Choline-deficient high-fat diet-induced MASH in Göttingen Minipigs: Characterisation and effects of a chow reversal period.

The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH) is increasing, and translational animal models are needed to develop novel treatments for this disease. The physiology and metabolism of pigs have a relatively high resemblance to humans, and the present study aimed to characterise choline-deficient, and high-fat diet (CDAHFD) fed Göttingen Minipigs as a novel animal model of MASLD/MASH. Göttingen Minipigs were fed CDAHFD for up to 5 months, and the phenotype was investigated by analysis of plasma parameters and repeated collection of liver biopsies. Furthermore, changes in hepatic gene expression during the experiment were explored by RNA sequencing. For a subset of the minipigs, the diet was changed from CDAHFD back to chow to investigate if the liver pathology was reversible. Göttingen Minipigs on CDAHFD gained bodyweight, and plasma levels of cholesterol, AST, ALT, ALP and GGT were increased. CDAHFD-fed minipigs developed hepatic steatosis, inflammation, and fibrosis, which in 5 of 16 animals progressed to cirrhosis. During an 11-week chow reversal period, steatosis regressed while fibrosis persisted. Regarding inflammation, the findings were less clear, depending on the type of readout. MASH Human Proximity Scoring (combined evaluation of transcriptional, phenotypic and histopathological parameters) showed that CDAHFD-fed Göttingen Minipigs resemble human MASLD/MASH better than most rodent models. In conclusion, CDAHFD-fed minipigs develop a MASH-like phenotype which in several aspects resemble the changes observed in human patients with MASLD/MASH. Furthermore, repeated collection of liver biopsies allow detailed characterisation of histopathological changes over time in individual animals.

Myocardial Changes in Diabetic and Nondiabetic Nonhuman Primates.

Diabetic human patients have increased risk of heart failure compared to healthy subjects. The underlying mechanisms for this are not fully understood, and to help develop improved treatment strategies, well-characterized animal models are essential. To investigate cardiac dysfunction in diabetes, this study evaluated myocardial changes in 10 aging rhesus monkeys with and without diabetes. Based on evaluation of plasma glycosylated hemoglobin and glucose, 7 of 10 rhesus macaques had diabetes for a minimum of 11 months, while 3 of 10 were categorized as nondiabetic. A detailed histological examination of formalin-fixed left ventricular myocardial samples was followed by a semiquantitative evaluation of myocardial fibrosis and fat infiltration; digital quantifications of myocardial collagen, lipofuscin, and nuclear area fractions; and measurements of cardiomyocyte diameter. Histological myocardial evaluation revealed the presence of lipofuscin; large nuclei; interstitial, replacement, and vascular fibrosis; adipocyte infiltration; and vacuolar degeneration with atrophy of cardiomyocytes and fibrosis. However, there were no differences between groups for semiquantitative fat infiltration, fibrosis, cardiomyocyte size, collagen, or nuclear and lipofuscin area fraction. Lipofuscin area fraction correlated with plasma insulin, triglyceride, total cholesterol, and high-density lipoprotein cholesterol concentrations. In conclusion, myocardial pathological changes were found in left ventricular myocardium in aged rhesus macaques, independent of the stage of diabetes. The duration of diabetes might have been too short to cause differences between groups.

Cardiac and metabolic changes in long-term high fructose-fat fed rats with severe obesity and extensive intramyocardial lipid accumulation.

