemotherapy; and (2) to determine whether postoperative weight change is a negative prognostic indicator for survival time in dogs with osteosarcoma. ANIMALS: Eighty-eight dogs diagnosed with appendicular osteosarcoma. Animals were accrued from 3 veterinary teaching hospitals. METHODS: Retrospective, multi-institutional study. Dogs diagnosed with appendicular osteosarcoma and treated with limb amputation followed by a minimum of 4 doses of single-agent carboplatin were included. Data analyzed in each patient included signalment, tumor site, preoperative serum alkaline phosphatase activity (ALP), and body weight (kg) at each carboplatin treatment. RESULTS: A slight increase in weight occurred over the course of chemotherapy, but this change was not statistically significant. Weight change did not have a significant effect on survival. Institution, patient sex, and serum ALP activity did not have a significant effect on survival. CONCLUSIONS AND CLINICAL IMPORTANCE: Weight change was not a prognostic factor in these dogs, and weight loss alone may not be a suitable method of determining cancer cachexia in dogs with appendicular osteosarcoma.

Influence of Various Factors on Circulating 25(OH) Vitamin D Concentrations in Dogs with Cancer and Healthy Dogs.

BACKGROUND: Low blood 25-hydroxyvitamin D (25(OH)D) concentrations have been associated with cancer in dogs. Little research has examined what other factors may affect 25(OH)D concentrations. OBJECTIVES: (1) To determine whether the presence of cancer (lymphoma, osteosarcoma, or mast cell tumor [MCT]) in dogs is associated with plasma 25(OH)D concentrations and (2) identify other factors related to plasma 25(OH)D concentrations in dogs. ANIMALS: Dogs newly diagnosed with osteosarcoma (n = 21), lymphoma (n = 27), and MCT (n = 21) presented to a tertiary referral oncology center, and healthy, client-owned dogs (n = 23). METHODS: An observational study design was used. Dietary vitamin D intake, sex, age, body condition score (BCS), muscle condition score (MCS), and plasma concentrations of 25(OH)D, 24,25-dihydroxyvitamin D (24,25(OH)2 D) (a marker of CYP24A1 activity), as well as ionized calcium (ICa), parathyroid hormone, and parathyroid hormone-related protein concentrations were measured. An analysis of covariance was used to model plasma 25(OH)D concentrations. RESULTS: Cancer type (P = 0.004), plasma 24,25(OH)2 D concentrations (P < 0.001), and plasma ICa concentrations (P = 0.047) had significant effects on plasma 25(OH)D concentrations. Effects of age, sex, body weight, BCS, MCS, and plasma PTH concentrations were not identified. A significant interaction between ICa and cancer was found (P = 0.005). Plasma 25(OH)D concentrations increased as ICa concentrations increased in dogs with cancer, whereas plasma 25(OH)D concentrations decreased as ICa concentrations increased in healthy dogs. CONCLUSIONS AND CLINICAL IMPORTANCE: Results support a relationship between cancer and altered vitamin D metabolism in dogs, mediated by plasma ICa concentrations. The CYP24A1 activity and plasma ICa should be measured in studies examining plasma 25(OH)D concentrations in dogs.

Owners' attitudes and practices regarding nutrition of dogs diagnosed with cancer presenting at a referral oncology service in Ontario, Canada.

OBJECTIVES: To investigate owner attitudes and dietary practices following cancer diagnosis in a dog. METHODS: A retrospective cross-sectional survey of 75 dog owners presenting with their dogs to a tertiary referral oncology service through a demographic questionnaire and in-person or telephone interviews regarding the dog's nutrition. RESULTS: Conventional diets (71%) were most commonly fed as a single diet to canine cancer patients followed by homemade cooked (7%) and homemade raw (4%). Several owners (18%) provided combinations of these diets. Owners reported some distrust towards conventional diets (51%). Appetite loss occurred in 35% of dogs and diet changes reported for 25% of dogs in the study involved exclusion of a conventional (63%) and/or inclusion of a homemade (54%) component. 90% of owners noted the diet change was associated with the cancer diagnosis. Supplements were given by 39% of owners. 85% of owners highly valued veterinary nutritional advice. CLINICAL RELEVANCE: Following a cancer diagnosis, dog owners appear to change their approach to managing their dog's nutrition. Given the value owners place on veterinary nutritional advice, veterinarians have a key role in guiding nutritional management of the canine cancer patient.

