Method Validation and Establishment of Reference Intervals for an Insulin-like Growth Factor-1 Chemiluminescent Immunoassay in Cats.

Previously, radioimmunoassay (RIA) has been the only assay to measure insulin-like growth factor-1 (IGF-1) to diagnose hypersomatotropism (HS). Due to radiation concerns, availability, and the cost of IGF-1 RIA, validation of assays for automated analysers such as a chemiluminescent immunoassay (CLIA) is needed. The aim of this study was to validate a CLIA for measurement of feline IGF-1 (IMMULITE 2000® XPi, Siemens Medical Solutions Diagnostics, Malvern, PA, USA) compared to IGF1 RIA, establish reference interval (RI), and determine a cut-off value for diagnosis of HS in diabetic cats. Validation of assay performance included precision, linearity, and recovery studies. Right-sided RI was determined using surplus serum of 50 healthy adult cats. Surplus serum samples of diabetic cats with known IGF-1 concentration with (n = 32/68) and without HS (n = 36/68) were used for method comparison with RIA. The cut-off for diagnosis of HS was established using receiver operating characteristic (ROC) analysis. The intra-assay coefficient of variation (CV) was ≤4.7%, and the inter-assay CV was ≤5.6% for samples with low, medium, and high IGF-1 concentration. Linearity was excellent (R2 > 0.99). The correlation between CLIA and RIA was very high (rs = 0.97), with a mean negative bias for CLIA of 24.5%. The upper limit of RI was 670 ng/mL. ROC analysis showed an area under the curve of 0.94, with best cut-off for diagnosis of HS at 746 ng/mL (sensitivity, 84.4%; specificity, 97.2%). The performance of CLIA was good, and the RI and cut-off for HS diagnosis established in this study allow for CLIA to be used in routine work-up of diabetic cats.

Cat alpha-1-acid glycoprotein enzyme-linked immunosorbent assay: performance characteristics and reference intervals.

OBJECTIVES: The aim of this study was to evaluate performance of a feline-specific ELISA for the measurement of alpha-1-acid glycoprotein (AGP) and to establish a reference interval (RI). METHODS: Surplus serum samples with low (~200 µg/ml), medium (~450 µg/ml) and high (~745 and 930 µg/ml) AGP concentrations were used to assess the intra- and inter-assay coefficients of variation (CVs). The quality goal for bioanalytical method validation was a CV of <20%. Linearity was assessed by serial dilution of a sample with a high AGP concentration. Spike recovery was evaluated by mixing samples with low, medium and high AGP concentrations at different ratios. To establish the RI, residual serum samples from 51 healthy adult cats that were presented for health examinations or blood donation between August 2020 and June 2021 were included. RESULTS: The intra-assay CV was 8.5%, 4.3% and 4.0%, and the inter-assay CV was 18.8%, 15.5% and 11.5% for serum samples with low, medium and high AGP concentrations, respectively. Excellent linearity (R2 = 0.98) was demonstrated for AGP concentrations ranging between 251.6 and 954.4 µg/ml. Average recovery was 95.0-99.7%. The right-sided RI for AGP was 328 µg/ml (90% confidence interval 300-354). Age had a statistically significant impact (increasing values with older age, P = 0.0026), but sex did not (P = 0.44), on AGP concentrations. CONCLUSIONS AND RELEVANCE: The ELISA was accurate and showed acceptable precision with the modification of dilution used in this study. AGP concentrations in this population appeared to increase with increasing age.

Survival in canine tetanus - retrospective analysis of 42 cases (2006-2020).

Objective: To define factors associated with survival in dogs with tetanus and to evaluate the prognostic significance of an established severity classification scheme. Methods: Medical records of dogs with the clinical diagnosis of tetanus were retrospectively reviewed with regard to signalment, clinical signs, clinicopathological findings on admission, wound characteristics, complications, therapeutic measures, and survival to discharge. Based on the extracted data, dogs were graded according to a previously published 4-class severity scheme. Non-parametric tests were applied for comparisons between survival categories. Results: Forty-two dogs fulfilled inclusion criteria, of which 32 survived. Of 10 non-survivors, 4 died and 6 were euthanised. Non-survivors were more often younger than 2 years of age (6/10 vs. 7/32 dogs, p = 0.023), had shorter duration of specific signs of tetanus (time from onset of typical signs to presentation) (2 vs. 4 days, p = 0.016), were prescribed less often antibiotics prior to presentation (p = 0.006), had higher tetanus severity grade (10/12 dogs in Class III or IV died, p < 0.001), more often received acepromazine (p = 0.009) and atropine (p = 0.012), and more often had hyperthermia (p = 0.005) and respiratory complications (pneumonia, laryngeal spasm; p = 0.008). Wound characteristics, the use of tube feeding, metronidazole, methocarbamol, magnesium and antitoxin were not significantly different between non-survivors and survivors. Clinical significance and conclusion: Young dogs with a rapid course of severe generalized tetanus have a guarded prognosis. The previously described severity classification scheme proved valuable in predicting survival. Prospective multi-center studies are needed to clarify the prognostic significance of age, sedative usage and modified versions of an established classification scheme, including the presence of respiratory complications.

