Acute cerebrovascular event in a dog with polycythemia vera

A 1-year-old neutered male Labrador retriever mixed breed dog was referred for peracute onset of ataxia and seizures. Hematocrit at presentation was 84%. Magnetic resonance imaging of the brain revealed a lesion in the right caudate nucleus consistent with infarction. Postmortem findings were consistent with polycythemia vera and presumed secondary cerebral infarction.

Evaluation of SNAP cPL, Spec cPL, VetScan cPL Rapid Test, and Precision PSL Assays for the Diagnosis of Clinical Pancreatitis in Dogs

BACKGROUND

The sensitivity, specificity, and agreement of 4 diagnostic assays (SNAP canine pancreatic lipase (cPL), specific cPL (Spec cPL), VetScan cPL Rapid Test, and Precision PSL) for pancreatitis in dogs have not been directly compared.

HYPOTHESIS/OBJECTIVES

To determine the level of agreement among each of the 4 assays and a clinical suspicion score, level of agreement among the assays, and sensitivity and specificity of each assay in a clinically relevant patient group.

ANIMALS

Fifty client-owned dogs with clinical signs of gastrointestinal disease.

METHODS

Prospective study. History, physical examination, complete blood count, serum biochemistry, abdominal ultrasound examination, and the 4 diagnostic assays for pancreatitis were performed. Intraclass correlation coefficients (ICC) were used to determine the level of agreement between each assay and a clinical suspicion score determined by a panel of 5 board-certified veterinary internists.

RESULTS

The ICC between the clinical suspicion score and the 4 assays were SNAP cPL, 0.61; Spec cPL, 0.68; VetScan cPL Rapid Test, 0.68; and Precision PSL, 0.60. The sensitivities of the assays ranged from 73.9 to 100.0%, whereas the specificities were SNAP cPL, 71.1-77.8%; Spec cPL, 74.1-81.1%; VetScan cPL Rapid Test, 76.9-83.8%; and Precision PSL, 64.0-74.3%.

CONCLUSIONS AND CLINICAL IMPORTANCE

A good to excellent level of agreement was demonstrated among the 4 assays. The previously unreported sensitivity and specificity of the VetScan cPL Rapid Test were 73.9-83.3% and 76.9-83.8%, respectively. Results of any of the 4 diagnostic assays alone, in the absence of supporting clinical findings, are insufficient to establish a diagnosis of clinical pancreatitis in dogs.

Effects of oral cyclosporine on canine T-cell expression of IL-2 and IFN-gamma across a 12-h dosing interval

The duration of immunosuppressive effects following oral cyclosporine in dogs is unknown. This study used flow cytometry and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) to evaluate the effects of high-dose oral cyclosporine across a 12-h dosing interval. Expression of interleukin-2 (IL-2) and interferon-gamma (IFN-γ) was compared before and after 8 days of cyclosporine at 10 mg/kg every 12 h in six healthy dogs. Samples were collected at 0, 2, 4, and 8 h postdosing for analysis of unactivated and activated T-cell and whole blood cytokine expression using flow cytometry and qRT-PCR, respectively, and at 0, 2, 4, 6, 8, and 10 h postdosing for measurement of cyclosporine concentrations. Flow cytometry and qRT-PCR both demonstrated significant marked reductions in IL-2 and IFN-γ levels at 0, 2, 4, and 8 h after dosing compared to pretreatment levels (P < 0.05) for activated samples, with less consistent effects observed for unactivated samples. Both flow cytometry and qRT-PCR are viable techniques for measuring cyclosporine pharmacodynamics in dogs, yielding comparable results with activated samples. Two hours postdrug administration is the preferred time for concurrent assessment of peak drug concentration and cytokine expression, and T-cell activation is needed for optimal results.

Anticoagulant effects of inhaled unfractionated heparin in the dog as determined by partial thromboplastin time and factor Xa activity

OBJECTIVE

To evaluate the anticoagulant effects of inhaled heparin in dogs.

DESIGN

This study was conducted in 3 phases. In phase 1, bronchoalveolar lavage fluid (BALf) was collected to generate an in vitro calibration curve to relate heparin concentration to the activated partial thromboplastin time (aPTT). In phase 2, heparin was administered via nebulization to determine the threshold dose needed to prolong systemic aPTT. In phase 3, the local anticoagulant activity of inhaled heparin was determined by measurement of BALf anti-Xa activity and aPTT.

