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![Pituitary Pars Intermedia Dysfunction (PPID) in Horses [Symptoms, Treatment & Management]](/wp-content/uploads/2021/12/Pituitary-Pars-Intermedia-Dysfunction-in-Horses.jpg)
Pituitary Pars Intermedia Dysfunction (PPID) is an endocrine-related disease that commonly affects older horses of all breeds. Twenty percent of senior horses, ponies, and donkeys are believed to have PPID.
The condition results in an overproduction of pituitary hormones, causing metabolic dysfunction. Horses with PPID may also have insulin resistance and an increased risk of laminitis.
Typical clinical symptoms of PPID include abnormal coat condition with delayed shedding, muscle loss, impaired immune function, and behavioural changes.
PPID is diagnosed by your veterinarian with tests and observation of clinical symptoms. Pergolide mesylate (Prascend) is the only medication licensed for the treatment of the disease.
Appropriate management of horses with PPID involves diet, exercise, regular veterinary care, and consistent monitoring of hormone levels. If your horse has PPID, submit their diet online for a free evaluation by our equine nutritionists.
What is PPID?
Pituitary Pars Intermedia Dysfunction is a common equine endocrine disorder, primarily afflicting horses over the age of 15, and becoming more likely to develop as the horse ages. [1]
It involves an excessive production of hormones, such as adrenocorticotrophic hormone (ACTH), from the pars intermedia lobe of the pituitary gland located at the base of the brain.
The level of hormones in the pars intermedia of a horse with PPID can be 100 times higher than in a healthy horse.
The overproduction of hormones is caused by degeneration of the dopamine-producing neurons in the hypothalamus, potentially due to oxidative stress. Low dopamine levels impair the normal regulatory function that shuts off the production of pituitary hormones.
PPID is an age-related disease; aging is the only major risk factor for the condition, although horses as young as 7 years of age have been diagnosed. Breed and sex do not predispose horses to develop the disease.
Epidemiologic studies estimate that 20% of horses over the age of 20 are affected by PPID, and 30% of those over 30 are affected. [3]
Although previously referred to as Equine Cushing’s Disease, this title is now considered inaccurate. Cushing’s Disease in humans affects a different location within the pituitary gland. [2]
How Does PPID Affect Horses?
The equine pituitary gland consists of 3 lobes including the pars distalis, pars intermedia, and pars nervosa. PPID affects the pars intermedia part of the gland.
The hypothalamus, a part of the brain, controls the release of hormones from the pituitary gland. This gland plays a key role in regulating hormones related to metabolism and affects the function of various organs.
PPID results in an overproduction of multiple hormones that cause an abnormal metabolic state. Increased levels of these hormones affect various processes throughout the body.
In healthy horses, the neurotransmitter dopamine is released by the hypothalamus to inhibit the production of hormones by the pars intermedia. Dopamine binds to receptors on the surface of cells to turn off the secretion of hormones from this part of the pituitary gland.
PPID results from the degeneration of dopamine-producing neurons in the hypothalamus. This prevents the hypothalamus from regulating the release of hormones by the pituitary gland, such as adrenocorticotrophic hormone (ACTH).
Horses with PPID have high levels of circulating ACTH, triggering the adrenal gland to increase production of the stress hormone cortisol. Higher cortisol levels lead to insulin resistance.
Low dopamine also causes the pituitary gland to increase in size as the cells of the pars intermedia divide and enlarge. Horses with PPID may develop benign tumours in this part of the gland.
The expansion of the pars intermedia can cause other lobes of the pituitary and the hypothalamus to become compressed. This may cause a loss of function in these structures and result in a range of clinical symptoms.
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What's your top priority with your horse's health?
Symptoms of PPID
Research shows that the clinical signs of PPID are often under-recognized. [4]
PPID can cause a range of symptoms depending on the severity of the condition. [5] Early symptoms include:
- Decreased athletic performance
- Changes in attitude
- Delayed shedding
- Muscle wasting and loss of topline
- Regional fat deposits
As PPID progresses, horses can develop additional symptoms, including:
- Weight loss
- Abnormal sweating
- Skeletal atrophy
- Tendon atrophy
- Infertility
- Neurological problems
- Increased thirst and urination
The suspensory ligaments of horses with PPID develop degenerative changes virtually identical to those seen in spontaneously occurring DSLD. In the case of PPID, it is the high cortisol inhibiting normal repair processes in the ligament. [24]
At advanced stages, horses are more susceptible to infections because of immune suppression. [6] Horses with PPID are more prone to dental, skin, sinus infections, and intestinal parasites.
