A semi-immobilization of a partial auricle induces hypertrophy and ultrastructural alteration of cardiomyocytes.

Semi-immobilization of a partial area of the ventral edge, lateral epicardium of the left auricle (ventrolateral of left auricle), by using quick adhesion glue induces moderate hypertrophy of myocytes with an average increase of 34% in cross-sectional area. Intercellular connective tissues increased, and cellular sizes varied markedly. The ultrastructure of immobilized (semi-immobilized) myocytes commonly exhibited degenerating features in myofibrils, various cytoplasmic organelles including mitochondrial cristae and sarcoplasmic reticulum (SR) were disrupted, and T-tubules disappeared. Z-line streaming and widening (hypertrophic Z-line, rod bodies) and increase of metabolic particle deposition are typical phenomena in addition to intercalated disc (Id) disorganization. The results suggest that semi-immobilization of the auricle induces hypertrophy of myocytes in association with degeneration and disruption of myofibrils and other cytoplasmic organelles, and an increase of intercellular connective tissues, rather than increase of myofibril mass. This is the first study to immobilize only a part of the heart rather than the whole animal. Our results using artificial immobilization of cardiac myocytes were extremely significant since the structural alterations obtained were similar to that observed in cardiomyopathies. This suggests that myocytes progressing to heart failure are also subjected to inhibition of movement. Therefore, this experiment may prove very useful as a model for studying the functional effect of heart failure observed in cardiomyopathy.

The variation in excretory urinary glycyl-prolyl dipeptidyl aminopeptidase in dogs.

We studied the excretory variation of urinary glycyl-prolyl dipeptidyl aminopeptidase (GP-DAP, EC 3.4.14.5) in dogs. Adult domestic mongrel dogs (seven males and nine females, 7.5 to 13 kg bodyweight) which were considered to be healthy by laboratory tests were used. Urine and blood samples were obtained every four hours. Urine volume was measured for each sample and urine GP-DAP activity, and creatinine levels were determined. Creatinine clearance, creatinine excretion, GP-DAP activity and GP-DAP index (GP-DAP/Cr ratio) did not show any significant variation between the time periods. However, urine volume and urinary GP-DAP excretion significantly increased from 8:00 am to 12:00 pm. The GP-DAP index in spot urine samples showed low correlation with 24 hour GP-DAP excretion. In addition, a sex difference was observed in GP-DAP excretion. In conclusion, urinary GP-DAP excretion showed a circadian variation and sex difference. Therefore, GP-DAP in spot urine is not of use for the detection of renal disorders, and the 24-hour excretion value of GP-DAP should be determined.

Intrahepatic portal-venous changes in dogs with dirofilariasis: scanning electron microscopy of resin casts of vasculature.

Intra hepatic portal-venous changes in dogs with dirofilariasis, in which characteristic cavernous transformation has been histologically observed, were studied by scanning electron microscopy (SEM) of resin casts of vasculature. Changes in the central and sublobular veins were the most significant. The venous channels were extremely dilated, thin-walled and showed cavernous structure. SEM observation showed multi-saccular formation with beads-like, helical and extremely dilated configuration. The conducting venules, i.e. terminal tributaries of the portal vein, showed a rapid taper just before the point of merging into sinusoids. Neither vascular proliferation nor collateral circulation around the portal channels could be detected in the present resin cast study.

A clinical study on velocity patterns of pulmonary venous flow in canine heartworm disease.

In this study, we evaluated methods of determining the velocity patterns of pulmonary venous flow (PVF) in dogs and then investigated the relationship of the patterns to cardiac functions in heartworm disease (HD) by transthoracic echocardiography (TTE). The results revealed that there was a good correlation between PVF patterns determined by transesophageal echocardiography (TEE) and TTE in animals lying on their left sides. The measurement of S and D wave velocities (PVS and PVD) by TTE was shown to allow clinical determination of the velocity patterns of PVF in dogs. The HD groups showed significant increases in PVS and PVD, and S and D wave time-velocity integrals (S-TVI and D-TVI) of the right cranial lobe PVF, when compared with the normal group, as determined by TTE (P<0.05). In contrast, the HD groups produced significant decreases in PVD and D-TVI of the right caudal lobe PVF compared with the normal group (P<0.05), and a significant increase in the ratio of S-TVI to (S-TVI + D-TVI) (P<0.05). It is, therefore, suggested that measurement of the velocity patterns of the right cranial and caudal lobe PVF could be one method of assessing the stages of obstructive lesions in the pulmonary artery.

