Risks of Anaesthesia

Preparing for Surgery

During Surgery

Anaesthetic Choices

After Surgery



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Home > Related Diseases > Anaesthesia



  • Many cats will need anaesthesia at some point in their lives.

  • Anaesthesia always carries a small risk, and this risk can be higher in a CKD cat.

  • This page explains more about the precautions you can take to minimise the risks.



Sometimes a CKD cat needs to have a general anaesthetic. The most usual reason in a CKD cat is dental surgery, but cats sometimes need anaesthesia for other reasons, perhaps to have a growth removed or to have kidney stones treated.


I know you don't want your cat to undergo general anaesthesia. The mere thought of it terrifies me, and I'm a gibbering wreck whenever one of my cats needs it. There are always risks associated with anaesthesia, but if your cat is in pain (and believe me, dental pain is horrible), or if s/he won't survive much longer without surgery, then you will have to decide whether to go ahead.


Long Beach Animal Hospital has detailed information on anaesthesia written for laypeople.


Pet Place gives an overview of anaesthesia.


Risks of Anaesthesia


The risks of anaesthesia are varied, but breathing and heart rate may be affected, and aspiration may occur if the airway is not protected.


Low  blood pressure (hypotension) can be caused by anaesthesia. 2013 AAHA/AAFP fluid therapy guidelines for dogs and cats (2013) Davis H, Jensen T, Johnson A, Knowles P, Meyer R, Rucinsky R & Shafford H Journal of the American Animal Hospital Association 49(3) pp149-159 say "Hypotension under anesthesia is a frequent occurrence, even in healthy anesthetized veterinary patients."


Hypotension tends to be the main concern for CKD cats because it may damage the kidneys and therefore increase the risk of CKD developing or worsening. Risk factors associated with the development of chronic kidney disease in cats evaluated at primary care veterinary hospitals (2014) Greene JP, Lefebvre SL, Wang M, Yang M, Lund EM & Polzin DJ Journal of the American Veterinary Medical Association 244 pp320–327 found that "Risk factors for CKD in cats included ... prior periodontal disease or cystitis, anesthesia or documented dehydration in the preceding year."


Fortunately, many of the risks can be managed, which reduces the chances of problems developing. The risk of death: the confidential enquiry into perioperative small animal fatalities (2008) Brodbelt DC, Blissitt KJ, Hammond RA, Neath PJ, Young LE, Pfeiffer DU & Wood JL Veterinary Anaesthesia & Analgesia 35(5) pp365-73 reports on the anaesthesia of 79,178 cats and found the risk of death was 0.24%, rising to 1.4% in sick cats. The study states that "Greater patient care in the postoperative period could reduce fatalities."


Preparing for Surgery


The first thing to do is to find a vet you trust to perform the surgery. As Robert Smith MD puts it, "There are no safe anesthetic agents, there are no safe anesthetic procedures. There are only safe anesthetists." (Introduction to anesthesia (2007) Muir WW, Hubbell JAE, Bednarski RM, Skarda RT, eds. Handbook of veterinary anesthesia. 4th ed. St. Louis: Elsevier.).


You also need to decide whether to use a specialist. Most vets can perform a variety of surgical procedures, but for certain types of surgery, such as kidney stone treatment such as SUBs or stents, you will need a specialist. You may also wish to use a dental specialist if your cat is undergoing dental surgery - see Dental Problems for more information.


You should always have a physical exam and bloodwork done and blood pressure checked before surgery, so any problems can be addressed. If your cat has heart issues, you may also wish to see a veterinary cardiologist prior to surgery.


If your cat is on blood pressure medication such as amlodipine (Norvasc) or benazepril (Fortekor), ask your vet if you need to stop the medication a couple of days before the surgery (since anaesthetics may reduce blood pressure).


All cats should be placed on intravenous (IV) fluids during and after any procedures. This is to avoid falls in blood pressure during the procedure, which may damage the kidneys.


CKD cats should be placed on intravenous fluids for a few hours before, during and after any surgery. Most vets will place cats on IV fluids during and sometimes after surgery, but not every vet wishes to place a CKD cat on IV fluids before anaesthesia. However, this is very important for your cat's safety. In Chronic kidney disease (2007) Polzin DJ Delaware Valley Academy of Veterinary Medicine, Dr Polzin (a kidney specialist) states "It appears that the medical prophylaxis most likely to be effective is related to pre-intervention fluid support. Pre-loading patients with fluids before potential ischemic or nephrotoxic interventions has thus far been shown to be the most effective therapy. Other options that have been investigated include diuretics, vasodilators, and some forms of metabolic support. However, none have thus far proven to be superior to support with a saline-based fluid. Usually, fluids should be administered in sufficient volume to induce diuresis."