The immunophenotype of peripheral blood lymphocytes in clinically healthy dogs and dogs with lymphoma in remission.

Lymphoma is a common cancer of dogs that frequently is treated with chemotherapy or radiation therapy. Response to therapy is variable and currently available diagnostic tests do not reliably predict response to therapy. Treatment for lymphoma often results in lymphopenia, but it is unknown whether the changes in circulating lymphocytes result from generalized or specific reduction of lymphocytes. In this study, blood lymphocytes from 12 clinically healthy dogs, 10 dogs in remission because of treatment for B-cell lymphoma, and 8 dogs in remission from T-cell lymphoma were analyzed by flow cytometry by using a panel of 20 antibodies reactive with canine leukocyte antigens. Results identified similar lymphocyte parameters in treated dogs regardless of the type of lymphoma. Treated dogs had >50% reduction in blood lymphocyte concentration, and an absolute decrease in most subsets of lymphocytes. Both groups of treated dogs had relative increases in the proportion of CD3+, T-cell receptor (TCR)alphabeta+, and CD90+ lymphocytes, and a decreased proportion of CD45RA+ cells. In addition, dogs with T-cell lymphoma in remission had a significant increase in the proportion of CD49d+ lymphocytes. These findings were interpreted as representing likely suppression of lymphocyte regeneration by chemotherapy, with a relative increase in the proportion of memory over naive lymphocytes. Lack of correlation with the T- or B-cell origin of the initial lymphoma suggested that, by using flow cytometric methods, residual circulating neoplastic cells could not be detected. However, the changes in the lymphocyte profile of dogs treated with chemotherapy may have relevance to their immunocompetence.

Comparison of concurrent imaging modalities for staging of dogs with appendicular primary bone tumours.

This study assessed the use of whole body computed tomography (CT) for the evaluation of metastasis in dogs with primary appendicular bone tumours compared to long bone survey radiography, bone scintigraphy and thoracic radiographs. Fifteen dogs were included in this pilot study. A construct reference standard was used for detection of bone metastasis, and negative thoracic radiographs were compared against CT. Definitive lesions were only identified on bone scintigraphy. Not all lesions agreed with the construct reference standard. No definitive lesions were identified on survey radiographs or CT. Lesions were identified on thoracic CT that were not visible radiographically. Equivocal ground glass pulmonary lesions progressed in three of four cases. Whole body CT was not a suitable alternative to bone scintigraphy; however, it was useful as an adjunctive diagnostic modality. Pulmonary lesions were visible on CT that were not seen radiographically and ground glass pulmonary lesions in dogs should be considered suspicious for metastasis.

Determination of beta-glucosidase enzymatic function of the histoplasma capsulatum H antigen using a native expression system.

The Histoplasma capsulatum H antigen is a major secreted glycoprotein of this pathogenic fungus that is a target of humoral and cell-mediated host responses. Its predicted protein sequence displays homology to beta-glucosidases of other organisms, but a recombinant antigen expressed in a prokaryotic system showed no enzymatic activity. We expressed a recombinant form of the protein carrying a carboxyl-terminus oligohistidine tag in the native fungal background to facilitate proper glycosylation and folding of a product that could then be purified from culture supernatants using nickel affinity chromatography. The recombinant protein was expressed and secreted by a transformant carrying the modified gene under the control of its native promoter. The purified protein from the native expression system showed beta-glucosidase enzymatic activity in substrate gels and quantitative microplate assays. This activity was blocked by glucosidase-specific inhibitors. These results are the first direct demonstration of the function of this protein, and show the utility of expression in a native system to achieve post-translational modification necessary for structural and functional integrity.

Transcript splicing is essential for functional Histoplasma capsulatum URA5 expression.

The isolation of auxotrophic markers is important for molecular genetic studies of the dimorphic fungus Histoplasma capsulatum. We have isolated a UV-induced mutant of H. capsulatum, resulting in nonreverting uracil auxotrophy due to a mutation in the URA5 gene. In this study, we show that this mutation is a GG to TA conversion bordering the 5' donor splice site of intron 2. The mutation results in the lack of splicing of intron 2 from the URA5 transcript, and subsequently premature termination of the peptide. This study is the first showing that consensus Group II intron sequences are both utilized and essential for functional expression of a gene in H. capsulatum.

