Tanya's Comprehensive Guide to Feline Chronic Kidney Disease

Tanya's Comprehensive Guide to Feline Chronic Kidney Disease

Treatments: Antibiotics

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Overview

  • CKD is not an infectious disease, so antibiotics are not a routine treatment for CKD cats.
  • However, sometimes a cat will need antibiotics to treat a bacterial infection such as a kidney, urinary tract or dental infection.

When to Use Antibiotics

Antibiotics are not an integral part of treating CKD, but their use is essential if your cat has a bacterial infection. In CKD cats, these are most commonly:

The good news is that although infections may make your cat sicker, and in the worst case may cause your cat to crash, getting the infection under control can make your cat feel much better and may even lead to an improvement in blood test results.

Length of Treatment

Most courses of antibiotics last for 5-14 days.

However, if your cat has a kidney infection (pyelonephritis), a longer course is necessary, for up to 4-8 weeks. Some urinary tract infections also need a longer course of around four weeks.

Although most antibiotics start to show an effect within 48 hours, once you begin a course of antibiotics it is very important that you complete the course, otherwise antibiotic resistance may occur (see immediately below).

If your cat reacts badly to an antibiotic, contact your vet and discuss switching to another type.

Antibiotic Resistance

Antibiotic resistance does not mean the cat is resistant to the antibiotic, or showing a bad reaction to it. Antibiotic resistance means the bacteria which are causing the infection have developed an immunity to the antibiotic, so will not be killed by it. US Centers for Disease Control and Prevention explain more about antibiotic resistance.

One reason antibiotic resistance occurs is if too short a course of antibiotics is given. This can mean the bacteria are weakened, but not all of them are killed, and the stronger bacteria which were not killed off will regroup and develop resistance to the antibiotic. The next time these bacteria are exposed to that antibiotic, it will not kill them.

Ideally you want to give an antibiotic to which you know the bacteria will respond. The best way to do this is through a culture and sensitivity test, which identifies to which antibiotics the bacteria are susceptible. This enables you to only give an antibiotic which is known to be effective for your cat’s infection.

Using Probiotics in Addition to Antibiotics

Antibiotics aim to eradicate the bacteria causing the infection. However, they will also eradicate “good” bacteria which normally protect the body from infection. Therefore, when giving antibiotics, you may need to re-balance the bacteria in the gut with probiotics (“good” bacteria).

This can be particularly important if your cat develops diarrhoea while on antibiotics. Probiotics for the prevention and treatment of antibiotic-associated diarrhea: a systematic review and meta-analysis (2012) Hempel S, Newberry SJ, Maher AR, Wang Z, Miles JN, Shanman R, Johnsen B & Shekelle PG Journal of the American Medical Association 307(8) pp1959-69 found that giving probiotics may help with this type of diarrhoea, though further studies are needed to determine which probiotics work best for which antibiotic.

Please see Treatments for more information.

Antibiotic Choices

The following antibiotics may be used in cats. Amoxicillin, enrofloxacin and clindamycin are those most commonly used in CKD cats:

Antimicrobial therapy in veterinary medicine (2013) 5th Ed. Giguère S, Prescott JF & Dowling PM (Eds) Wiley Blackwell has extremely detailed information about antibiotics.

Amoxicillin and Clavulanate (Clavamox or Augmentin, Synulox or Noroclav)

Amoxicillin is an antibiotic in the penicillin family. It may be used alone, but for cats it is often combined with clavulanate, an inhibitor of an enzyme produced by bacteria (this enzyme could render the amoxicillin inactive if the clavulanate were not present). Combining the two means more bacteria should be killed than amoxicillin alone could achieve.

Trade names include Clavamox (veterinary formulation) or Augmentin (human formulation) in the USA and Synulox or Noroclav in Europe.

Mar Vista Vet discusses amoxicillin.

Mar Vista Vet also discusses amoxicillin with clavulanate acid.

Amoxicillin and Clavulanate Usage

This antibiotic is used for upper respiratory infections, urinary tract infections and dental infections. In the UK it tends to be the antibiotic which most vets prescribe routinely for many infections.

