Sage Journals: Discover world-class research

Abstract

Objectives

This study aimed to evaluate the association of anaemia and thrombocytopenia with the presence and severity of ocular lesions in cats.

Methods

Cats were prospectively recruited into four groups in this cross-sectional study: anaemic (A) (haematocrit level ⩽24%, n = 20), thrombocytopenic (T) (platelet count of ⩽200 × 10⁹/l, n = 10), anaemic and thrombocytopenic (AT) (n = 33) and healthy controls (C) (n = 20). All cats underwent a comprehensive ophthalmic examination, with lesions classified as absent, minor (isolated retinal haemorrhages) or major (diffuse retinal haemorrhages, hyphaema or intravitreal bleeding). Signalment, clinical signs, diagnostic test results and final diagnoses were collected from the medical records.

Results

Ocular lesion prevalence was 20%, 10%, 48% and 0% in the A, T, AT and C groups, respectively. Among affected cats, minor and major lesions occurred in 67% and 33% of cases, respectively. All major lesions were observed in groups T and AT. Anaemia and thrombocytopenia were significantly associated with both the presence (P_anaemia = .001, P_{thrombocytopenia} = .002) and severity (P_anaemia <.001, P_{thrombocytopenia} = .006) of ocular lesions. A haematocrit value of ≤18.5% had a sensitivity of 91% and specificity of 58% for detecting ocular lesions.

Conclusions and relevance

Anaemia and thrombocytopenia were significantly associated with the presence and severity of ocular lesions in cats in this study. Cats with concurrent anaemia and thrombocytopenia exhibited a higher prevalence of ocular lesions than those with either condition alone. This finding warrants further investigation into potential underlying mechanisms. Based on these results, any cat presenting with anaemia or thrombocytopenia should undergo a complete ophthalmic examination.

Keywords

Anaemia thrombocytopenia retinal haemorrhage ocular lesion haematology

Introduction

Anaemia is a common clinical issue in cats, with reported prevalences of 3.6% (blood samples from cats that fulfilled criteria for anaemia)¹ and 10% (within the reference population).² It is characterised by a decrease in haematocrit (HCT) level below the reference interval (RI)² and develops because of haemorrhage, haemolysis or decreased bone marrow red blood cell (RBC) production.³ Common anaemia aetiologies in cats include immune-mediated haemolytic anaemia (IMHA),⁴ chronic kidney disease,⁵ gastrointestinal disease,⁶ retroviruses⁷ and neoplasia.⁸ Its clinical importance can vary from being the patient’s primary life-threatening problem to being relatively clinically inconsequential.⁹ Ocular manifestations of severe anaemia include pale retinal vasculature, varying degrees of retinal haemorrhage and subtle changes in tapetal reflectivity.¹⁰ Only two studies have investigated the association between anaemia and intraocular haemorrhages in cats, reporting retinal haemorrhages in 20/26 and 14/80 anaemic animals.^11,12

Thrombocytopenia is the most commonly encountered platelet (PLT) disorder in feline medicine,¹³ with a reported prevalence in the range of 1.2–5.9%.^14–17 These estimates are based on retrospective analyses of medical records from referral clinics or veterinary teaching hospitals, with prevalence calculated based on the total caseload during the respective study periods. Thrombocytopenia can result from decreased PLT production, increased PLT removal or increased consumption. A retrospective study of 194 cats with thrombocytopenia reported that the most common aetiologies were infectious, immune-mediated and neoplastic.¹⁶ Thrombocytopenia is associated with ocular and periocular haemorrhages. Although the PLT count threshold at which bleeding occurs varies among individuals, it is typically below 50 ×10⁹/l.¹⁰ Several studies in humans have investigated the association between anaemia, thrombocytopenia and ocular lesions; however, their findings remain inconsistent.^18–22

A prospective study in dogs found no association between anaemia and ocular lesion presence or severity but reported a significant relationship between ocular lesions and thrombocytopenia.²³ No studies have directly investigated the association between ocular lesions and thrombocytopenia in cats. Therefore, this study evaluated the association of anaemia and thrombocytopenia with ocular lesion presence and severity in cats.

Materials and methods

Study design and ethical considerations

This cross-sectional study was approved by the VetAgro Sup Committee for Ethics in the Use of Animals of the Veterinary University of Lyon (protocol number 2383). Owners provided written consent for the use of their pets’ clinical data and performance of an ophthalmic examination and blood pressure measurement. The study population comprised cats presented to the Internal Medicine or Emergency and Critical Care services of the Fregis Veterinary Hospital Centre in Gentilly (France) between October 2018 and October 2024.