Metabolic syndrome and obesity-related diseases are affecting more and more people in the Western world. The basis for an effective treatment of these patients is a better understanding of the underlying pathophysiology. Here, we characterize fructose- and fat-fed rats (FFFRs) as a new animal model of metabolic syndrome. Sprague-Dawley rats were fed a 60 kcal/100 kcal fat diet with 10% fructose in the drinking water. After 6, 12, 18, 24, 36, and 48 wk of feeding, blood pressure, glucose tolerance, plasma insulin, glucose, and lipid levels were measured. Cardiac function was examined by in vivo pressure volume measurements, and intramyocardial lipid accumulation was analyzed by confocal microscopy. Cardiac AMP-activated kinase (AMPK) and hepatic phosphoenolpyruvate carboxykinase (PEPCK) levels were measured by Western blotting. Finally, an ischemia-reperfusion study was performed after 56 wk of feeding. FFFRs developed severe obesity, decreased glucose tolerance, increased serum insulin and triglyceride levels, and an initial increased fasting glucose, which returned to control levels after 24 wk of feeding. The diet had no effect on blood pressure but decreased hepatic PEPCK levels. FFFRs showed significant intramyocardial lipid accumulation, and cardiac hypertrophy became pronounced between 24 and 36 wk of feeding. FFFRs showed no signs of cardiac dysfunction during unstressed conditions, but their hearts were much more vulnerable to ischemia-reperfusion and had a decreased level of phosphorylated AMPK at 6 wk of feeding. This study characterizes a new animal model of the metabolic syndrome that could be beneficial in future studies of metabolic syndrome and cardiac complications.

NASH-inducing Diets in Göttingen Minipigs.

BACKGROUND: Owing to the human-like physiology, a minipig model of nonalcoholic steatohepatitis (NASH) could be valuable. Pigs, however, rarely develop substantial hepatic steatosis, even when fed diets with high fat, fructose, and cholesterol (FFC) content. The potential of choline-deficient, amino acid-defined high-fat diets (CDAHFD) was therefore evaluated in Göttingen Minipigs. METHODS: Castrated male Göttingen Minipigs were fed either chow (n = 5) or one of the three NASH diets: FFC (n = 5), CDAHFD with sucrose (CDAHFD-S; n = 4), or fructose (CDAHFD-F; n = 4) for 8 weeks. Liver and blood samples were collected after 2 weeks and at termination. RESULTS: Compared with chow, the body weight was higher after FFC (9.8 ± 0.4 versus 8.5 ± 1.2 kg; mean ± SD) and less after CDAHFD-S (6.4 ± 0.8 kg) and CDAHFD-F (6.9 ± 0.8 kg). Liver weight per kg body weight was significantly increased in all 3 NASH groups (FFC 2.1 times; and both CDAHFD diets 3.1 times). Histologically, pronounced macrovesicular steatosis developed only in the CDAHFD groups. Inflammation was present in all three NASH groups. In the CDAHFD groups, inflammatory cells formed crown-like structures around steatotic hepatocytes. Sirius red staining revealed mild fibrosis in the two CDAHFD groups with the fibrotic potential being further supported by immunohistochemical staining for activated stellate cells and gene expression analyses. No noticeable differences were found between CDAHFD-S and CDAHFD-F. CONCLUSIONS: Göttingen Minipigs fed CDAHFD developed pronounced steatosis with inflammation around steatotic hepatocytes and incipient fibrosis, thereby showing potential as a model for human NASH. Further studies are needed to investigate the period needed for marked fibrosis to develop.

Predictive value of natriuretic peptides in dogs with mitral valve disease.

Natriuretic peptides are useful in diagnosing heart failure in dogs. However, their usefulness in detecting early stages of myxomatous mitral valve disease (MMVD) has been debated. This study evaluated N-terminal (NT) fragment pro-atrial natriuretic peptide (NT-proANP) and NT-pro-brain natriuretic peptide (NT-proBNP) in 39 Cavalier King Charles Spaniels (CKCS) with pre-clinical mitral valve regurgitation (MR), sixteen dogs with clinical signs of heart failure (HF) and thirteen healthy control dogs. Twenty seven CKCS and ten control dogs were re-examined 4 years after the initial examination and the status of the dogs 5 years after the initial examination was determined by telephone calls to the owner. All dogs were evaluated by clinical examination and echocardiography. CKCS with severe MR had higher NT-proANP and NT-proBNP compared to controls and CKCS with less severe MR. Dogs with clinical signs of HF had markedly elevated NT-proANP and NT-proBNP. Plasma concentrations of the natriuretic peptides measured at re-examination could predict progression in regurgitant jet size.