Insulin Resistance
Horses with PPID are often insulin resistant, which means the cells in their body do not respond normally to the hormone insulin.
Approximately 30% of horses with PPID have high blood insulin levels because their tissues are less sensitive to this hormone.
Insulin regulates the metabolism of sugar (glucose) in the body by signalling tissues to take in glucose from the bloodstream. It also stimulates tissues to utilize glucose to produce glycogen, a form of energy that is stored in the body.
In horses with insulin resistance, the signalling effect of this hormone is impaired and cells cannot take up as much glucose from the blood. As a result, the pancreas continues to produce more insulin, resulting in hyperinsulinemia (high blood insulin levels). [23]
Symptoms of insulin resistance include the accumulation of fatty deposits on the neck, top of the tail, shoulders, and mammary glands. Other signs include excessive urination and thirst.
Chronically high insulin levels are associated with Equine Metabolic Syndrome (EMS) and are often present in PPID. [7]
Horses with PPID should be tested for insulin resistance to avoid related health complications.
Increased Risk of Laminitis
Horses with both PPID and insulin resistance are at risk of developing laminitis. [8][9]
High levels of insulin (hyperinsulinemia) are implicated in the development of laminitis, although the exact mechanisms are still being researched. Inflammation, vasoconstriction and endothelial damage are three proposed disease pathways.
Insulin resistance is diagnosed in horses with elevated levels of this hormone or with abnormal insulin response after eating a meal or an oral sugar test (glucose challenge).
PPID is not on its own a risk factor for laminitis. Horses with PPID that do not have EMS and associated insulin resistance are typically not considered at high risk for laminitis.
Causes of PPID
Researchers do not know exactly what causes the degeneration of dopamine neurons in the hypothalamus.
One theory is that neurons are damaged by free radicals that are produced during metabolic processes. [10] Horses with PPID may be at greater risk of oxidative stress in their hypothalamus. [11]
Oxidative stress (excessive damage by free radicals), is known to alter the chemical structure of cells, proteins, and DNA. Ultimately, it can decrease the number of healthy dopamine-producing neurons that send signals between the hypothalamus and pituitary pars intermedia.
With fewer of these neurons, there is less inhibition of pituitary hormone production by dopamine. Higher levels of pituitary hormones in circulation lead to a broad range of symptoms, together indicating PPID.
How is PPID Diagnosed?
Your veterinarian may diagnose your horse with PPID after evaluating clinical signs and conducting diagnostic testing.
PPID diagnosis can be done at any time, but the interpretation of results will need to take into account seasonal variations in pituitary hormones.
Early intervention is necessary to avoid more advanced health complications due to the disease. If you observe the common symptoms in your senior horse, consult with your veterinarian as soon as possible.
Baseline ACTH Test:
To perform a baseline ACTH test, your veterinarian will collect a blood sample and measure the level of the hormone ACTH in the blood (plasma) compared to a reference range. [12]
A high level of ACTH in the blood can indicate that a horse has PPID. However, ACTH concentrations can vary with stress, illness, exercise, and diet.
Additionally, there is a physiologic (normal) increase in ACTH concentration July through November in North America. This can make test interpretation difficult! If your horse is tested during this season, your veterinarian will need to consider seasonal reference ranges or may recommend additional testing outside of the Fall. [13]
This test detects moderate to advanced cases of PPID, but may not detect mild or early-stage PPID in horses. [14]
Thyrotropin-Releasing Hormone (TRH) Stimulation Test:
TRH stimulation tests are used in combination with the ACTH test to confirm a positive diagnosis of PPID when ACTH testing is inconclusive. [15]
After collecting a blood sample for a baseline ACTH test, TRH is administered intravenously, and a second ACTH sample is collected approximately 10 minutes later. [9]
In horses with PPID, ACTH levels increase after administering TRH. An ACTH concentration higher than 100pg/mL is indicative of PPID. [9]
Dexamethasone Suppression Test:
Previously a popular test for diagnosing PPID, the dexamethasone suppression test is now considered less reliable than other tests.
