Clinical enzymology of the dog and cat.

Clinical enzymology studies the enzyme activity in serum or other body fluids for the diagnosis, prognosis or monitoring of a variety of diseases. Clinical enzymology has greatly benefited from advances in technology and is now an integral part of laboratory analysis. However, to maximise the clinical benefits of serum enzyme measurement, clinicians and clinical pathologists must have a good understanding of the pathophysiology behind serum enzyme alterations. They must also be aware of the preanalytical and analytical factors that can affect the accuracy of serum enzyme activity measurement. This review article first covers the basic concepts of clinical enzymology and the general mechanisms related to serum enzyme alterations. Then, the review discusses the potential effects of various preanalytical and analytical factors on enzyme activity measurement. Lastly, it explores the pathophysiology and clinical use of various serum enzymes in canine and feline medicine. The present review article aims to be a comprehensive one-stop source for clinical pathologists and small animal practitioners.

Serial measurement of cardiac troponin I in hospitalised dogs with canine parvoviral enteritis: Association with outcome and canine pancreas-specific lipase concentration.

The aim of this study was to serially evaluate serum cardiac troponin I (cTnI) concentrations in dogs with parvoviral enteritis (CPVE), and investigate the association with outcome and serum pancreas-specific lipase (Spec cPL) concentrations. Dogs with CPVE that were hospitalised for at least 5 days were included. cTnI and Spec cPL concentrations were measured on days 1, 3 and 5 of hospitalisation. Twenty-nine dogs (20 survivors, 9 non-survivors) were included. Spec cPL was indicative of pancreatitis (>400 µg/L) on at least one day in 10/29 (34.5%) dogs. Serum median (range) cTnI concentration was higher (P = 0.021) in non-survivors on day 5 [0.032 (0.001-0.395) ng/mL] compared to day 1 [0.012 (0.003-0.196) ng/mL]. Non-survivors had higher (P = 0.014) cTnI concentrations on day 5 [0.032 (0.001-0.395) ng/mL] compared to survivors [0.001 (0.001-0.042) ng/mL], but not at admission or on day 3 (P > 0.05). Serum cTnI concentrations were not significantly different (P = 0.465) between the three Spec cPL groups [group 1 (Spec cPL ≤ 200 µg/L): 0.007 (0.001-0.527) ng/mL; group 2 (Spec cPL: 201-399 µg/L): 0.0045 (0.001-0.196) ng/mL; group 3 (Spec cPL ≥ 400 µg/L): 0.011 (0.001-0.278) ng/mL]. cTnI and Spec cPL concentrations were not significantly correlated (rho = -0.043, P = 0.703). Serial measurement of cTnI had prognostic value in the examined cohort. However, cTnI was not correlated with spec cPL.

Diagnostic performance of glycated haemoglobin (HbA1c) for diabetes mellitus in dogs.

The objective of this study was to determine the diagnostic performance of glycated haemoglobin (HbA1c) for canine diabetes mellitus (DM) and compare it with that of serum fructosamine. Aliquots of blood samples collected for diagnostic purposes from adult dogs were used. HbA1c was measured using a previously validated capillary electrophoresis assay. The dogs were allocated into four groups: (1) DM; (2) hyperadrenocorticism (HAC); (3) long-term corticosteroid therapy (CST); and (4) various chronic diseases (VD). In total, 88 dogs were included as follows: DM (n = 11), HAC (n = 10), CST (n = 14), and VD (n = 53). Fructosamine was measured in all four groups as follows: DM (n = 6), HAC (n = 7), CST (n = 9), and VD (n = 42). Median (range) serum glucose concentration was higher (P < 0.001) in the DM group (22.8 mmol/L; range, 15.6-29.3 mmol/L) compared to HAC (5.9 mmol/L; range, 4.2-6.8 mmol/L), CST (5.6 mmol/L; range, 4.3-23.3 mmol/L), and VD (5.5 mmol/L; range, 4.1-9.4 mmol/L) groups. Mean (± standard deviation) HbA1c was higher (P < 0.001) in the DM group (6.3% ± 1.5%) compared to HAC (1.9% ± 0.5%), CST (1.7% ± 0.5%), and VD (1.9% ± 0.5%) groups. All diabetic dogs and none of the other dogs had HbA1c levels above the cut-off value for DM (3.3%), indicating an accuracy of 100% in diagnosing DM. Significant differences (P < 0.01) were observed in median fructosamine between the DM group (389 µmol/L; range, 348-865 µmol/L) and the HAC (306 µmol/L; range, 167-348 µmol/L) and the VD (316 µmol/L; range, 189-500 µmol/L) groups. Fructosamine had an accuracy of 84.4% for the diagnosis of DM. When used for the diagnosis of canine DM, HbA1c measured with this specific assay had excellent diagnostic accuracy and was superior to serum fructosamine.