[Granulomatous colitis in a French Bulldog puppy]. / Granulomatöse Kolitis bei einem Französische-Bulldogge-Welpen.

A 6-month-old French bulldog was presented due to chronic large intestinal diarrhea of 4 months duration. The diagnostic procedures initiated by the referring veterinarian had resulted in a tentative diagnosis of chronic enteropathy, however treatment consisting of elimination diet as well as antibiotic, anthelmintic, anti-inflammatory and immunosuppressive medication had been unsuccessful. By means of endoscopy and histological examination, pronounced erosions and ulcerations of the colonic mucosa were detected. Fluorescence in situ hybridization enabled the identification of invasive Escherichia coli within the colonic mucosa and colonic macrophages, allowing for the diagnosis of granulomatous colitis. The dog showed complete remission of clinical signs following 8 weeks of treatment with enrofloxacin. This case report describes the first successful treatment of granulomatous colitis with enrofloxacin in a French bulldog puppy in Germany and is intended to sensitize the reader to this disease in (young) dogs.

[Magnesium in dogs and cats - physiology, analysis, and magnesium disorders]. / Magnesium bei Hund und Katze ­ physiologische Aspekte, Messung und Störungen im Magnesiumhaushalt.

Magnesium is the second most abundant intracellular cation after potassium. It plays a vital role in almost every metabolic process in the body and is important for bone mineralization, muscle contraction and relaxation, and neuronal signal transduction. Because of its expanding role in intensivecare medicine, there has been a significant increase in knowledge during recent years regarding the functions of magnesium in the body, problems leading to magnesium disorders, and limitations of laboratory testing. Alterations of serum magnesium constitute one of the most prevalent electrolyte abnormalities in critically ill patients and can lead to lifethreatening complications. In addition to human literature, most of the information regarding the role of magnesium is derived from buiatrics. In recent years, a few studies in veterinary medicine have also started to consider the importance of magnesium in dogs and cats.

[Hypermagnesemia of ionized magnesium in 199 dogs - A hospital population-based study on prevalence, etiology and prognosis with special emphasis on kidney disease and the measurement of total magnesium]. / Hypermagnesiämie des ionisierten Magnesiums bei 199 Hunden.

OBJECTIVE: To investigate the prevalence and etiology of an increased concentration of ionized magnesium (iMg) in dogs and to evaluate its prognostic relevance. MATERIALS AND METHODS: From April 2009 to December 2013, serum electrolytes were measured in 9950 dogs using an ion-selective electrode. Inclusion criterion was an iMg concentration ≥ 0.68 mmol/l, whereby total Mg (tMg), potassium, ionized calcium, and micturition were also evaluated in this retrospective study. In the case of repeated measurements in an animal, only the initial measurement of the increased iMg concentration was considered. According to the etiology, patients were categorized in the diagnostic groups: azotemia, iatrogenic/medication associated, endocrine diseases, tissue damage, and unknown etiology of hypermagnesemia. The survival rate was analyzed and the iMg concentration was compared between the diagnostic groups. The correlation between iMg and tMg was assessed. RESULTS: The prevalence of increased iMg concentration was 2.0 % (199/9950). The most prevalent causes were azotemia (80/199; 40 %), followed by iatrogenic hyper-magnesemia (37/199; 19 %), tissue damage (21/199; 11 %), and endocrine diseases (12/199; 6 %). In 49/199 cases (25 %), the etiology of hypermagnesemia was unknown. An additional hypercalcemia was evident in 24/199 dogs (12 %) and 58/199 (29 %) dogs displayed hypocalcemia. In 64 % of the dogs (51/80) with azotemia, underlying renal disease was present, from which 53 % (27/51) exhibited hyperkalemia. Moreover, 37 % (19/51) of the animals with renal disease displayed anuria/oliguria, 59 % (11/19) of which were hyperkalemic. Overall, 83/199 (42 %) of the dogs died, whereby 48/83 (58 %) belonged to the azotemia group. The iMg concentration did not differ significantly between the groups (p = 0.15). There was a poor correlation between iMg and tMg (rs = 0.28). CONCLUSION: An increased iMg concentration is rare and indicative of a severe disease in the majority of cases. Particularly in patients with acute renal disease, hypermagnesemia can be associated with increased mortality. The tMg concentration does not reflect the iMg concentration.

[Alimentary thyrotoxcicosis in two dogs]. / Alimentäre Thyreotoxikose bei zwei Hunden.

Two dogs with increased thyroxin concentrations compatible with hyperthyroidism were referred for further examinations. One dog displayed clinical signs of hyperthyroidism. Based on history, clinical examination, laboratory evaluation and scintigraphy an alimentary thyrotoxicosis was identified. It was caused by feeding a BARF diet containing thyroidal tissue in one dog and by conventional dog food in the other patient. After changing the diet the clinical signs resolved in the affected dog. A control examination revealed thyroxin concentrations within the reference range in both dogs.