In spring 2021, an unusually large number of cats with severe pancytopenia began presenting to practices in the UK.
Glanemann et al1 reported on the process of investigation of this outbreak and the outcomes. A total of 580 cats with severe bicytopenia or pancytopenia of unknown cause were included in the study.
An online registration form was set up to collect data on the outbreak, including demographics and clinicopathological and other diagnostic findings, diet and drug history, and whether any COVID-19 cases had been reported in the household. Where certain diets were mentioned frequently, mycotoxicological feed analysis was performed and compared to control diets.
The mortality rate was 63.3%. A total of 86 cases were fed one of three diets, which were recalled halfway through the investigation. Five out of seven of the feed samples were found to be contaminated with haematotoxic trichothecene mycotoxins at higher levels than recommended by the European Commission, but none of the control samples were contaminated.
A mycotoxin was detectable in all the recalled diet samples, but none of the control samples.
The authors concluded dietary contamination with trichothecene mycotoxicosis should be considered as a differential diagnosis for pancytopenia in cats.
Long-acting insulin analogue
Concurrent diseases can complicate the management of diabetes; for example, by causing insulin resistance.
Harris-Samson et al2 performed a retrospective pilot study aiming to assess whether the synthetic long-acting insulin analogue detemir improved glycaemic control in dogs with diabetes that were poorly controlled by intermediate-acting insulin. Seven diabetic dogs were included in the study.
The dogs were given detemir for three months or more, and glucose levels were assessed at home by owners, with regular clinical evaluations by vets. The blood glucose concentrations were lower after using detemir compared to the prior treatment with intermediate-acting insulin. No clinical hypoglycaemia was observed.
The authors concluded that detemir may be useful in diabetic dogs with comorbidities and poorly controlled diabetes as an alternative to intermediate-acting insulin.
Diagnosing diabetes in dogs
Diagnosing and monitoring diabetes mellitus using glucose levels can be problematic since they can vary widely over the course of a day, and from day to day. Fructosamine measurement is routinely performed in dogs to give a longer range estimation of glucose, but in humans, glycated haemoglobin (HbA1c) is the routine test for diabetes, with fructosamine being reserved mainly for those cases with genetic variants of haemoglobin that make HbA1c testing inaccurate.
Oikonomidis et al3 performed a study to compare the diagnostic accuracy of HbA1c for diabetes mellitus in dogs with that of fructosamine. Dogs were placed into one of four groups: diabetes mellitus, hyperadrenocorticism, long-term glucocorticoid therapy, and a group of miscellaneous chronic diseases. A total of 88 dogs in total were included.
The median glucose concentration was predictably higher in the diabetes mellitus group than the other groups. HbA1c was also higher in the diabetes mellitus group.
All the diabetic dogs and none of the other dogs had HbA1c levels higher than the cut-off value of 3.3%, an accuracy in this group of 100%. By contrast, fructosamine had an accuracy of 84.4% for the diagnosis of diabetes.
The authors concluded that the accuracy of HbA1c for diagnosing diabetes mellitus is excellent, and superior to fructosamine.
Recording coronavirus in dogs and cats
The COVID-19 pandemic is receding, but it has not yet disappeared and maybe never will.
Animal reservoirs remain a possible source of reinfection and new variants, so surveillance of SARS-CoV-2 in companion animals is important. Liew et al4 reported the findings of national surveillance for SARS-CoV-2 in dogs and cats in the US.
Public and animal health officials, and academics involved in zoonotic research, reported the clinical, laboratory and epidemiological data of infections using a standardised process. A total of 109 cats, and 95 dogs with confirmed SARS-CoV-2 were detected between March 2020 and December 2021 in 33 US states.
A total of 94% of cases had exposure to a person with COVID-19 prior to becoming infected; 74% of cases identified using passive surveillance had clinical signs of illness compared to 27% of pets identified through active surveillance.
Dogs were ill for 12 days on average and cats for 15 days. The average time between the onset of human illness and pet illness was 10 days, with viral material being detected three days after exposure and antibodies after five days, titres peaking at nine days in cats and 14 days in dogs.