In CKD cats it is often prescribed for urinary tract infections.

Amoxicillin and Clavulanate Formulations

There are a number of different formulations available, including Clavamox, which comes as a 62.5mg tablet, a 62.5mg chewable flavoured tablet and an oral suspension with 62.5mg per ml; and Noroclav injectable.

Synulox in the UK comes in flavoured pills (known as “pink sweeties” in our house) which Harpsie would happily eat out of my hand.

Amoxicillin and Clavulanate Dosage

For amoxicillin alone (i.e. without clavulanate), Pet Place states “The dose of amoxicillin ranges from 5 to 12 mg per pound (10 to 25 mg/kg) two or three times a day orally. This would mean that a 10lb (4.5kg) cat would receive 50 to 120 mg two or three times a day of amoxicillin.

Referring to the Canadian amoxicillin 100mg tablets, Drugs talks about “a dosage rate of 11-22 mg/kg once daily” for cats, which is broadly similar to the Pet Place recommendation. However, it also says “In severe urinary tract and gastrointestinal tract infections requiring high concentration, the above dosages should be doubled.”

For Clavamox (which contains both amoxicillin and clavulanate), Pet Place states “the most common dose of clavamox used in dogs and cats is 6.875 mg per pound (13.75 mg/kg) every 12 hours.” This would mean that a 10lb cat would receive 68.75mg twice a day, slightly more than that recommended by Drugs, which says “The recommended dosage is 62.5 mg twice a day.”

Evaluation of urine concentrations of amoxicillin and clavulanate in cats (2021) KuKanich K, Woodruff K, Bieberly Z, Papich MG & KuKanich B Journal of Veterinary Internal Medicine 35(1) pp456-461 found that 62.5mg of amoxicillin and clavulanate given twice daily reached higher than necessary levels in a group of healthy cats.

These types of dosing may not be appropriate for CKD cats. Drugs says of the Canadian 100mg tablets “Since Amoxicillin 100 is excreted mostly by the kidneys, reduce the dosage for patients with renal impairment in proportion to the degree of loss of renal function.” Urinary tract infection: how to diagnose and treat correctly (2003) Brovida C Presentation to the World Small Animal Veterinary Association World Congress outlines how to modify the dosage for cats with kidney disease.

In light of a recent study (Benson 2020, see below), Amoxicillin/clavulanic acid in cats with and without chronic kidney disease (2020) Scherk M Clinician’s Brief Jul 2020 pp38-39 recommends using the lower end of the dose range in CKD cats.

Be guided by your vet as to the most suitable dosage for your cat.

Pet MD says of amoxicillin “This drug should be given for at least 7-10 days to be effective.”

Drugs says of Clavamox “The maximum duration of treatment should not exceed 30 days.”

Amoxicillin and Clavulanate Side Effects

Unfortunately this medication can cause loss of appetite, lethargy, drooling, vomiting and diarrhoea in some cats.

CKD cats appear to be more likely to experience more than one side effect, according to Pilot study of side effects and serum and urine concentrations of amoxicillin-clavulanic acid in azotemic and non-azotemic cats (2020) Benson KK, Quimby JM, Dowers KL, Sieberg LG, Daniels JB, Langston CE, Lunghofer PJ & Gustafson DL Journal of Feline Medicine and Surgery 22(8) pp729-735, which states “The data suggest that cats with azCKD have altered pharmacokinetics of amoxicillin, which may contribute to an increased incidence of multiple side effects.”

My Karma did not have CKD but she just could not tolerate this treatment for more than a few days, which my vet thought might be down to the added clavulanic acid. Apparently it is not uncommon for cats to be fine for a few days on this antibiotic but then exhibit side effects towards the end of the course. Rather bizarrely, the same thing happens to me (and no, as far as I know, I am not a cat), but I can tolerate amoxicillin on its own just fine.

Giving food before you give the antibiotic may help, as may probiotics (see above), but if not, contact your vet to see if you should switch to a different antibiotic. Your vet may wish to try amoxicillin without the clavulanate, or may wish to use a different type of antibiotic. Do not simply stop giving the medication because this may make the infection return (see above). 

