Major histocompatibility complex class II alleles and haplotypes associated with non-suppurative meningoencephalitis in greyhounds.

Non-suppurative meningoencephalitis is a breed-restricted canine neuroinflammatory disorder affecting young greyhounds in Ireland. A genetic risk factor is suspected because of the development of disease in multiple siblings and an inability to identify a causative infectious agent. The aim of this study was to examine potential associations between dog leucocyte antigen (DLA) class II haplotype and the presence of the disease. DLA three locus haplotypes were determined in 31 dogs with non-suppurative meningoencephalitis and in 115 healthy control dogs using sequence-based typing (SBT) methods. All dogs were unrelated at the parental level. Two haplotypes (DRB1*01802/DQA1*00101/DQB1*00802 and DRB1*01501/DQA1*00601/DQB1*02201) were significantly (P = 0.0099 and 0.037) associated with the presence of meningoencephalitis, with odds ratios (95% confidence interval) of 5.531 (1.168-26.19) and 3.736 (1.446-9.652), respectively. These results confirm that there is an association between DLA class II haplotype and greyhound meningoencephalitis, suggesting an immunogenetic risk factor for the development of the disease. Greyhound meningoencephalitis may be a suitable model for human neuroinflammatory diseases with an immunogenetic component.

Retrospective study evaluation of DGGR lipase for diagnosis, agreement with pancreatic lipase and prognosis in dogs with suspected acute pancreatitis.

OBJECTIVES: Activity of 1,2-o-dilauryl-rac-glycero-3-glutaric acid-(6'-methylresorufin) ester (DGGR) lipase is considered to be more pancreas specific than traditional lipase assays. The aim of this study was to evaluate the diagnostic performance of DGGR lipase activity for suspected acute pancreatitis in dogs and to assess its prognostic usefulness. METHODS: Retrospective study of case records for suspected acute pancreatitis based on clinician-stated diagnosis, point-of-care and quantitative canine pancreas-specific lipase (cPL) results and consistent ultrasonographic features. Diagnostic performance of DGGR lipase was assessed by receiver-operating characteristic curve analysis, agreement by Cohen's kappa (κ) and prognostic value by multiple regression analysis. RESULTS: Median DGGR lipase activity was significantly (P < 0.001) higher in dogs with suspected acute pancreatitis [93.7 (range, 11.0-2853.0) U/L (n = 158)] compared to those with no evidence of pancreatitis [range, 20.9 (6.7-89.0) U/L (n = 356)]. A DGGR lipase activity >42.15 U/L had the best combined diagnostic sensitivity (81.0%) and specificity (92.1%). Previously established cut-offs (>130 and >80 U/L) had sensitivities of 40.5 and 43.0%, and specificities of 100 and 99.7%, respectively. There was near perfect (κ = 0.821) and substantial (κ = 0.751) agreement between DGGR lipase activity >42.15 U/L and quantitative cPL concentrations ≥200 and ≥400 µg/L, respectively. DGGR lipase activity but not quantitative cPL concentration was statistically (P = 0.043, odds ratio = 0.999) predictive of discharge but clinical utility is questionable. CLINICAL SIGNIFICANCE: Using DGGR lipase at the lower cut-off could provide an additional test for supporting a diagnosis of acute pancreatitis in dogs particularly if cPL results are not available. Larger studies are required to more fully assess its value in prognostication.

Qualitative and semiquantitative assessment of thyroid hormone binding proteins in greyhounds and other dog breeds.

