Background The relationship between the development of SHPT and ionized magnesium (iMg) concentrations in blood of dogs with chronic gastrointestinal (GI) disease and abnormally low 25(OH)D is undefined. Objectives Evaluate relationships between ionized magnesium (iMg), PTH, ionized calcium (iCa), and 25(OH)D in dogs with chronic enteropathy (CE) with or without protein‐losing enteropathy (PLE) and abnormal 25(OH)D. Determine whether dogs with CE or PLE, decreased 25(OH)D and SHPT have differences in iMg, iCa, or 25(OH)D when compared to dogs that do not have SHPT. Animals Fifty dogs with CE +/− PLE and abnormally low serum 25(OH)D. Methods Retrospective search of submissions database at a veterinary diagnostic laboratory for vitamin D profiles submitted in years 2017 to 2020. Cases were excluded if supplemented with Ca, Mg, or vitamin D. Spearman correlation was performed to evaluate relationships between iMg, PTH, 25(OH)D, and iCa. Ionized Mg, iCa, and 25(OH)D concentrations were compared between dogs with SHPT and those with normal PTH concentrations. Results Concentrations of iMg were weakly negatively correlated with PTH (rho, −.31; P = .03), and weakly positively correlated with serum 25(OH)D (rho, .34, P = .02) and iCa (rho, .42, P = .003). Ionized magnesium concentrations were lower in dogs with abnormally low 25(OH)D and SHPT compared to dogs with abnormally low 25(OH)D and normal parathyroid hormone concentrations (P = .01). Conclusions and Clinical Importance Hypomagnesemia might contribute to alterations in iCa and parathyroid hormone in dogs with CE +/− PLE and abnormally low 25(OH)D.

An 8.5-month-old, male, entire golden retriever presented for 6-month history of large bowel diarrhoea and vomiting. Giardiasis was previously treated. Clinical signs recurred despite empirical antibiotics, food trials, probiotics and psyllium. Physical exam revealed circumferential cobblestone-like rectal mucosa. Rectal scrape cytology was consistent with cryptococcosis. Latex cryptococcal agglutination test was consistently negative. Thoracic radiographs were normal. Notable abdominal ultrasound findings included jejunal and suspected mesenteric cystic lymphadenopathy and multifocal areas of submucosal thickening. Abdominal lymph node aspirates revealed lymphoid hyperplasia. Faecal sedimentation and floatation revealed few Alaria species eggs and many Coccidia oocysts, respectively. Patient was treated with fluconazole, sulfadimethoxine, Drontal Plus and subsequently developed pancytopenia secondary to sulphonamide therapy requiring hospitalization, and recovered with supportive care and discontinuation of drug. Patient's clinical signs, rectal palpation and sonographic features resolved with continued fluconazole therapy. This case demonstrates localized intestinal cryptococcosis based on cytology with negative latex cryptococcal agglutination test and pancytopenia secondary to sulphonamide therapy for co-parasitism.