Medical dissolution of struvite nephrolithiasis using amino acid preparation in dogs.

A new chemolytic therapy with amino acid preparation was tried for use on struvite renal stones in two dogs, which were admitted to Azabu University Veterinary Teaching Hospital. No other special diet, for the purpose of dissolving the stones, was fed during the treatment. Dissolution of the stones began at week 1, and no stone was detected on radiography at week 4 in both cases. The amino acid preparation thereafter has been administered every 2-3 days to prevent formation of the stones. After 6 months from treatment, complete dissolution was confirmed, and no relapse has been observed. Therefore, it is concluded that chemolytic therapy with amino acid preparation might be useful for the treatment of nephrolithiasis with struvite renal stones in dogs.

Evaluation of urinary enzymes in dogs with early renal disorder.

We investigated urinary N-acetyl-beta-D-glucosaminidase NAG (EC 3.2.1.30), gamma-glutamyl transpeptidase gamma-GTP (EC 2.3.2.2) and glycyl-prolyl dipeptidyl aminopeptidase GP-DAP (EC 3.4.14.5) in dogs with heartworm disease and renal failure. In the renal failure dogs, the NAG, gamma-GTP and GP-DAP index were significantly higher than those in the healthy dogs. In the heartworm disease dogs with normal chest X-rays (HW I), none of the enzyme values was significantly different from those of the healthy controls. In the dogs with heartworm disease showing abnormal heart shadows on their chest X-rays (HW II), enzyme values were significantly higher than those in the healthy dogs (P < 0.01) and the HW I dogs (P < 0.01). Thus, these urinary enzymes tests are available for the early detection of renal disorders.

Circadian variation of urinary enzymes in the dog.

Circadian variations of N-acetyl-beta-D-glucosamidase (NAG, EC 3.2.1.30) and gamma-glutamyl transpeptidase (gamma-GTP, EC 2.3.2.2) were examined in dogs. Urine and blood were collected at 4-hr intervals from adult mongrel dogs (11 males, 11 females) weighing between 7 and 13 kg. The collected urine and blood were used to measure creatinine, NAG and gamma-GTP. The amount of urine was significantly higher (p < 0.05) during the period from 12:00 to 16:00. Creatinine clearance did not show any characteristic variations and creatinine excretion was significantly higher (p < 0.05) during the period from 8:00 to 16:00. No characteristic variations were observed in the amounts excreted, activity, or NAG and gamma-GTP creatinine index. There were high correlations between creatinine excretion and creatinine clearance (r = 0.693), gamma-GTP excretion and gamma-GTP creatinine index (r = 0.724), NAG excretion and NAG creatinine index (r = 0.878), and between the NAG and gamma-GTP creatinine index of each 4-hr specimen and the NAG and gamma-GTP excretion of the 24-hr specimens. These results suggest the diagnostic usefulness measuring enzyme activity in non-periodically collected urine.

Crossed fat embolism in a cow with tetralogy of Fallot.

A 10-month-old, female Holstein-Friesian cow with tetralogy of Fallot died during surgery for ameliorating pulmonary stenosis. Necropsy revealed no fracture of bones. Microscopically, fat emboli in the capillaries were detected in the brain, kidney, lung, adrenal gland and pituitary. In the kidney, many fat emboli were present in the glomeruli. No significant changes of the neurons were found throughout the brain, and perivascular hemorrhage and/or necrosis were rarely seen accompanying with fat emboli in the cerebral cortex. The trigger for fat embolism might be costectomy, and right-to-left shunt due to heart malformation might be attributed to crossed and systemic distribution of the fat emboli.

