Serial Bone Marrow Evaluation for Monitoring Myeloid Neoplasia

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-08-11

Key Takeaways

• Serial bone marrow aspirates are critical for monitoring myeloid neoplasia in dogs and cats, providing cytologic detail on blast percentage, cellularity, and dysplasia that peripheral blood counts alone cannot fully elucidate.
• Interpretation hinges on comparing serial samples to the diagnostic baseline, with significant changes in blast percentage (>5% or >20% thresholds) indicating remission, persistence, or relapse, and progressive dysplasia suggesting clonal evolution.
• Standardized sampling techniques (consistent site, needle gauge, slide preparation) and concurrent peripheral blood evaluation are essential to avoid artifactual changes and accurately interpret marrow findings, distinguishing treatment-related injury from progressive disease.
• The timing of recheck aspirates is context-dependent, typically occurring during induction therapy at the expected hematopoietic nadir or recovery point, and at defined intervals during consolidation/maintenance based on disease risk to detect subclinical relapse.
• Dysplasia scoring and monitoring of erythroid:myeloid ratio offer insights into lineage dominance and clonal evolution, while cellularity assessment helps differentiate regenerative recovery from treatment-induced aplasia.
• Species-specific considerations, such as the frequent association of feline myeloid neoplasia with FeLV infection and the potential for rapid transformation in cats, necessitate tailored monitoring intervals and concurrent retroviral status assessment.

Serial bone marrow evaluation is a monitoring strategy applied after a myeloid neoplasm has been diagnosed and treatment has begun. This article addresses the practicing veterinarian who must decide when a recheck aspirate is genuinely informative, how to interpret changes in cellularity, blast percentage, and dysplastic features, and how to distinguish progressive disease from treatment-related marrow injury. The focus is on dogs and cats with acute myeloid leukemia, myelodysplastic syndromes, and myelodysplastic/myeloproliferative overlap phenotypes. Initial diagnosis, staging, and primary treatment selection are covered elsewhere and are not repeated here.

The clinical question this article answers is direct: given a patient with a known myeloid neoplasm, what does a serial bone marrow aspirate add beyond the complete blood count, and at what intervals should sampling occur? Peripheral blood findings often lag behind marrow events, and cytopenias may reflect either persistent disease or drug effect. A marrow aspirate provides a snapshot of the dominant cell population, maturation trajectory, and residual normal hematopoiesis. Used serially, these snapshots reveal whether a remission is durable, whether a relapse is emerging, and whether the marrow has recovered enough to tolerate further therapy.

The evidence base for serial marrow monitoring in veterinary myeloid neoplasia is limited. Much of the framework derives from human hematology practice, extrapolated with caution to dogs and cats. Where the veterinary literature is sparse, this article states that explicitly and offers a reasoning structure that respects the uncertainty.

At a Glance

Rationale for Serial Sampling

Myeloid neoplasms are clonal disorders of hematopoietic stem or progenitor cells. Unlike lymphoid neoplasia, where peripheral lymph node cytology often reflects disease burden accurately, myeloid disease resides primarily in the marrow. The peripheral blood may show blasts, but it may also show only nonspecific cytopenias, particularly early in relapse. A normal or improving complete blood count does not exclude persistent marrow disease, and a worsening count does not distinguish progressive neoplasia from chemotherapy toxicity.

Serial marrow evaluation answers a different question at each phase of treatment. During induction therapy, the aspirate confirms whether a morphologic remission has been achieved. During consolidation or maintenance, it detects subclinical relapse before peripheral blood changes appear. After a suspected treatment-related complication, it distinguishes marrow recovery from persistent aplasia. The timing and interpretation of each aspirate depend on which of these questions is being asked.

The concept of clonal evolution is central to this monitoring logic. Myelodysplastic syndromes can progress to acute myeloid leukemia through the acquisition of additional genetic abnormalities. In human medicine, telomere attrition and telomere repair defects are recognized contributors to marrow failure and leukemic progression, and measurement of telomere length in peripheral blood leukocytes has been proposed as a screening assay for these processes. The veterinary relevance of telomere biology is not established, but the principle that myeloid neoplasms are dynamic, genetically unstable populations supports the value of repeated morphologic assessment.

