Does Cranberry Help UTI's

Hello Summarians!

We are faced daily with questions about OTC or “natural” products. The reality is that there are very few well-thought-out, reliable studies in veterinary medicine on these types of subjects.

Why? Funding is challenging to find if there is no specific product associated with the concept. Here is one that attempts to help with one aspect.

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COVID in Zoo Animals

This retrospective observational study examined SARS-CoV-2 infections in animals housed in U.S. zoological institutions between 2020 and 2023, focusing on exposure sources, clinical signs, and transmission dynamics. Using national surveillance data and detailed outbreak investigations from a subset of facilities, the study provides insight into how the virus moved between humans and animals in these settings. 

A total of 170 animals across 13 species and 28 jurisdictions were confirmed positive. Most infected animals showed clinical signs, with coughing, lethargy, and reduced appetite being the most common. Big cats and nonhuman primates were the most frequently affected groups. Evidence strongly suggested that humans, particularly infected caretakers, were the primary source of infection, accounting for nearly half of known exposures. Visitor-related transmission appeared less significant and was often unclear.  

Genomic analysis supported these findings, showing that viral strains in zoo animals closely matched those circulating in the human population at the same time, with no evidence of significant viral evolution within animal populations. This indicates that infections were typically introduced from humans rather than sustained within animal groups. 

Outbreak investigations at 12 facilities revealed that while biosecurity practices increased modestly after outbreaks, most institutions already had strong preventive measures in place. Common practices included sanitation, use of personal protective equipment, and animal isolation. However, maintaining these measures long term proved challenging due to staff fatigue and resource limitations. 

Although animal-to-human transmission was suspected in a small number of cases, it appeared to be rare. Overall, zoological institutions were not major drivers of pandemic spread but were identified as high-risk environments for human-to-animal transmission. The findings highlight the importance of a One Health approach, emphasizing coordinated efforts to protect animal health, human health, and conservation goals in environments where close interspecies interaction occurs. 

Cristiano, D. J., Varela, K. E., Anderson, C. E., Croft, L., Crook, E., Hanley, C., Junge, R., Montgomery, D., Newland, K., Rivera, S., Rosenberg, J. F., Worden, D., Yoshicedo, J., Young, S., Baker, M., Beddo, M., Carruthers, M., Feldpausch, A., Oltjen, H., Tewari, D., Rekant, S. I., Cleary, S., Kalinich, C. C., Liew, A., Behravesh, C. B., Ghai, R. R., & SARS-CoV-2 Zoos and Aquariums Working Group. (2026). SARS-CoV-2 infections among animals in US zoological institutions resulted primarily from human-to-animal transmission without evidence of sustained evolution in animals (2020–2023). Journal of the American Veterinary Medical Association https://doi.org/10.2460/javma.25.11.0738 

Bottom line — Human to animal was most important.

Cranberry for UTIs

This systematic review evaluates the evidence for cranberry and cranberry extract supplementation in the prevention and treatment of urinary tract disease, specifically bacterial cystitis and subclinical bacteriuria, in dogs and cats. Infectious urinary tract disease is a common clinical issue in companion animals and a significant driver of antimicrobial use, making alternative or adjunctive therapies of interest. Cranberry products are widely marketed as nutraceuticals for pets, and their proposed mechanism—primarily attributed to A-type proanthocyanidins—centers on inhibiting bacterial adhesion, particularly E. coli, to the urinary tract epithelium. However, despite their popularity, robust veterinary-specific evidence supporting their clinical efficacy has been lacking. 

The review identified only three relevant studies, encompassing a total of 122 animals (106 dogs and 16 cats). These studies varied in design, populations, and outcomes, and all were limited by small sample sizes. Importantly, none demonstrated a statistically significant or clinically meaningful benefit of cranberry supplementation for preventing or treating urinary tract disease. One randomized controlled trial evaluating bacteriuria in dogs with spinal cord injury found no benefit and was terminated early due to futility, with a numerically higher incidence of bacteriuria in the treatment group compared to controls. Another study assessing recurrence of cystitis in dogs reported no cases of recurrence in either the cranberry or antibiotic group, rendering conclusions impossible. A third study in cats compared cranberry supplementation plus antibiotics to antibiotics alone and found no difference, with all subjects responding to treatment. 

The overall quality of evidence was rated as low to very low due to high risk of bias, imprecision, and methodological limitations. Only one study was considered low risk, while the others had significant concerns related to randomization, outcome assessment, and reporting. Additionally, none of the studies systematically evaluated safety or adverse effects. 

Although in vitro studies and some human data suggest potential benefits of cranberry supplementation, these findings have not translated into convincing clinical evidence in veterinary patients. Consequently, current evidence is insufficient to support or refute the use of cranberry products for urinary tract disease in dogs and cats. The review highlights a clear need for larger, well-designed randomized controlled trials to better assess efficacy and safety. 

Weese, J.S. and Weese, H.E. (2026), Effectiveness of Cranberry Supplementation for Prevention and Treatment of Infectious Urinary Tract Disease in Dogs and Cats: A Systematic Review. J Vet Pharmacol Therap, 49: 102-109. https://doi.org/10.1111/jvp.70050 

Bottom line — Not a lot of support in vet med yet.

Lymph Node Mapping

 This study looked at whether fluorescein sodium could be used safely and effectively during surgery to find sentinel lymph nodes in dogs with skin or under-the-skin tumors. Sentinel lymph nodes are important because they are usually the first place cancer spreads, so identifying them helps veterinarians stage disease and plan treatment. 

Six client-owned dogs with tumors were included in the study. The dye was injected just under the skin around each tumor. Special lights—either blue or ultraviolet—were then used to track how the dye moved through the lymphatic system and to identify the sentinel lymph nodes. Researchers recorded how long it took for the dye to appear, how clearly it showed up, and whether any side effects occurred. 

The results were promising. Lymphatic vessels were visible in most dogs, and sentinel lymph nodes were successfully identified in all of them. On average, it took about 7 minutes to see the lymphatic vessels and about 8 minutes to see the lymph nodes. No adverse reactions were reported, suggesting the technique is safe. In addition, laboratory analysis of the removed lymph nodes showed that some contained cancer cells, confirming that the method can help detect metastasis.  

Compared to other methods, fluorescein has several advantages. Traditional techniques like CT scans or specialized imaging systems can be expensive, require advanced equipment, and are often limited to referral centers. Other dyes may not work consistently or can stain tissues in a way that makes surgery harder. In contrast, fluorescein is inexpensive, easy to use, and can be seen with simple light sources, making it more practical for everyday veterinary clinics. 

There were some limitations to the study. The sample size was small, and the tumors varied between dogs, so the results cannot be generalized to all cases. Also, the study did not directly compare fluorescein to other mapping techniques, and the assessment of dye uptake was somewhat subjective. 

Overall, the study suggests that fluorescein sodium is a safe, low-cost, and effective option for identifying sentinel lymph nodes in dogs during surgery. It may help make this important cancer staging technique more widely available in general veterinary practice. 

Perez-Rodriguez, V., Maxwell, E. A., Aisa, J., & Bertran, J. (2026). Expanding access to cancer care: 10% fluorescein sodium is a practical, low-cost method for intraoperative sentinel lymph node mapping in dogs. Journal of the American Veterinary Medical Association https://doi.org/10.2460/javma.25.11.0735 

Bottom line — An inexpensive technique could help.

Just putting things in perspective …