18F-FDG PET/MR-imaging in a Göttingen Minipig model of atherosclerosis: Correlations with histology and quantitative gene expression.

BACKGROUND AND AIMS: The advantage of combining molecular and morphological imaging, e.g. positron emission tomography and magnetic resonance imaging (PET/MRI), is reflected in the increased use of these modalities as surrogate end-points in clinical trials. This study aimed at evaluating plaque inflammation using 18F-fluorodeoxyglucose (18F-FDG)-PET/MRI, and gene expression in a minipig model of atherosclerosis. METHODS: Göttingen Minipigs were fed for 60 weeks with fat/fructose/cholesterol-rich diet (FFC), chow (Control) or FFC-diet changed to chow midway (diet normalization group; DNO). In all groups, 18F-FDG-PET/MRI of the abdominal aorta was assessed midway and at study-end. The aorta was analyzed using histology and gene expression. RESULTS: At study-end, FFC had significantly higher FDG-uptake compared to Control (target-to-background maximal uptake, TBRMax (95% confidence interval) CITBRMax: 0.092; 7.32) and DNO showed significantly decreased uptake compared to FFC (CITBRMax: -5.94;-0.07). No difference was observed between DNO and Control (CITBRMax: -2.71; 4.11). FFC displayed increased atherosclerosis and gene expression of inflammatory markers, including vascular cell adhesion molecule 1 (VCAM-1), cluster of differentiation 68 (CD68), matrix metalloproteinase 9 (MMP9), cathepsin K (CTSK) and secreted phosphoprotein 1 (SPP1) compared to Control and DNO (all, p < 0.05). FDG-uptake correlated with gene expression of inflammatory markers, including CD68, ρs = 0.58; MMP9, ρs = 0.46; SPP1, ρs = 0.44 and CTSK, ρs = 0.49; (p ≤ 0.01 for all). CONCLUSIONS: In a model of atherosclerosis, 18F-FDG-PET/MRI technology allows for detection of inflammation in atherosclerotic plaques, consistent with increased inflammatory gene expression. Our findings corroborate clinical data and are important in pre-clinical drug development targeting plaque inflammation.

Increased nitric oxide release and expression of endothelial and inducible nitric oxide synthases in mildly changed porcine mitral valve leaflets.

BACKGROUND AND AIM OF THE STUDY: Little is known of the local role of nitric oxide (NO) in heart valves in relation to heart valve diseases. The study aim was to examine NO release and the expression of both endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) in relation to early local changes in porcine mitral valves. METHODS: A histological evaluation of mitral valve leaflets from slaughter pigs and sows was made, and the expression of eNOS and iNOS protein measured using immunohistochemistry. Furthermore, mRNA levels of eNOS and iNOS were measured using real-time RT-PCR. A calibrated NO-specific electrode was used to measure local NO release in specific regions of the anterior mitral leaflet from slaughter pigs and sows interchordally at the tip of the leaflet (region A), at the chordal insertion (region B), and at the center of the leaflet (region C). RESULTS: Leaflets from sows had an increased accumulation of mucopolysaccharides (MPS) compared to those from slaughter pigs. Furthermore, mRNA levels of eNOS and iNOS were significantly increased in region C due to very high levels of expression in some sow leaflets. NO release in the sow mitral valve leaflet was increased in regions B and C compared to that in region A. CONCLUSION: The relative distribution of NO release is increased in regions of porcine mitral valve leaflets with deposition of MPS and defraction of the valve structure, which may reflect changes in both eNOS and iNOS expression.

Hemostatic biomarkers in dogs with chronic congestive heart failure.