What a Serial Aspirate Can and Cannot Show

A bone marrow aspirate provides cytologic detail that a core biopsy cannot: individual cell morphology, granulation, nuclear chromatin patterns, and cytoplasmic maturation. These features are essential for assigning blast lineage and grading dysplasia. The aspirate is also the most reliable sample type for estimating blast percentage when cell dispersion is adequate.

The aspirate has limits. It samples a small volume and may not represent the marrow uniformly, particularly in diseases with patchy involvement. Fibrosis, which can accompany myeloid neoplasia or develop after therapy, may cause hemodilution or dry taps. In those cases, a core biopsy is required for cellularity assessment and for detection of fibrosis. The aspirate also cannot distinguish between a regenerating normal marrow and a dysplastic marrow with certainty when blast counts are low, because both may show left-shifted hematopoiesis.

Serial comparison is therefore most useful when the same sampler, the same collection site, and the same slide preparation methods are used each time. Variability in sample quality is a common source of false interpretation. A hemodilute aspirate that appears hypocellular may be mistaken for aplastic marrow, while a well-dispersed, cellular aspirate from a different site may overestimate recovery.

Timing of Recheck Aspirates

The optimal interval for serial marrow sampling depends on the treatment protocol and the clinical context. During induction therapy, a recheck aspirate is typically performed at the expected nadir of normal hematopoiesis or at the point of peripheral blood count recovery, whichever occurs later. This timing captures the marrow at its most informative state: residual leukemic cells are more visible when normal hematopoiesis is suppressed, and recovery of normal progenitors indicates that the marrow niche has survived the insult.

After remission is documented, surveillance aspirates are performed at intervals dictated by the risk of relapse. High-risk phenotypes, such as acute myeloid leukemia with high blast counts or myelodysplastic syndromes with multilineage dysplasia, warrant more frequent sampling. Lower-risk phenotypes may be monitored with serial complete blood counts, with marrow sampling reserved for when the blood count changes in a suspicious direction.

A critical principle is that a single normal aspirate does not establish durable remission. The marrow is a dynamic tissue, and a sample taken on one day reflects only that moment. Serial sampling, with consistent technique and consistent interpretation criteria, is the only way to detect the trajectory of disease.

Interpretation Framework

Interpretation of a serial aspirate begins with comparison to the diagnostic sample. The blast percentage, cellularity, and dysplasia grade from the initial aspirate serve as the baseline. Changes are meaningful only in relation to that baseline and to the time elapsed since the last sample.

A blast percentage that falls below the remission threshold defined by the relevant classification system indicates morphologic remission. A blast percentage that rises above that threshold, or that increases substantially from a previous recheck, indicates relapse. The specific thresholds are published by the World Health Organization and adapted for veterinary use by the American Society for Veterinary Clinical Pathology, and the reader should consult those sources for current numeric criteria.

Dysplasia is graded on the proportion of abnormal cells within each lineage. An increase in the dysplasia score, even without a rise in blast percentage, may signal clonal evolution. Conversely, a reduction in dysplasia alongside a falling blast percentage supports a genuine remission instead of a transient treatment effect.

Standardized Sampling and Slide Preparation

Serial comparisons are only as reliable as the samples they are based on. Sampling technique, site selection, and slide preparation must be standardized across time points, or apparent changes in cellularity or blast percentage may reflect artifact instead of biology.

Select the same site for each aspirate when possible. The proximal humerus is the preferred site in most dogs and cats because it is accessible, well tolerated, and yields consistently cellular samples. The iliac crest and sternum are acceptable alternatives, but mixing sites across serial samples introduces variability in hemodilution and marrow stromal content. If the original diagnostic aspirate was taken from a particular site, return to that site for the first recheck.

Use the same needle gauge and syringe volume for each collection. A 22 gauge needle with a 3 to 6 mL syringe is standard for most patients. Smaller syringes generate less suction and reduce hemodilution, but they also yield smaller particles. The goal is to obtain multiple intact marrow spicules, not a bloody pool. If the first pull is hemodilute, reposition the needle and aspirate again instead of submitting a poor sample.

Prepare at least six to ten well-spread smears at each collection. Stain all slides from a single time point together, and ideally stain serial samples in the same batch or with the same protocol. Romanowsky-type stains are standard. If cytochemical stains such as myeloperoxidase or Sudan black B were used at diagnosis to establish blast lineage, repeat the same stains on recheck samples when lineage assignment is uncertain.