Enrofloxacin (Baytril)

Enrofloxacin belongs to the fluoroquinolone family of antibiotics. Trade names include Baytril and Zeden. Like amoxicillin, it is a broad spectrum antibiotic (i.e. it works on a wide range of bacteria). In high doses, it may in rare cases cause blindness.

Mar Vista Vet has a good overview of enrofloxacin.

Pet Place has some information about enrofloxacin

Enrofloxacin Usage

Enrofloxacin is a powerful antibiotic and is not normally used for minor infections. Summary of product characteristics says “Fluoroquinolones should be reserved for the treatment of clinical conditions which have responded poorly, or are expected to respond poorly, to other classes of  antimicrobials. Wherever possible, fluoroquinolones should be used based on susceptibility testing.”

Enrofloxacin is a popular choice for kidney infections (which can be difficult to treat), where it appears able to reach bacteria deep in the kidneys which less powerful antibiotics cannot touch. One of my cats was prone to kidney infections and enrofloxacin saved his life on several occasions.

The manufacturer states that this class of antibiotics is not considered to be harmful to the kidneys, and that tests on dogs indicated no evidence of kidney damage even at high dosing levels. However, ISFM consensus guidelines on the diagnosis and management of feline chronic kidney disease(2016) Sparkes AH, Caney S, Chalhoub S, Elliott J, Finch N, Gajanayake I, Langston C, Lefebvre H, White J & Quimby J Journal of Feline Medicine & Surgery 18 pp219-239 state “Avoid enrofloxacin in cats with CKD due to increased risk of retinopathy at standard therapeutic doses.” See below for more on this.

Enrofloxacin Formulations

Enrofloxacin in widely available in 15mg tablet form. It doesn’t taste very nice, so it is also available as a chewable tablet called Taste Tabs.

There is an injectable form of enrofloxacin but it is only approved for dogs. Some people have used it for cats, but this is not recommended because there is a small risk of an abscess at the injection site. Occasionally, however, a vet will start the treatment plan with an injection and then the course of treatment will continue at home with tablets. Plumb’s Veterinary Drug Handbook (7th Ed.) says “Use of the canine or bovine injectable products in cats is controversial and may result in significant adverse effects. Parenteral administration in cats at doses less than 5 mg/kg have reportedly caused ophthalmic toxicity (blindness).”

Enrofloxacin Dosage

The official recommended tablet dose in most countries is 5 mg of enrofloxacin per kg of bodyweight per day. 

For the injectable version, the usually recommended dose is 1ml per 5 kg of cat, which is the equivalent of 5mg per kg of bodyweight.

This is the recommended total daily dose for cats of the following weights:

Cat Weight lbCat weight kgRecommended dose mg
5 lb2.2711.25
8 lb3.6418.20
10 lb4.5022.5

The dosage of 5mg per kg of bodyweight was introduced because of the risk of higher doses causing blindness in cats. The issue did not arise until the recommended dosage limits were dramatically increased, and once the issue became known, the reduced dosage of 5mg per kg daily was introduced. See below for more on the blindness issue.

For the overwhelming majority of cats, this is a safe dosage, because, according to Baytril, 16 of the 17 cats who developed blindness were given doses six to ten times higher than the recommended dose. However, the other cat in the study who became blind had received a dose of only 4.6 mg/kg. This cat was fifteen years old.

Enrofloxacin-associated retinal degeneration in cats (2001) Gelatt KN, van der Woerdt A, Ketring KL, Andrew SE, Brooks DE, Biros DJ, Denis HM, Cutler TJ Veterinary Ophthalmology 4(2) pp99-106 reports on the risks of blindness and recommends adhering closely to the guidelines regarding the maximum recommended dose.

Plumb’s Veterinary Drug Handbook (7th Ed.) states “Patients with severe renal or hepatic impairment may require dosage adjustments to prevent drug accumulation.” Urinary tract infection: how to diagnose and treat correctly (2003) Brovida C Presentation to the World Small Animal Veterinary Association World Congress outlines how to modify the dosage of enrofloxacin for cats with kidney disease.