BACKGROUND: Chronic congestive heart failure (CHF) in humans is associated with abnormal hemostasis, and abnormalities in hemostatic biomarkers carry a poor prognosis. Alterations in hemostatic pathways can be involved in the pathogenesis of CHF in dogs, and microthrombosis in the myocardium could contribute to increased mortality. HYPOTHESIS: That plasma concentration or activity of hemostatic biomarkers is altered in dogs with CHF and that these factors predict mortality. ANIMALS: Thirty-four dogs with CHF caused by either dilated cardiomyopathy (DCM, n=14) or degenerative valvular disease (CDVD, n=20) compared with 23 healthy age-matched control dogs were included in this study. Dogs with CHF were recruited from 2 referral cardiology clinics, and control dogs were owned by friends or colleagues of the investigators. METHODS: Clinical examination and echocardiography were performed in all dogs. Plasma fibrinogen and D-dimer concentrations, antithrombin and protein C activity, and thrombin-antithrombin complex (TAT) were measured in all dogs. RESULTS: Dogs with CHF had significantly higher fibrinogen (P = .04), D-dimer (P = .002), and TAT concentration (P < .0001), lower antithrombin (P < .0001) and protein C activity (P < .001) compared with control dogs. None of the hemostatic biomarkers were associated with risk of death. CONCLUSIONS AND CLINICAL IMPORTANCE: There is evidence of a procoagulant state in dogs with CHF. The lack of predictive value for survival might be due to the small number of dogs examined. Further studies are necessary to investigate the presence and importance of microthrombosis in dogs with CHF.

Platelet function in dogs: breed differences and effect of acetylsalicylic acid administration.

BACKGROUND: Clinical studies investigating platelet function in dogs have had conflicting results that may be caused by normal physiologic variation in platelet response to agonists. OBJECTIVES: The objective of this study was to investigate platelet function in clinically healthy dogs of 4 different breeds by whole-blood aggregometry and with a point-of-care platelet function analyzer (PFA-100), and to evaluate the effect of acetylsalicylic acid (ASA) administration on the results from both methods. METHODS: Forty-five clinically healthy dogs (12 Cavalier King Charles Spaniels [CKCS], 12 Cairn Terriers, 10 Boxers, and 11 Labrador Retrievers) were included in the study. Platelet function was assessed by whole-blood aggregation with ADP (1, 5, 10, and 20 microM) as agonist and by PFA-100 using collagen and epinephrine (Col + Epi) and Col + ADP as agonists. Plasma thromboxane B(2) concentration was determined by an enzyme immunoassay. To investigate the effect of ASA, 10 dogs were dosed daily (75 or 250 mg ASA orally) for 4 consecutive days. RESULTS: A higher platelet aggregation response was found in CKCS compared to the other breeds. Longer PFA-100 closure time (Col + Epi) was found in Cairn Terriers compared to Boxers. Plasma thromboxane B(2) concentration was not statistically different between groups. Administration of ASA prolonged the PFA-100 closure times, using Col + Epi (but not Col + ADP) as agonists. Furthermore, ASA resulted in a decrease in whole-blood platelet aggregation. CONCLUSIONS: Platelet function is influenced by breed, depending upon the methodology applied. However, the importance of these breed differences remains to be investigated. The PFA-100 method with Col + Epi as agonists, and ADP-induced platelet aggregation appear to be sensitive to ASA in dogs.

Arteriosclerotic changes in the myocardium, lung, and kidney in dogs with chronic congestive heart failure and myxomatous mitral valve disease.

