Jonathan J. Mazelsky
President, Chief Executive Officer and Director at IDEXX Laboratories
Thanks, Brian, and good morning. Today, we're pleased to report another quarter of strong results, supported by continued favorable trends in our core CAG business and excellent execution by the IDEXX team. As noted, we delivered 25% organic revenue growth in the second quarter, supported by high organic CAG diagnostics recurring revenue growth. There were strong gains across all CAG business segments and testing modalities, representing a continuation of the accelerated growth trends we've seen since the second half of 2020. Strong sector growth and outstanding execution by the IDEXX team gives us confidence to raise our 2021 financial outlook as we continue to invest towards our significant long-term growth opportunity.
Today, I'll provide a brief update on the trends we're seeing in key regions in our companion animal sector and discuss the status of our initiatives to strengthen our international commercial capabilities. I'll also share an update on our ProCyte One launch and growing software portfolio, including the ezyVet acquisition, which will better position us to capitalize on favorable tailwinds, further enhance practice productivity and raise the standard of patient care.
Let me start with an update on sector trends. Global sector trends remained favorable in the second quarter, reflected, for example, in sustained high U.S. clinical visit models that support continued strong increases in veterinary service revenues, including diagnostics. As Brian noted, U.S. clinical visits increased 13% in the quarter and 4.8% on a two year average annual basis, with continued strong gains across wellness and nonwellness categories.
This growth was supported by a growing pet population and veterinarians focus on medical services, which are sustained even as pandemic restrictions have eased. These solid trends were seen across all global regions in Q2. Our strong commercial execution is building on this momentum, reflecting in IDEXX CAG diagnostics organic recurring revenue growth of 26% on a one year basis, and 16% on a two year average annual basis. Within the clinic, veterinarians and the teams continue to rise to the challenge of increased demand, working hard to keep up with industry growth while also delivering excellent patient care to ever more engaged pet parents. IDEXX is well positioned to provide them the tools and services necessary to meet these demands, supporting 15% diagnostics revenue growth per practice and even faster growth for IDEXX revenues. Overall, we feel very positive about the strong sector backdrop.
Our strategy to bring testing and information management and innovations to the practice and our team's level of execution, which is reflected in our raised full year revenue outlook. In terms of execution, our commercial team continues to deliver exceptional results despite continued constrained clinic access. Instrument placement showed increased momentum in the second quarter with over 3,750 total premium placements, up solidly from a strong Q1, helping to drive 14% growth in our premium worldwide installed base for the quarter. This included double-digit growth in premium chemistry, hematology and urinalysis installed bases as well as continued excellent growth in new and competitive accounts.
Veterinary customers are extremely busy due to high visit volumes. And they're investing in IDEXX instruments, diagnostics and tools to support practice growth, patient care and staff productivity. Our digital cytology solution is an excellent example of this point. An innovative service that extends the capability and reach of the practice by providing cytology testing results in the U.S. with a report authored by expert pathologists another two hours at any time during the day or week, 365 days a year, veterinarians are able to provide a higher standard of care to their patients, improve staff and clinical productivity and drive appropriate testing and practice revenues.
Validating this medical value proposition, we saw strong customer interest in orders for a digital cytology solution in Q2. We also continue to advance key programs like IDEXX Preventive Care that help clinics raise the standard of care aligned with higher levels of pet owner engagement. In Q2, we executed 150 new preventive care enrollments as we continue to advance towards our goal of 10,000 engaged customers in the U.S. by 2024. In terms of customer access, we continue to operate in a hybrid model, with access still limited but improving in both the U.S. and international regions. In the U.S., approximately 60% of customer visits were in person in Q2, whereas it was approximately 50% in Europe.
This has impacted our ability to deliver outstanding results as both new innovations and our excellent relationships we have with customers have driven significant growth across all regions. The deep customer relationships with our sales professionals have only been reinforced and strengthened by the best-in-class support we provided to customers throughout the pandemic. Of note, we're particularly pleased with our high levels of execution in regions like Europe, where we are expanding the successful go-to-market approaches we've applied in the U.S.
This was reflected in 400 catalyst placements at new and competitive accounts outside of North America, with half of these placements under IDEXX 360 agreements. The expansion of the IDEXX 360 program is also supporting sustained strong gains in lab revenues in Europe, accelerating new account acquisition and helping to inspire faster customer growth at IDEXX 360 customers. A key focus of our strategy in this context is on developing the long-term international revenue opportunity through an expansion of our direct commercial presence.
We've completed the commercial expansions first announced in Q3 of last year, which were focused on three countries: Germany, France and South Korea. By almost doubling our commercial footprint in these countries, we have appreciably increased the frequency and intensity of our calling activities with existing customers and competitive accounts. Our experience is that when we do this, our customers grow faster as they adopt our innovations. And so do we.
Three additional countries have been targeted at the next stage for expansion over the remainder of 2021 and into 2022. We're excited to share with you our broader commercial approach at the upcoming Investor Day. Our expanding global commercial capability will support the adoption of key innovations like ProCyte One, following our first U.S. shipments in late March, ProCyte One's international launch began in June with installations and presale customers in France, Germany, U.K. and in Southern Europe. Many of our international geographies are hematology-focused, meaning customers prioritize CBC for patient health assessment. Not surprisingly, we've seen an extremely positive reaction to the ProCyte One introduction in international regions.