Enrofloxacin may be given once daily or twice daily according to Plumb’s Veterinary Drug Handbook. However, the manufacturer states “once daily application of the total dose of fluoroquinolones will have greater therapeutic effect compared to treatment regimens where the dose is divided into two applications.” Therefore I would opt to dose once daily.

The manufacturer also states that research in dogs indicates that enrofloxacin is most effective when given one hour before food, preferably wet food. Plumb’s Veterinary Drug Handbook (7th Ed.) states “This drug is best given on an empty stomach without food, but if your animal vomits or acts sick after getting it, give with food or small treat (no dairy products, antacids or anything containing iron) to see if this helps.”

The recommended maximum course of treatment is 30 days (although Harpsie was on a longer course a couple of times for his kidney infections with no problems).

Enrofloxacin Side Effects

Possible side effects include nausea, vomiting or diarrhoea, though from what I have seen over the years, these side effects seem to occur far less commonly than they do with amoxicillin. Plumb’s Veterinary Drug Handbook (7th Ed.) says “enrofloxacin appears to carry a low risk of causing antibiotic-associated diarrhea.”

The main concern with enrofloxacin is that in certain rare cases it has caused retinal problems, including blindness, when given to cats in high doses. Plumb’s Veterinary Drug Handbook (7th Ed.) says “Use of the canine or bovine injectable products in cats is controversial and may result in significant adverse effects. Parenteral administration in cats at doses less than 5 mg/kg have reportedly caused ophthalmic toxicity (blindness).”

UK National Office of Animal Health states “In target animal studies, cats have been shown to suffer ocular damage after receiving doses of more than 15 mg/kg once daily for 21 consecutive days. Doses of 30 mg/kg given once daily for 21 consecutive days have been shown to cause irreversible ocular damage. At 50 mg/kg given once daily for 21 consecutive days, blindness can occur.”

The blindness has reversed in some cases once enrofloxacin is stopped, but not in all.

The manufacturer states that this class of antibiotics is not considered to be harmful to the kidneys, and that tests on dogs indicated no evidence of kidney damage even at high dosing levels. However, ISFM consensus guidelines on the diagnosis and management of feline chronic kidney disease(2016) Sparkes AH, Caney S, Chalhoub S, Elliott J, Finch N, Gajanayake I, Langston C, Lefebvre H, White J & Quimby J Journal of Feline Medicine & Surgery 18 pp219-239 state “Avoid enrofloxacin in cats with CKD due to increased risk of retinopathy at standard therapeutic doses.”

Summary of product characteristics says “Use the product with caution in cats with severe renal or hepatic impairment.”

Small Animal Clinical Pharmacology (2nd Ed.) (2008) Maddison JE, Page SW & Church DB Saunders Ltd says “It has been postulated that the relatively open blood-brain barrier of cats combined with the lipophilic properties of enrofloxacin predispose cats to accumulating high concentrations of the drug in the CNS. The risk may be higher in cats with urinary tract infections and concomitant renal failure and care should be taken with dosage in geriatric cats or those with liver or renal impairment.”

Enrofloxacin may lower the seizure threshold, so may not be the best choice in cats with a tendency to have seizures. Although Harpsie had epilepsy, fortunately for us he never had any problems with enrofloxacin.

Plumb’s Veterinary Drug Handbook (7th Ed.) says “Injectable enrofloxacin must not be mixed with, or come into contact with any IV solution containing magnesium (e.g., Normosol-R, Plasmalyte-R, -A, or –56); morbidity and mortality secondary to micro-precipitants lodging in patients’ lungs have been reported.”

Enrofloxacin Interactions

Enrofloxacin must not be given orally within two hours of products containing calcium, aluminium or lanthanum (such as phosphorus binders) or iron (such as Pet Tinic), because they may inhibit absorption of the enrofloxacin. Sucralfate must also be give separately from enrofloxacin for the same reason. Drugs has some information about this.

Enrofloxacin Research

Antibiotics and kidney disease in cats is a study at the University of California at Davis into enrofloxacin, which is aiming to ascertain whether there is decreased excretion of injectable enrofloxacin in cats with CKD.

