慢性腎臟病是貓常見的系統性疾病之一20，尤其好發於老貓18。在貓咪老化的過程中，除了代謝速度和活動力下降之外，器官們的做工能力也會逐漸降低2。因此，熟齡貓對蛋白質和脂質的消化能力較低14 ,25，且身體肌肉量的流失更容易發生於老年動物，甚至可能引發肌少症。6。
熟齡貓通常指年齡介於7至12歲的貓咪，而老貓則是指年齡超過12歲的貓咪。提供富含優質蛋白質的飲食、維持健康體態，並搭配規律的運動及定期的健康檢查，乃7歲以上的貓咪日常照護的重要部分。
獸研所的腎臟保養主食罐，除了依據美國飼料品管協會(Association of American FeedControl Officials, AAFCO)，美國國家科學研究委員會(National Research Council, NRC)和歐洲寵物食品產業聯盟(European Pet Food IndustryFederation, FEDIAF)之成貓每日基本營養需求建議量1, 5, 23進行配方之外，也根據國際上的研究報告與文獻，設計了一款適合健康的熟齡貓和罹患慢性腎病第一期(IRIS Stage 1) 9的貓咪，作為每日正餐食用的腎臟保養主食罐。以下是此產品的配方規劃:
1. 中等含量優質蛋白:
目前尚無文獻顯示高蛋白飲食會增加熟齡貓罹患慢性腎臟病的風險2, 17，且降低蛋白質的攝取可能造成熟齡貓蛋白質的營養不良，進而引起更多健康問題13 ,15 , 21。文獻指出，出現蛋白尿及尿毒症，或是被診斷為慢性腎病第三期(IRIS Stage 3)以上的病貓才需要嚴格限制飲食中的蛋白質含量19。對於慢性腎病初期的病貓，飲食上需適量限制蛋白質，以維持其體重及肌肉量8。另有研究指出，長期攝取含適量蛋白質及適度限磷的飲食，有助於維持慢性腎病初期病貓的腎臟功能27。因此，獸研所設定「中等含量優質蛋白」，以高品質的食材(雞胸肉、鮭魚和鮪魚肉為主，雞肝為輔)，滿足熟齡貓的營養需求，並有助於慢性腎病病貓的體態維持22, 24。
2. 適量限磷及最佳鈣磷比:
慢性腎病病貓因腎臟功能下降，磷的排出受到影響，可能造成磷的滯留。長期衍變成高血磷，高血磷會影響體內副甲狀腺素等一系列激素的調控，可能導致腎病繼發的副甲狀腺素亢進等問題17。許多研究顯示，限制磷的攝取有助於維持慢性腎病病貓的腎臟功能2, 24。獸研所依據各國文獻19, 21建議，將磷含量控制在150-200mg/100kcal ME，並將鈣磷比控制在1.0-1.2，適量限磷，但也讓健康的熟齡貓長期食用本產品不至於造成低血磷。
3. 功能性添加物:
左旋肉鹼(L-carnitine)可幫助脂肪代謝氧化後提供能量10。有研究顯示，飲食中添加左旋肉鹼有助於維持慢性腎病病貓的體重及肌肉量7, 8, 10, 12, 28, 29。此外，左旋肉鹼也可能對老年動物認知功能下降的問題是有所幫助2, 16。
茶胺酸(L-Theanine)是一種綠茶萃取而來的獨特胺基酸。研究發現，茶胺酸有助於舒緩貓咪的情緒3, 4。壓力是貓咪下泌尿道疾病(FLUTD)和慢性腎病的危險因子之一。因此，本產品添加茶胺酸，期許熟齡貓能有安穩的每一天。
4. 添加魚油、維生素與胺基酸:
飲食中加入富含ω3脂肪酸的魚油2, 21, 24，有助於維持慢性腎病病貓的腎臟功能8, 26。除此之外，魚油對老年動物的皮膚、關節和認知功能等也有所助益。獸研所以雞胸肉、鮭魚和鮪魚肉等食材為基礎，加入淬煉的雞油和魚油，並考量適口性和脂肪酸的比例去調配本產品。
可溶性纖維透過將部分含氮廢物轉由糞便排出，以減輕腎臟負擔，維持慢性腎病病貓的腎臟功2, 21。本產品添加洋車前子，含有可溶性和不可溶性纖維，除了腎臟保健，還有助於維持腸道功能。
抗氧化劑有助於保護慢性腎病病貓的腎臟機能8, 30。老年動物許多身體機能的退化和體內自由基的氧化有關。因此，飲食中添加抗氧化劑也對老年動物整體健康有益2, 21, 30。本產品添加了天然抗氧化劑維生素E，並提升其他水溶性維生素的含量，以補充慢性腎病病貓因尿液排出增加而造成水溶性維生素的流失14。
最後，本產品也額外添加必須胺基酸，期望能更加彌補老年動物對蛋白質相對較低的消化能力，保持肌肉量，亦有助初期慢性腎病病貓身體質量指數及體重的維持8, 10, 24。
by 獸研所 品牌共同創辦人暨研發長｜梁雁婷 獸醫師
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