Aplastic anemia in cats - clinicopathological features and associated disease conditions 1996-2004

Neoplastic and non-neoplastic diseases associated with feline leukaemia virus (FeLV) in cats in southern Brazil

The objective of this study was to categorise diseases associated with FeLV infection in cats. A total of 154 cats were submitted to necropsy, histopathology exam and anti-FeLV immunohistochemistry (IHC), and 83 (50.9 %) were IHC FeLV-positive. The cats age means of 4.1 years, including 3.6 % kittens, 34.9 % junior, 37.4 % prime, 18.1 % mature, 2.4 % senior, 3.6 % unknown age. Neoplastic diseases were most prevalent with leukaemia and lymphoma being most predominant, followed by viral diseases, bacterial, trauma, degenerative, intoxications, parasitic, malformation and others. FeLV+ cats were 5.73 times more likely to be diagnosed with neoplasms than other diseases. The odds ratio (OR) of FeLV+ cats developing leukaemia (OR = 7.75) and lymphoma (OR = 6.75) was higher than other neoplasms. FeLV infection was more prevalent in the mixed breed, junior to prime, male, with neoplastic diseases, including leukaemia and lymphoma. Therefore, understanding the diseases associated with FeLV is of paramount importance in Brazil due to its high prevalence, and it may encourage the implementation of prophylactic measures to reduce its dissemination.

An investigation into an outbreak of pancytopenia in cats in the United Kingdom

BACKGROUND

In spring 2021 increasing numbers of cats presenting with severe pancytopenia were noted in United Kingdom (UK).

OBJECTIVE

To describe process and outcome of the investigation performed into the outbreak of pancytopenia in cats.

ANIMALS

Five hundred and eighty client owned cats that presented with severe bi- or pancytopenia of unknown cause.

METHODS

Real-time data collection was performed by an online registration forum available to all veterinary surgeons in UK. Data collected included demographics, clinicopathological findings, diagnostic testing, dietary and drug history, outcome and COVID household status. Mycotoxicological feed analysis was performed on feed samples of 3 diets frequently mentioned in the database and 3 control diets.

RESULTS

Five hundred and eighty cats presented to 378 veterinary practices were included for analysis. Case fatality rate was 63.3%. Dietary history was available for 544 (93.8%) cats, of which 500 (86%) were fed 1 of 3 diets (which were recalled midinvestigation). 54 (9.3%) cats were not fed a recalled product, with diet information unknown in 26 (4.5%) cats. Analysis of feed samples revealed concentrations of hematotoxic trichothecene T-2/HT-2 mycotoxins greater than recommended by the European Commission in 5/7 recalled diet samples but in none of control diet samples. The trichothecene mycotoxin diacetoxyscirpenol (DAS) was detectable in all recalled diet samples but not in any of control samples.

CONCLUSION AND CLINICAL IMPORTANCE

Contaminated-feed induced trichothecene mycotoxicosis should be considered as a differential diagnosis for pancytopenia in cats.

Clinical and clinicopathological features and outcomes of cats with suspected dietary induced pancytopenia

BACKGROUND

After a strong epidemiological link to diet was established in an outbreak of pancytopenia in cats in spring 2021 in the United Kingdom, 3 dry diets were recalled. Concentrations of the hemato- and myelotoxic mycotoxins T-2, HT-2 and diacetoxyscirpenol (DAS) greater than the European Commission guidance for dry cat foods were detected in the recalled diets.

OBJECTIVES

To describe clinical and clinicopathological findings in cats diagnosed with suspected diet induced pancytopenia.

ANIMALS

Fifty cats presenting with pancytopenia after exposure to a recalled diet.

METHODS

Multicenter retrospective case series study. Cats with known exposure to 1 of the recalled diets were included if presented with bi- or pancytopenia and underwent bone marrow examination.