Customers applied its simplicity and small footprint while still delivering the excellent accuracy, usability and reliability profile veterinarians and their staff price so highly. Additionally, we expect a multiplier impact for ProCyte One as chemistry and hematology testing go hand-in-hand with the additional potential to inspire Reference Lab and Rapid Assay business when placed as part of the IDEXX 360 program. Speaking of Rapid Assay, we're very pleased with the strong momentum we continue to drive in this business globally. We achieved 20% plus organic growth in the U.S. in Q2, while raising customer retention levels to 97% supported by innovations like SNAP Pro, we now have over 80% of SNAP 4Dx customer volume engaged on this platform, which enhances insight and supports practice workflow. SNAP Pro is also helping to achieve accelerated growth in international regions.
In Europe, after installing a clinics first SNAP Pro, we see a significant expansion in testing volumes. We look forward to building on the strong momentum supported by continued IDEXX innovation. We're also excited with the progress we're advancing in our cloud-based software capability. We had another excellent quarter of new software installations with Cornerstone and Neo placements growing 21%, while cloud-based offerings continue to represent the majority of PIMS placements. As we continue to expand our installed base, we also continue to drive expansion of profitable recurring services, such as credit card processing, which grew at strong double-digit rates organically.
Software solutions have taken on significant importance to the effective management of the veterinary practice. Practices have never been busier, and IDEXX integrated, easy-to-use software solutions support patient care and workflow, staff productivity and communications amongst the care team and with the client. Moreover, IDEXX diagnostic solutions are seamlessly integrated into both our and third-party solutions, enabling practices to capture and invoice the full range of activities that veterinarian deliver. We know that IDEXX customers who use all of our solutions have a higher customer experience and tend to test more and grow faster.
Relating to the growing importance of practice software solutions, cloud-based technologies have the potential to make important contributions to the overall software experience of the veterinary clinic. For example, practice owners are free from the challenges of supporting on-premise IT solutions that include frequent hardware update. Moreover, providers of cloud-based solutions like IDEXX can provide frequent seamless updates in an environment that offers security advantages.
Our software capabilities were augmented in Q2 with the acquisition of ezyVet, a fast-growing, innovative practice information management system that is native cloud-based used by advanced general practices as well as specialty, emergency and large corporate groups worldwide. This acquisition complements our PIMS portfolio by providing additional options to practices with more complex needs and enterprise functionality. Customers appreciate ezyVet software for its easy use and rich features.
In fact, ezyVet is the number one rated full-feature practice management solution with 94% customer satisfaction according to Capterra, an industry standard business software customer review site. Bringing ezyVet into the IDEXX family also grows our cloud development talent enabling us to capitalize on the evolving nature of the veterinary clinic software product. With that, I'd like to welcome the ezyVet team to IDEXX. We look forward to working together with you to continue to develop best-in-class software products.
We're also excited about the progress we're driving in our diagnostic imaging business. We saw very strong growth in digital imaging placements in Q2 and strong growth in our backlog, reflecting a continued appreciation of our focus on providing a full range of premier low-dose imaging solutions. Growth in these placements also supports the expansion of recurring services, including cloud-based services like Web PACS. Our Web PACS subscriptions grew at high teens rates with much faster growth in premium and unlimited subscription tiers, reflecting the high value and diagnostic insight clinicians drive from IDEXX software solutions.
Overall, we're very pleased with our business momentum and optimistic as we continue to respond to the reopening of economies globally. In terms of IDEXX' specific plans, we're excited to advance plans to bring more IDEXX back to the office safely and in ways that ensure business continuity. We anticipate maintaining a more hybrid working environment and appreciate our employees flexibility, and adapt into new ways of working while continuing to deliver high growth, provide top-notch customer service and support our world-class product portfolio.
Before I wrap up my remarks, I'd like to publicly welcome a new leader to IDEXX. As Dr. Martin Smith will be joining my leadership team in August as Executive Vice President and Chief Technology Officer. Martin brings 30-plus years of experience in the life sciences industry, most recently as Chief Technology Officer at Cytiva and Pall Corporation, both subsidiaries of Danaher. He's a strong track record of driving R&D strategy in concert with enterprise strategic initiatives, commercial efforts. And we look forward to Martin leading our world-class R&D organization. Welcome, Martin. With that, I'd like to add that I'm extremely proud of the way the entire IDEXX team is executing as we are on track for another strong year in 2021 with financial performance aligned with our long-term goals.
Our growth and performance reflect a consistent business strategy focused on opportunity development within our core businesses and our employees continue to execute against this strategy daily. I look forward to sharing more on our strategy and long-term potential at our upcoming Investor Day on Thursday, August 12. The event remains virtual due to the evolving nature of COVID-19 and we invite you to register on the Investor Relations section of our website. Participating will be members of my senior management team, including Brian McKeon, Executive Vice President and CFO; and Dr. Tina Hunt, Executive Vice President and General Manager for Point of Care Diagnostics and Worldwide Operations; Mike Lane, Executive Vice President and GM for Reference Laboratories and Information Management; Jim Polewaczyk, Executive Vice President and Chief Commercial Officer; Kerry Bennett, Senior Vice President of Corporate Strategy and Advanced Analytics and Michael Schreck, Senior Vice President of Veterinary Software and Services. The event will last approximately three hours and will conclude with a Q&A session.
That concludes my opening remarks. We now have time for questions.