Total thyroxine (T4) concentrations are lower in healthy greyhounds compared to most other non-sighthound breeds. In humans, variations in the structure or concentration of the major thyroid hormone binding proteins are responsible for most reported differences between total T4 concentrations in healthy individuals from different ethnic groups or other subpopulations. The aim of this study was to determine if such variations are also responsible for the lower total T4 concentrations in greyhounds. The predicted protein sequences of thyroxine-binding globulin (TBG), transthyretin and albumin were determined in liver tissue from a euthyroid greyhound with decreased T4 concentration and a Jack Russell terrier using reverse-transcriptase PCR. Sequences were compared to each other and online reference sequences. Serum proteins from 21 greyhounds and 21 non-sighthound dogs were separated by denaturing electrophoresis and immunoblots probed with polyclonal antibodies to human TBG and transthyretin. Reactive bands were quantified by densitrometry, expressed relative to the mean of reference samples included in each gel. Serum albumin concentrations were measured using a commercially-available assay. Several SNPs were identified but none was thought likely to explain the lower total T4 concentrations in greyhounds. There was no significant difference between the quantity of any of the binding proteins in serum from greyhounds and non-sighthound dogs. However, total T4 and transthyretin concentrations were highly correlated in the greyhound group (r = 0.73, P = 0.0002). Variation in the sequence of thyroid hormone binding proteins is not responsible for low greyhound total T4 concentrations. Further evaluation of the role of transthyretin is warranted.

Clinical evaluation of a novel liquid formulation of L-thyroxine for once daily treatment of dogs with hypothyroidism.

BACKGROUND: A liquid solution of levothyroxine (L-T4) is available for treatment of canine hypothyroidism. HYPOTHESIS: Once daily oral administration of a liquid L-T4 solution is effective and safe for controlling hypothyroidism in dogs. ANIMALS: Thirty-five dogs with naturally occurring hypothyroidism. METHODS: Dogs received L-T4 solution PO once daily at a starting dosage of 20 microg/kg body weight (BW). The dose was adjusted every 4 weeks, based on clinical signs and peak serum total T4 (tT4) concentrations. Target peak serum tT4 and thyroid stimulating hormone (TSH) concentrations, 4-6 hours posttreatment, were 35-95 nmol/L and < 0.68 ng/mL, respectively. Dogs were followed for up to 22 weeks after establishment of the maintenance dose. RESULTS: Clinical signs of hypothyroidism improved or resolved in 91% of dogs after 4 weeks of L-T4 treatment at 20 microg/kg once daily. The maintenance dose was established in 76, 94, and 100% of dogs after 4, 8, and 12 weeks of treatment, respectively. This was 20 microg L-T4/kg BW for 79% of the dogs, 30 microg/kg BW for 15%, and 10-15 microg/kg BW in the remaining 6%, once daily. Thereafter, median peak tT4 and TSH concentrations were 51 nmol/L and 0.18 ng/mL, respectively, and remained stable during the 22-week follow-up; clinical signs did not recur. CONCLUSIONS AND CLINICAL IMPORTANCE: All of the hypothyroid dogs had rapid clinical and hormonal responses to supplementation with the PO-administered L-T4 solution. The starting dosage of 20 microg L-T4/kg BW once daily was suitable for 79% of dogs.

A comparison of canine whole and intact parathyroid hormone concentrations as measured by different assays.

OBJECTIVES: To compare an intact immunoradiometric parathyroid hormone assay with (1) a non-isotopic technique; and, (2) a whole parathyroid hormone immunoradiometric assay. MATERIALS AND METHODS: Intact parathyroid hormone concentrations were measured using immunoradiometric (Scantibodies) and chemiluminescent (Immulite 2000) assays. Whole parathyroid hormone concentration was measured using an immunoradiometric assay (Scantibodies). RESULTS: A total of 48 and 47 samples, respectively, were used to compare immunoradiometric and chemiluminescent intact parathyroid concentrations and intact and whole parathyroid hormone concentrations by immunoradiometric assays. Using chemiluminescence, 39 (81.3%) samples had intact parathyroid hormone concentrations at or below the reported limit of detection of the assay (0.3 pmol/L). Intact [6.3 (2.0 to 95.5) pmol/L] and whole [3.3 (0.8 to 125.2) pmol/L] immunoradiometric parathyroid hormone concentrations exhibited excellent correlation. CLINICAL SIGNIFICANCE: Not all parathyroid hormone assays perform similarly. The chemiluminescent assay in this study cannot be recommended for use in dogs. The immunoradiometric intact parathyroid hormone assay proved to be a more reliable method. Given the correlation between intact and whole parathyroid hormone concentrations, it remains unclear which one is superior for routine clinical decision-making.

Thyroid hormone abnormalities and outcome in dogs with non-thyroidal illness.