This test requires administering the corticosteroid dexamethasone to horses intravenously or as an injection into the muscle. Blood samples are collected 24 hours later to measure the level of the hormone cortisol. [9]
In horses with PPID, an injection of dexamethasone increases cortisol in the blood. [16] In healthy horses, dexamethasone suppresses cortisol levels.
Insulin Testing
PPID and Equine Metabolic Syndrome (EMS) occur together in some horses, but not all. It is recommended to test all PPID horses for insulin resistance. [17]
Insulin levels are tested using a combination of a basal insulin test and an oral glucose challenge test.
A basal insulin test involves collecting blood when the horse has had nothing but hay to eat overnight and on the day of the test. Fasted sampling is no longer recommended.
Only 30% of horses with EMS have high insulin levels when fasting. The oral glucose challenge is also recommended to identify horses with insulin resistance.
A glucose challenge test involves collecting blood before and after feeding a horse corn syrup to measure how much insulin is released in response to sugar. An analysis is performed on both samples to assess insulin sensitivity.
Treatment of PPID
While there is no cure for PPID, it is very manageable with appropriate treatment. Treatment is aimed at reducing the clinical symptoms of the disease is required for the lifespan of the affected horse. Many horses go on to have excellent quality of life post-diagnosis.
The prognosis for horses with PPID varies, as does the medication protocol required for a positive response.
Treating the condition earlier may improve the quality of life of affected horses and potentially avoid complications, including infections and laminitis.
Medication
Pergolide mesylate is the only drug licensed for the treatment of PPID in horses and is considered the gold-standard treatment. Originally developed to treat Parkinson’s disease in humans, it is an oral medication administered once per day.
Prascend is the only FDA-approved pergolide formulation for horses. Compounded formulations of pergolide are not recommended due to variations in drug concentration and instability over time.
Pergolide regulates the pituitary gland by acting as a dopamine replacement. It decreases the release of hormones, such as ACTH, from the pars intermedia, leading to improvement in PPID symptoms.
Pergolide promotes a normal coat, increased muscle mass, improved attitude, and reduced risk of developing laminitis and secondary infections. The drug also suppresses the enlargement of the pituitary gland and the growth of tumours.
Pergolide Results
Horses given Pergolide to treat PPID experienced improved clinical symptoms one to three months after their ACTH levels are controlled.
Determining the correct dose should be done carefully with a low dosage administered to start. After a few weeks of treatment, ACTH levels should be rechecked to determine if a higher dosage is needed.
Horses that fail to improve on high doses of pergolide may be given the drug cyproheptadine (Periactin) as an adjunctive therapy. A serotonin blocker, cyproheptadine is not as effective as pergolide in controlling clinical signs of PPID. Additionally, there is the human drug cabergoline, which is in the same family as pergolide. It is currently only available as compounded slow-release injectable formulation.
Monitoring how PPID-affected horses respond to medications is important. Hormone levels should be checked at least twice per year, including in the fall.
Horses suspected of having mild PPID but with normal ACTH levels may be given pergolide as a trial to determine if their condition improves. Trials are typically performed over a few months.
Not all symptoms of PPID may be controlled with pergolide. In a study of nine PPID-affected horses, immune function did not improve, despite improved ACTH levels. [18]
This demonstrates the importance of good management practices to keep your PPID horse healthy, even when they are taking medications.
Management of PPID Horses
PPID-affected horses should be managed appropriately to ensure their wellness and comfort.
Diet
Horses with PPID may have problems maintaining a healthy weight and body condition. While some are underweight and require additional calories, others may need to reduce their energy intake and exercise more.
Horses with PPID and concurrent insulin dysregulation require a low-carbohydrate diet. [19][20] These horses should be fed grass hays rather than legume hays and should have limited or no access to lush pastures.
Nutritional Supplements
Providing a balanced mineral and vitamin supplement to your horse with PPID is critical to support metabolic health and immune function.
Avoiding common deficiencies in the equine diet will also help to support hoof health and reduce the risk of secondary issues such as laminitis.
Researchers are currently investigating the effects of antioxidant supplementation on neuronal degeneration associated with PPID.