BACKGROUND: The occurrence of small vessel arteriosclerosis in the myocardium, kidney, and lung in dogs with naturally occurring myxomatous mitral valve disease has not been previously investigated systematically. METHODS: Twenty-one dogs with naturally occurring congestive heart failure and 21 age-matched, sex-matched, and weight-matched control dogs underwent extensive pathological and histopathological examination. Morphometry and scoring of tissue sections were used to measure arterial narrowing and fibrosis in the myocardium, kidney, and lung; and intimal thickness and plaque formation in the aorta and pulmonary artery. RESULTS: Dogs with congestive heart failure had significantly more arterial narrowing in the left ventricle (P < .003), lung (P < .0001), and kidney (P < .02); intimal-medial thickening in the pulmonary artery (P = .04); and fibrosis in the left ventricle (P < .0001) than control dogs. However, they did not have more plaque formation or intimal-medial thickening in the aorta than controls. There was significantly more arterial narrowing in papillary muscles than in all other locations in dogs with congestive heart failure (P < .002). In control dogs, arterial changes were less pronounced and did not differ in different locations. CONCLUSIONS: Dogs with naturally occurring myxomatous mitral valve disease have significantly more arterial changes in the myocardium, lung, and kidney, and significantly more fibrosis in the myocardium than control dogs. This could have important implications in the management of myxomatous mitral valve disease and raises interesting questions about the occurrence and importance of intramural small vessel disease in humans with primary mitral valve prolapse.

Circulating concentrations of insulin-like growth factor-1 in dogs with naturally occurring mitral regurgitation.

Insulin-like growth factor-1 (IGF-1), which mediates most effects of growth hormone, has effects on cardiac mass and function, and plays an important role in the regulation of vascular tone. In humans, an inverse relationship between degree of heart failure (HF) and circulating IGF-1 concentrations has been found in several studies. In dogs with HF, few studies have focused on IGF-1. We examined circulating IGF-1 concentrations in dogs with mitral regurgitation (MR) caused by myxomatous mitral valve disease. Study 1 included 88 Cavalier King Charles Spaniels (CKCSs) with a broad range of asymptomatic MR (median serum IGF-1: 76.7 microg/L; 25-75 percentile, 59.8-104.9 microg/L). As expected, standard body weight and percentage under- or overweight correlated directly with IGF-1. MR (assessed in 4 different ways) did not correlate with IGF-1. In study 2, 28 dogs with severe MR and stable, treated congestive HF had similar serum IGF-1 concentrations (median, 100.8 g/L; 25-75 percentile, 74.9-156.5 microg/L) as 11 control dogs (79.6 microg/L; 25-75 percentile, 64.1-187.4 microg/L; P = .84). In study 3, the plasma IGF-1 concentration of 15 untreated CKCSs with severe MR was 16.4 +/- 24.2 microg/L lower (P = .02) at the examination when decompensated HF had developed (80.8 +/- 30.9 microg/L) than at a visit 1-12 months earlier (97.2 +/- 39.8 microg/L), possibly in part due to an altered state of nutrition. The studies document that circulating IGF-1 concentrations are not altered before development of congestive HF in dogs with naturally occurring MR, but decrease by approximately 20% with the development of untreated HE In treated HF, circulating IGF-1 concentrations apparently return to within the reference range.

Dogs with heart diseases causing turbulent high-velocity blood flow have changes in platelet function and von Willebrand factor multimer distribution.

The purpose of this prospective study was to investigate platelet function using in vitro tests based on both high and low shear rates and von Willebrand factor (vWf) multimeric composition in dogs with cardiac disease and turbulent high-velocity blood flow. Client-owned asymptomatic, untreated dogs were divided into 4 groups: 14 Cavalier King Charles Spaniels (Cavaliers) with mitral valve prolapse (MVP) and no or minimal mitral regurgitation (MR), 17 Cavaliers with MVP and moderate to severe MR, 14 control dogs, and 10 dogs with subaortic stenosis (SAS). Clinical examinations and echocardiography were performed in all dogs. PFA100 closure times (the ability of platelets to occlude a hole in a membrane at high shear rates), platelet activation markers (plasma thromboxane B2 concentration, platelet surface P-selectin expression), platelet aggregation (in whole blood and platelet-rich plasma with 3 different agonists), and vWf multimers were analyzed. Cavaliers with moderate to severe MR and dogs with SAS had longer closure times and a lower percentage of the largest vWf multimers than did controls. Maximal aggregation responses were unchanged in dogs with SAS but enhanced in Cavaliers with MVP (regardless of MR status) compared with control dogs. No significant difference in platelet activation markers was found among groups. The data suggest that a form of platelet dysfunction detected at high shear rates was present in dogs with MR and SAS, possibly associated with a qualitative vWf defect. Aggregation results suggest increased platelet reactivity in Cavaliers, but the platelets did not appear to circulate in a preactivated state in either disease.

