Long-Term Consequences of Giardia Infection?

Hello, Summarians!

How does early infection with a disease impact an animal long-term? Typically, we tend to think that most recoveries do not have lasting consequences. Certain recent infections have changed that dogma — COVID, for example.

Could the same hold for some intestinal processes? I’ll let you decide …

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Long-Term Consequences of Giardia in Dogs

Acute enteritis in humans is known to increase the risk of developing chronic gastrointestinal conditions like irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD), as well as extraintestinal diseases such as reactive arthritis and Guillain–Barré syndrome. Similar long-term consequences are less well-documented in dogs, though a few studies suggest that severe acute mucosal damage, such as that caused by canine parvovirus (CPV) or acute hemorrhagic diarrhea syndrome (AHDS), increases the likelihood of chronic gastrointestinal issues later in life. This chronicity may result from permanent alterations to the intestinal mucosa or from disruption of the gut barrier and microbiome, leading to immune sensitization. 

In this context, the present study examined whether young dogs with Giardia-associated acute enteritis developed chronic gastrointestinal or dermatologic signs. Findings revealed that these dogs had a higher prevalence of chronic GI signs compared to controls, with patterns resembling those seen in CPV and AHDS cases. The presence of pruritus and moderate GI symptoms that improved with dietary modification suggests that some dogs may develop food hypersensitivity after Giardia-induced barrier dysfunction. 

While Giardia infection in dogs typically does not cause hemorrhagic diarrhea, damage to the brush border and intestinal epithelial cells has been documented in both humans and animal models. This damage may increase intestinal permeability, allowing antigens and microbes to interact with the immune system, a proposed mechanism for the transition to chronic disease. The study also found that while both fenbendazole and metronidazole were used to treat Giardia, dogs receiving metronidazole after severe enteritis appeared more likely to develop chronic GI signs. This supports previous findings about the drug’s potential to cause lasting dysbiosis. 

The study did not find a strong association between the age at initial infection and long-term outcomes within the included juvenile age range, but acknowledged that very young puppies—especially those under two months—might be more vulnerable due to an immature microbiome and immune system. Limitations included its retrospective design, reliance on owner questionnaires, possible diagnostic inaccuracies, small sample size (especially in the metronidazole subgroup), and confounding factors such as reinfection, co-infections, and incomplete ectoparasite control. 

Ultimately, the study adds to growing evidence that acute enteric infections, including those caused by Giardia, may predispose dogs to chronic gastrointestinal and dermatologic issues. The combination of severe intestinal damage and antibiotic-induced dysbiosis, particularly from metronidazole, may heighten this risk. Further prospective studies are needed to clarify causal relationships and identify protective or predisposing factors, with the goal of improving treatment and prevention strategies in veterinary medicine. 

Walz, K.C., Suchodolski, J.S., Werner, M., Grimm, F., Schnyder, M., Zablotski, Y., and Unterer, S. (2025), Long-Term Follow-Up After Acute Gastroenteritis Caused by Giardia Infection in Juvenile Dogs. J Vet Intern Med, 39: e70123. https://doi.org/10.1111/jvim.70123 

Bottom line — It may cause issues long-term.

TEER Success in Dogs

Myxomatous mitral valve degeneration (MMVD) is the most common heart disease in dogs, and while pimobendan remains the mainstay for delaying heart failure and improving quality of life in affected dogs, interest is growing in advanced interventions such as mitral valve repair. In human medicine, open mitral valve repair is the gold standard for treating mitral regurgitation (MR), and similar surgical approaches have been adopted in veterinary practice with high short-term success rates. However, for dogs with severe comorbidities or high surgical risk, transcatheter edge-to-edge repair (TEER) offers a less invasive alternative. This study retrospectively assessed the outcomes of TEER in dogs with advanced MMVD, including those in stages B2, C, and D, many of whom had additional health issues such as renal, endocrine, and metabolic disease. 

