Investigation of the relationship between ionised and total calcium in dogs with ionised hypercalcaemia.

OBJECTIVES: To investigate the relationship between total and ionised calcium concentrations in dogs with ionised hypercalcaemia and to evaluate how albumin influences this relationship. METHODS: Initially, a reference interval for ionised and total calcium was established using a large population of healthy adult dogs. Our teaching hospital clinical database was searched to identify adult dogs with ionised hypercalcaemia between 2012 and 2017, a time frame when the same sample handling and analysis protocols were in place as for the healthy reference interval population. The relationship between ionised and total calcium concentrations was then examined in the ionised hypercalcaemia population. RESULTS: Based on biochemical analysis of 351 healthy adult dogs, a reference interval of 1.18 to 1.53 mmol/L for ionised calcium and 2.24 to 2.85 mmol/L for total calcium was established. Using these reference intervals, 63 dogs with ionised hypercalcaemia were identified, of which 23 did not have total hypercalcaemia. Only seven of the 23 dogs with ionised hypercalcaemia and total calcium below the upper limit of the reference interval had hypoalbuminemia. The majority of dogs with ionised hypercalcemia and normal total calcium had a modest increase in ionised calcium. CLINICAL SIGNIFICANCE: If relying on total calcium alone, more than one third of dogs with ionised hypercalcaemia will be classified as normocalcaemic and the majority of these dogs had normal serum albumin.

Sensitivity and specificity of microRNA-122 for liver disease in dogs.

BACKGROUND: Current tests for diagnosing liver disease in dogs are sub-optimal. MicroRNA-122 (miR-122) is a sensitive and specific biomarker of liver injury in humans and rodents. Circulating miR-122 could have utility in identifying dogs with liver disease. OBJECTIVE: Establish the reference interval for miR-122 in healthy dogs and determine performance in a range of dog breeds with liver disease and control animals with non-liver disease. ANIMALS: Stored serum from 120 healthy dogs, 100 dogs with non-liver diseases, and 30 dogs with histologically confirmed liver disease was analyzed. METHODS: Retrospective study. Medical records of dogs with liver disease, non-liver disease and healthy dogs were reviewed. Serum miR-122 concentrations were measured by PCR and compared with the characteristics of the dogs and their conventional clinical measurements. RESULTS: In healthy dogs the 2.5th, 50th, and 97.5th quartiles of miR-122 were 110 (90% CI 80-114), 594 (505-682), and 3312 (2925-5144) copies/µL, respectively. There was no difference between healthy dogs and dogs with non-liver disease (median ± IQR: healthy dogs 609 [327-1014] copies/µL; non-liver disease 607 [300-1351] copies/µL). miR-122 was higher in dogs with liver disease (11 332 [4418-20 520] copies/µL, P < .001 compared to healthy dogs). miR-122 identified dogs with liver disease with high accuracy (receiver operating characteristic area under curve for comparison with healthy dogs: 0.93 [95% CI 0.86-0.99]). The upper limit of normal for healthy dogs (3312 copies/µL) had a sensitivity of 77% and specificity of 97% for identifying liver disease. CONCLUSION AND CLINICAL IMPORTANCE: Liver disease can be sensitively and specifically diagnosed in dogs by measurement of miR-122.

Vitamin D Receptor Expression in Dogs.

BACKGROUND: There is growing evidence linking low blood vitamin D concentration to numerous diseases in people and in dogs. Vitamin D influences cellular function by signaling through the vitamin D receptor (VDR). Little is known about which non-skeletal tissues express the VDR or how inflammation influences its expression in the dog. OBJECTIVES: To define which non-skeletal canine tissues express the VDR and to investigate expression in inflamed small intestine. ANIMALS: Thirteen non-skeletal tissues were collected prospectively from 6 control dogs. Thirty-five dogs diagnosed with a chronic enteropathy (CE) and 24 control dogs were prospectively enrolled and duodenal biopsies were evaluated for VDR expression. METHODS: Prospective; blinded assessment of canine intestinal VDR. Dogs with CE were included once other identifiable causes of intestinal disease were excluded. Age matched controls were included with no intestinal clinical signs. VDR expression was assessed immunohistochemically in all samples, using a Rat IgG VDR monoclonal antibody. Quantitative real-time polymerase chain reaction (qPCR) was also used for duodenal biopsies. RESULTS: VDR expression as assessed by immunohistochemistry (IHC) was highest in the kidney, duodenum, skin, ileum and spleen, and weak in the colon, heart, lymph node, liver, lung, and ovary. Gastric and testicular tissue did not express the VDR. There was no statistical difference in duodenal VDR expression between the 24 healthy dogs and 34 dogs with CE when quantified by either qPCR (P = 0.87) or IHC (P = 0.099). CONCLUSIONS AND CLINICAL IMPORTANCE: The lack of down regulation of VDR expression in inflamed intestine contrasts with previous studies in humans. Our findings support future studies to investigate whether vitamin D and its analogues can be used to modulate intestinal inflammation in the dog.