All animals underwent a comprehensive haematological evaluation, including blood smear analysis. Cats were classified as anaemic and thrombocytopenic if the HCT value was ≤24% and the PLT count was ≤200 × 10⁹/l, respectively. The HCT threshold represents the lower limit of the RI established by the clinic’s ANYDIAG laboratory. Although the laboratory’s lower RI for PLT count is 300 × 10⁹/l, this cut-off point was decreased in this study based on the inclusion criteria of other research investigating thrombocytopenia in cats.^14,16 Healthy controls were also included, consisting of animals hospitalised by the Surgery Department for various elective procedures, with blood work results within RIs. Based on these criteria, cats were assigned to groups A (anaemia), T (thrombocytopenia), AT (anaemia and thrombocytopenia) and C (healthy controls). Cats were excluded if clumping was reported on blood smear evaluation or if a manual PLT count had not been performed. The laboratory’s manual PLT count was used to determine the eligibility for inclusion where the manual and automated PLT counts were discrepant.

Clinical examination

Each cat underwent a comprehensive ophthalmic examination, including menace response, pupillary, dazzle and palpebral reflexes, rebound tonometry, slit-lamp biomicroscopy (Kowa SL17) and indirect ophthalmoscopy after pupil dilation with 0.5% topical tropicamide solution. Additional diagnostic testing was performed in some cats on a case-by-case basis, including fluorescein staining. Ocular involvement was classified as minor or major based on its presumed impact on vision or the globe. Minor lesions were characterised by isolated or sparse intraretinal or preretinal haemorrhages. In contrast, major lesions were characterised by diffuse retinal haemorrhages, hyphaema or intravitreal bleeding.

Conscious systolic blood pressure (SBP) measurement was performed in all cooperative cats using Doppler methodology, in accordance with the American College of Veterinary Internal Medicine consensus guidelines.²⁴ A comprehensive range of diagnostic tests was used to achieve a conclusive diagnosis for each cat, at the discretion of the attending clinician. These included various combinations of blood testing, urinalysis, faecal analysis, diagnostic imaging, cytology and histopathology. The signalment, clinical signs at presentation and final diagnoses were obtained from the medical records. Furthermore, the attending clinicians determined the final diagnoses, while the ophthalmologist remained unaware of the systemic diagnosis during the ophthalmic examination.

Statistical analysis

All statistical analyses were performed using SPSS Statistics for Windows version 29 (IBM Corp). A χ² test was employed to assess the association between anaemia and ocular lesions by comparing the prevalence of ocular lesions in cats with anaemia (groups A and AT combined) and those without anaemia (groups T and C combined). Similarly, a χ² test was used to evaluate the association between thrombocytopenia and ocular lesions by comparing the prevalence of ocular lesions in cats with thrombocytopenia (groups AT and T combined) and those without thrombocytopenia (groups A and C combined). Furthermore, a χ² test was used to assess the association between the prevalence of ocular lesions across all four groups, as well as between ocular lesion prevalence and cytopenia severity. HCT value and PLT count were categorised into moderate (HCT 16–24%, PLT 51–200 × 10⁹/l) and severe (HCT 0–15%, PLT 0–50 × 10⁹/l). The Kruskal–Wallis test was used to compare the median values of HCT and PLT count across the three categories of lesion severity (absent, minor and major). Receiver operating characteristic (ROC) curve analysis was employed to determine discriminatory HCT values for cats with and without ocular lesions. The Youden index was used to estimate the optimal cut-off value. Statistical significance was set at P <.05.

Results

Epidemiology

A total of 83 cats were included, comprising 47 males (37 neutered, 10 entire) and 36 females (31 neutered, five entire). Among these, 46 (55%) were European Shorthairs, with the remainder comprising 13 other breeds. Table 1 summarises the median and interquartile range values for age, HCT and PLT count across the four groups. Animals in group AT were the youngest across all groups. The median HCT was lower in group AT than in group A, while the median PLT count was lower in group T than in group AT. SBP measurements were conducted in 14/21 cats with ocular lesions, of which only one was hypertensive (190 mmHg, RI 120–160) and belonged to group T. Of the 43 cats with thrombocytopenia, only one (2%) had dermatorrhagia (subcutaneous ecchymoses and petechiae), and this cat was in group AT.