Molecular epidemiology, pathogenesis, and genetics of the dimorphic fungus Histoplasma capsulatum.

Histoplasma capsulatum, the causative agent of the most common systemic fungal infection, histoplasmosis, has become subject to increasing study in parallel with rising prevalence of human immunodeficiency. This review presents a summary of the advances made in the investigation of H. capsulatum genomics, molecular epidemiology, pathogenesis, and molecular genetics.

A new technological approach to radiant heat whole body hyperthermia.

A new methodology for administering radiant heat whole body hyperthermia (WBH) in humans is described. The technology utilized circulates hot water in a cylinder constructed from copper tubing; the design incorporates a counter current distribution system to maintain thermal constancy. The tubing is coated with a temperature resistant high emissivity finish. Other features include a humidification system to eliminate evaporative heat losses. Data accrued from initial evaluation of this apparatus with a canine model shows that there was no detectable WBH-related hematological, biochemical or physiological toxicity. The perceived advantages of this WBH-system are discussed.

Experimental transmission of Hepatozoon americanum Vincent-Johnson et al., 1997 to dogs by the Gulf Coast tick, Amblyomma maculatum Koch.

Experimental transmission of Hepatozoon americanum to dogs was attempted with four ixodid ticks, viz., Rhipicephalus sanguineus, Amblyomma americanum, Amblyomma maculatum and Dermacentor variabilis. Ticks that dogs ingested included some that were laboratory-reared and experimentally fed as nymphs on a dog with naturally occurring hepatozoonosis; other ticks were collected as replete or partially engorged larvae, nymphs and adults from dogs that had hepatozoonosis and natural infestations of ticks. Whole ticks used to expose susceptible dogs orally were partially dissected to help release oocysts. Among eight dogs exposed, only the three that were fed A. maculatum adults experimentally acquisition fed as nymphs became infected. Dogs developed elevated body temperature and other evidence of clinical disease starting 4 weeks after exposure. 'Cysts' typical of H. americanum were found in skeletal muscle when samples were first examined 5 weeks after dogs ingested ticks, and parasites were also observed in peripheral blood smears at approximately the same time. Our study demonstrates that A. maculatum nymphs can acquire H. americanum by feeding on a parasitemic dog and that transstadial transmission of the protozoan occurs, with dogs acquiring infection when they ingest newly molted adult ticks.

Canine hepatozoonosis: comparison of lesions and parasites in skeletal muscle of dogs experimentally or naturally infected with Hepatozoon americanum.

We report previously undescribed, early lesions in skeletal muscle of dogs experimentally infected with Hepatozoon americanum by ingestion of laboratory-reared, infected Amblyomma maculatum. The earliest muscle lesion was recognized at the first interval of examination 3 weeks following exposure. The lesion consisted of a large, modified host cell whose cytoplasm frequently contained a demonstrable parasite. In skeletal muscle, the cell was consistently located between muscle fibers or in loose connective tissue adjacent to those fibers. Evidence suggesting that the parasite arrives in muscle and other tissue within the host cell cytoplasm is presented. Mucopolysaccharide encystment of the host cell, absent at this early stage, was acquired gradually and approached maximal development 26 weeks post exposure. Completion of the asexual cycle as evidenced by the presence of parasites entering vascular lumens within granulomas and also by the presence of gamonts in peripheral blood leukocytes, occurred within 28-32 days postexposure. Progression of the parasite cycle from meront to passage of zoites into vessel lumens of granulomas can occur in 11 or fewer days. The density with which parasitic lesions occur in one named skeletal muscle compared to other named muscles, although somewhat variable, was not significantly different in either experimentally induced or natural infections. The distribution of developmental stages of the parasite/lesion in four experimental infections (969 lesions) is compared with those in eight dogs with natural infections (557 lesions).

Cats surviving natural infection with Cytauxzoon felis: 18 cases (1997-1998).

Eighteen cats surviving natural infection with Cytauxzoon felis were identified. All cats came from a limited geographic area in northwestern Arkansas and northeastern Oklahoma. Clinical signs in most cats were similar to those described for cytauxzoonosis; however, 4 cats were asymptomatic. All cases were initially diagnosed by microscopic identification of signet ring-shaped piroplasms in erythrocytes of peripheral blood smears. Four of 4 cats tested had detectable serum antibodies to C felis. Four different cats were positive by polymerase chain reaction (PCR). Partial sequencing of the PCR product from 1 cat revealed >99% homology with the reported sequence of C felis. Repeated examination of blood smears from 12 cats revealed that the erythroparasitemia was generally persistent for the duration of follow-up (3-154 days). Survival did not seem dependent on treatment, as only 1 cat was treated with a drug with potential antiprotozoal activity (imidocarb dipropionate), and 4 cats received no treatment. The findings of this study may indicate the existence of a less virulent strain of C felis.