SETTING

University teaching hospital.

ANIMALS

Six healthy intact female Walker Hounds were used in this study. Two dogs were used for each phase.

INTERVENTIONS

Inhaled unfractionated sodium heparin was administered in doses ranging from 50,000 to 200,000 IU.

RESULTS

In vitro addition of heparin to BALf caused a prolongation in aPTT. Inhaled heparin at doses as high as 200,000 IU failed to prolong systemic aPTT, and a threshold dose could not be determined. No significant local anticoagulant effects were detected.

CONCLUSIONS

Even at doses higher than those known to be effective in people, inhaled heparin appears to have no detectable local or systemic anticoagulant effects in dogs with the current delivery method.

Frequency of the MDR1 mutant allele associated with multidrug sensitivity in dogs from Brazil

To date, a 4-bp deletion in the MDR1 gene has been detected in more than ten dog breeds, as well as in mixed breed dogs, in several countries, however information regarding this mutation in dogs from Brazil is lacking. For this reason, 103 Collies, 77 Border Collies, 76 Shetland Sheepdogs, 20 Old English Sheepdogs, 55 German Shepherds, 16 Australian Shepherds, and 53 Whippets from Brazil were screened for the presence of the mutation. The heterozygous mutated genotype, MDR1 (+/−), frequency found for Collies, Australian Shepherd, and Shetland Sheepdog was 50.5% (95% CI =41.1%–59.9%), 31.3% (95% CI =8.6%–53.2%), and 15.8% (95% CI =7.7%–23.9%), respectively. Homozygous mutated genotype, MDR1 (−/−), was detected only in Collies 35.9%. The MDR1 allele mutant frequency found for Collies, Australian Shepherd, and Shetland Sheepdog was 61.2% (95% CI =54.8%–67.5%), 15.6% (95% CI =3.1%–28.2%), and 7.9% (95% CI =3.7%–12.1%), respectively. Additionally, even free of the mutant allele, the maximum mutant prevalence (MMP) in that population, with 95% CI, was 3.8%, 5.2%, 5.4%, and 13.8% for Border Collies, German Shepherds, Whippets, and Old English Sheepdogs, respectively. In this way, this information is important, not only for MDR1 genotype-based breeding programs and international exchange of breeding animals of predisposed breeds, but also for modification of drug therapy for breeds at risk.

Identification of canine platelet proteins separated by differential detergent fractionation for nonelectrophoretic proteomics analyzed by Gene Ontology and pathways analysis

During platelet development, proteins necessary for the many functional roles of the platelet are stored within cytoplasmic granules. Platelets have also been shown to take up and store many plasma proteins into granules. This makes the platelet a potential novel source of biomarkers for many disease states. Approaches to sample preparation for proteomic studies for biomarkers search vary. Compared with traditional two-dimensional polyacrylamide gel electrophoresis systems, nonelectrophoretic proteomics methods that employ offline protein fractionation methods such as the differential detergent fractionation method have clear advantages. Here we report a proteomic survey of the canine platelet proteome using differential detergent fractionation coupled with mass spectrometry and functional modeling of the canine platelet proteins identified. A total of 5,974 unique proteins were identified from platelets, of which only 298 (5%) had previous experimental evidence of in vivo expression. The use of offline prefractionation of canine proteins by differential detergent fractionation resulted in greater proteome coverage as compared with previous reports. This initial study contributes to a broader understanding of canine platelet biology and aids functional research, identification of potential treatment targets and biomarkers, and sets a new standard for the resting platelet proteome.