OBJECTIVES: To document thyroid hormone abnormalities in dogs with non-thyroidal illness and identify markers of prognostic value. METHODS: Circulating total and free thyroxine, total triiodothyronine and thyrotropin concentrations were measured in 196 dogs with non-thyroidal illness. Clinical signs, previous medications and outcome were recorded in each case. Data were analysed to determine endocrine prognostic factors, and to document the prevalence of thyroid hormone abnormalities. RESULTS: Total triiodothyronine, and total and free thyroxine concentrations were decreased in 75.9, 34.7 and 4.5 per cent of cases, respectively. Dogs which were euthanased had significantly decreased total triiodothyronine, and total and free thyroxine concentrations compared with those which made a full recovery. Total triiodothyronine concentrations were significantly lower in dogs that were euthanased compared with those which made a partial recovery. CLINICAL SIGNIFICANCE: Thyroid hormone concentrations may be used as prognostic indicators in dogs with non-thyroidal illness. Low triiodothyronine syndrome may be more common in dogs than previously recognised.

Thyroid hormone concentrations in young, healthy, pretraining greyhounds.

Total thyroxine (T(4)) concentrations were below the non-breed-specific reference range in 42 of 46 healthy young greyhounds (91.3 per cent) and 16 (34.8 per cent) were at or below the limit of detection of the assay. Free T(4) concentrations were below the standard reference interval in 20.5 per cent of the animals and 13 per cent were at or below the limit of detection of the assay. In contrast, all the dogs' total tri-iodothyronine concentrations were within or above the non-breed-specific reference range and 67 per cent were within the upper half. All the dogs' thyroid stimulating hormone concentrations were within the non-breed-specific reference range. The results show that young greyhounds have markedly lower total and free T(4) concentrations than other breeds, and neither analyte can reliably be used to investigate the hypothyroidism in this breed as values were found below the limit of detection of each respective assay.

Lymphocytic-plasmacytic thyroiditis and glomerulonephritis in a boxer.

An 18-month-old boxer was presented for investigation of profound lethargy, and primary hypothyroidism was diagnosed. A strong antithyroglobulin antibody titre was also present, indicating lymphocytic (immune-mediated) thyroiditis as the cause of hypothyroidism. A concurrent protein-losing glomerulonephropathy was also detected, although the aetiology could not be determined at initial presentation. Thyroid replacement and dietary therapy were prescribed. The dog improved clinically for approximately 12 months when it was re-presented with poorly controlled hypothyroidism and renal failure. Postmortem examination confirmed the presence of lymphocytic-plasmacytic thyroiditis, in conjunction with membranoproliferative glomerulonephritis and renal failure.

Changes in canine ionised calcium under three storage conditions.

OBJECTIVES: To determine the ionised calcium concentration following aerobic collection of blood and to compare ionised calcium concentration and pH of heparinised whole blood and plasma at 48 hours following collection under three different storage conditions to assess if ionised calcium concentration can be measured retrospectively. METHODS: Blood was collected from 17 dogs for analysis of ionised calcium concentration and pH using a Rapidpoint 400 (Bayer) blood gas analyser. Blood was collected into a commercial preheparinised syringe and into a plain syringe, with subsequent transfer to a commercially available heparinised sample tube. Samples were analysed within 10 minutes, and the remainder was divided for storage. One aliquot was set-aside at room temperature for 48 hours, and the other was immediately centrifuged and the plasma divided for storage at room temperature and at 4 degrees C for 48 hours each. In all samples, ionised calcium concentration and pH were measured again at 48 hours after storage. RESULTS: There was no significant difference in ionised calcium concentration or pH between anaerobically and aerobically collected heparinised whole blood analysed within 10 minutes of collection. At 48 hours, ionised calcium concentrations had decreased under all storage conditions irrespective of the direction of pH change. CLINICAL SIGNIFICANCE: Ionised calcium concentration can be measured in aerobically collected samples within 10 minutes and at 48 hours after collection under the conditions described.

Hydrocortisone in the management of acute hypoadrenocorticism in dogs: a retrospective series of 30 cases.