The authors concluded that most cases of SARS-CoV-2 in dogs and cats follow exposure to a person with COVID-19, usually their owners, and that more investigation is required to understand the dynamics of transmission between humans and animals of SARS-CoV-2, and similar zoonoses.
Evaluating risk factors for canine cruciate rupture
Cranial cruciate ligament (CCL) rupture in dogs is one of the most common orthopaedic injuries requiring surgery, with invasive and expensive surgery often being recommended.
Pegram et al5 analysed a large database of primary care clinical records to evaluate the risk factors for cruciate rupture. Statistical analysis was performed to evaluate the associations between various risk factors, and the diagnosis and management of the condition. A total of 1,000 unilateral CCL ruptures and 500,000 random cases without CCL ruptures were included in the analysis.
Dogs aged six to nine years, neutered dogs and insured dogs were more likely to be diagnosed with the condition, and the Rottweiler, bichon frise and West Highland white terrier were all over-represented.
Insured dogs and dogs weighing more than 20kg were more likely to be managed surgically than medically. Older dogs and dogs with comorbidities were less likely to have surgery.
The authors concluded this study provides information on the demographic risks associated with CCL rupture, including breed predispositions, and data on the decision making with regard to management.
Diseases associated with ionised hypercalcaemia and urolithiasis in cats
Ionised calcium represents the most biologically active fraction of serum calcium, and ionised calcium concentration is thought to be more sensitive than total calcium concentration when it comes to detecting disturbances of calcium metabolism. However, the literature on ionised hypercalcaemia in cats is limited.
Broughton et al6 performed an observational cross-sectional study of 238 cats that were seen at a referral hospital with ionised calcium concentrations higher than the reference range. Signalment, biochemistry, imaging results, and cause of the hypercalcaemia were analysed.
In total, 13% of the cases had acute kidney injury, 10.1% were associated with malignancy, 8.4% were associated with chronic kidney disease or renal diet, and 5.5% had an iatrogenic cause.
Primary hyperparathyroidism, vitamin D toxicity and granulomatous disease were other diagnoses. Idiopathic hypercalcaemia was diagnosed in 10.1% of cases.
In 47.1% of cases, no cause for the ionised hypercalcaemia was found, and in a small number of cases, the hypercalcaemia was transient or associated with a young age. Some 83.3% of cases with acute kidney injury had urolithiasis, and this was also common in chronic kidney disease/renal diet associated and idiopathic hypercalcaemia cases. Primary hyperparathyroidism, vitamin D toxicity, malignancy and granulomatous disease were associated with a high incidence of elevation of total calcium levels.
This study provides information about the diseases associated with ionised hypercalcaemia and urolithiasis in cats.
Biological variations in medical conditions
All measurements vary within an individual over time, sometimes due to predictable and systematic causes, but often due to random fluctuation around a homeostatic set point.
This has implications for diagnosis and management of conditions when relying on single measurements, which may or may not be representative of the true mean of that parameter in the individual.
However, this problem is under-recognised and, in both human and veterinary fields, a paucity exists of data on the extent of within-individual variability in many measurements – especially in the long term.
Smith et al7 performed a long-term biological variation study of 19 biochemistry measurements in healthy cats. A total of 15 cats were included in the study and serum biochemical analyses were performed every eight weeks for a year.
Co-efficients of variation describing within and between cat variation were calculated, and these were used to determine the indices of individuality and the reference change values.
Albumin, alkaline phosphatase, creatinine kinase and globulin had high indices of individuality, suggesting they should be evaluated using reference change values, while phosphorus, potassium, chloride, sodium, total CO2 and symmetric dimethylarginine had low indices of individuality, suggesting that population reference ranges can be used.
Other measurements were intermediate, and the authors suggested that using reference change values in these cases may give further information when interpreting results.
Clinicians are recommended to consider biological variability when interpreting changes in clinical measurements.
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