The study found that TEER significantly reduced the severity of MR and heart size, indicating reverse cardiac remodeling. Some dogs were able to discontinue cardiac medications post-procedure. However, variability in the extent of MR reduction and residual regurgitation was noted, reflecting similar trends observed in human patients. Four dogs experienced severe complications such as leaflet tears or device detachment, which were sometimes linked to preexisting leaflet abnormalities or operator inexperience. These events underline the importance of patient selection and technical proficiency. One case of thrombosis and another of bleeding emphasize the need for further research into appropriate post-procedural thromboprophylaxis. Transient arrhythmias like accelerated idioventricular rhythm occurred in all dogs shortly after TEER but resolved without intervention. 

Compared to open mitral valve repair, TEER required significantly less anesthesia time and was better suited for dogs with high-risk conditions, though the 3-month survival rate was 65%. The study acknowledged limitations, including its retrospective design, small sample size, and non-standardized follow-up protocols. Imaging variability and lack of consistent inclusion criteria may have influenced outcomes. Additionally, the learning curve for TEER was evident, with survival rates improving as operator experience increased. 

Overall, the findings support TEER as a viable, minimally invasive option for dogs with MMVD who are not ideal candidates for surgery. The procedure shows promise in reducing MR and promoting reverse remodeling, but larger, prospective studies with long-term follow-up are needed to further validate its efficacy and safety. 

Lee, J.-M., Youp, K.-a., Lee, S.-T., Lee, A.-R., Cho, Y.-W., Jung, Y.-S., Her, J. and Lee, S.-K. (2025), Retrospective Evaluation of Transcatheter Edge-To-Edge Mitral Valve Repair in Dogs With Myxomatous Mitral Valve Disease. J Vet Intern Med, 39: e70156. https://doi.org/10.1111/jvim.70156 

Bottom line — Seems to be a viable option for pets

Digital Radiographs to Diagnose Acute Laminitis

This study investigated the potential of using radiographic measurements of the lamellar lucent zone (LLZ) to aid in the diagnosis of acute and subacute laminitis in horses, prior to the onset of radiographic evidence of distal phalanx (Pd) rotation or sinking. LLZ corresponds to the lamellae and sublamellar dermis and can be visualized with modern digital radiography systems. The study compared LLZ measurements from horses with laminitis to those from a healthy control group and found that LLZ was significantly increased in affected horses. The most diagnostically useful measurement was the middle LLZ to palmar cortical length (LLZ:PCL) ratio, which offered 95% sensitivity and specificity at a cutoff >11%. Increases in LLZ likely reflect elongation, separation, or edema in the lamellar and sublamellar tissues, which are characteristic of acute laminitis. Other measurements, such as the dorsal hoof wall to Pd distance (DHW-Pd) were less sensitive and specific. The study also showed that ratios involving LLZ were more robust to common radiographic artifacts like magnification and obliquity than absolute measurements. Although some findings suggested mild palmar rotation and asymmetrical (medial) Pd displacement in subacute cases, especially evidenced by changes in LLZ and sole depth, the acute cases typically showed increased LLZ without radiographic signs of Pd rotation or sinking. The results support the clinical utility of LLZ measurements and LLZ-based ratios for early diagnosis and monitoring of laminitis, even in the absence of traditional radiographic markers of chronic disease. Despite limitations such as a lack of histological confirmation, small sample size, and inclusion of repeat radiographs, the findings provide a strong basis for incorporating LLZ metrics into diagnostic protocols. Further studies are needed to explore LLZ changes in hind feet, assess breed-specific reference values, and evaluate these metrics in ponies and draft horses. 

Skelton G, Acutt E, Stefanovski D, van Eps A. Evaluation of digital radiographic measurements for the diagnosis of acute laminitis. Equine Vet J. 2025; 57(4): 931–942. https://doi.org/10.1111/evj.14436 

Bottom line — Potentially useful for diagnosis earlier.

Just putting things in perspective …