Marbofloxacin (Marbocyl, Zeniquin or Marboquin)

Marbofloxacin belongs to the fluoroquinolone family of antibiotics, the same family as enrofloxacin (Baytril) and pradofloxacin (Veraflox). Trade names include Zeniquin and Marbocyl.

Pet Place has some information about marbofloxacin.

Mar Vista Vet has an overview of marbofloxacin.

Marbofloxacin Usage

Marbofloxacin is used for skin, upper respiratory or urinary tract infections, especially those which are not responding to other antibiotics.

Antimicrobial Use Guidelines for Treatment of Urinary Tract Disease in Dogs and Cats: Antimicrobial Guidelines Working Group of the International Society for Companion Animal Infectious Diseases (2011) Weese SJ, Blondeau JM, Boothe D, Breitschwerdt EB, Guardabassi L, Hillier A, Lloyd DH, Papich MG, Rankin SC, Turnidge JD & Sykes JE Veterinary Medicine International pp1-9 says “reserve for documented resistant UTIs but good first-line choice for pyelonephritis.”

Marbofloxacin Formulations

Marbofloxacin is only available in tablet form in the USA, starting with a 25mg size.

In 2020, generic marbofloxacin was approved in the USA under the name of Marboquin. This also comes in tablet form starting with a 25mg size.

In Europe, tablets start at 5mg size. Injectable marbofloxacin is also available in Europe.

Marbofloxacin Dosage

The usual dosage is 2.5mg per kg bodyweight (1.25mg per pound of body weight) once per day.

For urinary tract infections, it should be given for at least ten days. It can be given for up to thirty days if necessary.

ISFM consensus guidelines on the diagnosis and management of feline chronic kidney disease(2016) Sparkes AH, Caney S, Chalhoub S, Elliott J, Finch N, Gajanayake I, Langston C, Lefebvre H, White J & Quimby J Journal of Feline Medicine & Surgery 18 pp219-239 state “Consider dosage adjustment. Adjust dose in moderate or severe CKD (IRIS stages 3 and 4).”

Marbofloxacin Side Effects

Possible side effects include nausea, vomiting (less than 1% of cats), or diarrhoea (2.1%).

UK National Office of Animal Health states “At the therapeutic recommended dosage, no severe side-effects are to be expected in dogs and cats.”

Marbofloxacin may lower the seizure threshold, so may not be the best choice in cats with a tendency to have seizures.

There is some debate as to whether marbofloxacin can also cause blindness, as occasionally has happened with enrofloxacin. Plumb’s Veterinary Drug Handbook (7th Ed.) says that as at July 2007 the FDA Adverse Drug Reaction database had received 14 reports of blindness associated with marbofloxacin. Baytril says “Orbifloxacin and marbofloxacin, other fluoroquinolones approved for use in dogs and cats, have also been reported to cause retinal damage and/or blindness in cats. Results of these studies lead to the conclusion that most veterinary approved fluoroquinolones show variable affinity for retinal tissues in cats.”

Marbofloxacin Interactions

Marbofloxacin must not be given orally within two hours of products containing calcium, aluminium or lanthanum (such as phosphorus binders) or iron (such as Pet Tinic), because they may inhibit absorption of the marbofloxacin. 

Sucralfate must also be give separately from marbofloxacin for the same reason.

Pradofloxacin (Veraflox)

Pradofloxacin, trade name Veraflox, is a third generation antibiotic in the fluoroquinolone family of antibiotics, the same family as enrofloxacin (Baytril) and marbofloxacin (Zeniquin).

Clinical efficacy and palatability of pradofloxacin 2.5% oral suspension for the treatment of bacterial lower urinary tract infections in cats (2007) Litster A, Moss S, Honnery M, Rees B, Edingloh M &Trott D Journal of Veterinary Internal Medicine 21(5) pp990-5 says it is “designed to restrict the emergence of antimicrobial resistance during therapy.”  The manufacturer explains more about how it does this.

Pradofloxacin Usage

According to The European Medicines Agency, initially pradofloxacin was refused approval in the EU in 2006 because “the company had not been able to identify a  dose that was effective whilst at the same time providing an adequate margin of safety. For this reason the Committee concluded that the safety of pradofloxacin had not been conclusively proven.”