Prevalence of valvular regurgitation in normal beagle dogs detected by color Doppler echocardiography.

We examined the prevalence and characteristics of valvular regurgitation in 20 normal beagle dogs with no cardiac murmur by color Doppler echocardiography. The prevalence of pulmonary, mitral, aortic and tricuspid valvular regurgitation was 75%, 15%, 10%, and 0%, respectively. The peak flow velocity of pulmonary, mitral and aortic regurgitation was 57.1 +/- 18.5 cm/sec (mean +/- SD), 89.8 cm/sec (mean) and 96.5 cm/sec, respectively. The peak velocity of regurgitant flow was considered characteristically low, as the calculated pressure gradient derived from the modified Bernoulli equation (pressure gradient = 4 x velocity) was not as high as the normal pressure gradient existing across each valve. We consider that, in the evaluation of the characteristics of regurgitation in dogs, regurgitant signals having low peak velocity can be regarded as being physiological or trivial regurgitation.

A case report of surgical treatment of a dog with atrioventricular septal defect (incomplete form of endocardial cushion defect).

A 3-month-old female collie was diagnosed as having atrioventricular septal defect with ostium primum atrial septal defect (PASD). The diagnosis was made by echocardiographic observation of the PASD and goose-neck deformity on left ventriculogram. The PASD was treated surgically with a patch graft under cross-circulation cardiopulmonary bypass (CC). The PASD was identified above the ventricular septum after right atriotomy. The patch graft was sutured along the fibrous tissue of the tricuspid annulus on the ventricular side of the PASD to avoid injuring the conduction system. After the operation, cardiac function and renal output were well preserved, but the dog died 33 hr later. At postmortem examination, a mitral cleft was identified.

Non-invasive blood pressure measurements in cats: clinical significance of hypertension associated with chronic renal failure.

The systolic, mean and diastolic pressures as well as the heart rate were measured using the oscillometric method, on a total of 104 cats (60 cats in the normal group, and 44 in the renal disease group) which were brought into Azabu University Animal Hospital. The blood pressure in the normal group was systolic: 115.4 +/- 10.1 mmHg, mean: 96.2 +/- 12.2 mmHg, and diastolic: 73.7 +/- 10.7 mmHg. Although no difference in heart rate, the renal disease group showed significantly (p < 0.05) higher values for systolic, mean, and diastolic pressure when compared with the normal group. Moreover, when plasma renin activity, angiotensin I and II, and aldosterone concentrations were measured in other cats (11 normal and seven with chronic renal failure), all cats with chronic renal failure showed significantly (p < 0.05) higher values than the normal group. It is, therefore, indicated that hypertension due to stimulating renin-angiotensin-aldosterone system may have manifested in cats with renal dysfunction.

Preliminary results of short-term combination immunosuppressions of mizoribine, azathioprine, and prednisolone with pretreatment to canine kidney transplantation.

Serial combinations of immunosuppressive drugs (mizoribine: Mi, azathioprine: Az, and prednisolone: Pr) were administered for renal heterotopic allotransplantation in 50 mixed-breed dogs and 4 beagle dogs. The dogs were randomly divided in 5 groups depending upon immunosuppressive protocols. All immunosuppressive protocols were started at 5 days prior to transplantation and discontinued on the eighth day after transplantation. The mean survival time for the allograft recipients in the group receiving Az and Pr [Az (2.5) & Pr group; Az dosage, 2.5 mg/kg once a day with Pr] was 16.2 +/- 2.4 days and in the group receiving Az, Mi, and Pr (Mi & Az & Pr group; Mi dosage, 5.0 mg/kg once a day with Az and Pr), it was 14.0 +/- 2.6 days. These results were significantly longer than the control group (mean survival time, 8.7 +/- 2.4 days; P < 0.01). There was no statistical difference in survival time between these two groups. Groups with combinations of Az and Pr had significant elevations of hepatic enzymes (ALT and ALP) during the 7 days of immunosuppressive treatment after kidney transplantation. The Mi & Az & Pr group had lower elevations of hepatic enzymes than groups with combinations of Az and Pr. The combination immunosuppression of Mi, Az, and Pr with pre-treatment for canine, kidney transplantation revealed relatively fewer side-effects for the liver and longer survival-time.

Renal transplantation in cats with chronic renal failure.

Renal transplantation was performed on 6 cats with chronic renal failure. Clinical signs and the blood chemistry findings (BUN, Cr, IP) improved one week after renal transplantation. Renal anemia also improved 3-4 weeks after surgery. Two cases had the same complications, hydronephrosis and hydroureter within 1 or 2 weeks of surgery, evidenced by marked elevations of BUN and Cr, suggesting that ureteral obstruction at the site of ureterocystostomy is the main complication of renal transplantation in cats. As a new resolution for this problem, we transplanted the ureter with the intact ureteral opening of the bladder from the donor in the remaining 4 cats. Ureteral obstruction was not observed in them, thus the procedure was considered to be useful for avoiding this complication. Two cats died of pneumonia and other complications within 3 months. There were no acute rejections or side effects from the immunosuppressant during the observation period in the remaining four cats.

Relationship between degree of mitral protrusion assessed by use of B-mode echocardiography and degree of mitral regurgitation using an experimental model in dogs.

We studied the relationship between the degree of mitral protrusion and degree of mitral regurgitation in an experimental model in which the degree of mitral protrusion could be adjusted. The model was developed by dissecting the dorsal papillary muscle through a left atriotomy in 5 dogs and re-attaching the papillary muscle to the original site using a single mattress suture threading through the epicardium under cardiopulmonary bypass. By manipulating the suture from a position outside the epicardium, the degree of mitral protrusion could be adjusted. The long-axis view of the mitral valve was imaged by B-mode echocardiography with the transducer placed directly over the surface of the right ventricular outflow tract. The height (H) from the coaptation point or tip of the protruded cusp in relation to the mitral annular plane was measured as an index of mitral protrusion. Mitral regurgitation as a result of the mitral protrusion decreased the left ventricular systolic pressure, and increased the heart rate, mean left atrial pressure (LAPm), and ratio of left ventricular end-diastolic dimension to body weight (LVEDD/BW). H was negatively correlated to LAPm and LVEDD/BW (r = -0.723 and -0.697, respectively). Our results indicated that H expresses not only the degree of mitral protrusion but also the degree of mitral regurgitation, and were in agreement with the previous findings obtained on dogs with spontaneous mitral regurgitation.

Aberrant branch of the bronchoesophageal artery resembling patent ductus arteriosus in a dog.

An anomalous shunt between the bronchoesophageal artery and pulmonary artery was diagnosed in a 1-year- old, 3.5 kg female Miniature Dachshund by selective contrast angiography. A cardiac murmur had been observed in the dog during examination at another hospital. The machinery murmur was auscultated at the left side of the base of the heart. Although thoracic radiography revealed mild cardiomegaly, the characteristic findings of patent ductus arteriosus (PDA), including as aortic arch enlargement and pulmonary artery enlargement were not observed. Echocardiography demonstrated shunting of blood flow presumably from the arterial duct at the pulmonary artery carina. Based on the above findings the case was diagnosed as PDA. Angiocardiography was performed to confirm the diagnosis in preparation for surgical treatment, but later we confirmed that the shunt vessel was not PDA, but apparently a branch of the bronchoesophageal artery. The shunt vessel was branching in a complicated manner and shunted to the pulmonary artery.

A clinical evaluation of blood pressure through non-invasive measurement using the oscillometric procedure in conscious dogs.

The oscillometric procedure was used to measure the heart rate as well as the systolic, mean, and diastolic blood pressures of 152 dogs (102 in the control group, 13 in the group with renal disease, 37 in the group with heart disease) who were brought to Azabu University of Veterinary Teaching Hospital. It was demonstrated that the blood pressure and heart rate of the control group lowered and tended to become stable as the number of measurements increased. No appreciable difference was identified in the measurements of either blood pressure or heart rate in the forelimbs and tail head. With regard to gender, males showed a significantly higher value than females (p < 0.05). No interaction was identified between age and blood pressure. No difference was identified in the heart rate in all groups. In an investigation of blood pressure in all groups, the renal disease group showed significantly higher values (p < 0.05) than either the control or the heart disease group in all values of systolic, mean and diastolic pressures. These results indicated that dogs with renal disease can manifest hypertension.

Idiopathic renal hematuria in a dog; the usefulness of a method of partial occlusion of the renal artery.

Exploratory laparotomy was performed on a dog suspected of having idiopathic renal hematuria. Two catheters were inserted into the bilateral ureters, and hematuria from the left kidney was confirmed. The blood flow was occluded in the ventral and dorsal rami of the left renal artery in order to localize the site of hemorrhage. As hematuria disappeared when the dorsal ramus was occluded, the site of renal hematuria was localized to the area dominated by the dorsal ramus of the renal artery. As a result of ligating the dorsal ramus of the left renal artery in this dog, renal hematuria subsided, and the dog has shown a favorable course, to date, one year after surgery.

Diurnal variations of blood pressure in dogs.

Using the telemetry system, we measured the blood pressure (BP) invasively in seven adult mongrels while unanesthetized and unbound. Post-operative BP after implanting the telemetry BP transmitter showed temporarily high values due to the invasive nature of the surgery. It was, however, observed that BP gradually decreased thereafter, and showed settled trends from the eighth day post-operatively. When we took the average of the systolic, mean and diastolic BP at hourly intervals for each of the dogs once their BP had settled, a twin peak diurnal variation (at 8:00 and 19:00) was observed. Moreover, significantly high values (p < 0.05) were identified in active state compared with when sleeping or at rest. The 24 hr BP measured by the telemetry system in seven normal dogs resulted in the following values: systolic 123.4 +/- 7.9 mmHg, mean 91.1 +/- 5.6 mmHg, and diastolic 74.5 +/- 4.9 mmHg.

The circadian variation of urinary N-acetyl-beta-D-glucosaminidase and gamma-glutamyl transpeptidase in clinically healthy cats.

The circadian variation of urinary N-acetyl-beta-D-glucosaminidase (NAG, EC 3.2.1.30) and gamma-glutamyl transpeptidase (gamma-GTP, EC 2.3.2.2) was evaluated in cats. Urine and blood were collected at 4-hr intervals from adult cats (3 males, 9 females) weighing between 2.6 and 5.0 kg. There was no circadian variation in the urine volume, creatinine clearance, creatinine excretion, NAG excretion or gamma-GTP excretion. The average NAG and gamma-GTP indices in the 4-hr urine were similar to those for the 24-hr urine. However, the variance for the 4-hr urine samples was higher than that of 24-hr urine. In conclusion, although 4-hr urine samples can be used to estimate 24-hr urinary enzyme excretion, short-term spot urine samples may cause increased variation in the enzyme index.

Peritoneal dialysis using a recycling system in dogs.

In this study, Recirculation Peritoneal Dialysis (RPD) apparatus using a pump to circulate the dialysate was devised and its dialysis efficiency was investigated. In the experiment, 15 mongrel dogs with body weights of 6.6 +/- 0.7 kg were used. The surgery to induce azotemia was performed on the dogs, a disk catheter for drainage was placed between the liver and diaphragm, and a straight catheter for infusion was placed on the abdominal side of the bladder. RPD was conducted using 2 l of dialysate containing 1.3% glucose, and the dialysate was circulated by a pump through the peritoneal cavity and the dialysate chamber at the circulation rates of 30, 60, 90 and 120 ml/min. RPD was conducted for 3 hr and the clearances of urea nitrogen, creatinine, inorganic phosphorus and potassium were recorded every hour. The clearances in RPD became higher with an increase in the circulation rate. Although RPD requires two catheters in the peritoneal cavity, it has no appreciable technical difficulty in handling and is considered to be easier than hemodialysis. RPD enabled higher dialysis efficiency to be achieved in a short time compared with conventional peritoneal dialysis. It seems reasonable to conclude that RPD is a useful new dialysis technique for animals.