Submit paired peripheral blood smears with every marrow aspirate. The peripheral blood provides the context for interpreting marrow findings, including whether cytopenias are regenerating, whether circulating blasts are increasing, and whether dysplastic changes in the blood parallel those in the marrow. A CBC with manual differential should accompany each recheck aspirate.

Document the sample quality at the time of collection. Note the number of spicules, the degree of hemodilution, and whether the sample was adequate for cytologic evaluation. This information belongs in the medical record and should be reported to the clinical pathologist if the sample is submitted to a reference laboratory. Inadequate samples should be repeated promptly, not interpreted.

Cytologic Criteria for Response Assessment

Serial marrow evaluation in myeloid neoplasia rests on a small set of quantifiable parameters. These parameters must be assessed consistently at each time point, and changes must be interpreted in light of the peripheral blood findings and the patient's clinical status.

Blast Percentage

The blast percentage is the single most important cytologic parameter for monitoring disease burden. Count at least 200 to 500 nucleated cells in a representative area of the smear, avoiding the feathered edge and areas of cell crowding. Report the blast percentage as a proportion of all nucleated cells.

A decreasing blast percentage suggests a response to therapy. A stable or increasing blast percentage indicates persistent or progressive disease. In myelodysplastic syndromes, the blast percentage also carries prognostic weight. Progression from a lower blast percentage to a higher one, particularly across the 5% and 20% thresholds used in human classification schemes, signals transformation toward acute leukemia. The same thresholds are commonly applied in veterinary patients, although formal veterinary classification systems are less standardized.

Blast percentage must be interpreted with caution when the marrow is markedly hypocellular or when hemodilution is present. A low blast percentage in a poor-quality sample does not exclude residual disease. Conversely, regenerating normal hematopoietic precursors can be mistaken for blasts, particularly when the marrow is recovering after chemotherapy. Compare the morphology of the suspect cells with the blast population identified at diagnosis. If the original blasts had distinctive features, such as prominent nucleoli, cytoplasmic granules, or Auer rod-like inclusions, use those features to distinguish residual disease from regeneration.

Myeloid to Erythroid Ratio

The myeloid to erythroid (M:E) ratio provides a crude measure of lineage balance. Normal ratios in dogs and cats range from approximately 0.9 to 1.8 to 1, but wide variation exists between individuals and with marrow stimulation. Serial changes in the M:E ratio are more informative than a single value.

In myeloid neoplasms with erythroid predominance, such as erythroleukemia or some myelodysplastic syndromes, an increasing M:E ratio may indicate progressive myeloid expansion. In myeloid leukemias, a persistently elevated M:E ratio with a stable or increasing blast percentage indicates inadequate response. A falling M:E ratio toward the normal range, with maturation of the myeloid series, suggests recovery.

The M:E ratio is unreliable in hemodilute samples and in marrows with patchy cellularity. Report it as a range instead of a single number when the smear is uneven.

Dysplasia

Dysplastic changes in the erythroid, myeloid, and megakaryocytic lineages are a defining feature of myelodysplastic syndromes and may persist or evolve during treatment. Document the presence and severity of dysplasia at each recheck, using the same criteria applied at diagnosis. Common findings include megaloblastic erythroid precursors, nuclear-cytoplasmic asynchrony, ring sideroblasts (if iron stains are performed), hypogranular or hypersegmented neutrophils, pseudo-Pelger-Huet cells, and micromegakaryocytes or megakaryocytes with multiple separated nuclei.

Dysplasia can be induced by chemotherapy, so its presence during treatment does not automatically indicate persistent neoplasia. However, worsening dysplasia in the absence of other explanations, particularly when accompanied by progressive cytopenias, supports ongoing disease. Resolution of dysplasia with recovery of normal maturation is a favorable finding.

Cellularity

Marrow cellularity is estimated from the proportion of the marrow space occupied by hematopoietic cells. Normal cellularity declines with age, and the expected range for the patient's age must be considered. Serial changes in cellularity are useful for distinguishing aplastic or hypocellular marrows from hypercellular neoplastic infiltration.

A hypercellular marrow with a high blast percentage indicates active disease. A hypocellular marrow after chemotherapy may reflect treatment effect, and distinguishing residual disease from aplasia requires careful assessment of the cells that remain. If the marrow is too hypocellular to count 200 cells reliably, the sample should be reported as inadequate for blast enumeration and repeated after marrow recovery.