Inter- and intra-operator variability in the analysis of packed cell volume.

OBJECTIVES: To identify whether inter- and intra-operator variability occurs in the measurement of canine packed cell volume and, if so, at which stage these errors occur. MATERIALS AND METHODS: Undergraduate veterinary students and veterinary surgeons were recruited to measure the packed cell volumes of three samples in duplicate. Measurements from each sample were confirmed by one author, and it was then ascertained whether the error was made in the capillary preparation or reading. RESULTS: Data were obtained from 44 students and 11 vets. A total of 25% of students made errors associated with inadequate mixing; 23% students and 9% of vets made errors consistent with incorrect reading. There was also less intra-operator variation in values within the vet group (0·027 from the mean) in comparison to the student group (-0·21 from the mean). A total of 68·2% of students and 91% of vets filled the capillary tubes outwith World Health Organisation standards of two-thirds to three-quarters full. CLINICAL SIGNIFICANCE: Packed cell volume measurement is extremely useful when measuring erythroid mass, but it is crucial that the results upon which decisions are made are accurate and precise in order to manage these cases appropriately. Operator variation is a significant factor and must be addressed by proper training and following standard operating procedures.

Association of Vitamin D Status and Clinical Outcome in Dogs with a Chronic Enteropathy.

BACKGROUND: Dogs with a chronic enteropathy (CE) have a lower vitamin D status, than do healthy dogs. Vitamin D status has been associated with a negative clinical outcome in humans with inflammatory bowel disease. OBJECTIVES: To examine the relationship between serum 25 hydroxyvitamin D (25(OH)D) concentrations at diagnosis and clinical outcome in dogs with a CE. ANIMALS: Forty-one dogs diagnosed with CE admitted to the Royal Dick School of Veterinary Studies, Hospital for Small Animals between 2007 and 2013. METHODS: Retrospective review. Serum 25(OH)D concentrations were compared between dogs which were alive at follow up or had died because of non-CE-related reasons (survivors) and dogs which died or were euthanized due to their CE (non-survivors). A binary logistic regression analysis was performed to determine significant predictors of death in dogs with CE. RESULTS: Serum concentrations of 25(OH)D at the time a CE was diagnosed were significantly lower in nonsurvivors (n = 15) (median nonsurvivors 4.36 ng/mL, interquartile range 1.6-17.0 ng/mL), median survivors (n = 26) (24.9 ng/mL interquartile range 15.63-39.45 ng/mL, P < .001). Serum 25(OH)D concentration was a significant predictor of death in dogs with CE (odds ratio 1.08 [95% CI 1.02-1.18)]). CONCLUSIONS: Serum 25(OH)D concentrations at diagnosis are predictive of outcome in dogs with CE. The role of vitamin D in the initiation and outcome of chronic enteropathies in dogs is deserving of further study.

Serum cardiac troponin I concentrations decrease following treatment of primary immune-mediated haemolytic anaemia.