Flow cytometric immunophenotype of canine lymph node aspirates.

Increasing availability of reagents able to distinguish subtypes of lymphocytes and other leukocytes has enabled greater understanding of lymphocyte biology and pathology in the dog. Lymphocytes in circulation most commonly are subjected to immunophenotypic assessment by flow cytometry, but needle aspirates of lymph nodes can be similarly suitable for immunophenotypic examination. In this investigation, the feasibility of immunophenotyping samples obtained by needle aspiration of lymph nodes from 32 dogs with no physical abnormalities and 6 dogs with lymphoma was determined. In addition, samples from 6 dogs were stored overnight at 4 degrees C and reanalyzed 24 hours later. For each sample, stained smear preparations were examined microscopically for lymphocyte morphology, neoplasia, and the presence of inflammatory cells. Expression of antigens on a corresponding sample of aspirated cells was determined by flow cytometric detection of antibody binding on a minimum of 10,000 events. The distribution of data was determined with Anderson-Darling tests, and reference intervals incorporating the central 95% of values were established. Adequate samples were obtained from 30 of 32 clinically normal dogs. Immunophenotypic results after 24 hours of storage were consistent with those obtained immediately after sampling. Reference intervals for lymphocyte subsets from normal dog lymph nodes were similar to the proportions of CD3+, CD4+, CD8+, and CD21+ lymphocytes found in blood. Aspirates of enlarged lymph nodes from dogs with lymphoma were readily classified by this technique. Aspiration of lymph nodes from dogs for comprehensive analysis by flow cytometry is feasible and applicable to immunophenotyping of lymphoma.

Hematological effects of radiant heat-induced whole body hyperthermia on dogs.

The effects on hematological parameters of radiant heat-induced whole body hyperthermia (WBH) at 40.5 degrees C and 41.8 degrees C were determined in 6 normal dogs. Complete blood counts determined prior to WBH, immediately post WBH plateau, and at 1, 2, 7, and 14 days posttreatment did not change significantly following WBH at 40.5 degrees C or 41.8 degrees C. Similarly, no significant changes were detected in platelet counts measured following 40.5 degrees C WBH. In contrast, platelet counts 11 days following 41.8 degrees C WBH increased significantly (P < 0.05) consistent with the hypothesis of induction of putative WBH-induced platelet stimulating factors.

Assessment of lithium dilution cardiac output as a technique for measurement of cardiac output in dogs.

OBJECTIVES: To determine agreement of cardiac output measured by use of lithium dilution cardiac output (LiDCO) and thermodilution cardiac output (TDCO) techniques in dogs and to determine agreement of low- and high-dose LiDCO with TDCO. ANIMALS: 10 dogs (7 males, 3 females). PROCEDURE: Cardiac output was measured in anesthetized dogs by use of LiDCO and TDCO techniques. Four rates of cardiac output were induced by occlusion of the caudal vena cava, changes in depth of anesthesia, or administration of dobutamine. Lithium dilution cardiac output was performed, using 2 doses of lithium chloride (low and high dose). Each rate of cardiac output allowed 4 comparisons between LiDCO and TDCO. RESULTS: 160 comparisons were determined of which 68 were excluded. The remaining 92 comparisons had values ranging from 1.10 to 12.80 L/min. Intraclass correlation coefficient (ICC) between low-dose LiDCO and TDCO was 0.9898 and between high-dose LiDCO and TDCO was 0.9896. When all LiDCO determinations were pooled, ICC was 0.9894. For determinations of cardiac output < 5.0 L/min, ICC was 0.9730. Mean +/- SD of the differences of TDCO minus LiDCO for all measurements was -0.084+/-0.465 L/min, and mean of TDCO minus LiDCO for cardiac outputs < 5.0 L/min was -0.002+/-0.245 L/min. CONCLUSIONS AND CLINICAL RELEVANCE: The LiDCO technique is a suitable substitute for TDCO to measure cardiac output in dogs. Use of LiDCO eliminates the need for catheterization of a pulmonary artery and could increase use of cardiac output monitoring, which may improve management of cardiovascularly unstable animals.