Prevalence, association with systemic inflammatory response syndrome and outcome of stress hyperglycaemia in sick cats.

OBJECTIVES: To determine the prevalence of stress hyperglycaemia in sick cats, and to investigate the association of stress hyperglycaemia with systemic inflammatory response syndrome and outcome. MATERIALS AND METHODS: Medical records (2004 to 2013) from sick cats admitted to the Medicine Unit of a Veterinary Teaching Hospital were retrospectively reviewed. Cases were enrolled if a serum glucose measurement and a complete medical record were available. Cats that were healthy, hypoglycaemic, diabetic, sedated or had a previous administration of drugs (apart from vaccination and deworming) were excluded. RESULTS: The study included 647 cats; stress hyperglycaemia (serum glucose >8.3 mmol/L) was found in 194 (30%) cats, while 453 (70%) cats were normoglycaemic. The prevalence of systemic inflammatory response syndrome was significantly higher in cats with stress hyperglycaemia (25/174, 14.4%) compared to normoglycaemic cats (26/399, 6.5%). Significantly, more cats with stress hyperglycaemia were hospitalised [97/194 (50.0%)] compared to normoglycaemic cats [171/453 (37.7%)]. However, the median duration of hospitalisation was not significantly different [4 (1 to 26) days and 4 (1 to 24) days, respectively]. The prevalence of cats with negative outcome was not significantly different between the two groups (cats with stress hyperglycaemia: 37.1%, normoglycaemic cats: 33.9%). Nonetheless, when modelling of outcome prediction included breed, age, stress hyperglycaemia and disease category as factors, cats with stress hyperglycaemia had 2.8 times the odds to have a negative outcome (95% confidence interval: 1.3 to 6.4). CLINICAL SIGNIFICANCE: Based on the cut-off employed in this study, Stress hyperglycaemia, as defined by the cut-off is common in sick cats. Stress hyperglycaemia is associated with systemic inflammatory response syndrome development and seem to be a negative prognostic indicator.

Serial measurement of thyroid hormones in hospitalised dogs with canine parvoviral enteritis: Incidence of non-thyroidal illness syndrome and its association with outcome and systemic inflammatory response syndrome.