Things change, and pradofloxacin is approved for the treatment of respiratory and skin infections in cats in both the EU and the USA. It is not approved for the treatment of urinary tract infections in cats (it is in dogs), but Bacterial urinary tract infections (2016) Dowling PM Merck Veterinary Manual says “Pradofloxacin is only approved for skin infections in cats in North America, but it is approved for treatment of UTI in dogs in Europe and is used to treat feline UTI.”

Clinical efficacy and palatability of pradofloxacin 2.5% oral suspension for the treatment of bacterial lower urinary tract infections in cats (2007) Litster A, Moss S, Honnery M, Rees B, Edingloh M &Trott D Journal of Veterinary Internal Medicine 21(5) pp990-5 found it “is a highly effective and safe antimicrobial treatment for bacterial lower urinary tract infection in cats.”

Bacterial urinary tract infections (2016) Dowling PM Merck Veterinary Manual does say, however, “fluoroquinolones should be reserved for UTIs that involve gram-negative bacteria, especially Pseudomonas, and for UTIs in intact male dogs and cats because of their excellent penetration into the prostate gland and activity in abscesses.”

One major advantage of pradofloxacin is that, unlike enrofloxacin and marbofloxacin, it does not appear to cause blindness. Baytril says “In the development phase of pradofloxacin (Veraflox), a specific study was designed to investigate the effects of this molecule on the feline retina. This study clearly demonstrated retinal and ocular safety of pradofloxacin in the cat at doses up to 50 mg/kg, i.e. an at least tenfold safety margin.”

Pradofloxacin Formulations

Pradofloxacin is available in Europe and the UK in both tablet form, and in a 2.5% (25mg/ml) liquid suspension. In the USA it is only available in the suspension form, that the manufacturer states is designed to be palatable to cats. Clinical efficacy and palatability of pradofloxacin 2.5% oral suspension for the treatment of bacterial lower urinary tract infections in cats (2007) Litster A, Moss S, Honnery M, Rees B, Edingloh M & Trott D Journal of Veterinary Internal Medicine 21(5) pp990-5 found “the palatable formulation optimizes owner compliance.”

Pradofloxacin Dosage

Pradofloxacin is usually given once a day. Bacterial urinary tract infections (2016) Dowling PM Merck Veterinary Manual says “They are concentration-dependent killers with a long postadministration effect, so once daily, high-dose therapy for a relatively short duration of treatment is effective.”

The manufacturer recommends a course of 3-5 days treatment for an upper respiratory infection in cats. For urinary tract infections in dogs it recommends a 7-21 day course of treatment. Clinical efficacy and palatability of pradofloxacin 2.5% oral suspension for the treatment of bacterial lower urinary tract infections in cats (2007) Litster A, Moss S, Honnery M, Rees B, Edingloh M &Trott D Journal of Veterinary Internal Medicine 21(5) pp990-5 gave it for 11-30 days (median was 18 days) and no adverse effects were reported.

Tablets

Make sure you have 15mg cat size tablets.

The usual dose is 3mg per kg of body weight. A 10lb (4.5kg) cat should therefore receive 13.5mg.

The manufacturer used to recommends the following:

Cat Weight (kg)Number of 15mg TabletsTotal Dose Given (mg per kg)
3.4 – 5.013.0 – 4.4
5.0 – 7.51.53.0 – 4.5
7.5 – 10.023.0 – 4.0

Veraflox UK now simply says to give one 15mg tablet to a cat weighing 3.5-5.5kg.

Oral Suspension

The usual dose used to be 5mg per kg of body weight.

The manufacturer now states “The dose of Veraflox is 3.4 mg/lb. (7.5 mg/kg) body weight once daily for seven consecutive days. Use the syringe provided to ensure accuracy of dosing to the nearest 0.1 mL”

Pradofloxacin Side Effects

Pradofloxacin can lower the seizure threshold, so I would avoid using it in cats prone to seizures.

Pet Place mentions that “Administration can cause reversible drops in white blood cell counts. Drug should be discontinued if there is any unexplained drop in leukocyte, neutrophil and/or lymphocyte counts.”