OBJECTIVES: The objectives of this study were to describe the efficacy, outcome and adverse effects of intravenous hydrocortisone and fluid therapy for the management of acute hypoadrenocorticism in dogs. METHODS: A retrospective review of dogs with primary hypoadrenocorticism receiving intravenous hydrocortisone and fluid therapy was performed. RESULTS: Thirty newly-diagnosed dogs were included. There was an excellent clinical response, with all dogs surviving to discharge within a median of 2 days. In 23 cases with complete data, the mean rate of change of sodium over 24 hours was 0·48 (±0·28) mmol/L/hour, while the mean rate of change of potassium was -0·12 (±0·06) mmol/L/hour. Circulating potassium concentration normalised in 68·4% and 100% of cases of by 12 and 24 hours, respectively. Additional treatment for hyperkalaemia was not found necessary. Plasma sodium concentration increased by >12 mmol/L/24 hours on 7 of 23 (30·4%) occasions. One dog exhibited associated temporary neurological signs. CLINICAL SIGNIFICANCE: Intravenous hydrocortisone infusion and fluid therapy for the management of acute hypoadrenocorticism is associated with a rapid resolution of hyperkalaemia and is well tolerated with few adverse effects. Regular electrolyte monitoring is required to ensure that rapid increases in sodium concentration are avoided.

Treatment of insulinoma in a springer spaniel with streptozotocin.

An eight-year-old, female springer spaniel was treated for metastatic insulinoma with a single intravenous dose of 500 mg/m2 streptozotocin (SZN), and pre- and post-treatment diuresis. A tapering dose of corticosteroids was also administered over a 28 day period. SZN and corticosteroid administration resulted in resolution of hypoglycaemia and subsequent development of diabetes mellitus. Further metastases caused cervical spinal pain and the dog was euthanased 118 days after SZN administration. SZN can be safely used for the treatment of canine insulinoma, but, when compared with other published cases, a marked variation in clinical response to this drug exists and further study is warranted.

Canine serum thyroglobulin autoantibodies in health, hypothyroidism and non-thyroidal illness.

Thyroglobulin autoantibody (TGAA) was measured in serum from dogs with hypothyroidism (n = 42), non-thyroidal illness (NTI) (n = 77) and clinically healthy dogs (n = 70) using a commercially available enzyme immunoassay kit. Precision studies were consistent with good intra-assay and inter-assay repeatability. TGAA positive results occurred in 15 of the 42 (36 per cent) hypothyroid and four healthy dogs of the remaining 147 animals resulting in a lower incidence of false positive results than obtained with previous TGAA assays. The presence of TGAA was not influenced by age, sex, neutering or pedigree status. Of the four apparently healthy TGAA -positive dogs, two had additional clinicopathological evidence of hypothyroidism. TGAA was positive in 43 per cent of hypothyroid dogs with unexpectedly normal serum c TSH concentrations and was particularly useful in the classification of these cases.

Serum fructosamine concentrations in hyperthyroid cats.

Serum fructosamine concentrations were measured in 35 healthy cats and in 30 hyperthyroid cats before and 30 days after curative radioiodine ((131)I) treatment. Hyperthyroid cats were divided into those with 30 day post-treatment total thyroxine (T4) concentrations within (EuT4) or below (HypoT4) the reference range. The median (semi-interquartile range, SIR) fructosamine concentration was significantly lower in hyperthyroid compared with healthy cats (295. 0 (18.5) micromol l(-1)) both before (254.0 (27.6) micromol l(-1)) and after (268.5 (28.0) micromol l(-1)) treatment (P < 0.001 in each case). (131)I therapy was associated with increases in serum fructosamine (mean increase 20.4 micromol l(-1), P = 0.039) and total protein (6.3 g l(-1), P < 0.002) in the HypoT4 group and in globulin concentration in both EuT4 (5.9 g l(-), P < 0.002) and HypoT4 (5.2 g l(-1), P = 0.023) groups. There were no direct relationships between the observed elevations in fructosamine concentration and those in total protein or globulin concentrations suggesting that the effect may be due to reduced rates of protein turnover. Reduced values may need to be considered when interpreting serum fructosamine concentrations for monitoring the degree of glycaemic control in diabetic cats with concurrent hyperthyroidism.