RESULTS

Case fatality rate was 78%. Bone marrow aspirates and biopsy examination results were available in 23 cats; 19 cats had a bone marrow aspirate, and 8 cats had a biopsy core, available for examination. Bone marrow hypo to aplasia-often affecting all cell lines-was the main feature in all 31 available core specimens. A disproportionately pronounced effect on myeloid and megakaryocytic cells was observed in 19 cats. Myelofibrosis or bone marrow necrosis was not a feature.

CONCLUSION AND CLINICAL IMPORTANCE

Mycotoxin induced pancytopenia should be considered as differential diagnosis in otherwise healthy cats presenting with bi- or pancytopenia and bone marrow hypo- to aplasia.

Gelatinous transformation of bone marrow in a rabbit

A 9-y-old, spayed female rabbit was presented for evaluation of hypoglycemia and lateral recumbency. The patient was hypothermic and had diffuse muscle wasting; weight loss since a previous visit was also noted. Hematologic abnormalities included progressive nonregenerative anemia and severe heteropenia. Evaluation of a bone marrow aspirate sample revealed active hematopoiesis with abundant pink matrix. The matrix material stained positively with periodic acid-Schiff and alcian blue, and a diagnosis of gelatinous transformation of the bone marrow (GTBM, serous atrophy of fat) was made. Although its precise prevalence remains to be determined, GTBM should be suspected in rabbits with persistent cytopenias following prolonged starvation or gastrointestinal disease.

Feline non-regenerative anemia: Diagnostic and treatment recommendations

PRACTICAL RELEVANCE

Non-regenerative anemia, or anemia with reticulocytopenia, is a daily diagnosis in feline practice.

CLINICAL CHALLENGES

The disease processes underlying non-regenerative anemia are many and diverse. A major diagnostic evaluation may be required to correctly diagnose and treat the underlying cause.

AUDIENCE

All veterinarians caring for cats will face the diagnostic and therapeutic challenge of non-regenerative anemia. Readers will benefit from the review of diagnostic testing and therapeutic options for non-regenerative anemia.

EVIDENCE BASE

This review summarizes the currently available literature informing diagnostic and treatment recommendations related to non-regenerative anemia. The evidence available to support the recommendations in this review is graded as low and includes predominantly expert opinion, case reports and cases series, on which the authors' interpretation/consensus is based.

Life-threatening haematological complication occurring in a cat after chronic carbimazole administration

Case summary

An 11-year-old spayed female domestic shorthair cat with a history of hyperthyroidism treated with carbimazole for 7 months was presented for a check-up after a few episodes of vomiting. The cat had been receiving prednisolone at 0.5 mg/kg PO q12h for recent pancreatitis and concurrent inflammation of liver and small intestines confirmed by biopsies. Clinical examination revealed pale mucous membranes with a capillary refill time of <2 s. Haematology showed severely decreased packed cell volume (16%), and increased prothrombin time (42 s), partial thromboplastin time (>120 s) and fibrinogen serum concentration (3.5 g/l). Morphological changes of thrombocytes in the absence of thrombocytopenia were also noted. In-saline agglutination test was positive. Abdominal radiographic and ultrasonographic examinations excluded the presence of organ abnormalities and peritoneal effusion. Blood biochemistry was unremarkable. Feline leukaemia virus and feline immunodeficiency virus tests were negative. On the basis of these findings, immune-mediated anaemia secondary to chronic carbimazole administration was suspected. Prednisolone was increased to 2 mg/kg PO q24h and carbimazole tablets were stopped. Despite close monitoring and intensive care, the cat died the same evening of admission to the hospital.

Relevance and novel information

This report suggests that severe haemotoxicity may occur as a sequel of chronic carbimazole administration in cats. Routine bloodwork and accurate follow-up of cats under treatment with thyrotoxic therapy may be advisable, in order to detect haematological changes before lethal complications occur.

