Acute vitamin D3 toxicosis in horses: case reports and experimental studies of the comparative toxicity of vitamins D2 and D3.
Abstract: Acute vitamin D toxicosis was diagnosed in 2 horses fed a grain ration containing 1,102,311 IU of cholecalciferol (vitamin D3)/kg (500,000 IU/lb) for about 30 days. Horse 1 died acutely with extensive mineralization of cardiovascular and other soft tissues. Horse 2, which had severe clinical signs and clinicopathologic changes of toxicosis, was treated with nonsteroidal antiinflammatory drugs and recovered in about 6 months. In an experimental study, the toxicity of ergocalciferol (vitamin D2) and cholecalciferol was compared in 2 horses (No. 3 and 4) given the respective vitamins at a daily dosage of 33,000 IU/kg of initial (day 0) body weight for 30 days. Except for slight loss in body weight (8%) during the 1st few days of treatment, horse 3 remained clinically normal. Horse 4 developed limb stiffness and tachycardia, became anorectic, weak, and recumbent, lost 29% of body weight, and had polydipsia and polyuria. Horses 2, 3, and 4 developed persistent hyperphosphatemia. Horse 2 remained normocalcemic whereas horses 3 and 4 became hypercalcemic by day 28. In horse 3, serum vitamin D2 metabolite concentrations on days 0, 1, 14, and 26 were: vitamin D2 (ng/ml) = less than 5.0, 5.7, 71.4, and 188.0; 25-hydroxy-vitamin D2 (ng/ml) = less than 5.0, less than 5.0, 43.1, and 117.5; and 1,25-dihydroxy-vitamin D (pg/ml) = 19.7, 23.2, 25.0, and 45.7, respectively. In horse 4, serum vitamin D3 metabolite concentrations on the same days were: vitamin D3 (ng/ml) = less than 5.0, 110.0, 1,049.0, and 887.0; 25-hydroxy-vitamin D3 (ng/ml) = less than 5.0, 18.9, 201.0 and 182.0; and 1,25-dihydroxy-vitamin D (pg/ml) = 21.5, 18.9, 25.2, and 21.6, respectively. Urine of horses 2 and 4 became acidic (pH 6). Horses 2, 3, and 4 became hyposthenuric, but the decrease in urine specific gravity (sp gr) in horse 3 occurred only after 3 weeks of treatment and was only moderate (sp gr, 1.018 to 1.021) and nonprogressive. Hyposthenuria was evident in horse 4 on day 4 (sp gr, 1.028), and was progressive and marked (sp gr, days 28 to 32: 1.006 to 1.009). Urine sp gr of horse 2 ranged from 1.002 to 1.007. Fractures were demonstrated radiographically and histologically in the costochondral junctions of horses 3 and 4. Mineralization of cardiovascular and other soft tissues developed in horses 3 and 4, with lesions being more severe and having a wider tissue distribution in horse 4.
Publication Date: 1983-06-15 PubMed ID: 6307954
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Case Reports
- Journal Article
- Research Support
- U.S. Gov't
- Non-P.H.S.
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
The research article discusses a case of severe vitamin D3 toxicity in horses due to high dosage, and compares the toxicity levels of vitamins D2 and D3 in experimental conditions.
Initial Case
- The study begins with the case of two horses that were diagnosed with acute vitamin D toxicosis, i.e., extremely high vitamin D levels, due to consuming feed ration containing elevated amount of cholecalciferol (vitamin D3).
- Horse 1 died abruptly, with the autopsy revealing widespread mineralization of cardiovascular and other soft tissues, a possible consequence of high vitamin D levels.
- Horse 2 experienced severe clinical indications and changes at laboratory levels, suggesting toxicosis. However, with the application of nonsteroidal antiinflammatory drugs, the horse managed to recover over a period of six months.
Comparative Study between Vitamin D2 and D3 Toxicity
- To study the comparative toxicity of Vitamin D2 and D3, two other horses were treated with either ergocalciferol (vitamin D2) or cholecalciferol at a daily dosage of 33,000 IU/kg of their initial body weight for a month.
