Naoyuki Takemura

Relationship between glomerular filtration rate and plasma N-terminal pro B-type natriuretic peptide concentrations in dogs with chronic kidney disease.

Plasma N-terminal pro B-type natriuretic peptide (NT-proBNP) concentrations increase in dogs with azotemia. However, the correlation between glomerular filtration rate (GFR) and NT-proBNP concentrations in dogs has not been evaluated. The objective of this study was to evaluate the correlation between GFR and plasma NT-proBNP concentrations in dogs with chronic kidney disease (CKD). In this retrospective cross-sectional study, plasma creatinine (Cre) and NT-proBNP concentrations, plasma iohexol clearance (PCio) values and blood pressure were measured in dogs with CKD. Dogs were classified according to PCio values into D group (dogs with decreased PCio values), and N group (dogs with normal PCio values). Dogs were further categorized on the basis of their systolic blood pressure and PCio values into NT-D group (normotensive dogs with decreased PCio values), NT-N group (normotensive dogs with normal PCio values), HT-D group (hypertensive dogs with decreased PCio values) and HT-N group (hypertensive dogs with normal PCio values). Significant correlations were observed between plasma NT-proBNP and Cre concentrations (r=0.360, P<0.05) and PCio values (r=-0.470, P<0.01). Plasma NT-proBNP concentrations were significantly higher in the D group than in the N group (P<0.001). Plasma NT-proBNP concentrations were significantly higher in the HT-D group than in the other three groups (P ≤ 0.007). No differences in plasma NT-proBNP concentrations were observed between the NT-D and HT-N groups (P=0.28). Plasma NT-proBNP concentrations were significantly lower in the NT-N group than in the other three groups (P ≤ 0.043). Our findings suggest that decreased GFR might be associated with increased plasma NT-proBNP concentrations in dogs, similar to that in humans. In addition, the complication of hypertension in CKD might be associated with further increases in plasma NT-proBNP concentrations. In conclusion, the effects of GFR and blood pressure on the plasma NT-proBNP concentration were small, but it could be necessary to consider the effects when this marker is used to evaluate canine cardiac disease.

Predictive model for the detection of pulmonary hypertension in dogs with myxomatous mitral valve disease

Pulmonary hypertension (PH) often occurs due to a left heart disease, such as myxomatous mitral valve disease (MMVD), in dogs and is diagnosed using Doppler echocardiography and estimated pulmonary arterial pressure. Diagnosis of PH in dogs requires expertise in echocardiography: however, the examination for PH is difficult to perform in a clinical setting. Thus, simple and reliable methods are required for the diagnosis of PH in dogs. The purpose of this study was to develop models using multiple logistic regression analysis to detect PH due to left heart disease in dogs with MMVD without echocardiography. The medical records of dogs with MMVD were retrospectively reviewed, and 81 dogs were included in this study and classified into PH and non-PH groups. Bivariate analysis was performed to compare all parameters between the groups, and variables with P values of <0.25 in bivariate analysis were included in multiple logistic regression analysis to develop models for the detection of PH. In multiple logistic regression analysis, the model included a vertebral heart scale short axis of >5.2 v, and a length of sternal contact of >3.3 v was considered suitable for the detection of PH. The predictive accuracy of this model (85.9%) was judged statistically adequate, and therefore, this model may be useful to screen for PH due to left heart disease in dogs with MMVD without echocardiography.

Comparison of the effects of long-term pimobendan and benazepril administration in normal cats

Pimobendan (PIMO) can cause adverse effects, such as mitral valve degeneration, in dogs; however, it is unclear whether these effects occur in cats. Therefore, we aimed to determine whether PIMO or benazepril produces adverse cardiac effects in healthy cats. This was a blinded, randomized, prospective parallel study. Twelve cats were randomly divided into two groups of six cats, namely, an angiotensin-converting-enzyme inhibitor group that received benazepril and a PIMO group. Cats were administered their respective treatments for 506 days, and we evaluated cardiac parameters, blood biochemistry and glomerular filtration rates during that time. At the end of the trial, the cats were euthanized, and histopathological examinations were performed by a pathologist who was blinded to the treatment groups. No significant changes were observed in any of the parameters measured in either of the groups. In particular, no significant cardiac lesions were observed in either of the groups. In healthy cats, neither PIMO nor benazepril appears to cause cardiac lesions, but future studies are needed to examine the effects of PIMO in cats with heart disease.

Pathological features of proteinuric nephropathy resembling Alport syndrome in a young Pyrenean Mountain dog

The renal biopsy tissue from a 9-month-old, male Pyrenean Mountain dog with renal disorder and severe proteinuria was examined. Ultrastructural examination revealed multilaminar splitting and fragmentation of the glomerular basement membrane (GBM) and diffuse podocyte foot process effacement. Immunofluorescent staining for α(IV) chains revealed presence of α5(IV) and complete absence of α3(IV) and α4(IV) chains in the GBM. Immunohistochemistry also revealed decreased and altered expression of nephrin and podocin in the glomeruli compared with normal canine glomeruli. These results suggested that the glomerular disease of the present case might be consistent with canine hereditary nephropathy resembling human Alport syndrome caused by genetic defect of type IV collagen, and indicated possible contribution of podocyte injury to severe proteinuria in this case.