Comparison of manual and automated methods for determining platelet counts in dogs with macrothrombocytopenia.

Platelet counts were performed in 43 Cavalier King Charles Spaniels (CKCS, a breed predisposed to macrothrombocytopenia) and in 10 control dogs using 3 automated systems and 3 manual methods (erythrocyte-lysing agents + counting chamber or evaluation of blood smear). Good correlations were found between platelet counts using all methods (all P < 0.0001; R2 = 0.71-0.85). Best correlations were found between the manual methods. Significantly larger platelets were found in CKCS with platelet count < or = 100,000/microl when compared with control dogs and CKCS with platelet count > 100,000/microl (both P < 0.0001). All platelet counts--except when made with the 2 counting chamber methods--were underestimated at platelet counts < or = 100,000/microl.

Decreased platelet function in Cavalier King Charles Spaniels with mitral valve regurgitation.

With aggregometry, increased platelet activity has been reported in Cavalier King Charles Spaniels (CKCS) without mitral regurgitation (MR). In contrast, dogs with MR have been found to have decreased platelet activity. The purpose of this study was to test an easy bedside test of platelet function (the Platelet Function Analyzer [PFA-100]) to see if it could detect an increase in platelet activity in CKCS without MR and a decrease in platelet activity in CKCS with MR. This study included 101 clinically healthy dogs > 1 year of age: 15 control dogs of different breeds and 86 CKCS. None of the dogs received medication or had a history of bleeding. The PFA-100 evaluates platelet function in anticoagulated whole blood under high shear stress. Results are given as closure times (CT): the time it takes before a platelet plug occludes a hole in a membrane coated by agonists. The CT with collagen and adenosine-diphosphate as agonists was similar in control dogs (median 62 seconds; interquartile interval 55-66 seconds) and CKCS with no or minimal MR (55; 52-64 seconds). The CT was higher in CKCS with mild MR (regurgitant jet occupying 15-50% of the left atrial area) (75; 60-84 seconds; P = .0007) and in CKCS with moderate to severe MR (jet > 50%) (87: 66-102 seconds; P < .0001). CKCS with mild, moderate, and severe, clinically inapparent MR have decreased platelet function. The previous finding of increased platelet reactivity in nonthrombocytopenic CKCS without MR could not be reproduced with the PFA-100 device.

Decreased plasma concentration of nitric oxide metabolites in dogs with untreated mitral regurgitation.

Endothelium-dependent (nitric oxide [NO]-mediated) vasodilation is impaired in humans with heart failure. This dysfunction is an important therapeutic target. The plasma concentration of the NO metabolites nitrate and nitrite (collectively referred to as NOx) is a measure of whole-body NO production, provided that the dietary intake of the ions is low. Fifty clinically healthy dogs older than I year (median 5.0 years; interquartile interval 2.6-8.2 years) were studied, including 9 controls of various breeds, 23 Cavalier King Charles Spaniels (CKCSs) with no or minimal mitral regurgitation (MR), 9 CKCSs with mild MR (regurgitant jet occupying 15-50% of the left atrial area), and 9 CKCS with moderate to severe MR (jet >50%) due to myxomatous valve disease. None of the dogs received medication. The dogs were given NOx-free water and a diet with a low concentration of NOx for 96 hours before blood sampling. Multiple linear regression analysis revealed that dog group, but not gender, age, serum creatinine concentration, and platelet count, was associated with NOx concentrations. Control dogs had the same NOx concentration (median 20.0 microM; interquartile interval 15.1-25.5 microM) as CKCSs without MR (median 18.7 microM; interquartile interval 15.5-25.9 microM). Compared to CKCSs without MR, the NOx concentration was lower in CKCSs with mild (median 12.9 microM; interquartile interval 11.0-13.5 microM; P = .04) and moderate to severe (median 11.2 microM; interquartile interval 6.9-17.1 microM; P = .02) MR. In conclusion, CKCSs with mild to severe, clinically silent MR have decreased plasma NOx concentrations, suggesting that endothelial dysfunction develops early in the course of developing MR in dogs.