OBJECTIVES: The measurement of serum cardiac troponin I concentrations in dogs with a range of non-primary cardiac illnesses suggests that cardiac myocyte damage is commonplace. Dogs with primary immune-mediated haemolytic anaemia have increased serum cardiac troponin I concentrations at the time of diagnosis. However, it is unclear whether biochemical evidence of cardiac myocyte damage improves following successful treatment of anaemia. METHODS: A haematology profile was performed and serum cardiac troponin I concentrations were measured in 19 dogs with primary immune-mediated haemolytic anaemia before and after treatment. RESULTS: The haematocrit increased significantly (P = 0 · 0001) following treatment of primary IMHA (median pre: 0 · 13 L/L, median post: 0 · 33 L/L). The serum cardiac troponin I concentrations decreased significantly (P < 0 · 05) after treatment (median pre: 0 · 26 ng/mL, median post: 0 · 16 ng/mL). CLINICAL SIGNIFICANCE: Serum cardiac troponin I concentration decreases following successful treatment of primary immune-mediated haemolytic anaemia. The clinical and prognostic significance of serum cardiac troponin I concentrations before and after treatment in dogs with primary immune-mediated haemolytic anaemia merits further investigation.

Hepatic hepcidin gene expression in dogs with a congenital portosystemic shunt.

BACKGROUND: Microcytic anemia is common in dogs with a congenital portosystemic shunt (cPSS) and typically resolves after surgical attenuation of the anomalous vessel. However, the pathophysiology of the microcytic anemia remains poorly understood. Hepcidin has been a key role in controlling iron transport in both humans and animals and in mediating anemia of inflammatory disease in humans. The role of hepcidin in the development of microcytic anemia in dogs with a cPSS has not been examined. HYPOTHESIS: To determine whether hepatic hepcidin mRNA expression decreases, while red blood cell count (RBC) and mean corpuscular volume (MCV) increase in dogs after surgical attenuation of a cPSS. ANIMALS: Eighteen client-owned dogs with confirmed cPSS undergoing surgical attenuation. METHOD: Prospective study. Red blood cell count (RBC) and mean corpuscular volume (MCV), together with hepatic gene expression of hepcidin, were measured in dogs before and after partial attenuation of a cPSS. RESULTS: There was a significant increase in both RBC (median pre 6.17 × 10(12) /L, median post 7.08 × 10(12) /L, P < .001) and MCV (median pre 61.5fl, median post 65.5fl, P = .006) after partial surgical attenuation of the cPSS. Despite the increase in both measured red blood cell parameters, hepatic gene expression of hepcidin remained unchanged. CONCLUSIONS AND CLINICAL IMPORTANCE: This study found no evidence that dysregulated production of hepcidin was associated with anemia in dogs with a cPSS.

Whole blood manganese concentrations in dogs with primary hepatitis.

OBJECTIVES: Increased whole blood manganese concentrations have been reported in humans with primary liver disease. Due to the neurotoxic effects of manganese, altered manganese homeostasis has been linked to the development of hepatic encephalopathy. Whole blood manganese concentrations are increased in cases of canine congenital portosystemic shunts, but it remains unclear whether dogs with primary hepatopathies also have altered manganese homeostasis. METHODS: Whole blood manganese concentrations were measured by graphite furnace atomic absorption spectrometry in 21 dogs with primary hepatitis, 65 dogs with a congenital portosystemic shunt, 31 dogs with non-hepatic illnesses and 18 healthy dogs. RESULTS: The whole blood manganese concentrations were significantly different between dogs with primary hepatitis, dogs with non-hepatic illnesses and healthy dogs (P=0·002). Dogs with primary hepatitis had significantly increased whole blood manganese concentrations compared with healthy dogs (P<0·05) and dogs with non-hepatic illnesses (P<0·01). Dogs with primary hepatitis had significantly lower whole blood manganese concentration compared with dogs with congenital portosystemic shunts (P=0·0005). CLINICAL SIGNIFICANCE: Dogs with primary hepatopathies have increased concentrations of whole blood manganese although these concentrations are not as high as those in dogs with congenital portosystemic shunts. The role of altered manganese homeostasis in canine hepatic encephalopathy is worthy of further study.

Serum haptoglobin concentrations in dogs with liver disease.