Diagnosis and management of diabetes mellitus in five cats with somatotrophic abnormalities.

The clinical findings and management of five cats with abnormalities consistent with acromegaly were examined retrospectively. Growth hormone (GH) concentrations were elevated in four cats. In one, a minimal elevation of GH was accompanied by a marked elevation in insulin-like growth factor-1 (IGF-1). Insulin-like growth factor-1 concentrations supported the diagnosis in three of four cats measured, but was not elevated initially in one cat, despite a markedly elevated GH concentration. These findings suggest that elevated IGF-1 concentrations are a reliable indicator of acromegaly, but that values within the reference range do not exclude such a diagnosis. Clinical signs of acromegaly were similar to those previously reported, although upper respiratory stridor occurred in one cat, and insulin-resistant diabetes mellitus was not a consistent feature. Despite the lack of a widely available definitive treatment for acromegaly, good control of the clinical signs of diabetes mellitus can be achieved for long periods despite high doses of insulin often being required.

Serum thyroxine and triiodothyronine responses of hyperthyroid cats to thyrotropin.

OBJECTIVE: To document circulating total thyroxine (T4) and triiodothyronine (T3) responses after administration of thyrotropin (thyroid-stimulating hormone [TSH]) to hyperthyroid and healthy cats and assess the value of these responses as an additional diagnostic test for hyperthyroidism. DESIGN: Prospective case series. ANIMALS: 21 healthy and 40 hyperthyroid cats. PROCEDURES: Serum total T4 and T3 concentrations were measured by radioimmunoassay before and 6 hours after administration of 0.5 IU of bovine TSH/kg of body weight. RESULTS: In healthy cats, serum total T4 concentration increased after administration of TSH (mean +/- SD, 114.0 +/- 36.4 nmol/L) representing a mean increment 3 times baseline concentration (mean +/- SD, 33.7 +/- 7.6 nmol/L). In hyperthyroid cats, the relative increase in serum total T4 concentration was significantly (P < 0.001) different; baseline values (mean +/- SD, 236.2 +/- 146.0 nmol/L) increased minimally after TSH administration (mean +/- SD, 308.1 +/- 178.9 nmol/L) There was a significant negative correlation (rs = -0.366) between relative increase in serum total T4 concentration after TSH administration and baseline concentration in hyperthyroid cats. In 3 cats with equivocal baseline serum total T4 concentration, the T4 response to TSH administration was indistinguishable from that in healthy cats. Serum total T3 response to TSH administration was significantly (P < 0.001) lower in hyperthyroid, compared with healthy, cats but the T3 response in healthy cats was more variable than that for T4 CONCLUSIONS: Thyrotoxic cats with high baseline serum total T4 concentration have a limited T4 response to TSH stimulation. Hyperthyroid cats with equivocal baseline serum total T4 concentrations have T4 response after TSH stimulation similar to those of healthy cats. Measurement of serum total T3 concentration provides no additional information. CLINICAL RELEVANCE: The TSH response test is of limited value in diagnosing hyperthyroidism in cats.

Effect of illness not associated with the thyroid gland on serum total and free thyroxine concentrations in cats.

OBJECTIVE: To determine circulating concentrations and fate of total and free thyroxine (T4) in cats with various illnesses not associated with the thyroid glands (nonthyroidal illnesses). DESIGN: Prospective study. ANIMALS: 98 cats with nonthyroidal illness and 50 clinically normal cats. PROCEDURE: Serum total T4 concentrations were measured by radioimmunoassay, and serum free T4 concentrations were measured by direct equilibrium dialysis. Free T4 fraction was calculated from these 2 values. RESULTS: Serum total T4 concentrations were significantly (P < 0.001) lower in sick cats (mean +/- SD, 17.18 +/- 8.14 nmol/L), compared with healthy cats (mean +/- SD, 26.00 +/- 7.62 nmol/L). Serum total T4 concentrations were inversely correlated with mortality. Differences in serum free T4 concentrations in sick cats (mean +/- SD, 27.70 +/- 13.53 pmol/L), compared with healthy cats (mean +/- SD, 24.79 +/- 8.33 pmol/L), were not significant. A few sick cats had serum free T4 concentrations greater than the reference range. Calculated free T4 fraction was significantly (P < 0.001) greater in sick cats (mean +/- SD, 0.24 +/- 0.30%), compared with healthy cats (mean +/- SD, 0.10 +/- 0.06%). CLINICAL IMPLICATIONS: Euthyroidism is maintained in sick cats, despite low serum total T4 concentrations. Measurement of serum total T4 concentrations is a valuable prognostic indicator. Serum free T4 concentrations should be used cautiously as a sole diagnostic criterion for confirmation of hyperthyroidism.