Increased mean arterial pressure and aldosterone-to-renin ratio in Persian cats with polycystic kidney disease.

Polycystic kidney disease (PKD) in Persian cats has been increasingly reported and compared to human autosomal dominant polycystic kidney disease (ADPKD) in the last decade. In cats, however, few studies have dealt with the occurrence and hormonal determinants of hypertension, one of the most common extrarenal manifestations of ADPKD in humans. The purpose of this study was to compare Persian cats >4 years old with PKD to unaffected control cats with regard to blood pressure (BP), plasma renin activity (PRA), serum aldosterone concentration, plasma atrial natriuretic peptide (ANP) concentration, and aldosterone-to-renin ratio (ARR). Three gender- and age-matched groups were studied, each consisting of 7 cats: (1) a control group without cysts, (2) a group with mild PKD, and (3) a group with severe PKD (multiple cysts and renal enlargement). Mild renal insufficiency was found in only 1 of 14 cats with PKD. Cats with PKD had a higher mean arterial pressure (P = .04) and more often had a high ARR (P = .047) than did control cats. Tendencies toward higher diastolic and systolic arterial pressures (DAPs and SAPs, respectively) and lower PRAs were observed in cats with PKD compared to controls (.05 < P < or = .1). No significant differences were found between the groups in serum aldosterone and plasma ANP concentrations. None of the cats had echocardiographic evidence of cardiac hypertrophy. In conclusion, cats with PKD had a minor increase in mean arterial pressure compared to control cats, and half of the cats had a high ARR.

Idiopathic asymptomatic thrombocytopenia in Cavalier King Charles Spaniels is an autosomal recessive trait.

Cavalier King Charles Spaniels (CKCS) often have idiopathic asymptomatic thrombocytopenia. In affected dogs, the thrombocytes often are large, and it has been speculated that the condition could be an inherited macrothrombocytopenia. The aim of this study was to examine the inheritance of idiopathic, asymptomatic thrombocytopenia in CKCS. Sixteen families (both parents and > or = 3 offspring) of privately owned CKCS were included. There were 105 clinically healthy dogs (50 from Denmark and 55 from Sweden): 81 offspring and 26 parents (2 dogs had both roles). Because autoanalyzers have difficulty counting large platelets, the platelets were counted manually, with a counting chamber. Platelet counts were not influenced by age, gender, or heart murmur status. Thrombocytopenia (< or = 100,000 platelets/microL) was found in 46% of the parents. The pedigrees indicated that thrombocytopenia segregated as an autosomal recessive trait and that 100,000 platelets/microL was appropriate as a lower limit of normal. Affected offspring were found in all families, showing that all of the included parents were at least carriers. Therefore, the expected segregation ratios (which were in good accordance with the observed ones) were 1:0, 1:1, and 1:3 for the 3 crosses: affected x affected, normal x affected, and normal x normal. Within a given cross, the mean parental platelet count had no influence on the platelet counts of the offspring. We conclude that idiopathic, asymptomatic thrombocytopenia in CKCS is inherited in an autosomal recessive manner. The condition most likely constitutes an inherited macrothrombocytopenia in dogs.

Allometric scaling of M-mode cardiac measurements in normal adult dogs.