Table 1

Age, haematocrit (HCT) value and platelet (PLT) count across the study groups

Study group	Total numberof cats	Age (years)	HCT (%)	PLT count (× 10⁹/l)	Cats with ocular lesions	Lesion type
A	20	10.50 (3–13.62)	15.50 (12.25–20.50)	374.50 (237.50–538)	4 (20)	Minor
T	10	8 (0.75–11)	33.30 (28.50–36)	27 (6–46.25)	1 (10)	Major
AT	33	3 (1.85–8.50)	11 (8.85–15)	85 (40–145)	16 (48)	10 minor, 6 major
C	20	6 (2.50–9)	35.80 (33.23–40.28)	332 (306.25–416.25)	0	–

Data are n (%) or median (interquartile range)

A = anaemic group; AT = anaemic and thrombocytopenic group; C = control group; T = thrombocytopenic group

Ophthalmic findings

Table 2 summarises the signalment and clinical characteristics of the 21 cats with anaemia and/or thrombocytopenia and ocular lesions. Ocular lesions were observed in 4/20 (20%), 1/10 (10%), 16/33 (48%) and 0/20 (0%) cats in groups A, T, AT and C, respectively. In group A, four cats exhibited minor ocular lesions, characterised by small, isolated or scattered intraretinal or preretinal haemorrhages (Figure 1). Major and minor ocular lesions were observed in six (18%) and 10 (30%) cats within group AT, respectively. The major lesions in this group were characterised by extensive retinal haemorrhages, hyphaema (Figure 2) or intravitreal bleeding. One cat in group T with ocular pathology had major lesions, comprising a haemorrhage in the iris stroma and concurrent hyphaema, which prohibited a complete fundic examination. Anaemia and thrombocytopenia were significantly associated with both the presence (P_anaemia = .001, P_{thrombocytopenia} = .002) and severity (P_anaemia <.001, P_{thrombocytopenia} = .006) of ocular lesions. A significant association was also found between ocular lesion prevalence across all four groups (P <.001). The Kruskal–Wallis test revealed significantly lower median HCT values and PLT counts in the major ocular lesion group (Table 3). When assessing the relationship between cytopenia severity and ocular lesion presence, the χ^² test revealed a significant association for anaemia but not for thrombocytopenia (P_anaemia = .002, P_{thrombocytopenia} = .834) (Figures 3 and 4). The area under the ROC curve (AUC) for HCT was 0.793 (95% confidence interval [CI] 0.691–0.894) (Figure 5). Specifically, the Youden index provided an optimal HCT cut-off value of 18.5%, resulting in sensitivity and specificity values of 91% and 58%, respectively. The AUC was markedly different from 0.5, indicating a significant ability of HCT to discriminate between cats with and without ocular lesions.

Table 2

Clinical data of cats with anaemia and/or thrombocytopenia and ocular lesions

Case number	Age(years)	Sex	Breed	HCT(%)	PLT(× 10⁹/l)	Group	Aetiology	Ocular lesion	SBP (mmHg)	Signs of dermatorrhagia
1	3	FS	Siberian	22	895	A	ACID	Isolated/sparse intraretinal haemorrhage	N/A	None
2	1	F	Maine Coon	12	490	A	IMHA	Isolated/sparse intraretinal haemorrhage	140	None
3	14	MC	Siamese	10	296	A	IMHA	Isolated/sparse intraretinal haemorrhage	50	None
4	11	M	ESH	16	788	A	Intestinal lymphoma	Isolated/sparse intraretinal haemorrhage	150	None
5	8	MC	ESH	27	7	T	Unknown	Hyphaema and haemorrhage in the iris stroma	190	None
6	9	FS	ESH	15	98	AT	Acute leukaemia	Isolated/sparse intraretinal haemorrhage	N/A	None
7	3	FS	Chartreux	15	83	AT	IMHA	Isolated/sparse intraretinal haemorrhage	N/A	None
8	10	MC	ESH	15	1	AT	DIC of unknown origin	Isolated/sparse intraretinal haemorrhage	N/A	None
9	6	MC	Exotic Shorthair	10	71	AT	Evans syndrome	Isolated/sparse intraretinal haemorrhage	120	None
10	2	MC	ESH	7	131	AT	IMHA	Isolated/sparse intraretinal haemorrhage	N/A	None
11	14	F	ESH	11	22	AT	Intestinal neoplasia with ulceration	Isolated/sparse intraretinal haemorrhage	130	None
12	6	MC	Exotic Shorthair	10	71	AT	ACID	Isolated/sparse intraretinal haemorrhage	150	None
13	3	F	Birman	17	88	AT	DIC of unknown origin	Isolated/sparse intraretinal haemorrhage	N/A	None
14	3	MC	ESH	8	62	AT	Pancytopenia of unknown origin	Isolated/sparse intraretinal haemorrhage	N/A	None
15	1	FS	Abyssinian	17	145	AT	IMHA	Preretinal haemorrhage	140	None
16	2	FS	ESH	7	68	AT	IMHA	Multiple intra- and preretinal haemorrhages	130	None
17	0.08	F	Turkish Angora	6	3	AT	Parvovirus	Multiple intra- and preretinal haemorrhages	120	None
18	0.3	FS	ESH	5	94	AT	Evans syndrome	Multiple intra- and preretinal haemorrhages	110	None
19	2	M	British Shorthair	9	192	AT	IMHA	Multiple intra- and preretinal haemorrhages	145	None
20	0.75	MC	ESH	18	4	AT	DIC of unknown origin	Iris haematoma and hyphaema	150	None
21	5	MC	Persian x Maine Coon	7	15	AT	Evans syndrome	Hyphaema, vitreal and intraretinal haemorrhages	160	Cutaneous petechia and ecchymoses