Dogs with liver disease have been shown to have increased serum C-reactive protein (CRP) concentrations. However, it is unclear whether dogs with liver disease also have increased serum haptoglobin concentrations. The aim of the study was to measure serum haptoglobin concentrations in healthy dogs, hospitalised dogs and dogs with liver diseases. Haptoglobin concentrations were measured in 30 healthy dogs, 47 hospitalised dogs with non-hepatic illness, 46 dogs with congenital portosystemic shunt (cPSS) and 11 dogs with primary hepatopathy. Haptoglobin concentrations were not significantly different between cPSS dogs with and without hepatic encephalopathy (HE), thus all cPSS dogs were considered as one group. Haptoglobin concentrations were significantly different between the remaining groups (P<0.0001). Hospitalised ill dogs had significantly higher haptoglobin concentrations than healthy dogs (P<0.001), dogs with cPSS (P<0.001) and dogs with primary hepatopathy (P<0.05). There was no significant difference between haptoglobin concentrations in healthy dogs, dogs with cPSS and dogs with primary hepatopathy. Haptoglobin concentrations were not significantly increased in dogs with liver diseases or in dogs with cPSS and HE. This is in contrast with the previously reported CRP results. This study demonstrates that liver function should be considered when interpreting haptoglobin concentrations in dogs.

Urine concentrations of xanthine, hypoxanthine and uric acid in UK Cavalier King Charles spaniels.

OBJECTIVES: Xanthine urolithiasis and asymptomatic xanthinuria have been diagnosed in Cavalier King Charles spaniel dogs suggesting that primary xanthinuria may be a breed-related disorder, although its prevalence remains unclear. The hypothesis of this study was that asymptomatic xanthinuria is common in Cavalier King Charles spaniel dogs. METHODS: Free catch urine samples were collected from 35 client-owned Cavalier King Charles spaniel dogs and from 24 dogs of other breeds. The purine metabolites were measured by high-performance liquid chromatography. The urine ratios of xanthine/creatinine and hypoxanthine/creatinine were calculated and compared between the two groups of dogs. RESULTS: The urine concentrations of purine metabolites were not significantly different between the two groups and were very low in both. The urine concentrations of xanthine in all 35 Cavalier King Charles spaniel were markedly lower than in the previously reported case of xanthine urolithiasis in a UK Cavalier King Charles spaniel dog. CLINICAL SIGNIFICANCE: Asymptomatic xanthinuria was not detected in this UK Cavalier King Charles spaniel population. This data may be used as a reference for urinary purine metabolite concentrations in the dog.

A prospective study of basal insulin concentrations in dogs with congenital portosystemic shunts.

OBJECTIVES: Hypoglycaemia is a common cause of morbidity in dogs with congenital portosystemic shunts but the aetiology is unknown. The hypothesis of this study was that dogs with congenital portosystemic shunts would have significantly higher insulin concentrations than dogs without congenital portosystemic shunts. The main objective of the study was to compare peripheral glucose and insulin concentrations between dogs with congenital portosystemic shunts and dogs without congenital portosystemic shunts. METHODS: Peripheral serum insulin and plasma glucose concentrations were measured in dogs with congenital portosystemic shunts and without congenital portosystemic shunts and compared both between groups as well as to reference intervals derived from healthy dogs. RESULTS: Congenital portosystemic shunts were diagnosed in 41 dogs. Forty-eight dogs hospitalised with other conditions acted as controls. Serum insulin concentrations were mildly elevated (Ä40 µU/mL) in seven dogs and were markedly elevated in two dogs with congenital portosystemic shunts, yet mild hypoglycaemia (3·3 mmol/L) was detected in only one of these dogs. Four dogs with congenital portosystemic shunts showed fasting hypoglycaemia, yet insulin concentrations were within or below the reference interval in three. There was no difference between the median insulin concentration of dogs with congenital portosystemic shunts and without congenital portosystemic shunts. CLINICAL SIGNIFICANCE: Hyperinsulinaemia is infrequently observed in dogs with congenital portosystemic shunts. The aetiology of hypoglycaemia in dogs with congenital portosystemic shunts merits further investigation.

Dogs with congenital porto-systemic shunting (cPSS) and hepatic encephalopathy have higher serum concentrations of C-reactive protein than asymptomatic dogs with cPSS.