Indices for M-mode measurements in dogs usually have been based on the assumption that a linear relationship exists between these measurements and body weight (BW) or body surface area (BSA). The relationships between the geometry of 3-dimensional objects do not support this assumption. The purposes of this study were to retrospectively examine M-mode data from a large number of dogs of varying sizes and breeds that were examined by a large number of ultrasonographers, to use the allometric equation to determine the appropriate BW exponent required to predict these cardiac dimensions, and to determine normal mean values and prediction intervals for common M-mode variables. Linear regression analyses of data from 494 dogs (2.2-95 kg) revealed a good correlation between M-mode measurements and BW after logarithmic transformation of the data (r2 = .55-.88). Most variables were most closely related to an index of body length, BW(1/3), although the exponent that best predicted diastolic and systolic left ventricular wall thicknesses was closer to 0.25. No variable indexed well to BW or BSA. With these data, appropriate mean values and prediction intervals were calculated for normal dogs, allowing veterinarians to correctly and appropriately index M-mode values. The equations developed from this study appear to be applicable to adult dogs of most breeds.

Assessment of changes in hemostatic markers in Cavalier King Charles Spaniels with myxomatous mitral valve disease.

OBJECTIVE: To evaluate markers of hemostasis and their relationship to the degree of mitral regurgitation (MR) and platelet function in Cavalier King Charles Spaniels (CKCSs) with myxomatous mitral valve disease. ANIMALS: 76 clinically healthy CKCSs and 24 control dogs. PROCEDURE: All dogs underwent echocardiographic examination; various hemostatic, hematologic, and biochemical variables were evaluated in blood. The CKCSs were allocated to 1 of 3 groups on the basis of MR severity. In 8 control dogs and 8 CKCSs, plasma von Willebrand factor (vWF) multimer analysis was performed. RESULTS: Compared with control dogs, plasma fibrinogen concentration was higher in all CKCSs and related to left ventricular end diastolic diameter and left atrial-to-aortic root ratio among all CKCSs. The activated partial thromboplastin times and plasma D-dimer concentration were similar among the 4 groups. Plasma vWF concentration was lower in CKCSs with moderate to severe MR, compared with that of CKCSs with no MR and control dogs. There was a relationship between plasma vWF concentration and platelet function in CKCSs but not in control dogs. In 4 CKCSs with moderate to severe MR and low plasma vWF concentration, amounts of vWF high-molecular-weight multimers (HMWMs) were low. CONCLUSIONS AND CLINICAL RELEVANCE: In CKCSs, MR appeared to be associated with a low plasma vWF concentration and likely a loss of vWF HMWMs (possibly through their destruction via shear stress to the blood). The importance of the changes in plasma fibrinogen concentration and the thromboembolic risk in dogs with MR remain to be investigated.

Evaluation of an oscillometric blood pressure monitor for use in anesthetized cats.

OBJECTIVE: To determine accuracy of an oscillometric blood pressure monitor used over a wide range of pressures in anesthetized cats. DESIGN: Prospective study. ANIMALS: 6 healthy cats. PROCEDURE: 4 female cats and 2 male cats that weighed 2.7 to 4.5 kg (5.9 to 9.9 lb) and were 2 to 8 years old were anesthetized. Blood pressure was measured directly with an arterial catheter placed in the right femoral artery and indirectly from the left antebrachium by use of an oscillometric monitor. A series of diastolic arterial pressure (DAP), mean arterial pressure (MAP), and systolic arterial pressure (SAP) measurements were obtained during hypotension, normotension, and hypertension. Values obtained indirectly and directly were compared. RESULTS: The oscillometric monitor was accurate for DAP and MAP throughout the entire pressure range and met the standards of the Association for the Advancement of Medical Instrumentation (mean +/- SD difference from values obtained directly, < or = 5 +/- 8 mm Hg). The SAP was increasingly underestimated with increasing overall pressure; mean differences from direct measurements were -5.2, -12.1, and -17.7 mm Hg during hypo-, normo-, and hypertension, respectively. Standard deviations for SAP were all < or = 8 mm Hg. The monitor gave readings during all attempts. The direct blood pressure recording system appeared to perform well with neither under- nor overdamping. CONCLUSIONS AND CLINICAL RELEVANCE: Except for a minor underestimation of SAP during normo- and hypertension, the oscillometric monitor yielded reliable and easily obtainable blood pressure measurements in anesthetized cats.