Oral cyclosporine treatment in dogs: a review of the literature

Cyclosporine is an immunomodulatory drug used to treat an increasing spectrum of diseases in dogs. Cyclosporine is a calcineurin inhibitor, ultimately exerting its inhibitory effects on T-lymphocytes by decreasing production of cytokines, such as interleukin-2. Although, in the United States, oral cyclosporine is approved in dogs only for treatment of atopic dermatitis, there are many other indications for its use. Cyclosporine is available in 2 oral formulations: the original oil-based formulation and the more commonly used ultramicronized emulsion that facilitates oral absorption. Ultramicronized cyclosporine is available as an approved animal product, and human proprietary and generic preparations are also available. Bioavailability of the different formulations in dogs is likely to vary among the preparations. Cyclosporine is associated with a large number of drug interactions that can also influence blood cyclosporine concentrations. Therapeutic drug monitoring (TDM) can be used to assist in attaining consistent plasma cyclosporine concentrations despite the effects of varying bioavailability and drug interactions. TDM can facilitate therapeutic success by guiding dose adjustments on an individualized basis, and is recommended in cases that do not respond to initial oral dosing, or during treatment of severe, life-threatening diseases for which a trial-and-error approach to dose adjustment is too risky. Pharmacodynamic assays that evaluate individual patient immune responses to cyclosporine can be used to augment information provided by TDM.

Ultra-pure platelet isolation from canine whole blood

Background

Several research applications involving platelets, such as proteomic and transcriptomic analysis, require samples with very low numbers of contaminating leukocytes, which have considerably higher RNA and protein content than platelets. We sought to develop a platelet purification protocol that would minimize contamination, involve minimal centrifugation steps, and yield highly pure platelet samples derived from low volume whole blood samples from healthy dogs.

Results

Using an optimized OptiPrep density gradient technique, platelet recovery was 51.56% with 99.99% platelet purity and leukocyte contamination of 100 leukocytes per 10⁸ platelets, on average. Platelet samples were subjected to additional purification with CD45-labeled Dynabeads after density barrier centrifugation resulting in a 95-fold depletion of residual leukocytes. Platelets purified using these methods remained inactivated as assessed by Annexin V and P-selectin labeling with flow cytometry.

Conclusions

The use of OptiPrep density gradient is a quick method for obtaining highly purified platelet samples from low volumes of canine whole blood with minimal contamination. Additional depletion of residual leukocytes can be achieved using CD45-labeled beads. These platelet samples can then be used for many downstream applications that require ultra-pure platelet samples such as RNA and protein analysis.

Gastroesophageal reflux and laryngeal dysfunction in a dog

CASE DESCRIPTION

A 7-year-old neutered male Saint Bernard was evaluated because of a 6-month history of coughing, gagging, change in phonation, excessive panting, and chronic intermittent vomiting and diarrhea.

CLINICAL FINDINGS

Physical examination revealed no remarkable findings other than panting. Total thyroxine concentration and results of a CBC, serum biochemistry analysis, urinalysis, and thoracic radiography were within reference limits. A laryngeal examination revealed edema, erythema, and ulceration of the larynx and pharynx, with normal laryngeal movement. Results of bronchoscopy and cytologic examination of bronchoalveolar lavage fluid were diagnostic only for distal tracheitis. Esophagoscopy and an esophagography revealed esophagitis consistent with gastroesophageal reflux. Gastroduodenoscopy and histologic examination of biopsy specimens revealed Helicobacter colonization and lymphocytic or plasmacytic enteritis.

TREATMENT AND OUTCOME

Following treatment for gastroesophageal reflux and suspected Helicobacter infection with combination antacid and antimicrobial treatment, the dog's respiratory signs resolved but vomiting continued. Gastroduodenoscopy revealed complete resolution of the previous laryngitis, pharyngitis, and esophagitis. Treatment for the lymphocytic or plasmacytic enteritis was initiated with prednisone (1 mg/kg [0.45 mg/lb], p.o., q 12 h) and a novel protein diet. The previous treatment was also continued. Complete resolution of clinical signs was maintained 4 months after initiation of appropriate treatment.

CLINICAL RELEVANCE

Laryngeal dysfunction induced by gastroesophageal reflux as occurred in the patient described in this report is a previously undocumented association in the veterinary literature. This association could be a potential consideration in dogs with concurrent respiratory and gastrointestinal signs. The present report may provide a basis for further studies investigating this association.

Pharmacodynamic monitoring of canine T-cell cytokine responses to oral cyclosporine

BACKGROUND

Pharmacodynamic assays measure the immunosuppressive effects of cyclosporine on T-cells and offer an alternative assessment of efficacy in individual patients.