The aim of this study was to serially evaluate the serum concentrations of total thyroxine (tT4), free thyroxine (fT4) and thyroid-stimulating hormone (TSH) in dogs with canine parvoviral enteritis (CPVE) during a 5-day hospitalisation period and assess the association of these hormone concentrations with the outcome and the development of systemic inflammatory response syndrome (SIRS). Dogs with confirmed CPVE that were hospitalised for at least 5 days were included. The thyroid hormones concentrations were measured on days 1, 3 and 5 of hospitalisation. Twenty-eight dogs were included. All (28/28, 100%), 19/28 (69.7%) and 23/28 (82.1%) dogs had a low serum tT4, fT4 and TSH concentration, respectively, on at least 1 day during the hospitalisation period. Overall, 11/28 (39.3%) dogs were diagnosed with SIRS on at least 1 day. In survivors, serum tT4 concentration was significantly higher on day 5 (median, range: 11.8 nmol/L, <6.4-32.2 nmol/L) compared to those on days 1 (<6.4 nmol/L, <6.4-20.1 nmol/L; P = 0.010) or 3 (7.6 nmol/L, <6.4-25.2 nmol/L; P = 0.019). Survivors had a significantly higher tT4 concentration (median, range: 11.8 nmol/L, <6.4-32.2 nmol/L) on day 5 compared to non-survivors (<6.4 nmol/L, <6.4-7.2 nmol/L; P = 0.002). Regardless of the day of hospitalisation, dogs with SIRS had significantly lower tT4 (<6.4 nmol/L, <6.4-16.3 nmol/L) compared to dogs without SIRS (8.6 nmol/L, <6.4-32.2 nmol/L; P = 0.006). A significant difference was also found in fT4 between dogs with SIRS (<3.9 pmol/L, <3.9-16.2 pmol/L) and dogs without SIRS (15.1 pmol/L, <3.9-59.2; pmol/L; P < 0.001). Non-thyroidal illness syndrome was frequently observed in dogs with CPVE, and a negative association between tT4 and fT4 concentrations and SIRS was noted. Serial measurements of tT4 concentrations appeared to have prognostic value.

Eosinophilic pericardial effusion in a cat with complex systemic disease and associated peripheral eosinophilia.

An 11-year-old domestic shorthair cat was referred for investigation of dry cough of 1-week duration and cardiomegaly. Echocardiography revealed pericardial effusion, and eosinophils were identified as the predominant cell type in fluid collected by pericardiocentesis. Thoracic computed tomography imaging and bronchoscopy were supportive of mild lower airway disease, while bronchoalveolar lavage confirmed eosinophilic inflammation and concurrent Mycoplasma felis infection. A few months after the initial presentation, there was clinical deterioration, and further investigation suggested intestinal lymphoma. It was hypothesized that pericardial effusion and lower airway inflammation were an early manifestation of hypereosinophilic syndrome, possibly as a paraneoplastic consequence of lymphoma.

Brainstem phaeohyphomycosis due to Curvularia lunata (Cochliobolus lunatus) in a cat.

A 13-year-old female neutered domestic short-hair cat was presented with chronic progressive vestibular ataxia, lethargy and anorexia. Clinical examination revealed bilateral mucopurulent nasal discharge. Neurological examination revealed obtundation, a right head tilt, ambulatory tetraparesis, generalised vestibular ataxia, decreased postural reactions in all limbs, right Horner's syndrome, spontaneous conjugate jerk rotatory nystagmus and right positional ventral strabismus. Neuroanatomical localisation was observed in the right central vestibular system. Computed tomography revealed a solitary ill-defined contrast-enhancing mass lesion at the level of the right cerebellopontine angle. Cerebrospinal fluid (CSF) analysis revealed mild mononuclear pleocytosis and fungal elements. CSF culture was positive for Curvularia spp. Further tests for underlying diseases were all negative. The cat was treated with antibiotic and antifungal treatment, but it deteriorated rapidly and was euthanased. Necropsy of the brainstem mass lesion revealed pyogranulomatous inflammation. Panfungal polymerase chain reaction (PCR) targeting the internal transcribed spacer (ITS) region and subsequent sequencing identified Curvularia lunata in the formalin fixed brain tissue. This is the first report of brainstem phaeohyphomycosis by Curvularia lunata (Pleosporales) in a cat. In addition, this is the first report among animal and humans where fungal elements of Curvularia lunata were found in the CSF cytology. Opportunistic fungal pathogens should be always considered within the differential diagnoses list in cats with neurological signs and advanced imaging findings compatible with solitary mass lesions in the brain. In feline patients with pyogranulomatous meningoencephalitis and a suspicion of a fungal aetiology, panfungal PCR for the ITS region and sequencing should be performed regardless of the absence of fungal elements in histopathology.