- Horse 3, which was given vitamin D2, showed a small reduction in body weight but remained clinically normal for most of the trial period.
- Horse 4, treated with vitamin D3, developed several severe clinical symptoms such as limb stiffness, tachycardia (abnormally rapid heart rate), loss of appetite, weakness, increase in drinking and urination and a significant weight loss of 29%.
- All three horses from the experiment (Horses 2, 3 and 4) developed consistent hyperphosphatemia (above-average phosphate levels in the blood). Horse 2 had normal level of calcium while both horses 3 and 4 developed high levels of calcium in their blood by the end of the trial.
Further Findings
- The study registers the levels of vitamin D2 and D3 metabolite concentrations on different days in the serum of horses 3 and 4. As expected, horses receiving high dosages of respective vitamins showed elevated concentrations of those vitamins and its metabolites over time.
- The urine of horses 2 and 4 turned acidic (lower pH) and all three horses became hyposthenuric (lower urine specific gravity) during the trial period. This decrease in urine specific gravity was observed to be more severe and progressive in Horse 4.
- Radiographical and histological examinations showed the presence of fractures in the costochondral junctions (where the ribs join with the costal cartilage) of horses 3 and 4. Both these horses also displayed signs of widespread mineralization of cardiovascular and other soft tissues, with Horse 4 showing much severe symptoms and more tissue involvement.
Conclusion
- The study conclusively shows the toxic effects of both vitamins D2 and D3 when consumed excessively in horses, with D3 toxicity manifesting in more severe clinical symptoms and physical damage.
Cite This Article
APA
Harrington DD, Page EH.
(1983).
Acute vitamin D3 toxicosis in horses: case reports and experimental studies of the comparative toxicity of vitamins D2 and D3.
J Am Vet Med Assoc, 182(12), 1358-1369.
Publication
Researcher Affiliations
MeSH Terms
- Acute Disease
- Animal Feed / poisoning
- Animals
- Cholecalciferol / poisoning
- Cholecalciferol / toxicity
- Edible Grain / poisoning
- Ergocalciferols / toxicity
- Horse Diseases / chemically induced
- Horse Diseases / diagnosis
- Horses
- Male
Citations
This article has been cited 7 times.- Dosi MCM, Riggs CM, May J, Lee A, Cillan-Garcia E, Pagan J, McGorum BC. Thoroughbred Racehorses in Hong Kong Require Vitamin D Supplementation to Mitigate the Risk of Low Vitamin D Status.. Animals (Basel) 2023 Jun 29;13(13).
- Vecchiato CG, Delsante C, Galiazzo G, Perfetti S, Pinna C, Sabetti MC, Zagnoli L, Biagi G, Pietra M. Case Report: A Case Series Linked to Vitamin D Excess in Pet Food: Cholecalciferol (Vitamin D3) Toxicity Observed in Five Cats.. Front Vet Sci 2021;8:707741.
- Ruggiero CE, Backus RC. Effects of Vitamin D(2) and 25-Hydroxyvitamin D(2) Supplementation on Plasma Vitamin D Epimeric Metabolites in Adult Cats.. Front Vet Sci 2021;8:654629.
- Kumar R, Brar RS, Banga HS. Hypervitaminosis D(3) in broiler chicks: histopathological, immunomodulatory and immunohistochemical approach.. Iran J Vet Res 2017 Summer;18(3):170-176.
- Hawkes CP, Schnellbacher S, Singh RJ, Levine MA. 25-Hydroxyvitamin D Can Interfere With a Common Assay for 1,25-Dihydroxyvitamin D in Vitamin D Intoxication.. J Clin Endocrinol Metab 2015 Aug;100(8):2883-9.
- Lee JY, So TY, Thackray J. A review on vitamin d deficiency treatment in pediatric patients.. J Pediatr Pharmacol Ther 2013 Oct;18(4):277-91.
- Bundza A, Stevenson DA. Arteriosclerosis in seven cattle.. Can Vet J 1987 Jan;28(1-2):49-51.
Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists
