家里的小玛尔济斯也有常见的泪腺/红眼的问题
同样有养玛尔济斯的朋友，推荐使用泪腺粉
因为很好奇这类产品的作用原理，所以上网查询了一些资讯
发现一些2014年左右的国外文献指出，美国FDA曾经对几家宠物腺痕产品提出警示
因为这些产品含有tylosin tartrate 一种尚未取得用在宠物许可的macrolide类抗生素
节录我查到的一些资讯(我把指名道姓的产品名字先用****取代)：
While this claim may spark the interest of some pet owners, consumers should
know that the FDA last month shipped warning letters to ************ and the
makers of similar tear stain removal products, notifying the companies that
their goods contain an antibiotic (tylosin tartrate) that is not approved for
use on pets.
The FDA also sent letters to the makers of ********* and ********. The agency
said the products fall under its classification for unapproved animal drugs,
and should cease being marketed or else the companies would face potential
enforcement action.
“FDA has serious concerns about unapproved animal drugs,” the agency said.
“Unapproved animal drugs are not reviewed by FDA and may not meet FDA’s
strict standards for safety and effectiveness.
就我所知泪痕的问题一部份跟鼻泪腺管不通、泪水分泌过多->滋生细菌(和酵母菌)有关
所以在学理上，给予抗生素的确可以很有效的抑制泪痕 (就像抗生素也能抑制挫疮)
但抗生素的问题是不宜持续长期的使用(会培养出抗药性菌株)
再加上有文章指出Tylosin在当时没有拿到FDA用在狗身上的许可
比如Acta Veterinaria Scandinavica volume 56, Article number: 43 (2014)
https://actavetscand.biomedcentral.com/articles/10.1186/s13028-014-0043-5
一篇研究Tylosin治疗狗腹泻的研究就写道：
Currently, oral tylosin treatment is not approved for the treatment of
canine enteritis (canine就是狗)
不过相关的这些资讯多半是在2014年左右，所以很好奇现在的这些抑制泪痕产品，
是不是已经不含抗生素了，还是只是把抗生素从成份标示拿掉?
2017年，美国FDA仍然再次针对含有tylosin的tear stain remover
发布warning letter：https://reurl.cc/aND65Z (美国FDA官网)
(根据这篇warning，Tylosin应该是仍未拿到用来处理tear stain的许可)