Validation, reference intervals and overlap performance of a new commercially available automated capillary electrophoresis assay for the determination of the major fraction of glycated haemoglobin (HbA1c) in dogs.

Haemoglobin A1c (HbA1c), the major fraction of glycated haemoglobin, is widely used for the diagnosis and monitoring of diabetes mellitus in human beings. However, there is a paucity of literature on the most reliable methods available for measurement of canine HbA1c. The aim of this study was to validate a new automated capillary electrophoresis assay for canine HbA1c, to generate a reference interval and to assess the overlap performance of the assay for the diagnosis of diabetes mellitus. Eighty-three blood samples treated with EDTA were included in the study, comprising 63 from healthy dogs and 20 from diabetic dogs. Linearity was assessed by mixing canine samples of known HbA1c percentage in different proportions, precision was assessed by repeated (n=8) measurement of five canine samples, and stability was assessed by measuring canine samples stored at 4°C for 96h and -20°C for 4 weeks. The robust method was used to determine the reference interval. The assay was demonstrated to be linear (R2=0.943). Intra-assay and inter-assay coefficients of variation (CVs) were 4.8% and 7.0%, respectively. CVs for blood samples stored at 4°C and -20°C were 7.2% and 11.2%, respectively. The reference interval was 0.6-2.7%. Dogs with diabetes mellitus had significantly (P<0.001) higher mean HbA1c (5.24±0.88%) compared to the reference population (1.64±0.55%), with no overlap between results. A HbA1c cut-off of 3.3% clearly differentiated diabetic from healthy dogs. The capillary electrophoresis assay was properly validated for canine HbA1c and the reference interval was determined, while the overlap performance of the assay was excellent.

Canine pancytopoenia in a Mediterranean region: a retrospective study of 119 cases (2005 to 2013).

OBJECTIVES: To further clarify the causes of pancytopoenia and to investigate whether underlying cause or severity were associated with survival in an area endemic for vector-borne pathogens. METHODS: Retrospective review of medical records of 119 dogs with and 238 dogs without pancytopoenia. RESULTS: Mixed-breed dogs and dogs younger than one year had higher odds of being pancytopoenic. The most common diagnoses included monocytic ehrlichiosis (n=42), leishmaniasis (n=28) and parvoviral enteritis (n=19). The mean white blood cell counts were lower in dogs with ehrlichiosis and parvoviral enteritis compared to dogs with leishmaniasis, while platelet counts were lower in ehrlichiosis compared to leishmaniasis or parvoviral enteritis. Total protein concentrations were lower in dogs with parvoviral enteritis compared to ehrlichiosis and leishmaniasis. Higher haematocrit, platelet and white cell counts were associated with better odds of survival. CLINICAL SIGNIFICANCE: Infectious diseases appear to be the leading causes of canine pancytopoenia in endemic areas; severe leukopoenia (ehrlichiosis, parvoviral enteritis), thrombocytopoenia (ehrlichiosis) and hypoproteinaemia (parvoviral enteritis), represented potentially useful disease-specific diagnostic determinants. The severity of pancytopoenia significantly affects the clinical outcome.

Α case of multiple bilateral testicular capsule mast cell tumours in a dog.

A 5-year-old intact male German Shepherd dog was referred with a diagnosis of leishmaniasis. Several testicular masses were palpated during the physical examination, while the diagnostic screening yielded no remarkable findings. Fine needle aspiration cytology of the masses revealed the presence of intermediately differentiated mast cell tumours. Scrotal ablation and orchiectomy were performed as a definitive treatment option. The pathological examination of the surgical specimens confirmed the diagnosis of grade II mast cell tumours and showed that they were all confined to the testicular capsule. At 7 months post-admission, the dog exhibited neither postsurgical complications nor metastatic foci and was, therefore, given a favourable prognosis. Despite their exceptionally rare occurrence, mast cell tumours should be considered for the differential diagnosis of testicular tumours.