OBJECTIVE

To assess the immunosuppressive effects of high and low dosage cyclosporine on canine T-cells and to develop a novel testing system for individualized dose adjustment.

ANIMALS

Seven healthy female Walker hounds.

METHODS

Experimental study using a paired comparison design. Flow cytometry was used to measure T-cell expression of IL-2, IL-4, and IFN-γ. Cytokine expression 8 days after oral administration of high and low dosages of cyclosporine was compared to baseline and washout values, respectively. The high dosage was initially 10 mg/kg q12h and was then adjusted to attain established immunosuppressive trough blood drug concentrations (>600 ng/mL). The low dosage was 5 mg/kg q24h.

RESULTS

High dosage cyclosporine resulted in significant decreases in IL-2 and IFN-γ expression (P = .0156, P = .0156), but not IL-4 expression (P = .2188). Low dosage cyclosporine was associated with a significant decrease in IFN-γ expression (P = .0156), while IL-2 expression was not affected (P = .1094).

CONCLUSIONS AND CLINICAL IMPORTANCE

T-cell function is suppressed at trough blood drug concentrations exceeding 600 ng/mL, and is at least partially suppressed in some dogs at low dosages. Direct evaluation of T-cell function could be an effective, more sensitive alternative to measuring blood drug concentrations for monitoring immunosuppressive therapy.

Cyclosporine A affects the in vitro expression of T cell activation-related molecules and cytokines in dogs

Cyclosporine is a powerful immunosuppressive drug that is being used with increasing frequency to treat a wide range of immune-mediated diseases in the dog. To date, ideal dosing protocols that will achieve immunosuppression with cyclosporine in dogs remain unclear, and standard methods that can measure effectiveness of immunosuppression have not been established. The aim of our study was to evaluate the effects of in vitro cyclosporine exposure on a panel of molecules expressed by activated T cells to ascertain their potential as biomarkers of immunosuppression in dogs. Blood was drawn from six healthy dogs, and peripheral blood mononuclear cells (PBMC) were isolated and activated. Half of the cells were incubated with 200 ng/mL cyclosporine prior to activation, and the other half were not exposed to cyclosporine. Samples were analyzed using flow cytometry, and the expression of intracellular cytokines IL-2, IL-4, and IFN-γ was evaluated after 6, 12, and 24h of drug exposure. Each cytokine exhibited a time-dependent suppression profile, and all but two samples activated in the presence of cyclosporine showed lower cytokine expression than untreated controls. We also evaluated the expression of the surface T cell activation molecules CD25 and CD95 by flow cytometry after 36 h of drug exposure. Expression of these surface molecules decreased significantly when activated in the presence of cyclosporine. Our results suggest that suppressed expression of the markers related to T cell activation could potentially be utilized as an indicator of the efficacy of cyclosporine therapy in dogs.

Pharmacokinetics of Subcutaneous Low Molecular Weight Heparin (Enoxaparin) in Dogs

Unfractionated heparin has been the standard heparin used in human and veterinary medicine for its anticoagulation effect; however, it has a complex pharmacodynamic profile that requires close monitoring. Low molecular weight heparins have a more predictable bioavailability, allowing standardized dosing without individual patient monitoring. This project was designed to a) evaluate the pharmacokinetics of the subcutaneous (SC) administration of the low molecular weight heparin, enoxaparin, in dogs using anti-Xa activity as a marker of plasma enoxaparin concentrations and b) to establish the dose necessary to maintain activity within an established target range. Enoxaparin at 0.8 mg/kg SC q 6 hours consistently maintained target levels of anti-Xa activity in normal dogs without evidence of hemorrhagic complications.

Thromboembolic Therapies in Dogs and Cats: An Evidence-Based Approach

In veterinary medicine, we are forced to make use of less than ideal "evidence," such as extrapolation from experimental studies in dogs and cats without naturally occurring diseases and from clinical trials in other species (particularly human clinical trials), as well as limited information gained from veterinary clinical experience, small clinical trials, case studies, and anecdotal reports. In this article, specific treatment recommendations are made for each of the common thromboembolic conditions seen in dogs and cats. These recommendations are made with the important caveat that, to date, such suggested therapeutic approaches are based on limited evidence.