A = anaemic group; ACID = anaemia of chronic inflammatory disease; AT = anaemic and thrombocytopenic group; DIC = disseminated intravascular coagulation; ESH = European Shorthair; F = female; FS = female spayed; IMHA = immune-mediated haemolytic anaemia; M = male; MC = male castrated; N/A = not available; SBP = systolic blood pressure; T = thrombocytopenic group

Figure 1

(a) Multiple intraretinal haemorrhages (red arrows) in the right fundus of a 9-year-old female spayed European Shorthair cat with a haematocrit (HCT) value of 15% and a platelet (PLT) count of 98 × 10⁹/l with acute lymphoblastic leukaemia (case 6). (b) Preretinal (keelboat-shaped) haemorrhage (red arrow) in the left fundus of a 2-year-old female spayed European Shorthair cat with an HCT value of 7% and a PLT count of 68 × 10⁹/l with immune-mediated haemolytic anaemia (case 16). This cat was bilaterally affected. OD = oculus dexter; OS = oculus sinister

Figure 2

Hyphaema in the right eye of a 9-month-old male castrated European Shorthair cat with a haematocrit value of 18% and a platelet count of 4 × 10⁹/l with disseminated intravascular coagulation (case 20)

Table 3

Comparison of haematocrit (HCT) values and platelet (PLT) counts across the ocular lesion severity groups using the Kruskal–Wallis test

Variable		Ocular lesion group
	No lesion (n = 62)	Minor lesion (n = 14)	Major lesion (n = 7)	P value	H	Df
HCT (%)	22 (13–34.88)	13.5 (10–16.25)	7.2 (6–18)	<0.001	16.64	2
PLT count (× 10⁹/l)	231 (99.25–373.75)	93 (68.75–344.50)	42.5 (4–94)	0.006	10.10	2

Data are median (interquartile range)

Df = degrees of freedom

Figure 3

Box plot of haematocrit (HCT) values (%) for cats with and without ocular lesions

Figure 4

Box plot of platelet (PLT) counts (× 10⁹/l) for cats with and without ocular lesions

Figure 5

Receiver operating characteristic (ROC) curve for haematocrit (HCT) in discriminating between cats with and without ocular lesions. The area under the ROC curve was 0.793 (95% confidence interval 0.691–0.894), demonstrating a significant discriminatory ability. A Youden index analysis identified an optimal HCT cut-off of 18.5%, resulting in a sensitivity of 91% and specificity of 58%

Aetiologies

The most common causes of anaemia were anaemia of chronic inflammatory disease, haemolysis and bone marrow suppression, while those of thrombocytopenia were immune-mediated destruction and bone marrow suppression. Among the 22 cats with immune-mediated disease (IMHA, n = 13; immune-mediated thrombocytopenia [IMTP], n = 4; Evans syndrome, n = 5), 10 (45%) had ocular lesions. Immune-mediated disease was diagnosed in 10/21 (48%) cats with ocular lesions and in 12/62 (19%) cats without ocular pathology.

Discussion

This study describes the association of anaemia and thrombocytopenia with ocular lesion presence and severity in cats. Although the pathway through which thrombocytopenia results in ocular haemorrhage is evident, given the essential function of PLTs in primary haemostasis, the role of anaemia in the development of ocular lesions is not fully understood.^19,23 Anaemia-associated vascular hypoxia is hypothesised to induce endothelial fragility, leading to increased vascular permeability and subsequent retinal haemorrhages.^19,25–27 The overall ocular lesion prevalence in this study (21/83, 25%) aligns closely with findings documented in a canine report and in human research.^19,23,28 The ocular lesion prevalence in group A (20%) observed in the current study aligns with findings from previous studies in cats¹² and humans,^19,29 whereas an older feline study reported a higher prevalence of 77%.¹¹ In contrast, other studies in dogs and humans reported a lower prevalence of 12%²³ and 10%, respectively.²⁸

The current study found a significant relationship between anaemia and the presence of ocular lesions. However, this and the following significant results should be interpreted with caution since no a priori sample size calculation was performed, and statistically significant findings in studies with potentially low power warrant careful consideration.³⁰ An HCT of 18.5% could predict the presence of ocular lesions with a sensitivity and specificity of 91% and 58%, respectively. The AUC was 0.793, indicating good model performance across all possible thresholds.³¹ A recent study in human patients with anaemia reported a sensitivity and specificity of 80% and 52%, respectively, for an HCT of 30.5%.³² Although previous studies have examined the correlation between anaemia and retinal haemorrhages in cats, they do not report any association with thrombocytopenia.^11,12 Furthermore, several studies in humans have identified a correlation between anaemia and ocular lesions.^{18,19,21,28,32,33} However, the present finding of a positive correlation between anaemia and ocular lesion prevalence in cats differs from the result of a similar study in dogs, where ocular lesion prevalence and severity were not significantly associated with anaemia.²³

