Induction of a hypocoagulable state is imperative in the treatment of feline arterial thromboembolism. Publications in human medicine report the use of enoxaparin intravenously in selected cases. The aim of our retrospective study was to report the regain of perfusion, short-term outcome, and complications of cats treated with a novel intravenous enoxaparin protocol (1 mg/kg bolus injection followed by 3 mg/kg/day continuous infusion) combined with oral clopidogrel administration. The secondary aim was to report the monitoring of enoxaparin with anti-Xa activity. There were 36 cats included. The probability of reaching limb reperfusion was significantly (p = 0.0148) higher with anti-Xa activity within or above the target range compared to results below the target range (19/21, 90% versus 11/20, 55%). The complications observed were acute kidney injury (15/36, 42%), hemorrhage (2/36, 6%), and neurological signs (6/36, 17%). The most common causes of death/euthanasia were cardiac instability, acute kidney injury, neurological abnormalities, and limb necrosis. The hospital discharge rate was 83% (10/12) for single limb and 29% (7/24) for dual limb thrombosis; the difference was significant (p = 0.0039). The median hospitalization time for the survivors was 119.5 (95–480) h. Our study supports the use of intravenous continuous rate infusion of enoxaparin in combination with oral clopidogrel for cats with aortic thromboembolism. We report similar discharge rates and lower hemorrhage rates than previously reported with thrombolytic treatment.

Radioiodine therapy (RAIT) is the gold standard for treatment of hyperthyroidism in cats. The aim of this study was to evaluate the effect of the presence of uni- or bilateral thyroid adenoma on changes in total thyroxine (TT4), thyroid-stimulating hormone (TSH), and creatinine concentration over a period of 6 to 12 months following RAIT. Fifty-one hyperthyroid cats presented for RAIT between April 2021 and April 2022 were prospectively enrolled. Cats with an increased creatinine concentration (creatinine ≥ 140 µmol/L), renal morphology abnormalities, and suspected thyroid carcinoma were excluded. TT4, TSH, and creatinine were determined before and one week and one, three, six, and twelve months following RAIT. The effects of the re-examination timepoint following RAIT and the presence of uni- or bilateral thyroid adenoma based on technetium-99m scintigraphy on TT4, TSH, and creatinine were analysed by mixed effects modelling. Cats with bilateral adenoma had significantly higher TSH concentrations after RAIT compared to those with unilateral adenoma. TT4 concentration significantly decreased one week (p < 0.001) and again one month following RAIT (p < 0.001). TSH and creatinine concentration significantly increased one month post RAIT (both p < 0.001). As indicated by an increase in TSH concentration, the pituitary–thyroid axis needs a minimum of one month post RAIT to recover from hyperthyroidism-induced suppression, but hypothyroidism necessitating levothyroxine supplementation might not be diagnosed before 6 or even 12 months post RAIT. Although creatinine did not increase significantly after one month post RAIT in this cohort, an increased creatinine concentration was detected at later timepoints in individual cats.

Adult-onset spontaneous feline hypothyroidism (SH) is considered rare, but its prevalence is unknown. This study aimed to screen laboratory submissions for cats with laboratory suspected SH (LSSH) and to identify laboratory abnormalities associated with LSSH. Submissions to a commercial laboratory in Germany between January 2022 and April 2023 were prospectively screened for cats aged 3–12 years with low total thyroxine (TT4); in these cats, thyrotropin (TSH) was measured. Iatrogenic hypothyroidism was excluded by contacting submitting veterinarians. Creatinine, triglyceride and cholesterol concentration and red blood cell count (RBC) of cats with LSSH (low TT4, TSH > 0.53 ng/mL; i.e., [one sided TSH reference change value (76%) of TSH upper reference interval (RI)] + [TSH upper RI] = 0.53) were compared to euthyroid cats (TT4 within RI) and cats with suspected non-thyroidal illness (SNTIS) (low TT4, normal TSH (<0.3 ng/mL; upper RI)) by non-parametric tests. p < 0.05 was significant. In total, 31,572 submissions of cats were included, 25,169 (79.7%) were euthyroid, 3818 (12.1%) had SNTIS and 61 (0.2%) had LSSH. Cats with LSSH had higher creatinine (p = 0.002) and lower RBC count (p < 0.0001) than euthyroid cats as well as higher creatinine (p = 0.00035) than cats with SNTIS. Azotaemia (creatinine > 140 µmol/L) and anaemia (RBC < 7.2 × 10¹²/L) were present in 28/49 (57%) and 19/44 (43%) cats with LSSH, respectively. There was no difference between LSSH and SNTIS for the remaining parameters. In cats with low TT4, azotaemia and anaemia might indicate the presence of SH and reinforce the need for TSH testing. Hypercholesterolaemia and hypertriglyceridaemia are not indicators of SH.