Fibrosis and Stromal Changes

Aspirates cannot assess fibrosis reliably. If myelofibrosis is suspected, or if serial aspirates become progressively more difficult to obtain despite consistent technique, a core biopsy is indicated. Myelofibrosis can accompany myeloid neoplasia and may worsen with disease progression. The American Society for Veterinary Clinical Pathology quality assurance guidelines address sample adequacy and interpretation standards that apply to both aspirates and core biopsies.

Integrating Peripheral Blood and Marrow Findings

Serial marrow evaluation should never be interpreted in isolation. The peripheral blood CBC and manual differential provide complementary information that changes the interpretation of marrow findings.

The peripheral blood also guides the timing of recheck aspirates. If the CBC shows a marked improvement or a marked deterioration, an aspirate may be warranted earlier than the scheduled interval. Conversely, if the CBC is stable and the patient is clinically well, a scheduled aspirate can sometimes be deferred, although this decision should be made with the understanding that marrow disease can progress before peripheral blood changes become apparent.

Species and Patient Considerations

Dogs and cats differ in the expected presentation and behavior of myeloid neoplasms, and these differences affect monitoring strategy.

Feline myeloid neoplasia is frequently associated with feline leukemia virus (FeLV) infection, although the case report of a myelodysplastic/myeloproliferative neoplasm in an FeLV-negative cat demonstrates that retrovirus-negative disease occurs. In FeLV-positive cats, serial marrow evaluation should be paired with monitoring of retroviral status, as viral reactivation or clearance can influence disease behavior. The same case report illustrates the potential for rapid transformation from a myelodysplastic phenotype to a high-blast acute leukemia within months, supporting the use of relatively short recheck intervals in cats with myelodysplasia.

Canine myeloid neoplasms are less commonly associated with an identifiable underlying cause. Chronic inflammation has been proposed as a driver of myeloid neoplasia through accelerated telomere attrition, a mechanism discussed in the review of telomere biology and its implications for hematologic disease. In dogs with a history of chronic inflammatory disease, serial marrow evaluation may be combined with monitoring of inflammatory markers, although the clinical utility of this approach is not established.

Patient status also changes the correct monitoring approach. A patient receiving intensive chemotherapy requires more frequent marrow evaluation than a patient on a palliative protocol. A patient with significant comorbidities may not tolerate repeated marrow aspiration under sedation, and the risk-benefit balance of each recheck must be assessed individually. In patients where repeated aspiration is not feasible, peripheral blood monitoring becomes the primary tool, with marrow evaluation reserved for decision points where cytologic confirmation is essential.

Documentation and Reporting

Serial marrow evaluation generates data that must be recorded in a format that supports comparison across time points. A standardized marrow report template should include the sample site, sample quality, estimated cellularity, M:E ratio, blast percentage, a description of dysplasia by lineage, and a summary interpretation. The same template should be used at every time point.

Photomicrographs of representative fields, particularly of the blast population, are valuable for longitudinal comparison. If a reference laboratory is used, request that prior reports be made available to the reviewing pathologist. If samples are evaluated in-house, maintain a file of images or archived slides from each time point.

The medical record should document the indication for each recheck, the clinical question being addressed, and how the results will change management. This framing ensures that each aspirate is performed with a clear purpose and that the results are acted upon.

Recognized Complications and Failure Modes

Serial bone marrow evaluation carries inherent procedural and interpretive risks. The most common complication is sampling error, where the aspirate does not represent the overall marrow population. A hemodilute sample, a poorly cellular particle, or aspiration from a region of patchy disease can produce a falsely reassuring blast percentage or an artifactual shift in the myeloid to erythroid ratio. Detection depends on correlating the aspirate with the peripheral blood count and the clinical trajectory. If the marrow appears improved but the blood count has deteriorated, repeat sampling from a different site is indicated before treatment decisions are made.

A second failure mode is misinterpretation of regenerative versus neoplastic responses. After myelosuppressive chemotherapy, the marrow may show a transient left shift with increased immature myeloid forms that mimics persistent neoplasia. Serial sampling at intervals shorter than the expected recovery window, typically 7 to 14 days, will misclassify this recovery phase as progressive disease. The corrective action is to time recheck aspirates according to the expected neutrophil nadir and recovery for the specific protocol used, and to interpret blast percentage in the context of overall cellularity and maturation sequence.