The current study’s ocular lesion prevalence in group T was 10%. Two human studies reported prevalence rates of 0% and 12%.^19,28 To our knowledge, no similar data in cats have been published in the veterinary literature. The present study found a significant association between thrombocytopenia and ocular lesion presence. In human studies, the association between thrombocytopenia and retinal lesions remains contentious. Some investigations have demonstrated a significant relationship between severe thrombocytopenia and the presence of retinal lesions,^19,21 while others reported no such correlation.^18,28,32,34 Despite severe thrombocytopenia (PLT count <50 × 10⁹/l) being sufficient to cause spontaneous bleeding, three studies suggest that isolated thrombocytopenia rarely induces significant retinal haemorrhage in individuals, even in the presence of cutaneous haemorrhages.^20,33,35 In contrast to the current study, a previous canine study found a higher ocular lesion prevalence (42%) in animals with isolated thrombocytopenia.²³ One potential explanation for this discrepancy might be that feline platelets are more easily stimulated by aggregation inducers, including collagen or thrombin, than canine platelets,^17,36 and less bleeding is usually observed in cats with thrombocytopenia than in dogs.^14,36–38 In this study population, only 2% (1/43) of cats with thrombocytopenia showed signs of dermatorrhagia, while 6.3% of dogs with thrombocytopenia presented this clinical sign in one study.³⁹ Thrombocytopenia severity is likely a more critical factor influencing bleeding tendencies. Without stratifying for PLT count severity, direct comparisons of bleeding prevalence between species or studies should be cautiously interpreted.

Ocular lesion prevalence in group AT (48%) aligns with findings in both canine^21,23 and human literature.^19,28 More ocular lesions were identified in group AT than in groups A and T. Carraro et al¹⁹ reported a similar observation, indicating that ocular lesion prevalence in humans was highest in group AT. Furthermore, Rubenstein et al²⁸ reported that only 2/187 human patients with anaemia without thrombocytopenia had retinal haemorrhages; however, 44% of 39 patients presented with retinal haemorrhages when anaemia and thrombocytopenia were combined. A similar study in dogs reported no significant difference in lesion prevalence between groups T and AT.²³

Human studies suggest that anaemia aetiology influences ocular lesion prevalence.^40,41 In the current study, an immune-mediated disorder was more frequently identified in animals with ocular lesions (48%) than in those without (19%). This finding suggests a potential link that warrants further investigation in a future prospective study focusing on the association of immune-mediated anaemia and/or thrombocytopenia with the presence of ocular lesions. Besides thrombocytopenia, PLT dysfunction has been described in cats with IMTP, which might increase the bleeding tendency.⁴² These results should be interpreted with caution, as IMHA, IMTP and Evans syndrome are highly likely to be associated with significantly lower HCT values and PLT counts.^4,38 The Kruskal–Wallis test in the current study revealed that the median HCT values and PLT counts were significantly lower in the major lesion group, suggesting that immune-mediated conditions have a pronounced impact on lesion severity and prevalence due to these markedly reduced values. Korman et al⁴³ reported a significant association between anaemia severity and underlying aetiology. Nevertheless, investigating the potential relationships between cytopenia severity, aetiology and ocular lesion presence was beyond the scope of this study. A previous study in cats found no correlation between the underlying cause of anaemia and the presence of ocular lesions.¹²

Minor lesions were overrepresented in this study, consistent with findings in humans, cats and dogs.^{12,18,19,23,28,32} These were characterised in this cat population by single or sparse, small intraretinal and/or preretinal haemorrhages, which aligns with observations in dogs, cats and humans.^19,21,23 Ocular lesion severity is not well described in previous human studies, although the impact on vision is usually minimal,^19,32 which aligns with our results. Most retinal haemorrhages secondary to haematological abnormalities are described as ‘flame-shaped’ in human literature.^19,21 In contrast to the absence of retinal haemorrhages in dogs with isolated anaemia reported by Shelah-Goraly et al,²³ intraretinal haemorrhages were observed in four cats in group A in this study. Major lesions were only identified in groups AT (n = 6) and T (n = 1). The major lesions identified in this study encompassed several types of intraocular haemorrhages, including hyphaema, intravitreal haemorrhages and diffuse retinal haemorrhages; however, no retinal detachments were observed. A previous study in cats with anaemia identified similar major lesions but also reported a bullous retinal detachment in one case.¹² The concomitant presence of systemic hypertension in the cat precludes definitive attribution of the lesion solely to anaemia.¹² Although retinal detachments were also absent in human reports, hyphaema was not documented, and some human cases in the literature presented with intraretinal inflammatory exudates.^19,21,28 This contrasts with findings in dogs,²³ where several retinal detachments were observed.

