Breed is associated with the ABCB1-1Δ mutation in Australian dogs.

OBJECTIVE: The ABCB1 gene encodes P-glycoprotein (P-gp), a cellular membrane pump. One functional mutation that leads to expression of a less functional form of P-gp, ABCB1-1Δ, has been described in dogs. Individuals with this mutation can have severe adverse reactions to common veterinary pharmaceuticals that are known substrates of this pump. We investigated the detection of this mutation in samples submitted to two Australian diagnostic laboratories. METHODS: A total of 4842 dogs across 27 breeds were tested for the ABCB1-1Δ mutation from buccal swabs or EDTA blood using standard PCR, multiplex PCR, or genotyping chip. Statistical analysis was applied to determine the proportions and odds ratios of the ABCB1-1Δ mutation in herding breeds compared with non-herding breeds. RESULTS: The ABCB1-1Δ mutation was detected in nine breeds. The most commonly affected breeds were collies, Australian shepherds, white Swiss shepherds, and Shetland sheepdogs. Of 32 dogs in 18 non-herding breeds tested, one cocker spaniel and one labradoodle were positive for the mutation, both heterozygous. CONCLUSION: The most frequently affected breeds for ABCB1-1Δ mutation are the collie, Australian shepherd, white Swiss shepherd and Shetland sheepdog. As the mutation is associated with an increased incidence of adverse reactions to commonly used pharmaceuticals, veterinarians need to be aware of the breeds at most risk of carrying this mutation and consider testing these individuals prior to administering these medications.

Clinicopathologic features of lingual canine T-zone lymphoma.

Canine T-zone lymphoma (TZL) is a subtype of T-cell lymphoma characterized by unique histologic pattern and cytomorphology, immunophenotypic loss of CD45 expression, and an indolent clinical behaviour. Dogs with TZL typically present with 1 or more enlarged lymph nodes and/or lymphocytosis. We describe a novel extranodal presentation of TZL involving the tongue. Twelve dogs with tongue masses were diagnosed with lingual TZL based on a variable combination of immunophenotyping via flow cytometry, cytology, histopathology, immunohistochemistry and/or PCR for antigen receptor rearrangement (PARR) assay. Eleven dogs exhibited concurrent lymphocytosis and/or lymph node enlargement. Three cases were initially diagnosed as plasma cell tumours based on histology alone, thereby revealing a potential diagnostic challenge. Seven dogs achieved clinical remission and 4 achieved stable disease following variable treatment, consistent with the indolent nature of typical TZL involving the lymph nodes and peripheral blood. In 1 case the TZL resulted in progressive disease and failure to respond to treatment. In this case, the TZL exhibited histologic features of a higher grade neoplasm. This case series highlights a unique presentation of TZL and identifies a new differential diagnosis for lingual neoplasia. In this study, we characterize the clinical presentation, diagnostic features and patient outcomes of 12 dogs with lingual TZL.

Prior joint disease is associated with increased risk of periarticular histiocytic sarcoma in dogs.

Periarticular histiocytic sarcoma (PAHS) is the most common synovial tumour in dogs and is characterized by aggressive local disease with a high rate of distant metastasis. Previously, an association between PAHS and prior joint disease has been demonstrated in the Bernese Mountain Dog breed and suggested in the Rottweiler. We hypothesized that this association would be present in other breeds and investigated this via a retrospective, case-controlled analysis. Cases were dogs diagnosed with PAHS of the stifle or elbow. Controls were age, breed and sex-matched dogs without a diagnosis of histiocytic sarcoma. Diagnosis of prior joint disease was determined based on review of medical records and direct veterinarian and owner communications. Data were evaluated using logistic regression, 2-sampled t tests, and chi-squared analysis. Our study population consisted of 28 cases and 46 controls, including Flat-Coated, Golden and Labrador Retrievers, Rottweilers, English Bulldogs, Shih Tzus, Australian Shepherds, Staffordshire Terriers and mixed breed dogs. Dogs with PAHS were more likely to have prior joint disease in the tumour-affected joint compared with the control population (odds ratio [OR] = 13.42, P < .0001, 95% confidence interval [CI] = 4.33-48.63). A total of 88.2% of dogs with stifle PAHS had prior joint disease in their tumour-affected joint, most commonly cranial cruciate ligament rupture. This study confirms that the previously noted association between prior joint disease and PAHS in Bernese Mountain Dogs also applies to other breeds. Additional studies are needed to further investigate for a causal relationship.

Histiocytic sarcoma in 14 miniature schnauzers - a new breed predisposition?