Antioxidant nutrients, such as selenium and Vitamin E, are particularly important to prevent damage to cells caused by harmful free radicals, which are products of normal cellular metabolism.
PPID horses with insulin resistance also benefit from chromium and magnesium supplementation to support glucose metabolism. [21][22]
Mad Barn’s AminoTrace+ vitamin and mineral supplement is designed specifically for horses with PPID and metabolic dysfunction. It contains elevated levels of key nutrients to support metabolic health and more.
Chasteberry
The herb Chasteberry (Vitex agnus-castus) may benefit some horses with early PPID. According to veterinary case reports, it may reduce clinical symptoms of elevated ACTH levels, including excessive hair growth and abnormal shedding. [19]
However, chasteberry is not as effective as pergolide in horses in advanced stages of the disease. Research shows that chasteberry does not lower ACTH levels, unlike Pergolide. [19]
Although not a suitable replacement, chasteberry may be used as an adjunct therapy to support horses with PPID.
Dental Wellness
Horses with PPID should have regular dental checks since they have an increased risk for periodontal disease.
Parasite Treatment
The immune system impairment that occurs in PPID horses can leave them more susceptible to internal parasites. [6]
An appropriate deworming protocol should be discussed with a veterinarian. Fecal-egg count testing helps determine which anthelmintic agent to use and whether a deworming program is working.
Hoof Care
Horses with PPID and insulin dysregulation have a higher risk of developing hoof problems including abscesses and laminitis.
These horses should have their hooves checked regularly for any signs of damage that could promote infection and subclinical signs of laminitis.
Grooming
PPID affected horses with excessive coats (hypertrichosis) that fail to shed out in the spring and summer may have difficulty staying cool in warm weather. Clipping excess hair can help to keep them more comfortable.
Blanketing
Some horses affected by PPID have difficulty maintaining their body condition during cold temperatures. Blanketing these horses during cold winter months may help them retain heat more effectively and prevent unwanted weight loss.
Can PPID Be Prevented?
There is no way to prevent your horse from developing PPID. However, early detection and treatment can slow the progression of the disease and minimize symptoms.
Some of the most common signs of PPID include low energy levels, muscle wasting, a loss of topline, recurrent infections, and delayed shedding.
Monitor senior horses for signs of the disease and talk to your veterinarian if you suspect PPID. Horses should have a regular veterinary wellness check one to two times per year to track changes occurring over time.
If your horse has PPID, consult with a nutritionist to design a feeding plan that meets your horse’s vitamin and mineral needs. You can submit your horse’s diet online for a free evaluation from our university-trained nutritionists.
Frequently Asked Questions
Here are some frequently asked questions about Pituitary Pars Intermedia Dysfunction in horses:
Pituitary Pars Intermedia Dysfunction is a common endocrine disorder in horses that causes overproduction of hormones from the pars intermedia lobe of the pituitary gland. It mainly affects older horses, ponies, and donkeys, especially those over 15 years of age. [1] The condition occurs when dopamine-producing neurons in the hypothalamus degenerate, reducing normal control over pituitary hormone release. Although it was previously called Equine Cushing's Disease, that name is now considered inaccurate because human Cushing's Disease affects a different part of the pituitary gland. [2]
Pituitary Pars Intermedia Dysfunction is common in senior horses and becomes more likely as horses age. Epidemiological studies estimate that 20% of horses over 20 years old are affected, and approximately 30% of horses over 30 years old are affected. [3] Aging is the only major risk factor, although horses as young as 7 years old have been diagnosed. Breed and sex are not considered major risk factors for developing the disease.
Pituitary Pars Intermedia Dysfunction is caused by degeneration of dopamine-producing neurons in the hypothalamus, although the exact reason this degeneration occurs is not fully understood. One theory is that oxidative stress damages neurons involved in regulating hormone production. [10] Horses with Pituitary Pars Intermedia Dysfunction may have greater risk of oxidative stress in the hypothalamus. [11] With reduced dopamine signaling, the pituitary gland produces excessive hormones, including adrenocorticotrophic hormone, which contributes to the clinical signs of disease.