A potential explanation for this difference could be the overrepresentation of canine ehrlichiosis in the canine population, a condition known to induce thrombocytopenia and vasculitis. However, this study did not identify any cases of ehrlichiosis, and disease due to Ehrlichia in cats remains poorly understood and appears to be rare compared with dogs.⁴⁴

We found a significant association of anaemia and thrombocytopenia with ocular lesion severity, consistent with results from two human studies,^19,21 but contrasting with findings in dogs.²³ In addition, this study revealed a significant association between anaemia severity and ocular lesion occurrence, which aligns with a previous study in cats.¹²

The present study has some limitations. First, since isolated thrombocytopenia is relatively uncommon in cats, the sample size of group T was relatively small. Although IMTP is a well-known cause of isolated thrombocytopenia in dogs,^39,45–47 it is considered rare in cats, with most publications consisting of small case series.^{14,36,48–53} Feline thrombocytopenia is usually associated with concurrent conditions, including anaemia, which is frequently linked to viral infections or neoplasia,¹⁴ and IMHA in cats typically occurs alongside mild thrombocytopenia.⁵⁴ In this study, the HCT values were primarily obtained from automated analysers, and a systematic comparison with packed cell volume (PCV) was not performed in all cases. Although both HCT and PCV are measures of RBC volume, discrepancies can occasionally arise because of differences in measurement techniques or sample handling.

Blood pressure measurement was not conducted in a significant proportion of the cats with ocular lesions (7/21, 33%). Although their clinical presentation suggested a low likelihood of systemic hypertension, this cannot be excluded as a potential cause or contributing factor for their ocular lesions. Only one cat with ocular lesions had documented systemic hypertension, making it challenging to confirm whether this or its thrombocytopenia was responsible. Finally, causality cannot be fully confirmed because of the cross-sectional nature of the study. The ocular lesions may have predated the development of anaemia or thrombocytopenia, suggesting that these findings represent an association rather than a definitive causal relationship. However, since the ocular lesions identified appeared to be recent in the fundus and anterior chamber, they are likely associated with the identified cytopenias.

Conclusions

Anaemia and thrombocytopenia were significantly associated with ocular lesion presence and severity in cats. Cats with concurrent anaemia and thrombocytopenia demonstrated a higher ocular lesion prevalence than those with either condition alone. This observation warrants further investigation to explore potential underlying mechanisms. Based on these findings, any cat presenting with anaemia and/or thrombocytopenia should undergo a comprehensive ophthalmic examination.

Footnotes

Acknowledgements

We wish to thank IVC Evidensia Research Fund for providing the funding for this study.

Accepted: 27 August 2025

Conflict of interest

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

This study received funding from the IVC Evidensia Research Fund.

Ethical approval

The work described in this manuscript involved the use of non-experimental (owned or unowned) animals. Established internationally recognised high standards (‘best practice’) of veterinary clinical care for the individual patient were always followed and/or this work involved the use of cadavers. Ethical approval from a committee was therefore not specifically required for publication in JFMS. Although not required, where ethical approval was still obtained, it is stated in the manuscript.

Informed consent

Informed consent (verbal or written) was obtained from the owner or legal custodian of all animal(s) described in this work (experimental or non-experimental animals, including cadavers, tissues and samples) for all procedure(s) undertaken (prospective or retrospective studies). No animals or people are identifiable within this publication, and therefore additional informed consent for publication was not required.

ORCID iD

Moranne Frejlich

References

Furman

Leidinger

Hooijberg

, et al. A retrospective study of 1,098 blood samples with anaemia from adult cats: frequency, classification, and association with serum creatinine concentration. J Vet Intern Med 2014; 28: 1391–1397.

Evans

Gruffydd

Jones T.

Anaemia in cats.

In Pract 1984; 6: 168–178.

Mills

. Anaemia. In: Day

Kohn

(eds). BSAVA manual of canine and feline haematology and transfusion medicine. 2nd ed. British Small Animal Veterinary Association, 2012, p 34.

Garden

Kidd

Mexas

, et al. ACVIM consensus statement on the diagnosis of immune-mediated hemolytic anemia in dogs and cats. J Vet Intern Med 2019; 33: 313–334.

Chalhoub

Langston

Eatroff

Anaemia of renal disease: what it is, what to do and what’s new.

J Feline Med Surg 2011; 13: 629–640.

Hunt

Jugan

MC.

Anemia, iron deficiency, and cobalamin deficiency in cats with chronic gastrointestinal disease.

