GI Ulcers and NSAID's

Hello, Summarians!

This newsletter is an attempt to help us all cope with the deluge of information we face every day. It usually contains 3-4 summaries and citations related to animal health.

Here’s how I suggest using it: If you find any of the studies even remotely useful, throw them into your archive folder. If not, hit delete.

If you have found it helpful, please consider sending it on to a friend 😄 

GI Ulcers and NSAID’s in Dogs

Gastrointestinal (GI) ulceration in dogs is a notable complication often associated with systemic diseases like neoplasia, inflammatory bowel disease, hepatic dysfunction, and various drug therapies, including NSAIDs and corticosteroids. NSAIDs, especially nonselective COX inhibitors, are among the most common causes of GI ulcers in dogs, primarily due to their effects on the COX-1 and COX-2 pathways, which inhibit prostaglandin production critical for gastroprotection. Although COX-2–selective NSAIDs are considered safer, they still carry risks of ulceration. Corticosteroids are also implicated in GI ulceration, albeit through less well-defined mechanisms. 

Studies show that clinical signs of GI ulceration in dogs can vary widely, often presenting as abdominal pain, hematemesis, melena, and anorexia, with imaging inconsistently identifying ulcer sites. The study at hand focused on understanding the incidence, characteristics, and outcomes of GI ulcers in a large cohort of dogs on NSAIDs or corticosteroids. Carprofen was the most commonly implicated NSAID, causing clinical ulcers even at recommended doses, which suggests potential underestimation of its risk profile, especially in dogs not dosed according to lean body weight. Additionally, the concurrent administration of NSAIDs or NSAIDs with corticosteroids increased the risk of severe ulceration, often leading to full-thickness perforations and septic peritonitis. 

Ultrasound findings frequently included peritoneal effusion and GI tract thickening, although ulcer localization was rarely possible without CT imaging. The study highlighted the limitations of relying solely on the detection of intracellular bacteria in cases of septic peritonitis, recommending comprehensive evaluation based on clinical history and diagnostic imaging. Ulcers were most commonly located in the duodenum and pylorus, likely due to higher gastric acid exposure in these areas. 

The study's limitations include a small sample size, retrospective data collection, and the lack of lean body weight dosing assessments. Overall, findings emphasize the importance of cautious NSAID and corticosteroid use in dogs, particularly in those with comorbid conditions, with close monitoring for GI complications. Further research is recommended to identify factors contributing to the progression from subclinical to full-thickness ulceration and clarify corticosteroids' role in GI ulceration. 

Hillier, T. N., Watt, M. M., Grimes, J. A., Berg, A. N., Heinz, J. A., & Dickerson, V. M. (2024). Dogs receiving cyclooxygenase-2–sparing nonsteroidal anti-inflammatory drugs and/or nonphysiologic steroids are at risk of severe gastrointestinal ulceration. Journal of the American Veterinary Medical Association https://doi.org/10.2460/javma.24.06.0430

Bottom line — Useful to remember.

Breed-Specific Bloodwork Differences in Horses

Understanding breed-specific hematologic differences is crucial for accurate interpretation of complete blood count (CBC) results in horses. Misinterpretation due to unawareness of these differences can lead to clinical errors, unnecessary treatments, and increased veterinary costs. This study evaluated CBC variables among adult Warmbloods, Thoroughbreds, and stock horses (SH) to identify potential breed-related differences. 

The findings revealed that Warmbloods have significantly lower white blood cell (WBC) counts, characterized by decreased lymphocyte counts, compared to Thoroughbreds and SH. While neutrophil counts were also lower in Warmbloods, this difference was not statistically significant in direct comparisons. The reduced lymphocyte counts in Warmbloods are unlikely due to stress or age factors, suggesting a genetic or breed-specific trait. Despite lower lymphocyte and neutrophil counts, the neutrophil-to-lymphocyte ratio remained consistent across breeds because both cell types were proportionally reduced in Warmbloods. 

