Myopathy in horses with pituitary pars intermedia dysfunction (Cushing’s disease).
Abstract: Fifteen horses with pituitary pars intermedia dysfunction were studied. The horses were of various breeds and between 15 and 28 years of age. Control horses matched for breed and age were studied for comparison. Evaluations included complete blood cell count and serum biochemical analysis, electromyography, and gluteus medius muscle biopsies for histochemical, morphometric, and ultrastructural analysis. No differences were found between groups of horses on routine laboratory analysis or electromyography. We demonstrated that muscle wasting in diseased horses was the result of atrophy of types 2A and 2B muscle fibers and loss of type 2B myofibers. Mild non-specific non-inflammatory myopathic alterations such as myofiber size variation, internal nuclei, perimysial, endomysial and sarcoplasmic fat accumulation were observed. At the ultrastructural level, subsarcolemmal mitochondrial accumulation and increased lipid droplets were evident. Similar to other species, this study confirmed atrophy of type 2 fibers as the cause of muscle mass loss in horses with Cushing's disease.
Publication Date: 2006-09-26 PubMed ID: 17005399DOI: 10.1016/j.nmd.2006.07.019Google Scholar: Lookup
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- Journal Article
- Biopsy
- Clinical Pathology
- Clinical Study
- Comparative Study
- Diagnosis
- Disease Diagnosis
- Disease Etiology
- Equine Diseases
- Equine Health
- Equine Science
- Geriatric Horses
- Horses
- Morphometry
- Muscle Fiber Types
- Musculoskeletal System
- Myography
- Pathology
- Pituitary Pars Intermedia Dysfunction
- Ultrastructure
- Veterinary Medicine
- Veterinary Research
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.
This research examines the factors causing muscle wasting in horses suffering from pituitary pars intermedia dysfunction, commonly known as Cushing’s disease. The study specifically identifies atrophy in type 2A and 2B muscle fibers as the main cause of this issue.
Study Participants and Procedure
- The study involved fifteen horses suffering from pituitary pars intermedia dysfunction, a condition also known as Cushing’s disease. These horses varied in breed and age, ranging between 15 and 28 years old.
- To create a comparison, a control group of horses, matched in breed and age, was also studied.
- Each horse was subjected to comprehensive evaluations, including a complete blood cell count, serum biochemical analysis, electromyography, and biopsies of the gluteus medius muscle.
Findings and Analysis
- No significant differences were found between the Cushing’s horses and control horses based on routine laboratory analysis or electromyography.
- However, muscle wasting in Cushing’s horses was found to be mainly due to the atrophy (decrease in mass) of type 2A and 2B muscle fibers and loss of type 2B myofibers.
- Mild non-specific, non-inflammatory myopathic alterations were also noted; these included variations in myofiber size, internal nuclei, perimysial, endomysial, and sarcoplasmic fat accumulation. These are typical signs of muscle damage or disease.
- On examining the muscle tissues at an ultrastructural level, researchers found an accumulation of mitochondria under the sarcolemma (cell membrane) and increased lipid droplets, possibly indicating disturbances in muscle metabolism due to the disease.
Conclusion
- This research confirms similar findings from previous studies on different species, substantiating that type 2 muscle fiber atrophy is a primary cause of muscle mass loss in horses with Cushing’s disease.
- This understanding can guide future research and shaped therapeutic strategies to counter muscle wasting in horses with Cushing’s disease.
Cite This Article
APA
Aleman M, Watson JL, Williams DC, LeCouteur RA, Nieto JE, Shelton GD.
(2006).
Myopathy in horses with pituitary pars intermedia dysfunction (Cushing’s disease).
Neuromuscul Disord, 16(11), 737-744.
https://doi.org/10.1016/j.nmd.2006.07.019 Publication
Researcher Affiliations
- Department of Veterinary Medicine and Epidemiology, University of California, Davis, USA. mraleman@ucdavis.edu
MeSH Terms
- Animals
- Electromyography
- Female
- Horse Diseases / etiology
- Horse Diseases / pathology
- Horses
- Male
- Mitochondria, Muscle / pathology
- Mitochondria, Muscle / ultrastructure
- Muscle Fibers, Skeletal / pathology
- Muscle Fibers, Skeletal / ultrastructure
- Muscle Weakness / etiology
- Muscle Weakness / physiopathology
- Muscle Weakness / veterinary
- Muscle, Skeletal / pathology
- Muscle, Skeletal / physiopathology
- Muscle, Skeletal / ultrastructure
- Muscular Diseases / etiology
- Muscular Diseases / pathology
- Muscular Diseases / veterinary
- Pituitary ACTH Hypersecretion / complications
- Pituitary ACTH Hypersecretion / pathology
- Pituitary ACTH Hypersecretion / veterinary
- Pituitary Gland, Intermediate / pathology
- Pituitary Gland, Intermediate / physiopathology
Citations
This article has been cited 7 times.- Kirkwood NC, Hughes KJ, Stewart AJ. Pituitary Pars Intermedia Dysfunction (PPID) in Horses. Vet Sci 2022 Oct 10;9(10).
- Tatum RC, McGowan CM, Dean RS, Ireland JL. Equine pituitary pars intermedia dysfunction: Identifying research priorities for diagnosis, treatment and prognosis through a priority setting partnership. PLoS One 2021;16(1):e0244784.
- Zakia LS, Palumbo MIP, Teixeira RBC, Resende LAL, Soares MP, de Oliveira-Filho JP, Amorim RM, Borges AS. Neuromyotonia in a horse. J Vet Intern Med 2019 Jan;33(1):287-291.
- Hunyadi L, Sundman EA, Kass PH, Williams DC, Aleman M. Clinical Implications and Hospital Outcome of Immune-Mediated Myositis in Horses. J Vet Intern Med 2017 Jan;31(1):170-175.
- Parmantier S, Kyriazopoulou P, McClendon M, Adams A, Murphy BA. Influence of Extended Photoperiod Using Blue Light Masks on Hypertrichosis, Coat Condition and General Health Parameters in Horses with Pituitary Pars Intermedia Dysfunction. Animals (Basel) 2025 Oct 5;15(19).
- Sillence MN, Holt K, Li FI, Harris PA, Coyle M, Fitzgerald DM. Sources of Environmental Exposure to the Naturally Occurring Anabolic Steroid Ecdysterone in Horses. Animals (Basel) 2025 Jul 17;15(14).
- Román Durá B, Dunham O, Grulke S, Salciccia A, Dupont J, Sandersen C. A Retrospective Study on Pre- and Intraoperative Predictors on the Recovery Quality of Horses After General Anesthesia. Vet Sci 2025 Mar 11;12(3).
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