2013 AAHA/AAFP fluid therapy guidelines for dogs and cats (2013) Davis H, Jensen T, Johnson A, Knowles P, Meyer R, Rucinsky R & Shafford H Journal of the American Animal Hospital Association 49(3) pp149-159 state "patients with uremia benefit from preanesthetic fluid administration."


Depending upon the type of surgery involved, antibiotics may need to be given to the cat for several days in advance, and continued for 5-7 days afterwards.


During Surgery


All cats should be placed on IV fluids during and after any procedures. This is to avoid reduced blood flow and falls in blood pressure during the procedure, which may damage the kidneys.


Anesthesia for patients with renal disease (2015) Rezende M & Mama K Clinician's Brief Mar 2015 pp41-44 states "The kidneys are particularly susceptible to ischemic injury because the distribution of blood flow within the kidneys is not uniform or proportional to demand; despite its higher metabolic rate, for example, the renal medulla only gets 15% of the overall renal blood flow (RBF). Therefore, a decrease in cardiac output and blood pressure— as may be observed with anesthetic drug administration—has the potential to further compromise renal function." They go on to say "vascular volume and blood pressure support remain the most important aspects of protecting renal function during anesthesia management."


The American Association of Feline Practitioners Senior Care Guidelines (2009) Pittari J, Rodan I, Beekman G, Gunn-Moore D, Polzin D, Taboada J, Tuzio H & Zoran D Journal of Feline Medicine & Surgery 11 pp763-778 gives guidance on anaesthesia for older cats, especially those with CKD.


What monitors can and can't tell you: real world monitoring for field and high volume anaesthesia (2014) McCobb E Pet Smart Charities National Spay/Neuter Conference gives an overview of standard monitoring procedures which can give you some idea of the basics.


Any drugs used on a CKD cat during anaesthesia which are cleared by the kidneys may require a reduction in the dose, since damaged CKD kidneys may not clear them as fast as healthy kidneys.


Anesthetic hypotension (2017) Jimenez Lozano MA Clinician's Brief Mar 2017 pp27-30 discusses steps your vet can take should your cat's blood pressure fall too low during the procedure.


Anaesthetic Choices


The main concern during the surgery is often the anaesthetic. You should discuss with your vet the type of anaesthesia that will be used on your cat. Generally speaking, animals undergoing surgery receive two types of anaesthesia:

  • an induction agent to induce unconsciousness; and

  • general anaesthesia to keep them unconscious whilst the procedure is being performed.


Anaesthesia for the geriatric dog and cat (2008) Hughes JML Irish Veterinary Journal 61(6) pp380–387 discusses the use of anaesthesia in older cats, including cats with kidney disease.


Renal disease management basics (2004) Stein B Veterinary Anesthesia and Analgesia Support Group recommends a particular anaesthesia protocol for anaesthesia in patients with kidney disease. Ask your vet to follow this, or to explain any changes to you.


The Veterinary Anesthesia and Analgesia Support Group also provides information on anesthesia protocol generally.


Anesthesia for patients with renal disease (2015) Rezende M & Mama K Clinician's Brief Mar 2015 pp41-44 discusses anaesthetics which are suitable for CKD cats.


American Animal Hospital Association Anesthesia Guidelines for Dogs and Cats (2011) Bednarski R, Grimm K, Harvey R, Lukasik VM, Penn WS, Sargent B, Spelts K Journal of the American Animal Hospital Association 47 pp377–385 discusses anaesthesia, including for kidney and heart patients.


Induction Agents

Induction agents used in cats are usually in the form of injections. A commonly used induction agent is propofol.


Veterinary Anaesthesia and Analgesia Support Group mentions that "alfaxalone has little or nocardiovascular effects when given in the normal dose." This might make it a better choice for a cat with heart disease.


Ketamine is not recommended because it has to be cleared by the kidneys.


Some vets do not use an injectable induction agent, but instead use an inhaled anaesthetic both to induce unconsciousness and to provide general anaesthesia. Using inhaled anaesthetics in this way is sometimes referred to as "masking down." I would ask your vet not to do this, because injected induction agents are safer. Serenity now: practical sedation options for cats (2015) Shafford HL, a veterinary anaesthetist, says "Box inductions should be avoided because they are 1) scary and stressful for patients, 2) dangerous to personnel (exposure to inhalants associated with numerous adverse health effects including impaired reproductive function), and 3) dangerous to the patient (exposure to high levels of potent cardiorespiratory depressant, inability to monitor and support cardiovascular or respiratory system during induction, increased mortality)."