Hepatic encephalopathy (HE) is a cause of significant morbidity and mortality in patients with liver disorders and a wide range of rodent models of HE have been described to facilitate studies into the pathogenesis and treatment of HE. However, it is widely acknowledged that no individual model perfectly mimics human HE and there is a particular need for spontaneous, larger animal models. One common congenital abnormality in dogs is the portosystemic shunt (cPSS) which causes clinical signs that are similar to human HE such as ataxia, disorientation, lethargy and occasionally coma. As inflammation has recently been shown to be associated with HE in humans, we hypothesised that inflammation would similarly be associated with HE in dogs with cPSS. To examine this hypothesis we measured C-reactive protein (CRP) in 30 healthy dogs, 19 dogs with a cPSS and no HE and 27 dogs with a cPSS and overt HE. There was a significant difference in CRP concentration between healthy dogs and dogs with HE (p < 0.001) and between dogs with HE and without HE (p < 0.05). The novel finding that there is an association between inflammation and canine HE strengthens the concept that HE in dogs with cPSS shares a similar pathogenesis to humans with HE. Consequently, dogs with a cPSS may be a good spontaneous model of human HE in which to further examine the role of inflammation and development of HE.

Insulin concentrations in dogs with hypoadrenocorticism.

Hypoglycaemia is frequently identified in canine cases of hypoadrenocorticism. Potassium and glucose cellular uptake are intimately linked by insulin. We hypothesized that in canine hypoadrenocorticism, hyperkalaemia would stimulate insulin release as a protective mechanism, translocating potassium from the extracellular compartment to the intracellular compartment and also lower glucose concentrations. Serum insulin concentrations were measured in 11 consecutive cases of canine hypoadrenocorticism which were hyperkalaemic and 33 dogs with non-adrenal illness. There was no significant difference between insulin concentrations in the two populations, and no correlation between insulin and potassium concentration in the hypoadrenal group. Thus, no support for the hypothesis was found, although multiple other factors such as pH and osmolality may be obscuring an effect.

Hypovitaminosis D in dogs with inflammatory bowel disease and hypoalbuminaemia.

OBJECTIVES: To compare serum vitamin D metabolites and plasma parathyroid hormone concentrations in dogs with inflammatory bowel disease and normal albumin concentration, dogs with inflammatory bowel disease and hypoalbuminaemia, healthy dogs and hospitalised ill dogs with non-gastrointestinal illness. METHODS: Serum 25 hydroxyvitamin D and 1,25 dihydroxyvitamin D concentrations were measured in 36 healthy dogs, 49 hospitalised ill dogs with non-gastrointestinal illnesses, 21 dogs with inflammatory bowel disease and normoalbuminaemia and 12 dogs with inflammatory bowel disease and hypoalbuminaemia. Plasma parathyroid hormone and ionised calcium concentrations were measured in a subset of these dogs. RESULTS: Concentrations of serum 25 hydroxyvitamin D were lower in hypoalbuminaemic dogs with inflammatory bowel disease than in the healthy dogs (P<0·001), hospitalised ill dogs (P<0·001) and normoalbuminaemic dogs with inflammatory bowel disease (P<0·001). Dogs with inflammatory bowel disease and hypoalbuminaemia had a higher plasma concentration of parathyroid hormone (P<0·01) and lower plasma concentration of ionised calcium (P<0·001) than hospitalised ill dogs. Dogs with inflammatory bowel disease had a positive correlation between serum 25 hydroxyvitamin D concentrations and serum albumin (P<0·0001), serum calcium (P<0·0001) and plasma ionised calcium (P<0·0005) concentrations. CLINICAL SIGNIFICANCE: Dogs with inflammatory bowel disease and hypoalbuminaemia frequently have ionised hypocalcaemia, high parathyroid hormone and low serum 25 hydroxyvitamin D concentrations. Further studies are indicated to establish the pathogenesis of this disease complication as well as therapeutic strategies to reverse this state.

Serum cardiac troponin I in dogs with primary immune-mediated haemolytic anaemia.