Follow-up on long-term antiretroviral therapy for cats infected with feline immunodeficiency virus

OBJECTIVES

Feline immunodeficiency virus (FIV) is a lentivirus that induces AIDS-like disease in cats. Some of the antiretroviral drugs available to treat patients with HIV type 1 are used to treat FIV-infected cats; however, antiretroviral therapy (ART) is not used in cats as a long-term treatment. In this study, the effects of long-term ART were evaluated in domestic cats treated initially with the nucleoside transcriptase reverse inhibitor (NTRI) zidovudine (AZT) over a period ranging from 5-6 years, followed by a regimen of the NTRI lamivudine (3TC) plus AZT over 3 years.

METHODS

Viral load, sequencing of pol (reverse transcriptase [RT]) region and CD4:CD8 lymphocyte ratio were evaluated during and after treatment. Untreated cats were evaluated as a control group.

RESULTS

CD4:CD8 ratios were lower, and uncharacterized resistance mutations were found in the RT region in the group of treated cats. A slight increase in viral load was observed in some cats after discontinuing treatment.

CONCLUSIONS AND RELEVANCE

The data strongly suggest that treated cats were resistant to therapy, and uncharacterized resistance mutations in the RT gene of FIV were selected for by AZT. Few studies have been conducted to evaluate the effect of long-term antiretroviral therapy in cats. To date, resistance mutations have not been described in vivo.

A retrospective study of 180 anaemic cats: features, aetiologies and survival data

The study comprised 180 anaemic cats. Descriptive and survival data were obtained. Cats were classified by aetiology of anaemia development and degenerative, anomalous, metabolic, miscellaneous, neoplastic, infectious, inflammatory, immune-mediated, toxic, traumatic or vascular disease (DAMNITV) classification and anaemia severity. Sixty-four (35.6%) cats had mild [packed cell volume (PCV)/haematocrit (HCT) 20-24.9%], 58 (32.2%) moderate (14-19.9%), 23 (12.8%) severe (11-13.9%) and 35 (19.4%) very severe (<10.9%) anaemia. By aetiology of anaemia development, bone marrow (BM) abnormalities were more common (95, 52.8%) than haemorrhage (37, 20.6%) or haemolysis (19, 10.6%). By DAMNITV classification, infectious diseases were more common (39, 21.7%) than neoplasia (36, 20%), metabolic (21, 11.7%), trauma (15, 8.3%), miscellaneous (14, 7.8%), inflammatory (11, 6.1%), immune-mediated (11, 6.1%), anomalous (8, 4.4%), toxic (2, 1.1%) or vascular disease (1, 0.6%). BM abnormalities were significantly associated with more severe anaemia (P = 0.003). Most cats (112, 62.2%) survived to discharge whereas 55 (30.6%) were euthanased and 13 (7.2%) died. Survival to discharge was not associated with anaemia severity but was associated significantly with aetiology of anaemia development (P = 0.046), as cats with haemolysis were more likely to survive to discharge than cats with BM abnormalities. Survival to discharge was also associated significantly with DAMNITV classification (P = 0.010), with cats with neoplasia being less likely, and cats with immune-mediated disease more likely, to survive to discharge. Cox regression analysis found that survival was not associated with anaemia severity, but was associated with DAMNITV classification (P = 0.011) and age (P = 0.082), with cats with immune-mediated disease and younger cats more likely to survive.

Hydrogen therapy may be an effective and specific novel treatment for aplastic anemia

Aplastic anemia (AA) is a rare bone marrow failure disorder with high mortality rate, which is characterized by pancytopenia and an associated increase in the risk of hemorrhage, infection, organ dysfunction and death. The oxidation phenomenon and/or the formation of free radicals have been suggested to be causally related to various hematological disorders, including aplastic anemia. TNF-α, IL-6, and IL-2 also play important roles in the pathogenesis of AA. Recent studies have provided evidence that hydrogen inhalation can selectively reduce cytotoxic oxygen radicals and exert antioxidant effects. It was also reported that hydrogen could suppress the levels of TNF-α and IL-6. Based on these findings, we hypothesize that hydrogen therapy may be an effective, simple, economic and novel strategy in the treatment of aplastic anemia.