OBJECTIVES: To describe a series of miniature schnauzers diagnosed with histiocytic sarcoma and assess for possible breed predisposition. MATERIALS AND METHODS: Medical records of miniature schnauzers with a diagnosis of histiocytic sarcoma between January 2008 and April 2015 were reviewed. Data collected included signalment, body weight, presenting complaint, date of diagnosis, clinicopathologic and diagnostic imaging findings, treatment, therapeutic response, date of death or last follow-up and necropsy findings. Breed predisposition was assessed with odds ratios, using breed-matched dogs without histiocytic sarcoma admitted during the study period as controls. Pedigree analysis was performed for dogs with available registration information. RESULTS: Fourteen miniature schnauzers were diagnosed with histiocytic sarcoma during the study period, making them over-represented among the hospital population (odds ratio=4·8, P=0·0009). Disease was considered localised in ten dogs and disseminated in four. Of the dogs with localised disease, nine were diagnosed with primary pulmonary histiocytic sarcoma based on the presence of a large pulmonary mass with (n=7) or without (n=2) evidence of intra-thoracic metastasis, and one had gastric histiocytic sarcoma with nodal metastasis. Treatments varied, but an aggressive clinical course was found in most patients. Pedigree analysis revealed a recent common ancestor for a subset of the dogs assessed. CLINICAL SIGNIFICANCE: Miniature schnauzers were over-represented among dogs with histiocytic sarcoma in this patient population. Pedigree analysis supports an inherited risk factor, which has not previously been suggested in the breed. Primary pulmonary involvement with or without intra-thoracic metastasis was common in this cohort.

Canine osteosarcoma cells exhibit resistance to aurora kinase inhibitors.

We evaluated the effect of Aurora kinase inhibitors AZD1152 and VX680 on canine osteosarcoma cells. Cytotoxicity was seen in all four cell lines; however, half-maximal inhibitory concentrations were significantly higher than in human leukaemia and canine lymphoma cells. AZD1152 reduced Aurora kinase B phosphorylation, indicating resistance was not because of failure of target recognition. Efflux mediated by ABCB1 and ABCG2 transporters is one known mechanism of resistance against these drugs and verapamil enhanced AZD1152-induced apoptosis; however, these transporters were only expressed by a small percentage of cells in each line and the effects of verapamil were modest, suggesting other mechanisms contribute to resistance. Our results indicate that canine osteosarcoma cells are resistant to Aurora kinase inhibitors and suggest that these compounds are unlikely to be useful as single agents for this disease. Further investigation of these resistance mechanisms and the potential utility of Aurora kinase inhibitors in multi-agent protocols is warranted.

A novel combination of methods to assess sarcopenia and muscle performance in mice.

A novel combination of assays was developed to assess sarcopenia and muscle performance. Three techniques were tested to assess muscle function both during and upon termination of treatments designed to induce sarcopenia. In unsuspended (US) and hindlimb suspended (HS) mice, a Hindlimb Exertion Force Test (HEFT), cage wheel running, and in vitro muscle electrophysiology were performed. Twelve-week old, mature male C57BL/6J mice were HS (n = 24) for two weeks, or served as US controls (n = 26). Both groups were subjected to a HEFT on day 13; that is, the maximum force exerted against a beam force transducer (2 lb. linear range, Transducer Techniques, Temecula CA) following applied tail shock stimulus (0.15 mA, 300 msec). This test primarily evaluated the hindlimb muscles used for an escape response (i.e., hamstrings, quadriceps and calf muscles). Mice (n = 10-11/group) were given voluntary access to running wheels for 7 days post treatment to evaluate muscle endurance. On day 13, HS mice showed a mean 18.9% (p = 0.002) decrease in the maximum force exerted compared to US mice. After 7 days of wheel running, HS running distance tended to decrease (13.2%, p = 0.084). HS mice ran an average of 2.0 km/day less than US control mice, with similar running patterns: distance declined on day 2 following completion of HS but increased steadily thereafter. With in vitro testing, the maximum soleus tetanus response decreased by 31.8% (p = 0.01) with HS, in agreement with the changes observed by the other assays. These three assays, combined, appear to provide effective and complementary ways to measure muscle performance and functional differences.

Comparison of tail-suspension and sciatic nerve crush on the musculoskeletal system in young-adult mice.