A third complication is progression of disease between sampling intervals. Myelodysplastic syndromes can transform to acute myeloid leukemia within weeks, as reported in a feline case where marrow blasts increased from 15% to 52% over approximately three months despite treatment. This rapid evolution argues for shorter recheck intervals when dysplasia is severe or when peripheral blood blasts are increasing, and for repeat sampling whenever clinical deterioration occurs instead of waiting for a scheduled recheck.

Common Errors and Corrective Actions

Less experienced clinicians frequently overinterpret a single abnormal value. A blast percentage of 10% on one aspirate does not establish progression if the sample was hemodilute or if the patient received growth factor support that expanded the progenitor pool. The corrective action is to require concordance between at least two of three parameters: marrow blast percentage, peripheral blood blast count, and cytopenias in one or more lineages.

Another common error is neglecting to compare current samples with the prior aspirate side by side. Blast morphology, dysplastic features, and cellularity are best assessed with the previous slides available for direct comparison. Standardized slide preparation and staining, as outlined in laboratory quality assurance guidelines, reduce variation between sampling events. Clinicians should request that prior slides be retrieved from the laboratory before interpreting a new aspirate.

A third error is failing to account for concurrent disease. Chronic inflammation, infectious disease, or drug effects can alter marrow cellularity and lineage distribution. For example, bone marrow cytology in canine leishmaniasis may show erythroid hypoplasia with myeloid hyperplasia, a pattern that could be misread as a myeloproliferative process. The corrective action is to review the complete clinicopathologic database, including serology and PCR results where relevant, before attributing marrow changes to the myeloid neoplasm.

Troubleshooting Table

Limitations of Current Evidence

The evidence base for serial marrow monitoring in veterinary myeloid neoplasia is largely extrapolated from human hematology and from single case reports. Controlled prospective studies defining optimal recheck intervals, prognostic thresholds for blast percentage change, and criteria for treatment modification are lacking. Expert opinion differs on whether aspirate cytology alone is sufficient or whether core biopsy with histopathology should be performed at intervals, particularly when fibrosis or patchy disease is suspected. The human literature on telomere biology suggests that telomere length measurement may eventually inform prognosis and monitoring in myeloid neoplasia, but this has no established veterinary application. Clinicians should acknowledge this uncertainty when advising owners on the frequency and value of serial sampling.

Referral and Consultation Criteria

Referral to a veterinary clinical pathologist is warranted when the aspirate is nondiagnostic, when dysplasia is present but blast lineage cannot be determined, or when serial samples show discordant findings that cannot be reconciled with the clinical picture. Specialist consultation with an oncologist should occur before treatment modification based on marrow findings alone, particularly when considering dose escalation, protocol change, or hematopoietic growth factor therapy. Laboratory involvement is appropriate when sample quality is consistently poor, as the laboratory can provide guidance on collection technique and slide preparation. Regulatory reporting is rarely required for myeloid neoplasia in companion animals, but clinicians should be aware that unusual disease presentations or suspected emerging pathogens may warrant notification of public health or veterinary authorities according to regional standards.

Frequently Asked Questions

How should I prioritize serial bone marrow sampling when the owner has limited financial resources?

Prioritize peripheral blood monitoring first. Serial CBCs with manual smear review provide the most cost-effective longitudinal data on blast percentage, cytopenias, and dysplastic changes in circulation. Reserve marrow aspiration for decision points where blood findings are ambiguous or where treatment modification depends on marrow status. If a single recheck aspirate is affordable, time it to the expected nadir or response assessment window most relevant to the protocol used. Discuss explicitly with the owner what each sampling tier can and cannot answer, and document that the monitoring plan was tailored to available resources. Reference laboratory quality standards from the American Society for Veterinary Clinical Pathology can help justify which samples merit submission.

What can I do when I cannot obtain a diagnostic-quality aspirate despite repeated attempts?

Submit the best available material instead of abandoning the sample. A hemodilute or partially clotted smear may still permit estimation of cellularity and identification of dominant cell populations. If aspiration repeatedly yields dry taps, pursue core biopsy for histopathology, which allows assessment of architecture and fibrosis that cytology cannot provide. Compare current sample quality against prior preparations to distinguish sampling failure from true marrow change. When interpreting suboptimal samples, state the limitation explicitly in the report and avoid overinterpreting blast percentages from smears with excessive hemodilution. The MSD Veterinary Manual provides guidance on alternative marrow collection techniques when standard aspiration fails.

How does serial marrow evaluation differ between dogs and cats with myeloid neoplasia?