Environmental lead exposure as a risk for childhood aplastic anemia

Concern about environmental lead exposure as a significant public health threat has increased as evidence has accumulated regarding adverse health effects at successively lower levels. Aplastic anemia is a hematological disorder of unknown etiology with a high lethality rate. Lead is a known toxicant for the hematopoietic system. Oxidative stress appears to be the possible mode of lead toxicity. We evaluated the effects of blood lead level on oxidative stress parameters in children suffering from aplastic anemia disease. Seventeen children with aplastic anemia disease (15 male and 2 female, age 3-12 y) were recruited in the study group. Fifty one healthy children (45 male and 6 female, age 3-12 y) having normal blood profiles and not suffering from any chronic disease(s) were used as controls. Blood lead level and oxidative stress parameters were determined. Mean blood lead level was significantly higher while δ-aminolevulinic acid dehydratase (δ-ALAD) activity, a biomarker for lead exposure was significantly lower in the study group as compared to the control group (p < 0.05 for each). Thiobarbituric acid reactive species (TBARS), a marker of lipid peroxidation, was significantly higher while the antioxidant glutathione (GSH) level was significantly lower in the study group as compared to the control group (p < 0.05 for each). Activity of the antioxidant enzyme catalase (CAT) was significantly higher in the study group than in the control group (p < 0.05). There was a significant negative correlation of blood lead levels with δ-ALAD (r = -0.45; p < 0.05) and GSH (r = -0.32; p < 0.05), and a positive correlation with TBARS (r = 0.41; p < 0.05) and CAT (r = 0.37; p < 0.05). Although a causal pathway cannot be determined from this study, our results indicated that lead induces oxidative stress in children suffering from aplastic anemia. Lead-induced oxidative stress as an underlying mechanism for aplastic anemia warrants further research.

Protective effects of selenium on methimazole-induced anemia and oxidative stress in adult rats and their offspring

The present study investigates the potential ability of selenium, considered as an antioxidant with pharmacological property to alleviate oxidative stress and hematological parameter disorders induced by methimazole, an antithyroid drug. Pregnant Wistar rats were randomly divided into four groups of six each: group I served as negative control and received a standard diet; group II received 250 mg/L of methimazole in drinking water and a standard diet; group III received both methimazole (250 mg/L, orally) and selenium (0.5 mg/kg of diet) supplemented to the standard diet; group IV served as positive control and received a supplement of selenium in the diet (0.5 mg/kg of diet) as sodium selenite (Na(2)SeO(3)). Treatment was started from the 14th day of pregnancy until day 14 after delivery. Methimazole reduced the number of red blood cells, hemoglobin concentration and hematocrit in mothers and their pups. Besides, plasma iron, vitamins B(9), B(12), C and E levels were reduced. Lipid peroxidation increased, objectified by high malondialdehyde levels and lactate dehydrogenase activity in plasma, while glutathione, glutathione peroxidase, superoxide dismutase and catalase activities showed a significant decline. Co-administration of selenium through diet improved all the parameters cited above. It can be concluded that the administration of selenium alleviates methimazole-induced toxicity, thus demonstrating its antioxidant efficacy.

Pharmacologic Management of Feline Hyperthyroidism

Radioiodine is considered the treatment of choice for hyperthyroidism, but in some situations, methimazole therapy is preferred, such as in cats with preexisting renal insufficiency. Unfavorable outcomes from methimazole are usually attributable to side effects, such as gastrointestinal upset, facial excoriation, thrombocytopenia, neutropenia, or liver enzyme elevations. Because restoration of euthyroidism can lead to a drop in glomerular filtration rate, all cats treated with methimazole should be monitored with blood urea nitrogen and creatinine levels in addition to serum thyroxine (T(4)) and a complete blood cell count. Transdermal methimazole is associated with fewer gastrointestinal side effects and can be used in cats with simple vomiting or inappetence from oral methimazole. Hypertension may not resolve immediately when serum T(4) is normalized, and moderate to severe hypertension should be treated concurrently with atenolol, amlodipine, or an angiotensin-converting enzyme inhibitor.