Feline hyperthyroidism. Diagnostics and therapeutics.

Today, hyperthyroid cats are less symptomatic than those 10 or 15 years ago, and early diagnosis impacts the range and severity of the routine clinicopathological abnormalities traditionally associated with this disorder. In addition, a greater range of tests may be required to confirm a diagnosis as cats may be assessed before a serum total T4 concentration exceeds the reference range. Curative treatment options may be more desirable in early cases, but renal function may be adversely affected by the induction of euthyroidism and should be carefully evaluated before treatment.

Historical, clinical and laboratory features of 126 hyperthyroid cats.

The historical and clinical features and the haematological and biochemical changes in 126 cats with hyperthyroidism are described; 125 of the cats were domestic short- or longhaired, and one was a chinchilla. There were 62 males and 64 females with a mean age of 13.0 years. The duration of signs ranged from two days to two years with a mean of 5.4 months. The historical and clinical features were weight loss, polyphagia, polyuria/polydipsia, tachycardia, hyperactivity, diarrhoea, respiratory abnormalities, other cardiac abnormalities, skin lesions, vomiting, moderately raised temperature, decreased activity, decreased appetite, congestive cardiac failure, haematuria and intermittently decreased appetite. Goitre was palpable in 123 cats. The serum total thyroxine concentrations of the cats were more than three standard deviations above the mean of the reference range. Serum total tri-iodothyronine concentrations ranged from 0.78 to 14.96 nmol/litre and were within the reference range in 11 of the cats. Mild hyperthyroidism was a much commoner cause of high normal or marginally above normal thyroid hormone concentrations than severe, concurrent, non-thyroidal illness. Other common biochemical changes were increased of serum alanine aminotransferase, urea, aspartate aminotransferase, alkaline phosphatase and lactate dehydrogenase. There were minimal changes in the red cell parameters. Leucocyte changes showed two trends: a mature neutrophilia, either with or without an accompanying leucocytosis often in association with a lymphopenia, or an eosinophilia, either with or without a lymphocytosis.

Dynamic adrenal function testing in eight dogs with hyperadrenocorticism associated with adrenocortical neoplasia.

The results of adrenocorticotropin (ACTH) stimulation and low-dose dexamethasone suppression tests (LDDST) were evaluated retrospectively in eight dogs with clinical signs of hyperadrenocorticism arising from functional adrenocortical tumours, and compared with the results from 12 dogs with confirmed pituitary-dependent hyperadrenocorticism (PDH). The post-ACTH cortisol concentration in the dogs with adrenocortical tumours ranged from 61 to 345-6 nmol/litre (median 251.5 nmol/litre) and they were within the reference range (150 to 450 nmol/litre) in five and unexpectedly low (< 150 nmol/litre) in three dogs. Both the basal and post-ACTH cortisol concentrations were significantly lower in the dogs with adrenocortical neoplasia than in the dogs with PDH. Eight hours after the LDDST, only two of six dogs with adrenocortical tumours had a cortisol concentration above 30 nmol/litre, and the median resting, three, and eight-hour cortisol concentrations were 31.5, 23.0, and 22.7 nmol/litre respectively. There was no significant cortisol suppression during the LDDST, although interpretation was complicated by the low cortisol concentrations, but two dogs showed a pattern of apparent suppression. Two dogs with adrenal tumours showed a diagnostically significant increase in 17-OH-progesterone concentration in response to ACTH although their cortisol concentrations did not increase greatly. These results differ from previous reports of the response of functional adrenal tumours to dynamic endocrine tests.