Can probiotics help treat canine atopic dermatitis? What the research really says

Photo: Artur/Adobe Stock

In a lecture at the 2025 American Veterinary Medical Association (AVMA) Convention in Washington, DC, Andrew Simpson, DVM, MS, DACVD, specialist at VCA Animal Hospitals, set out to debunk various dermatology fads circulating the veterinary world.¹ One of the topics Simpson covered was the use of probiotics for treating canine atopic dermatitis and other dermatologic symptoms.

In veterinary medicine, studies on the dermatological effect of probiotics are few. However, as Simpson explained during the session, studies in human medicine show probiotics can be beneficial in treating atopic dermatitis in children. Researchers hypothesize that probiotics work in this capacity by modulating the immune system response, shifting it away from a T helper 2 (Th2)-dominated profile, which is commonly associated with atopic dermatitis, towards a T helper 1 (Th1)-mediated response.

Still, results across studies remain inconsistent, suggesting that probiotic effectiveness depends on the species and/or strain of lactobacillus that is being used.

Lactobacillus rhamnosus

In a study by the University of Florida, pregnant dogs with high levels of immunoglobulin E (IgE), which is a factor for atopic dermatitis predisposition, were given L. rhamnosus of the strain GGin the third week of gestation. The puppies continued receiving this probiotic until they were 6 months old.¹

The study found L. rhamnosus was partially effective in preventing the development of atopic dermatitis in these dogs, with clinical results being mixed and some puppies still developing atopic dermatitis.¹ According to Simpson, skin barrier function benefits were also still evident 3 years later. However, no decrease in clinical signs was observed.

Lactobacillus paracaseiK71

In a different 2015 study comparing cetirizine with L. paracasei K71, a similar reduction in clinical signs of mild canine atopic dermatitis was observed at 38.1% vs 45.8% throughout 12 weeks of treatment. Fewer clinical signs for pruritus were also observed (38.1% vs 26.8%).^1,2

Although the study on L. paracasei K71 showed positive dermatological effects, Simpson expressed reservation about the study’s design. “It's interesting [the researchers] chose antihistamines, since...antihistamines, in general, tend to have a lower yield of efficacy,” he said.¹ “I think it would be better to maybe compare [L. paracasei K71] to steroids or Cytopoint or Apoquel or something with a higher success rate.”

“We'd be interested to see, you know, what is it like in severe cases? You know, some of these mild cases, those might sort of fluctuate very subtly throughout the week or throughout the month,” he continued.

Lactobacillus sakei

An 8-week trial conducted in 2015 using L. sakei probio-65 for 2 monthsin participants with severe canine atopic dermatitis found that the probiotic significantly reduced the disease severity index in the patients. Specifically, lesional and itch scores were lower compared to placebo groups.^1,3

Enterococcus faecium

In a separate 2019 study, researchers investigated the effects of E. faecium (FortiFlora; Purina Pro Plan Veterinary Diets), on dogs already on oclacitinib (Apoquel; Zoetis) to see if the addition of the probiotic helped reduce the dose of the medication or the need for it.^1,4

The study’s results found that the addition of E. faecium to the dogs’ diet was not associated with oclacitinib dose reduction compared to the placebo. Overall, no difference was noted in participants being supplemented with E. faecium.^1,4

Gut microbiota dysbiosis and atopic dermatitis

More recently, a study published this year found that probiotics can improve canine atopic dermatitis by improving gut microbial dysbiosis.^1,5

The study looked at changes in the gut microbiota using polymerase chain reaction (PCR) after administering Bifidobacterium animalis, Lactobacillus acidophilus, and Enterococcus faecium at a concentration of 50 million colony-forming units per gram over 16 weeks.^1,5 Comparisons of fecal microbiota at baseline, 8 weeks, and 16 weeks highlighted the association between gut microbiota dysbiosis and canine atopic dermatitis. Most notably, the study’s results found that daily administration of the probiotics for 16 weeks significantly reduced the severity of clinical symptoms.^1,5

Additional studies

Still, as Simpson emphasized, findings from studies on the benefits of probiotics for dermatological use are limited and vary, with a retrospective study this July 2025 assessing 5 studies on probiotic use for atopic dermatitis—3 oral and 2 topical—findings that probiotics did not show any significant effect against atopic dermatitis.

“We definitely need more prospective studies, things that are controlled, comparing it to what we know are acceptable or effective products,” said Simpson. “And then there could be some differences between genera, or differences between species, or maybe differences with, ‘Are we using a single organism or using multiple organisms? Are we using a certain concentration, certain parts of their development? [Are these] mild cases? [Are they] severe cases?’”

“I... think we need to fine tune and understand, really, what is that connection between the gut health and skin health? I think it's there. We just really haven't defined it as much as we would need to,” he concluded.

References

1. Simpson A. Debunking derm fads. Presented at: American Veterinary Medical Association Convention; Washington, DC; July 18-22, 2025.
2. Ohshima-Terada Y, Higuchi Y, Kumagai T, Hagihara A, Nagata M. Complementary effect of oral administration of Lactobacillus paracasei K71 on canine atopic dermatitis. Vet Dermatol. 2015;26(5):350-353.e74-e75. doi:10.1111/vde.12224
3. Kim H, Rather IA, Kim H, et al. A double-blind, placebo-controlled trial of a probiotic strain Lactobacillus sakei Probio-65 for the prevention of canine atopic dermatitis. J Microbiol Biotechnol. 2015;25(11):1966-1969.
4. Yamazaki C, Rosenkrantz W, Griffin C. Pilot evaluation of Enterococcus faecium SF68 as adjunctive therapy for oclacitinib-responsive adult atopic dermatitis in dogs. J Small Anim Pract. 2019;60(8):499-506. doi:10.1111/jsap.13042
5. Song H, Mun SH, Han DW, et al. Probiotics ameliorate atopic dermatitis by modulating the dysbiosis of the gut microbiota in dogs. BMC Microbiol. 2025;25(1):228.