Thoroughbreds exhibited higher red blood cell (RBC) counts and increased hematocrit and hemoglobin concentrations compared to Warmbloods and SH, aligning with their breeding as performance athletes requiring enhanced oxygen-carrying capacity. Platelet clumping was common among samples from all breeds, potentially leading to pseudothrombocytopenia and highlighting the need for careful interpretation of platelet counts. 

Total protein concentrations were higher in SH compared to Thoroughbreds, although the study could not determine the exact cause due to limitations like lack of detailed dietary information. The study's limitations also include a relatively small sample size, minimal seasonal variation, and geographic restrictions, indicating that further research is needed. 

In conclusion, the study demonstrates significant breed-related hematologic differences among Warmbloods, Thoroughbreds, and SH. Warmbloods may have WBC, lymphocyte, and neutrophil counts below standard laboratory reference intervals, while Thoroughbreds show elevated erythrocyte parameters. These findings suggest that clinicians should consider breed-specific reference intervals when interpreting CBC results in healthy horses to avoid misdiagnosis and inappropriate clinical decisions. 

Schaefer EA, Edman J, Magdesian KG. Comparison of hematologic variables among Warmbloods, Thoroughbreds, and Western stock horse breeds. Vet Clin Pathol. 2024; 53: 179-185. doi:10.1111/vcp.13343 

Bottom line — There can be significant differences in breeds.

Point of Care Bloodwork Analyzer Accuracy

This study evaluated the clinical utility of two point-of-care (POC) biochemistry analyzers—the Heska Element DC and the IDEXX Catalyst—by comparing their performance with a commercial laboratory analyzer, the Cobas 8000, using feline plasma samples. The aim was to determine if these POC analyzers could meet established analytical quality goals based on biological variation and consensus standards, specifically the ASVCP (American Society for Veterinary Clinical Pathology) performance guidelines. 

The findings revealed that only 50% (7 out of 14 analytes) on the Heska analyzer and 14% on the IDEXX analyzer had limits of agreement (LOAs) within the desirable total error (TE_des) quality goal derived from biological variation. However, when considering the less stringent ASVCP total allowable error (TEA) performance guidelines, 85% of analytes on the Heska and 62% on the IDEXX met the criteria. The stringent nature of biological variation-derived quality goals makes them challenging to achieve with current technology, especially for analytes with low inherent biological variation. 

The methodology involved offsetting the quality goals by the mean bias for each analyte on each analyzer to account for inherent bias from factory calibration in POC analyzers, which cannot be adjusted by the end user. While this approach was effective for most analytes, it did not account for proportional bias—where the amount of bias varies at different analyte concentrations. For analytes like alanine aminotransferase (ALT) and alkaline phosphatase (ALP), proportional bias at low concentrations affected the applicability of the method. By excluding low concentration results, which are often not clinically relevant, the analyzers met the quality goals, indicating that proportional bias had minimal practical effect in these cases. 

The study acknowledged limitations in the methodology, particularly when proportional bias could not be accounted for by exclusions, as seen with chloride and globulins. These limitations highlight that while the methodology is sound for most analytes, it may not be universally applicable. The authors emphasize the importance of understanding the implications of quality goals and advocate for a greater awareness of measurement uncertainty among practitioners. They suggest that repeating unusual results can reduce clinical errors from unreliable measurements. 

In conclusion, the study demonstrated that while POC analyzers may not meet the stringent quality goals based on biological variation for all analytes, they can still be clinically useful when assessed against less stringent consensus-based goals like the ASVCP TEA performance guidelines. Only 7 of 14 analytes on the Heska analyzer and 2 of 14 on the IDEXX analyzer achieved LOAs within TE_des goals, but the number increased with less stringent criteria or if accepting that less than 95% of comparisons need to meet the quality standards. The authors stress that understanding the quality goals and their relationship to analyzer performance is crucial for interpreting results and ensuring clinical utility. 

Baral RM , Jaensch SM , Hayward DA , Freeman KP . Analytical performance of feline plasma on current Heska and IDEXX point-of-care biochemistry analyzers compared with a commercial laboratory analyzer. Vet Clin Pathol. 2024; 53: 343-357. doi:10.1111/vcp.13310

Bottom line — They have their limitations.

Just putting things in perspective …