Are you looking for resources for small animal clinical practice? Or building a library while a student?
Either way, I would advise against either resource. Merck Manual you can just search on the web. If you just want to look up CKD in cats, just google "chronic kidney disease feline merck" and voila. I bought Saunder's dictionary prior to starting vet school and never ever cracked it open. Probably the worst investment I ever made in my life. If you lived nearby I'd probably give it to you for free... if I can find it after moving 4 times with it.
If you're a student, I'd wait to buy books until you've tried them out through the school library or the ones lying around the teaching hospital during clinics. They're only really worth getting if you use them all the time. Seriously, save that money for a nice stethoscope or white coats, or scrubs or whatever. I bought the Clinical Vet Adviser by Etienne Cote because I love it... but even then I probably should have just waited until I started working because my workplace I'm pretty sure has one available. A lot of people buy and carry around the Nerdbook. It's another bad investment of mine. I bought it and opened it once... the one piece of information I looked up on it was wrong... I think it was like a decimal point issue (I don't remember what it was was, but was important and the clinician was horrified. Maybe it was Phenobarb levels or something). Never opened it again. Not just because of that mistake, because I'm sure there's a lot of good info on there, but I just never needed it. The only thing I consistently carried around with me were laminated pocket sized sheets with anesthesia protocols, as well as a notebook I handwrote of common drug dosages. In the notebook, I also had pasted in consensus statements (found free online) of important things like Diabetes management, IRIS stages/guidelines, fever of unknown origin, PU/PD, and such. I also put in a chart of chem profile and cbc changes (low or high) and what the differentials were for each change. I've also started going through the "getting through the night" series through VIN and handwriting step by step notes on how to deal with common ER presentations. The other thing I have is a handwritten mini-text for myself on diagnosis and treatment of derm things. It just makes you sound so much smarter and with it when you can not only diagnose something, but then say what drug, dosage, and duration of treatment/followup you'd like to do 🙂
If you sign up for purina university, you can also get hematology, cytology, parasitology, etc... PDF versions of their booklet resources for free. There are a ton of other free resources on VIN, which is free as a student. One website I can't live without is VSS😵rg, which stands for veterinary society of surgical oncology I think. You can search for specific neoplasms by species and body part/organ where it's located, or just the name of the neoplasm. And it pretty much gives you a concise run-down of everything you would want to know in a 5-10 min read before you need to give news to a client. Oncologists don't like it because they don't cite their sources so you don't know what study the median survival times come from, etc... But at least you get the gist of "if you do nothing, the MST is ___, with surgery alone it tends to extend it to ___, and with additional radiation/chemo, ____." I mean... is it a few weeks, a few months, or a couple of years? Those are the things the owners want to know. Not so much that that the most current paper says MST of 420 days, when the last paper was 360. It gives you whether it is a surgical disease or a medical disease, or the animal is SOL no matter what you do. It also tells you what further workup is warranted. And then you can refer to an oncologist when it comes to exact chemo protocol/radiation and they can get more info there.
If you're in practice, Plumb's would probably be worth investing in (though you can access it free if you're on VIN). Some people have different preferences between the Clinical Vet Advisor and 5 minute Consult, but a lot of people I know refer to them. If you need a surgery text, Slatter or Fossum are the ones I've used (I'm sure there are others around, but I think these are the classics). If you need a medicine text, Ettinger is your friend.