J Vet Intern Med 2021; 35: 172–178.

Shelton

Linenberger

ML.

Hematologic abnormalities associated with retroviral infections in the cat.

Semin Vet Med Surg Small Anim 1995; 10: 220–233.

Olson

Hohenhaus

AE.

Feline non-regenerative anaemia: diagnostic and treatment recommendations.

J Feline Med Surg 2019; 21: 615–631.

Maddison

. Anaemia. In: Maddison

Volk

Church

(eds). Clinical reasoning in small animal practice. Wiley Blackwell, 2015, p 208.

10.

Webb

Cullen

. Ocular manifestations of system disease. Part 2: the cat. In: Gelatt

Ben-Shlomo

Gilger

, et al (eds). Veterinary ophthalmology volume II. 6th ed. Wiley Blackwell, 2021, pp 2373, 2430, 2432.

11.

Fischer

CA.

Retinopathy in anemic cats.

J Am Vet Med Assoc 1970; 156: 1415–1427.

12.

Cinquoncie

Occurrence of acute pathologic ophthalmologic findings in cats with systemic disease [in German].

Inaugural-Dissertation zur Erlangung des Grades eines Doktors der Veterinärmedizin an der Freien Universität Berlin, 2015.

13.

Rebar

AH.

The feline hemogram. In: Feline Medicine 111. Proceedings of the 3rd Annual Kal Kan Seminar, Eastern States Veterinary Conference; Orlando, Florida, 1987, pp 23–32.

14.

Jordan

Grindem

Breitschwerdt

EB.

Thrombocytopenia in cats: a retrospective study of 41 cases.

J Vet Intern Med 1993; 7: 261–265.

15.

Norman

Barron

RCJ

Nash

, et al. Prevalence of low automated platelet counts in cats: comparison with prevalence of thrombocytopenia based on blood smear estimation. Vet Clin Pathol 2001; 30: 137–140.

16.

Ellis

Bell

Barnes

, et al. Prevalence and disease associations in feline thrombocytopenia: a retrospective study of 194 cases. J Small Anim Pract 2018; 59: 531–538.

17.

Kohn

Thrombocytopenia in cats.

Proceedings of the 31st World Small Animal Veterinary Association World Congress; 2006 Oct 11–14;

Prague, Czech Republic, October 11–14, 2006, pp 373–375. WSAVA.

18.

abu el-Asrar

al-Momen

Kangave

, et al. Correlation of fundus lesions and hematologic findings in leukemic retinopathy. Eur J Ophthalmol 1996; 6: 167–172.

19.

Carraro

Rossetti

Gerli

GC.

Prevalence of retinopathy in patients with anaemia or thrombocytopenia.

Eur J Haematol 2001; 67: 238–244.

20.

Goel

Arora

Jain

, et al. Massive subretinal and vitreous haemorrhages at presentation in idiopathic thrombocytopenic purpura: report of a case and review of literature. Clin Exp Optom 2014; 97: 270–273.

21.

Guyer

Schachat

Vitale

, et al. Leukemic retinopathy. Relationship between fundus lesions and hematologic parameters at diagnosis. Ophthalmology 1989; 96: 860–864.

22.

Hassan

Badr

Hanna

, et al. Retinopathy in Egyptian patients with sickle cell disease: a cross-sectional study. Medicine (Baltimore) 2021; 100. DOI: 10.1097/MD.0000000000028355.

23.

Shelah-Goraly

Aroch

Kass

, et al. A prospective study of the association of anaemia and thrombocytopenia with ocular lesions in dogs. Vet J 2009; 182: 187–192.

24.

Acierno

Brown

Coleman

, et al. ACVIM consensus statement: guidelines for the identification, evaluation, and management of systemic hypertension in dogs and cats. J Vet Intern Med 2018; 32: 1803–1822.

25.

Metelitsina

Sheth

Patel

, et al. Peripheral retinopathy associated with aplastic anemia. Retin Cases Brief Rep 2017; 11: 108–110.

26.

Shweiki

Itin

Soffer

, et al. Vascular endothelial growth factor induced by hypoxia may mediate hypoxia-initiated angiogenesis. Nature 1992; 359: 843–845.

27.

Collins

Connolly

Williams

TJ.

Characterization of the increase in vascular permeability induced by vascular permeability factor in vivo.

Br J Pharmacol 1993; 109: 195–199.

28.

Rubenstein

Yanoff

Albert

DM.

Thrombocytopenia, anemia, and retinal hemorrhage.

Am J Ophthalmol 1968; 65: 435–439.

29.

Merin

Freund

Retinopathy in severe anemia.

Am J Ophthalmol 1968; 66: 1102–1106.

30.

Desquilbet

Enhancing clinical decision-making: challenges of making decisions on the basis of significant statistical associations.