Musculoskeletal unloading and disuse result in significant muscle and bone loss. These phenomena can be modeled using sciatic nerve crush or tail-suspension. Mature animals eliminate the complication of growth superimposed on bone and muscle loss. In the current study, young-adult (12-week old male) C57BL/6J mice were subjected to sciatic nerve crush (NC; n = 9) or tail-suspension (TS; n = 9) for 14 days, with a normal ambulatory control (n = 10). The soleus, gastrocnemius, and EDL muscles were collected and weighed at sacrifice. Femurs were analyzed in three-point bending for stiffness, elastic force and maximum force. Muscle masses in tail suspended mice were reduced by 41.9% (p < 0.001), 17.5% (p < 0.001), and 9.1% (N.S.) for the soleus, gastrocnemius, and EDL, respectively. In NC mice, muscle masses were reduced by 18.6% (p = 0.004), 37.2% (p < 0.001), and 22.5% (p = 0.003). Femur stiffness, elastic and maximum forces were reduced by 20.9% (p = 0.014), 14.7% (N.S.), and 11.6% (N.S.) in TS, compared to NC where masses were reduced by 15.5% (p = 0.022), 0.2% (N.S.) and 11.2% (N.S.) in the crushed leg compared to the contralateral control. NC resulted in a greater reduction of muscle mass in the gastrocnemius and EDL muscle; whereas tail-suspension had a greater effect on the soleus. Tail-suspension had the greatest effect on bone mechanical properties. When comparing these results to actual spaceflight data, it appears as though TS most closely models muscle loss, and NC most closely models changes in bone mechanical properties. These unloading models have tissue-specific effects that impact their applications for musculoskeletal research.

Exercise prevention of unloading-induced bone and muscle loss in adult mice.

Skeletal unloading causes bone and muscle loss that may be reversed by post-unloading exercise. This study examines the effects of unloading and exercise, using tail-suspension for 14 days combined with a week of post-suspension cage wheel running in mice. Twenty-four adult, male, C57BL/6J mice were divided into four groups (n = 6 mice/group); unsuspended non-running, tail-suspended non-running, unsuspended running, and tail-suspended running. At sacrifice, the calf (soleus, gastrocnemeius and plantaris complex), heart, tibia and femur were collected and weighed. The femora and tibiae were cleaned of non-osseous tissue, subjected to 3-point bending (femurs only), and weighed for dry (105 degrees C; 24h) and ash mass (800 degrees C; 24h). The mean calf mass from the tail-suspended groups (157.13 +/- 2.83 mg) was significantly less than in the unsuspended groups (167.33 +/- 2.83 mg; p = 0.019), with no significant effect of cage wheel running. The mean heart mass in running groups (166.58 +/- 4.78 mg) was significantly greater than the non-running groups (148.17 +/- 4.78 mg; p = 0.013), with no effect of hindlimb suspension. The mean femur ash mass from tail-suspended groups (24.02 +/- 0.38 mg) were significantly less than the unsuspended groups (25.11 +/- 0.34 mg; p = 0.050), and the running groups (25.13 +/- 0.38 mg) were significantly greater than the non-running groups (24.00 +/- 0.34 mg; p = 0.043). No effect was observed for the femur dry mass or percent mineralization. Measurements of mechanical length tended to be lower in tail-suspension, with no significant affects do to cage wheel running. This study suggests that tail-suspension in adult mice significantly decreases skeletal muscle and bone mass, with no change in percent mineralization. Furthermore, one week of running does not reverse the effects on the skeletal muscle and bone mass.

Effect of A23187 or angiotensin II on ovarian metalloproteinase inhibitors and steroidogenesis in rats.