General Anaesthetics

General anaesthetics take various forms. For CKD cats, inhaled anaesthetics are a good choice. These are gases, which put less strain on the cat's body than other types of anaesthetic, and they also enable the vet to stop the procedure and bring your cat round immediately if there are any problems during surgery. 


One commonly used inhaled anaesthetic is isoflurane. Some vets prefer another inhaled anaesthetic called sevoflurane, but Anesthesia for patients with renal disease (2015) Rezende M & Mama K Clinician's Brief Mar 2015 pp41-44 states "Because of the known nephrotoxic metabolites (eg, compound A) produced by sevoflurane, it is best to avoid this drug even though any toxic effect may be minimal in a stable patient with renal disease. Therefore, the use of isoflurane is generally recommended."


If your cat is to receive an inhaled anaesthetic following induction with an injectable induction agent, usually an endotracheal tube is inserted into the cat's throat to administer the inhaled anaesthetic and to help the cat to breathe.


The main downside of inhaled anaesthetics is that they may cause low blood pressure, which can damage the kidneys. It is therefore essential that your cat's blood pressure is monitored during the procedure and that intravenous fluids are given before, during and after the procedure.


After Surgery


Some cats develop a low temperature following anaesthesia, so ensure that your cat's temperature will be monitored afterwards. Some vets warm the fluids given to the cat but Heated intravenous fluids alone fail to prevent hypothermia in cats under general anaesthesia (2017) Jourdan G, Didier C, Chotard E, Jacques S & Verwaerde P Journal of Feline Medicine and Surgery 19(12) pp1249-1243 found that "heated fluid alone fails to prevent intraoperative hypothermia in cats." It speculates that this might have been the case in this study because of the low infusion rate of  5 ml per kg of cat per hour.


Your cat might benefit from a heat pad immediately following surgery. The American Association of Feline Practitioners Senior Care Guidelines (2009) Pittari J, Rodan I, Beekman G, Gunn-Moore D, Polzin D, Taboada J, Tuzio H & Zoran D Journal of Feline Medicine & Surgery 11 pp763-778 states "Since hypothermia is common, evaluate body temperature every 15 mins, continuing postoperatively until the cat is ambulatory or normothermic. Support body temperature by using tools such as a heated cage, hot air blankets, water-circulating heating pad, and/or booties."


Your cat should also receive intravenous fluids during the recovery period. 2013 AAHA/AAFP fluid therapy guidelines for dogs and cats (2013) Davis H, Jensen T, Johnson A, Knowles P, Meyer R, Rucinsky R & Shafford H Journal of the American Animal Hospital Association 49(3) pp149-159 state "Patients that may benefit from fluid therapy after anesthesia include geriatric patients and patients with either renal disease or ongoing fluid losses from gastrointestinal disease."


Blood pressure should also be monitored for a week or so afterwards because although low blood pressure is a risk during surgery, surgery and anaesthesia may cause increases in blood pressure following the procedure.


If inhaled anaesthesia has been used, your cat will have a tube down the throat during surgery (intubation), which can cause the throat to feel a little sore for a day or two afterwards.


After most types of surgery painkillers are necessary. WSAVA guidelines for recognition, assessment and treatment of pain (2014) Mathews K, Kronen PW, Lascelles D, Nolan A, Robertson S, Steagall PVM, Wright B & Yamashita K Journal of Small Animal Practice 55(6) ppE10–E68 points out that "pain associated with surgery is 100% predictable."


Your cat may be able to come home a few hours after surgery, or may have to stay in the hospital overnight or for a day or so. If you bring him or her home soon after surgery, keep him/her in a warm, quiet place. Your cat may be a little wobbly at first, but this should soon improve. If you have any concerns, contact your vet.


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This page last updated: 01 March 2018

Links on this page last checked: 12 June 2017






I have tried very hard to ensure that the information provided in this website is accurate, but I am NOT a vet, just an ordinary person who has lived through CKD with three cats. This website is for educational purposes only, and is not intended to be used to diagnose or treat any cat. Before trying any of the treatments described herein, you MUST consult a qualified veterinarian and obtain professional advice on the correct regimen for your cat and his or her particular requirements; and you should only use any treatments described here with the full knowledge and approval of your vet. No responsibility can be accepted.


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