The Pros and Cons of Scrubbing With Betadine, Chlorhexidine

Which is best to clean the patient’s skin, the mouth, the eye and the prepuce?

“Should I scrub patients with Betadine or chlorhexidine?”

This is probably one of the most frequently asked questions, yet practices seem to be divided between the Betadine clinics and the chlorhex hospitals. Based on a non-representative sample, my impression is that there are far more practices that use chlorhexidine to scrub patients. So what should we do?

When quizzed, few people even know why they do what they do.

“That’s the way we’ve always done it” is usually the answer. Most times, the protocol has been transmitted from technician to technician for years. Likewise, many practitioners scrub patients the way they were taught in vet school.

Let’s investigate the pros and cons of each preparation to clean the skin, the mouth, the eye and the prepuce.

What is the best way to scrub the skin?

Once clipped, the surgical site may be cleaned up with a rough prep in the treatment room. Regardless, a sterile scrub is applied in the OR. The skin cannot be sterilized.

“What we are trying to do is to significantly reduce the number of bacteria present. Then the immune system can take care of the remaining flora,” explains Scott Weese, DVM, Dipl. ACVIM. Our colleague at the University of Guelph vet school is a board-certified internist-turned-infectious-disease specialist.

The recent literature (mostly human) suggests that chlorhexidine provides better asepsis than Betadine. The reduction in surgical site infection is significantly lower with chlorhexidine scrub.

A total duration of five minutes of contact time seems universally accepted. There should be no such thing as “a quick scrub” because antiseptics work based on contact time, not how vigorously you scrub.

As we have all noticed, scrubbing skin too enthusiastically will cause irritation and possible self-mutilation once the patient goes home. There is no need for that; we merely need to “paint” the skin for a full five minutes.

There is some debate about the residual activity of chlorhexidine, and how much it truly binds to keratin. So if you use alcohol, don’t necessarily use it because it “activates” your antiseptic. If anything, alcohol helps in rinsing the scrub soap off the skin.

You can then finish the preparation with a povidone iodine or chlorhexidine spray.

What is the best way to scrub the mouth?

In dogs, any part of the mouth can be safely scrubbed with 0.05-0.1 percent aqueous solution of chlorhexidine.

But  in cats, chlorhexidine can cause severe oral ulcers, laryngitis, pharyngitis and tracheitis. Besides direct application, these consequences can also occur after intubating a cat with an endotracheal tube that was washed with chlorhexidine (see photo). This can be prevented by not using chlorhexidine to clean small tubes, or by thoroughly rinsing them if chlorhexidine is used.

It can also occur after a cat licks a surgical site that had been scrubbed with chlorhexidine. This can be prevented by rinsing the skin postop and using an Elizabethan collar.

Photos Courtesy of Dr. Phil Zeltzman

Pharyngitis after chlorhexidine exposure (the result of washing ET tub in Novasan disinfectant and not rinsing the tube thoroughly afterwards) in a cat's pharynx.

What is the best way to scrub the eye?

Chlorhexidine in any form and povidone iodine scrub cause corneal ulcerations. It is therefore recommended to use diluted povidone iodine solutions (0.2 percent), either made in-house or purchased as an ophthalmic preparation from your supplier.

The skin around the eye can be prepped as usual, but scrub or alcohol should never touch the eye. A generous amount of eye lube can be used to protect the eye from harsh chemicals.

What is the best way to scrub the prepuce?

Anytime the penis is going to be touched during surgery, for example to flush stones out of the urethra during a cystotomy, the prepuce should be flushed. The same concept applies to surgery performed on the penis, e.g. to correct urethral prolapse.

A fascinating study1 was performed to compare flushing the prepuce using 1 percent povidone iodine solution, 0,05  percent chlorhexidine solution and saline. 

Saline (not surprisingly) and povidone iodine (shockingly) had the same poor results, while chlorhexidine caused a significant decrease in the culture results.

The authors suggest the following protocol: fill a 12 ml syringe with 0,05 percent  chlorhexidine solution (e.g. in a sterile bowl). Fill and distend the prepuce. Massage it. Empty the solution. Repeat the procedure six times over two minutes.

The patient’s skin can be scrubbed as usual.

The best method to scrub patients and avoid SSIs is still a work in progress. However, it seems that overall chlorhexidine has several important benefits over Betadine. But banning povidone from your practice entirely would not be ideal if you plan on performing oral surgery in cats or ophthalmic surgery in any pet.

Scott Weese concludes: “So what should you do? Start by assessing your specific needs, based on the information provided above and the procedures you actually perform. Then pick and choose between povidone solution, alcohol, chlorhexidine scrub and chlorhexidine solution.

CliffsNotes™ on chlorhexidine

Chlorhexidine is positively charged, so it binds to the negatively charged bacterial cell membrane. Disruption of the cell wall and precipitation of cell proteins cause the cell membrane to rupture. In addition, chlorhexidine has good residual activity because it binds to keratin in the patient’s skin.

Chlorhexidine is bacteriostatic at low concentrations, and bactericidal at high concentrations (100% within 30 seconds). It has a broad-spectrum (more effective against Gram positive than Gram negative, fungi, viruses). It is not inactivated by organic material.

It might be less irritating than iodophors, with fewer hypersensitivity reactions compared to iodophors. Importantly, chlorhexidine is toxic to the tympanic membrane and the cornea.

CliffsNotes™ on povidone iodine

Iodophors penetrate the bacterial wall and replace intracellular molecules with free iodine. A 1% concentration is usually recommended. A higher concentration may cause tissue necrosis, so more is not better here.

It is broad-spectrum (Gram positive, Gram negative, fungi, viruses, some spores) with a minimum of 2 minutes of skin contact.

Disadvantages include:

  • Inactivation by organic material such as blood, pus and necrotic tissue.
  • Staining of skin and cloth.
  • Hypersensitivity reactions in up to half of patients!
  • Systemic absorption of iodine through mucous membranes and open wounds, to the point of causing transient malfunction.

Kelly Serfas, a certified veterinary technician in Bethlehem, Pa., contributed to this article.


  1. SA Neihaus et al. “Presurgical Antiseptic Efficacy of Chlorhexidine Diacetate and Providone-Iodine in the Canine Preputial Cavity”. JAAHA 2011, Vol. 47, N. 6, p. 406-412.

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One thought on “The Pros and Cons of Scrubbing With Betadine, Chlorhexidine

  1. I was wondering what reference was used for the statement about chlorhexidine causing oral ulcers, pharyngitis and tracheitis? Is this anecdotal? I am not challenging it at all, I just want to include it in another publication.