BackgroundLittle information is available about posthypoglycemic hyperglycemia (PHH) in diabetic cats, and a causal link between hypoglycemia and subsequent hyperglycemia is not clear. Fluctuations in blood glucose concentrations might only represent high glycemic variability.HypothesisInsulin induces PHH in healthy cats, and PHH is associated with poorly regulated diabetes and increased glycemic variability in diabetic cats.AnimalsSix healthy cats, 133 diabetic cats.MethodsInsulin (protamine‐zinc and degludec; 0.1‐0.3 IU/kg) administered to healthy cats. Blood glucose curves were generated with portable glucose meter to determine the percentage of curves with PHH. Data from insulin‐treated diabetic cats with blood glucose curves showing hypoglycemia included data of cats with and without PHH. Post‐hypoglycemic hyperglycemia was defined as blood glucose concentrations <4 mmol/L followed by blood glucose concentrations >15 mmol/L within 12 hours. Glycemic variability was calculated as the standard deviation of the blood glucose concentrations.ResultsIn healthy cats, all insulin doses caused hypoglycemia but PHH was not observed; glycemic variability did not differ between insulin preparations. Among diabetic cats with hypoglycemia, 33 (25%) had PHH. Compared with cats without PHH, their daily insulin dose was higher (1.09 ± 0.55 versus 0.65 ± 0.56 IU/kg; P < .001), serum fructosamine concentration was higher (565 ± 113 versus 430 ± 112 µmol/L; P < .001), remission was less frequent (10% versus 56%; P < .001), and glycemic variability was larger (8.1 ± 2.4 mmol/L versus 2.9 ± 2.2 mmol/L; P < .001).Conclusions and Clinical ImportanceInsulin‐induced hypoglycemia did not cause PHH in healthy cats but it occurred in 25% of diabetic cats with hypoglycemia, particularly when diabetes was poorly controlled. Glycemic variability was increased in cats with PHH.
Objectives Systemic hypertension (SHT) causes severe target organ damage (TOD) and blood pressure (BP) measurement should be routine in at-risk populations. Fundoscopy is a tool to corroborate acute clinical relevance of high BP results and to decide on immediate therapy. Not every cat with a high BP result can be examined by an ophthalmologist. The study objective was to determine the reliability of fundoscopy in cats with SHT performed by a veterinarian without ophthalmology specialty training. Methods Cats with suspicion of hypertensive TOD or belonging to a risk population for SHT with a first measurement of elevated BP >160 mmHg were enrolled. Indirect ophthalmoscopy was performed by a recent graduate veterinarian followed by a veterinary ophthalmologist. Confirmation of SHT was based on two additional sets of systolic BP measurements >160 mmHg by Doppler sphygmomanometry. Results Thirty-three cats were included. SHT was confirmed in 27 cats. SHT was detected on routine examinations in 12/27 cats; fundoscopic lesions were observed in 9/12 by the non-trained veterinarian and in 11/12 by an ophthalmologist. Nine of 27 cats were neurological patients; fundoscopic lesions were detected in 4/9 by the non-trained veterinarian and in 7/9 by an ophthalmologist. Six of 27 cats were presented for acute blindness; fundus lesions were detected in all six cats by the non-trained veterinarian and ophthalmologist. SHT was not confirmed and fundoscopic lesions were not detected by either examiner in 6/33 cats. Compared with a veterinary ophthalmologist, reliability of detecting fundus abnormalities by the non-trained veterinarian was 72% (13/18) for cats with, and 100% (6/6) for cats without, vision. Conclusions and relevance Fundus examination by a non-specialty trained veterinarian has reasonably high reliability for the detection of ocular TOD. Private practice veterinarians are encouraged to perform an initial fundic examination in suspected hypertensive cats.
Case summary This report describes the appearance of facial nerve paralysis in a 16-year-old hypertensive cat. MRI was helpful in visualising and characterising mesencephalic and facial nerve lesions thought to be induced by hypertension. Neurological signs rapidly resolved under antihypertensive therapy. Relevance and novel information Systemic hypertension is an important medical condition in geriatric cats causing damage in various target organs, including the brain. Hypertensive encephalopathy is an umbrella term for a multitude of different clinical manifestations of cerebral target organ damage. Facial nerve paralysis secondary to hypertension is recognised in human medicine, particularly in children, but so far has not been reported in veterinary medicine.
Objectives Hypertensive encephalopathy in cats is an important entity but is underestimated in clinical practice. This could be explained, in part, by non-specific clinical signs. The objective of this study was to characterise the clinical manifestations of hypertensive encephalopathy in cats. Methods Cats with systemic hypertension (SHT) recognised by routine screening, associated with underlying predisposing disease or a clinical presentation suggestive of SHT (neurological or non-neurological), were prospectively enrolled over a 2-year period. Confirmation of SHT was based on at least two sets of measurements of systolic blood pressure >160 mmHg by Doppler sphygmomanometry. Results Fifty-six hypertensive cats with a median age of 16.5 years were identified; 31 had neurological signs. In 16/31 cats, neurological abnormalities were the primary complaint. The other 15 cats were first presented to the medicine or ophthalmology service, and neurological disease was recognised based on the cat’s history. The most common neurological signs were ataxia, various manifestations of seizures and altered behaviour. Individual cats also showed paresis, pleurothotonus, cervical ventroflexion, stupor and facial nerve paralysis. In 28/30 cats, retinal lesions were detected. Of these 28 cats, six presented with a primary complaint of visual deficits, and neurological signs were not the primary complaint; nine presented with non-specific medical issues, without suspicion of SHT-induced organ damage; in 13 cats, neurological issues were the primary complaint and fundic abnormalities were detected subsequently. Conclusions and relevance SHT is common in older cats and the brain is an important target organ; however, neurological deficits are commonly ignored in cats with SHT. Gait abnormalities, (partial) seizures and even mild behavioural changes should prompt clinicians to consider the presence of SHT. A fundic examination in cats with suspected hypertensive encephalopathy is a sensitive test to support the diagnosis.
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