Quantification of hepatic and renal cortical echogenicity in clinically normal cats.

OBJECTIVE: To quantitatively determine echogenicity of the liver and renal cortex in clinically normal cats. ANIMALS: 17 clinically normal adult cats. PROCEDURE: 3 ultrasonographic images of the liver and the right kidney were digitized from video output from each cat. Without changing the ultrasound machine settings, an image of a tissue-equivalent phantom was digitized. Biopsy specimens of the right renal cortex and liver were obtained for histologic examination. Mean pixel intensities within the region of interest (ROI) on hepatic, renal cortical, and tissue-equivalent phantom ultrasonographic images were determined by histogram analysis. From ultrasonographic images, mean pixel intensities for hepatic and renal cortical ROI were standardized by dividing each mean value by the mean pixel intensity from the tissue-equivalent phantom. RESULTS: The mean (+/- SD) standardized hepatic echogenicity value was 1.06 +/- 0.02 (95% confidence interval, 1.02 to 1.10). The mean standardized right renal cortical echogenicity value was 1.04 +/- 0.02 (95% confidence interval, 1.01 to 1.08). The mean combined standardized hepatic and renal cortical echogenicity value was 1.02 +/- 0.05 (95% confidence interval, 0.99 to 1.04). CONCLUSIONS AND CLINICAL RELEVANCE: Quantitative determination of hepatic and renal cortical echogenicity in cats is feasible, using histogram analysis, and may be useful for early detection of diffuse parenchymal disease and for serially evaluating disease progression.

Prevalence of American trypanosomiasis (Chagas disease) among dogs in Oklahoma.

OBJECTIVE: To determine the prevalence of Trypanosoma cruzi infection among dogs in Oklahoma. DESIGN: Cross-sectional study. ANIMALS: 301 owned or impounded dogs related by ownership or general geographic location to 3 dogs determined to have trypanosomiasis. PROCEDURES: Blood samples were obtained from dogs between November 1996 and September 1997. Infection status was determined by use of a radioimmunoprecipitation assay. Second blood samples were obtained from some of the seropositive dogs for study by hemoculture and polymerase chain reaction (PCR) assay. Sites where infected dogs were found were inspected for triatomine insects, and light traps were used for vector trapping. RESULTS: 11(3.6%) dogs were seropositive for T. cruzi infection. Ten of the 11 were owned rural hunting dogs. Protozoal organisms isolated from the blood of 1 seropositive dog were identified as T. cruzi by PCR testing. Only 1 adult Triatoma sanguisuga was captured in a light trap at a site near infected dogs; this insect was not infected. CONCLUSIONS AND CLINICAL RELEVANCE: Our findings suggest that T. cruzi is enzootic in eastern Oklahoma. Measures that would reduce the risk of dogs acquiring T. cruzi infection are unlikely to be acceptable to their owners, and no effective drugs are available for treatment. The presence of T. cruzi-infected dogs poses a threat of transmission to persons at risk of exposure to contaminated blood Veterinarians who practice in the southern United States should be cognizant of this blood borne zoonosis and educate all personnel about appropriate precautions.

Tularemia in two cats.

Tularemia was diagnosed in 2 cats that were examined because of pyrexia and lethargy; both cats had a history of exposure to wild rabbits. One cat was vomiting, and the other was anorectic. Physical examination revealed dehydration, lymphadenopathy, and hepatomegaly. Hematologic and serum biochemical abnormalities included toxic neutrophils, high band neutrophil count, thrombocytopenia, and hyperbilirubinemia. Diagnosis was confirmed by isolating Francisella tularensis subsp tularensis from bone marrow or lymph node aspirates. Evaluation of samples collected during the acute and convalescent phases of the disease revealed an increase in serum F tularensis antibody titer. Both cats responded to treatment with fluids and antibiotics.

Myasthenia gravis and masticatory muscle myositis in a dog.

A 21-month-old, castrated male Vizsla was presented for pelvic limb weakness, difficulty opening his mouth, ptyalism, voice change, and urinary incontinence. Myasthenia gravis and masticatory myositis were diagnosed. The unusual clinical findings, diagnosis, treatment, and case outcome are described, followed by a brief discussion of myasthenia gravis and masticatory myositis.