The present study examined the effect of the calcium ionophore A23187 or angiotensin II (AII) on the expression of ovarian metalloproteinase inhibitor and activity in rat granulosa cells and intact ovaries. Granulosa cells were collected from rats primed with pregnant mares' serum gonadotrophin (PMSG) and cultured for 24 h with A23187, AII, or the AII receptor antagonist, saralasin, in the presence or absence of LH. Metalloproteinase inhibitor activity and progesterone concentrations were determined in the media. In the A23187 experiment, addition of A23187 to granulosa cells, cultured without LH, decreased inhibitor activity, especially at the concentrations of 10 and 100 mumol l-1 (decrease to 33 +/- 7% and 31 +/- 5% of control culture values, respectively). Addition of LH to the media increased inhibitor activity 3.04 +/- 0.39 times compared with the control; however, A23187 (10 and 100 mumol l-1), in the presence of LH, decreased inhibitor activity by approximately 67%. The ionophore had disparate effects on progesterone production. Without LH, A23187 increased progesterone production by 2.96 +/- 0.47 times at 10 mumol l-1 and by 5.53 +/- 0.65 times at 100 mumol l-1. However, in LH-stimulated cells, progesterone was inhibited by A23187 at 1 and 10 mumol l-1 but was unchanged at 100 mumol l-1. In the angiotensin experiment, addition of AII (0-10,000 nmol l-1) or saralasin (1 mumol l-1) did not affect inhibitor activity or progesterone concentrations compared with control values in the absence or presence of LH. For the angiotensin experiment in vivo, PMSG-primed rats were injected with hCG followed by saralasin (10 mmol l-1) 1 or 3 h later and killed at 4, 8, or 12 h after hCG. Expression of the ovarian tissue inhibitor of metalloproteinase-1 (TIMP-1) increased by 1.7 times at 4 h, 3.3 times at 8 h, and 3.0 times at 12 h after hCG compared with values in ovaries collected at the time of hCG injection. Administration of saralasin at 1 or 3 h after hCG had no effect on expression of TIMP-1 or on serum concentrations of progesterone or oestradiol. In summary, A23187 decreased granulosa cell-derived inhibitor activity, whereas All had no effect. We propose that calcium may play a role in modulating proteolysis associated with ovulation, while AII does not appear to regulate ovarian metalloproteinase inhibitor activity.

A health program for commercial dairy herds. 1. Objectives and methods.

A health program for dairy herds is defined as a planned and coordinated approach to achieving and maintaining optimal health and productive efficiency of livestock. A program is described, which has been developed over a period of eight years to fulfill this definition in providing veterinary services to commercial dairy herds. It is demonstrated that clinical veterinary services to participating herds did not satisfactorily achieve the stated aim and therefore an alternative approach was developed. This approach is centred around the concept of performance targets, and each herd is monitored closely by means of a computer-based health and productivity monitoring system in order to detect deviation from target performance. When such deviations occur, the monitoring system is used to diagnose the nature of the problem. The detailed targets adopted in this study are described and the examinations which are undertaken on cattle are outlined. These examinations are aimed at correcting problems, or at confirming satisfactory performance. Further details of the findings of the study are outlined in following papers.

A health program for commercial dairy herds. 2. Data processing.

The development of a computerised data handling and analysis system to aid the operation of a health and management program for commercial dairy herds is described. The aims for the system are outlined, and the development of the system over a period of 8 years to meet these aims is described. The documentation used in the current system is described in relation to the various procedures involved in the operation of the dairy herd health program. Two features which make this system unique are its use for the selection of problem and high risk cows for examination and treatment, and the provision of analyses of recent performance in a number of facets of health and production, which aid in the identification of emerging problems. It is considered that future improvements in the system will be in the areas of milk production recording and calf rearing and disease recording.

A health program for commercial dairy herds. 3. Changes in reproductive performance.

A health program service was implemented on 9 farms, for periods ranging up to 7 years. Reproductive performance was substantially improved, when performance indicators were compared with values for the herds prior to commencement of the service. On average, the mean calving to conception intervals for the herds were reduced by 24 days over their periods of participation in the program, from an initial value of 119 days. The intercalving interval was reduced by an average of 27 days. This improvement was associated with a reduction in the mean dry period length of 20 days, from an initial value of 117 days. There was a tendency for the lactation lengths to be reduced to an undesirable extent due to slow adaptation by management to the improvement in reproductive performance, but the problem was corrected late in the study. The improvement in performance was attributed to improved oestrus detection, correction of temporary nutritional deficiencies, and prompt treatment of genital tract disorders in individual animals. Results for a range of performance indicators related to reproductive function are reported in detail.

A health program for commercial dairy herds. 4. Changes in mastitis prevalence.

A study of mastitis prevalence in 10 herds which participated in a herd health program is reported for varying periods, up to a maximum of 10 years. The program was based on teat dipping with idophor or sodium hypochlorite teat dip, regular maintenance of the milking machine, and selective dry period treatment of quarters which were classified as infected on the basis of California Mastitis Test score and bacteriological examination of milk samples taken before drying off. The procedures reduced mastitis prevalence (measured in cows being dried off), incidence of clinical mastitis, and disposal of cows due to mastitis. Results obtained were similar to those found in short-term studies of control programs based on teat dipping and dry period therapy. The only significant difficulty which arose in maintaining the control program over 10 years was loss of enthusiasm by farmers for teat dipping. This was usually induced by teat irritation problems apparently caused by teat dipping. The use of a monitoring procedure for mastitis prevalence was important in persuading farmers to return to the use of teat dip.