OBJECTIVES: The assessment of serum cardiac troponin I concentrations in dogs with a range of nonprimary cardiac illnesses has revealed that cardiac myocyte damage is commonplace in many canine diseases. Whilst it is well established that dogs with fatal immune-mediated haemolytic anaemia frequently have cardiac pathology based on post-mortem examinations, there is limited information on the incidence of cardiac myocyte damage in this population of dogs. METHODS: Serum cardiac troponin I concentrations were measured in 11 healthy dogs, 27 dogs with primary haemolytic anaemia and 49 hospitalised dogs without primary cardiac or haematological disorders. RESULTS: Dogs with primary haemolytic anaemia have higher serum concentrations of cardiac troponin I than hospitalised ill dogs (P<0.005) and healthy dogs (P<0.01). Using a cut-off of less than 0.1 ng/mL, 20 of 27 dogs with primary haemolytic anaemia had increased serum cardiac troponin I concentrations, which was a significantly higher proportion compared to the hospitalised ill dogs (P<0.001, 16 out of 49 dogs) and healthy dogs (P<0.05, 3 out of 11 dogs). CLINICAL SIGNIFICANCE: Dogs with primary haemolytic anaemia have a higher incidence of subclinical myocyte damage than healthy dogs or dogs with non-haematological or primary cardiac illnesses. The prognostic significance of increased serum cardiac troponin I concentrations in dogs with primary haemolytic anaemia merits further investigation.

Acute phase protein concentrations in dogs with nasal disease.

The concentrations of C-reactive protein (CRP), serum amyloid A, haptoglobin (Hp) and α(1)-acid glycoprotein were measured in dogs with clinical signs of nasal disease and compared with those of healthy dogs in order to determine the expression of these proteins in cases of canine nasal disease. A significant difference (P<0.001) between the symptomatic group and the control group was found for both CRP and Hp. Among the animals with nasal disease, a significant intergroup difference (P<0.05) was found in the expression of Hp between dogs with aspergillosis and those with chronic rhinitis.

Whole blood manganese concentrations in dogs with congenital portosystemic shunts.

BACKGROUND: Manganese (Mn) is an essential mineral that is a cofactor for many enzymes required in the synthesis of proteins, carbohydrates, and lipids. Because hepatic clearance is essential in Mn homeostasis, conditions in humans resulting in hepatic insufficiency including cirrhosis and both acquired and congenital portosystemic shunting have been reported to result in increased blood Mn concentrations and increased Mn content in the central nervous system. Because Mn toxicity causes neurologic disturbances, increased Mn concentrations have been implicated in the pathogenesis of hepatic encephalopathy. HYPOTHESES: Dogs with congenital portosystemic shunts (cPSS) have significantly higher whole blood Mn concentrations than do healthy dogs or those with nonhepatic illnesses. ANIMALS: Eighteen dogs with cPSS, 26 dogs with nonhepatic illnesses, and 14 healthy dogs. METHODS: Whole blood Mn was measured by graphite furnace atomic absorption spectrometry. The diagnosis of cPSS was made by ultrasonography or during celiotomy either by visual inspection of a shunting vessel or portovenography. RESULTS: Dogs with a cPSS had significantly higher whole blood Mn concentrations than did healthy dogs and dogs with nonhepatic illnesses. Whole blood Mn concentrations were not significantly different between healthy dogs and dogs with non-hepatic illnesses. CONCLUSION AND CLINICAL IMPORTANCE: Dogs with a cPSS have significantly increased whole blood Mn concentrations. Additional studies are warranted to investigate the role of Mn in cPSS-associated hepatic encephalopathy.

Calcium metabolism in eight dogs with hypoadrenocorticism.

Hypoadrenocorticism is a well-described endocrinopathy in dogs that results from deficient production and secretion of glucocorticoids and/or mineralocorticoids. Although hyperkalaemia, hyponatraemia and hypochloraemia are the most common electrolyte disturbances, hypercalcaemia also occurs in approximately 30 per cent of cases. The pathogenesis of hypercalcaemia in dogs with hypoadrenocorticism is unknown. This case series reports ionised calcium, parathyroid hormone, parathyroid hormone-related protein and vitamin D metabolite concentrations that were measured in eight dogs with concurrent hypercalcaemia and hypoadrenocorticism. Ionised calcium was increased in five of seven dogs with hypercalcaemia associated with hypoadrenocorticism. Parathyroid hormone, parathyroid hormone-related protein and 1,25 dihydroxyvitamin D concentrations were within their reference ranges in seven of eight dogs, six of seven cases and six of seven dogs, respectively. This case series highlights that hypercalcaemia associated with hypoadrenocorticism is rarely associated with increases in plasma parathyroid hormone, parathyroid hormone-related protein or serum 1,25 dihydroxyvitamin D concentrations.