Congestive Heart Failure due to Bilateral Atrioventricular Valve Insufficiency in Two Dogs

Congestive heart failure resulted from bilateral atrioventricular insufficiency was diagnosed in two, small breed, intact male aged dogs. In both cases, the clinical signs were mainly associated with right heart failure, while those related to left heart failure were seldom observed. Radiographic and echocardiographic examinations revealed the dilatation of the right heart due to tricuspid valve insufficiency. Mitral regurgitation was also observed without pulmonary hypertension. Both patients responded to medications of diuretics, methyldigoxin and angiotensin converting enzyme inhibitor. As congestive signs deteriorated, they became unresponsive to the treatment. Ultimately, the dogs died 9 and 13 months later from the first admission.

A Cat with Dilated Cardiomyopathy

初診時の検査所見 症例 は ヒマ ラヤ ン種猫,雌,8歳,体 重3.8kgで ある. 食欲不振,腹 部膨満および呼吸促迫 を主訴 に日本獣医畜 産大学付属家畜病 院に来院 した.畜 主 は腹部膨満 に約1 ヵ月前か ら気付 いて いたが,元 気,食 欲 が正常 であった たあ放置 して いた.初 診時,腹 水 の貯留 による腹部膨満 および呼吸促迫,腹 部表皮の静脈 の怒脹,肝 臓 の腫大 な らびに軽度 の脱水 が観察 された.心 拍数 は81回/分 で 第IV音 が聴取 され たが,心 雑音 はなか った.ま た,視 覚 に異常 はな く,眼 底所見 も正常であ った. 血液検 査で は中等 度 の貧血,BUNお よび ク レアチニ ンの軽度増 加が認 め られた(表1).胸 部 エ ックス線像 では心陰影 が拡大 して いたが,肺 野 は明瞭であ った.心 電 図検 査 で は正 常洞 調律 で あ ったが,QT間 隔 の延長 (0.28秒),T波 の平 低化 お よ びR波 の増 高(2.5mV) が認 め られ た.ウ イル ス検査 で はFIP,FeLVお よび FIVは 陰性 であ った.腹 水 は変 性漏 出液 であ った(総 蛋 白量4.4g/dl,比 重1.033).心 エ コー検査 で は心腔 が 著 しく拡 張 し,左 心房 と大動脈 の内径 の比 は約1.2で あ った.そ れ以外 に弁の閉鎖不全な どの異常 は認 め られな か った(図1).Mモ ー ド心 エ コーか ら求 めた左心室 収 縮末 期お よび拡張末期 直径(ESDお よびEDD)は 高値 を示 した.左 室駆 出時間(ET)は おおむね正常 であ った が,左 室 短 径短 縮 率(FS)お よ び平 均 円周 短 縮 速 度 (VCF)は 明 らか に低値 を示 し,心 室 の収 縮性 は著 し く 低下 していた(表2).以 上 の所見 か ら,臨 床 的にDCM と診断 した. 治療および臨床経過 フロセ ミド(2mg/kg,1日2回,皮 下注)お よび サ イク リックAMP(cAMP)製 剤(20μg/kg/min,一 昼 夜持 続 注入)を 投与 し,乳 酸 加 リンゲル(10ml/kg/ hr)を2日 間点滴 した. 第2病 日にな ると元気,食 欲 が回復 し,呼 吸が安定 し て第IV音 が消失 した.こ の ため,フ ロ セ ミ ド(2mg/ kg)お よび硝酸 イ ソソル ビ ド製 剤(ISDN,2mg/kg) の経 口投与(1日2回)に 加えて,β-メ チル ジゴキ シ ン (β-MD,0.015mg)を 隔 日投与 した.血 清中 ジゴキ シン 濃度の推移を表3に 示 した.第4病 日か らはス ピロノ ラ ク トン(2mg/kg)お よび タウ リン(300mg/head)の 経 口投与 を加え た(1日2回),第9病 日の心 エ コー検 査で はFSが 増大 してお り,心 収縮 力の改善が確認 され た.腹 水の軽減 に ともない元気,食 欲 および呼吸状態 が

The Physiological Range of Electrocardiographic Measurment Values Recorded by Apex-Base Lead in Healthy Sows

供試豚 は千葉県香取地区 の養豚場で飼育 されていた繁 殖豚467頭 で,分 娩舎 内にいた妊娠後期か ら子豚 離乳時 まで のものを対象 と した.心 電図は大井 らの提 唱す る A-B誘 導法8)と し,心 電計は内野 らの開発 した 自動解 析 心電計13)(以 下,自 動心電計 と略す)を 用 い,針 電極 を 使用 した. 第1実 験 では,イ ヌ用 に開発 された 自動心電計が,ブ タの心電 図の解析 に応用可能か否かを検討 した.す なわ ち,記 録 した467頭 か ら任意に抽出 した60頭 の ブタの 心電図に関 して,自 動心電計が算出 した測 定値 と著 者 ら の実測値 との相関性を直線回帰に より確認 した.そ の後 に第2実 験 を行 った. 第2実 験 ではP, Q, R, Sお よびTの 各波につい て波 *1) 日本 獣 医 畜 産 大 学(東 京 都武 蔵 野 市 境 南町1-7-1) *2) 千 葉 県 農 業 共 済 組 合 連 合 会 家 畜臨 床研 修 所(佐 原