Pradofloxacin Interactions

Pradofloxacin must not be given orally within two hours of products containing calcium, aluminium or lanthanum (such as phosphorus binders) or iron (such as Pet Tinic), because they may inhibit absorption of the pradofloxacin. 

Sucralfate must also be give separately from pradofloxacin for the same reason.

Mar Vista Vet states “If pradofloxacin is used with oral cyclosporine (an immunosuppressive medication used for inflammatory bowel disease), the kidney damaging properties of cyclosporine may become worse.”

Clindamycin (Antirobe)

Clindamycin belongs to the lincosamide family of antibiotics. One trade name is Antirobe.

Pet Place has an overview of clindamycin.

Mar Vista Vet has some information about clindamycin.

Clindamycin Usage

Clindamycin is approved for treating skin and dental infections in cats. It is often prescribed for dental problems because it is particularly good at killing anaerobic bacteria which are commonly found in the mouth. I have used it for this purpose in my own cats, and it is the antibiotic I would choose for this purpose.

Clindamycin should be used with caution in CKD cats – the normal dosage may need to be adjusted. Mar Vista Vet states “The manufacturer has recommended blood tests of liver and kidney function if use of clindamycin is to persist beyond 30 days.”

Clindamycin Formulations

Clindamycin is available in 25mg and 75mg capsules (which in theory are for dogs only). It is also available as a liquid medication in a 25mg/ml strength.

Clindamycin Dosage

The manufacturer recommends a dose for cats of 5-15 mg per pound (11-33mg per kg) once a day for a maximum of fourteen days.

Always give with food or follow with water to avoid damaging the oesophagus.

Clindamycin Side Effects

Clindamycin is notorious for tasting awful, so it may be better to give it in a gelcap.

Like most antibiotics, clindamycin may cause diarrhoea, vomiting and drooling.

Clindamycin (2015) Clarke M Plumb’s Therapeutic Brief May 2015 says “Administer with caution in patients with very severe renal disease and/or hepatic disease accompanied by severe metabolic aberrations.”

Cefpodoxime (Simplicef)

Cefpodoxime is an antibiotic in the cephalosporin class of antibiotics, the same family as cefovecin (Convenia).

Pet Place has some information about cefpodoxime.

Mar Vista Vet has an overview of cefpodoxime.

Cefpodoxime Usage

Cefpodoxime is commonly used to treat skin infections and urinary tract infections.

Cefpodoxime Formulations

Cefpodoxime is available in 100mg and 200mg capsules.

It is also available as a liquid medication in 50 mg/5ml and 100 mg/5ml strengths.

Cefpodoxime Dosage

A typical dose is 10 mg per kg (5mg per pound) of cat, given once a day, or 5 mg per kg (2.5 per pound) of cat, given twice a day. It can be given with or without food.

Drugs says “Dosage adjustments may be necessary and modifications should be based on the degree of renal impairment as well as severity of infection in accordance with the individual product package labeling.”

Cefpodoxime Side Effects

As with many antibiotics, loss of appetite, vomiting, lethargy and diarrhoea may be seen. Vomiting is the most common side effect with cefpodoxime.

Drugs says “Renal function tests should be performed periodically during prolonged and/or high-dose therapy, since nephrotoxicity and alterations in renal function have occasionally been associated with the use of these drugs.”

Cefpodoxime Interactions

Mar Vista Vet says “Drugs that decrease stomach acidity (any antacids) may decrease absorption and thus efficacy of cefpodoxime.” This would include medications such as famotidine (Pepcid), ranitidine (Zantac) and cimetidine (Tagamet).

Cefovecin (Convenia)

Cefovecin is a third generation antibiotic in the cephalosporin class of antibiotics, the same family as cefpodoxime (Simplicef). The brand name is Convenia.

Cefovecin Usage

Cefovecin under the brand name of Convenia was approved as follows:

  • in Europe in 2006 for the treatment of skin infections and urinary tract infections in cats and dogs.
  • in the USA in 2008 for the treatment of skin infections in dogs and cats, and urinary tract infections in dogs only.