J Am Vet Med Assoc 2020; 256: 187–193.

31.

Mandrekar

JN.

Receiver operating characteristic curve in diagnostic test assessment.

J Thorac Oncol 2010; 5: 1315–1316.

32.

Venkatesh

Reddy

Jayadev

, et al. Determinants for anemic retinopathy. Beyoglu Eye J 2023; 8: 97–103.

33.

Holt

Gordon-Smith

EC.

Retinal abnormalities in diseases of the blood.

Br J Ophthalmol 1969; 53: 145–160.

34.

Saadé

Haddad

Sukkarieh

, et al. The role of funduscopy in severe thrombocytopenia: a prospective study. Transfus Clin Biol 2022; 29: 138–140.

35.

Capua

Cohen

Anafy

, et al. Routine funduscopy in immune thrombocytopenic purpura–is it really necessary? Eur J Pediatr 2019; 178: 957–960.

36.

Wondratschek

Weingart

Kohn

Primary immune-mediated thrombocytopenia in cats.

J Am Anim Hosp Assoc 2010; 46: 12–19.

37.

Jain

Switzer

JW.

Autoimmune thrombocytopenia in dogs and cats.

Vet Clin North Am Small Anim Pract 1981; 11: 421–434.

38.

LeVine

Kidd

Garden

, et al. ACVIM consensus statement on the diagnosis of immune thrombocytopenia in dogs and cats. J Vet Intern Med 2024; 38: 1958–1981.

39.

Botsch

Küchenhoff

Hartmann

, et al. Retrospective study of 871 dogs with thrombocytopenia. Vet Rec 2009; 164: 647–651.

40.

Stripe

The fundus oculi in anemias and hemoblastoses. Observations on the cases examined in the Policlinico of Rome during the 10-year period 1955–1964 [article in Italian].

Boll Ocul 1965; 44: 577–591.

41.

Marshal

RA.

A review of lesions in the optic fundus in various diseases of the blood.

Blood 1959; 14: 882–891.

42.

Kristensen

Weiss

Klausner

, et al. Detection of antiplatelet antibody with a platelet immunofluorescence assay. J Vet Intern Med 1994; 8: 36–39.

43.

Korman

Hetzel

Knowles

, et al. A retrospective study of 180 anaemic cats: features, aetiologies and survival data. J Feline Med Surg 2013; 15: 81–90.

44.

Stubbs

Holland

Relf

JS.

Feline ehrlichiosis.

Compend Contin Educ Pract Vet 2000; 22: 307–318.

45.

Brooks

Goggs

Frye

, et al. A prospective cohort study to identify clinical diagnostic and prognostic markers of primary immune thrombocytopenia in dogs. J Vet Intern Med 2024; 38: 1022–1034.

46.

Francés

Seth

Sharman

, et al. Causes of thrombocytopenia in dogs in the United Kingdom: a retrospective study of 762 cases. Vet Med Sci 2023; 9: 1495–1507.

47.

Simpson

Chapman

Klag

Long-term outcome of primary immune-mediated thrombocytopenia in dogs.

J Small Anim Pract 2018; 59: 674–680.

48.

Bianco

Armstrong

Washabau

RJ.

Presumed primary immune-mediated thrombocytopenia in four cats.

J Feline Med Surg 2008; 10: 495–500.

49.

Garon

Scott

Selting

, et al. Idiopathic thrombocytopenic purpura in a cat. J Am Anim Hosp Assoc 1999; 35: 464–470.

50.

Kohn

Linden

Leibold

Platelet-bound antibodies detected by a flow cytometric assay in cats with thrombocytopenia.

J Feline Med Surg 2006; 8: 254–260.

51.

Öberg

Tvedten

Thromboelastography in a cat with steroid-responsive thrombocytopenia.

Comp Clin Path 2010; 19: 429–431.

52.

Peterson

Couto

Wellman

ML.

Hemostatic disorders in cats: a retrospective study and review of the literature.

J Vet Intern Med 1995; 9: 298–303.

53.

Tasker

Mackin

Day

MJ.

Primary immune-mediated thrombocytopenia in a cat.

J Small Anim Pract 1999; 40: 127–131.

54.

Black

Adamantos

Barfield

, et al. Feline non-regenerative immune-mediated anaemia: features and outcome in 15 cases. J Feline Med Surg 2016; 18: 597–602.

Prevalence of ocular lesions in cats with anaemia and thrombocytopenia

Abstract

Objectives

Methods

Results

Conclusions and relevance

Keywords

Introduction

Materials and methods

Study design and ethical considerations

Clinical examination

Statistical analysis

Results

Epidemiology

Ophthalmic findings

Aetiologies

Discussion

Conclusions

Footnotes

Acknowledgements

Conflict of interest

Funding

Ethical approval

Informed consent

ORCID iD

References