Cats require additional consideration of retroviral status, particularly FeLV, because progressive marrow failure and transformation to acute leukemia carry different prognostic weight in retrovirus-positive patients. Feline myeloid neoplasms more frequently present with concurrent erythroid dysplasia, and the distinction between myelodysplastic syndrome and early leukemia can shift rapidly between samplings. Dogs more commonly show lineage-specific responses that track with targeted therapies. In both species, the same cytologic criteria apply, but the interval between rechecks may need to be shorter in cats given the potential for rapid progression. A case report of a FeLV-negative cat documented transformation from myelodysplastic syndrome with 15% blasts to marrow dominated by 52% blasts within three months, illustrating the speed of progression possible in feline patients (Suspected myelodysplastic/myeloproliferative neoplasm in a feline leukemia virus-negative cat).

What documentation should accompany each serial marrow sample to ensure valid comparisons?

Submit a standardized marrow submission form with every sample, also the first. Record collection site, needle gauge, smear preparation method, estimated particle content, and concurrent CBC values. Include the current treatment protocol, time since last chemotherapy dose, and any growth factor administration, since these directly affect cellularity and maturation. Note any changes in sampling technique, as a different collector or site can introduce apparent shifts in cellularity. Retain prior slides for side-by-side comparison with the current preparation. The American Society for Veterinary Clinical Pathology quality guidelines emphasize that consistent preanalytical handling is essential for valid longitudinal interpretation.

How should I explain the need for repeat bone marrow sampling to a client who is reluctant?

Frame the recheck aspirate as a treatment decision tool, not a routine procedure. Explain that blood tests show what the marrow is releasing, while the marrow sample shows why, and that the two can diverge during therapy. Use concrete language: the sample tells us whether the abnormal cell population is shrinking, whether normal blood cell production is recovering, and whether the current drug is still the right choice. Acknowledge the cost and the brief procedural discomfort honestly. Offer to combine the aspirate with other scheduled procedures to reduce anesthetic events. If the client declines, document the discussion and propose a peripheral blood monitoring schedule as an alternative, noting the reduced diagnostic certainty.

When should I refer a case for specialist marrow evaluation instead of continuing serial sampling in general practice?

Refer when serial samples show progressive blast percentage increases despite treatment, when dysplasia worsens across two consecutive samplings, or when peripheral blood and marrow findings conflict in ways that affect therapeutic decisions. Refer also when cytopenia fails to improve at the expected recovery time point, since distinguishing persistent disease from treatment-related marrow suppression requires experienced cytologic interpretation. Cases with suspected myelodysplastic syndrome benefit from early specialist input because the classification and prognostic framework is nuanced and evolving. The AVMA practice resources can help identify board-certified clinical pathologists and oncology referral centers in your region. Earlier referral is preferable to delayed referral after multiple inconclusive samplings.

Related Clinical & Scientific Guides

• Peripheral Blood Smear Evaluation: A Step-by-Step Guide
• Reticulocyte Counts in Veterinary Medicine: Clinical Utility and Interpretation
• Cerebrospinal Fluid Analysis in Veterinary Neurology: Collection and Interpretation

References and Further Reading

• Laboratory tests for diagnosing and monitoring canine leishmaniasis.. 2016.
• Telomere biology and telomere diseases: implications for practice and research.. 2010.
• Suspected myelodysplastic/myeloproliferative neoplasm in a feline leukemia virus-negative cat.. 2016.
• Small-Animal PET/CT Imaging of Local and Systemic Immune Response Using ⁶⁴Cu-αCD11b.. 2019.
• [[Future perspectives of bone marrow and stem cell activation for autologous transplantation].](https://pubmed.ncbi.nlm.nih.gov/1725633/). 1991.
• American Society for Veterinary Clinical Pathology Guidelines. American Society for Veterinary Clinical Pathology.
• MSD Veterinary Manual, Professional Edition. MSD Veterinary Manual.
• American Veterinary Medical Association Practice Resources. American Veterinary Medical Association.
• WOAH Terrestrial Animal Health Code. WOAH.

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• Serial Cytology for Treatment Response Assessment in Lymphoma
• Serial Fecal Testing for Monitoring Parasite Control Programs

This article is educational professional reference material for veterinary audiences. It is not a substitute for veterinary diagnosis, individual clinical judgment, current product labeling, or applicable regulatory requirements.