The European Medicines Agency states “It is prudent to reserve third generation cephalosporins for the treatment of clinical conditions, which have responded poorly, or are expected to respond poorly, to other classes of antimicrobials or first generation cephalosporins.”

The UK National Office of Animal Health states “The safety of Convenia has not been assessed in animals suffering from severe renal dysfunction.”

Cefovecin Formulations

Cefovecin is only available as a subcutaneous injection. It lasts 14 days, so is very convenient, particularly for cats who hate to be pilled.

Efficacy and safety of cefovecin for the treatment of urinary tract infections in cats (2008) Passmore CA, Sherington J, Stegemann MR Journal of Small Animal Practice 49(6) pp295-301 found that an injection of cefovecin was as effective as a 14 day course of cephalexin.

Cefovecin Dosage

Pet Place mentions that “Maximum treatment should not exceed 2 injections.” Other sources state that it may be used up to three times.

However, the manufacturer has stated (2013) that Convenia “should be administered as a single, one-time subcutaneous injection at a dose of 3.6 mg/lb (8 mg/kg) body weight.”

If you do give it more than once, it should not be given more frequently than once every two weeks.

Cefovecin Side Effects

Possible side effects include lethargy, vomiting and diarrhoea. There may also be skin irritation at the injection site.

Other, more worrying possible side effects include haemolytic anaemia or pulmonary oedema, though fortunately these are rare. Drugs reports on possible side effects.

Cefovecin has not been tested in cats with severe kidney problems, but Drugs reports that some cats in a safety study had mild elevations in BUN and creatinine levels after they were given it.

There are a number of websites claiming that cefovecin is very dangerous for cats, and certainly some cats have had problems which might have been caused by the medication. Plumb’s Veterinary Drug Handbook 7th Ed. states “Hypersensitivity reactions, anaphylaxis and death associated with this drug are possible and have been reported.” Center for Veterinary Medicine adverse drug events report listing (2013) reports (page 294) on the adverse effects reported to be associated with the use of cefovecin in cats up until 1 March 2013, including 166 deaths and 148 cases of anaemia. Whilst this is worrying, people never seem unduly concerned that 66 deaths were also reported as being associated with amoxicillin and clavulanate.

Cefovecin can remain in the body for up to 65 days. If your cat does have a bad reaction, the fact that it is so long lasting becomes a disadvantage, because your cat’s body remains exposed to the drug.

Many people I have heard from who have used cefovecin were pleased with it. My Ollie was given this for a urinary tract infection and he did not show any adverse reactions, but his UTI symptoms began to return about 10 days after the shot, so we switched to amoxicillin and clavulanate, which seemed to work better for him.

Cefovecin Interactions

Famotidine (Pepcid AC) can interfere with antibiotics in the cephalosporin family such as cefovecin, so you should separate the two treatments by two hours. I am sometimes asked why I mention this when cefovecin is an injectable medication. H2-antagonist cephalosporin interactions (2003) Ali A Thesis states “These interaction studies with H2-receptor antagonists in gastric as well as blood pH revealed that simultaneous use of these drugs depressed the availability of the antibiotic as well as cimetidine, ranitidine and famotidine.”

Plumb’s Veterinary Drug Handbook does not mention cefovecin specifically, but does mention that taking other members of the cephalosporin family with food may offset the reduced absorption of the antibiotic.

Metronidazole (Flagyl)

Metronidazole is an anaerobic antibiotic which is not commonly used in CKD cats, but it is anti-inflammatory in the digestive tract, so it can be very helpful for diarrhoea. Therefore it is often used in cats with colitis or IBD. It is occasionally used for dental problems, since oral bacteria are often anaerobic. Because of its anti-inflammatory effects, it is also sometimes used in cats with pancreatitis.

Metronidazole is known for its horrible taste.

Neurological problems can occasionally be seen, though these are rare and usually associated with either long term use (over a period of months) or high doses. The neurological problems usually resolve within a couple of weeks of stopping the medication. Pet Place discusses metronidazole toxicity but mentions it is uncommon and usually associated with long term use.

Mar Vista Vet has some information about metronidazole.

This page last updated: 21 September 2025

Links on this page last checked: 14 July 2020