Signs of Pituitary Pars Intermedia Dysfunction in horses can include delayed shedding, abnormal coat condition, muscle wasting, loss of topline, reduced athletic performance, attitude changes, and regional fat deposits. [5] As the disease progresses, horses may also develop weight loss, abnormal sweating, skeletal and tendon atrophy, infertility, neurological signs, increased thirst, and increased urination. Clinical signs are often under-recognized, especially in the early stages. [4] Recurrent infections, hoof problems, and poor immune function can also occur because the disease affects multiple body systems.
Pituitary Pars Intermedia Dysfunction can increase laminitis risk when it occurs with insulin resistance or Equine Metabolic Syndrome. [8][9] High insulin levels are strongly linked to laminitis, although the exact mechanisms are still being researched. Pituitary Pars Intermedia Dysfunction by itself is not usually considered a high laminitis risk if the horse does not also have insulin dysregulation. Horses diagnosed with Pituitary Pars Intermedia Dysfunction should be tested for insulin resistance so diet and management can be adjusted appropriately. [17]
Pituitary Pars Intermedia Dysfunction is diagnosed by a veterinarian using clinical signs and hormone testing. The baseline adrenocorticotrophic hormone test measures hormone levels in a blood sample and can identify moderate to advanced cases. [12] Interpretation must account for stress, illness, exercise, diet, and seasonal hormone changes, especially from July through November in North America. [13] Mild or early-stage cases can be harder to detect, so additional testing may be needed when signs are present but baseline results are normal. [14]
The thyrotropin-releasing hormone stimulation test is used when baseline adrenocorticotrophic hormone testing is inconclusive. A veterinarian collects a baseline blood sample, administers thyrotropin-releasing hormone intravenously, and then collects another blood sample about 10 minutes later. [9] Horses with Pituitary Pars Intermedia Dysfunction show an exaggerated increase in adrenocorticotrophic hormone after stimulation. This test can help confirm a diagnosis when clinical signs suggest disease but standard testing is unclear. [15]
Pituitary Pars Intermedia Dysfunction is treated with pergolide mesylate, the only drug licensed for this condition in horses. Pergolide acts as a dopamine replacement and helps reduce hormone release from the pars intermedia of the pituitary gland. It can improve coat quality, muscle mass, attitude, and reduce the risk of laminitis and secondary infections. Horses usually start on a low dose, and hormone levels are rechecked after a few weeks to determine whether the dose needs adjustment.
Pergolide may improve clinical signs within one to three months after adrenocorticotrophic hormone levels are controlled. Hormone levels should be monitored regularly to ensure the medication is working and the dose remains appropriate. Horses with Pituitary Pars Intermedia Dysfunction should have hormone levels checked at least twice per year, including in the fall when seasonal hormone increases can affect interpretation. Pergolide may not control every sign of disease, and one study found immune function did not improve even when adrenocorticotrophic hormone levels improved. [18]
Horses with Pituitary Pars Intermedia Dysfunction should be fed according to body condition, insulin status, and laminitis risk. Some affected horses are underweight and need more calories, while others need reduced energy intake and more exercise. Horses with Pituitary Pars Intermedia Dysfunction and insulin dysregulation require a low-carbohydrate diet. [19][20] These horses are usually better suited to grass hay rather than legume hay and should have limited or no access to lush pasture.
Supplements for horses with Pituitary Pars Intermedia Dysfunction should focus on correcting nutrient gaps and supporting metabolic health, immune function, and hoof health. A balanced vitamin and mineral supplement is important because common deficiencies can affect immunity, hoof quality, and overall health. Antioxidant nutrients such as selenium and vitamin E may be especially relevant because oxidative stress is being investigated as part of neuronal degeneration in this disease. Horses with insulin resistance may also benefit from magnesium and chromium to support glucose metabolism. [21][22]
Horses with Pituitary Pars Intermedia Dysfunction need long-term management with medication, diet, regular veterinary monitoring, and supportive daily care. Dental checks are important because affected horses have increased risk of periodontal disease, and parasite control should be guided by fecal egg count testing because immune impairment can increase parasite susceptibility. [6] Hooves should be monitored closely for abscesses, infection, and subtle signs of laminitis, especially when insulin dysregulation is present. Horses with excessive coats may need clipping in warm weather, and horses that struggle to maintain weight in winter may benefit from blanketing.
Summary
Pituitary Pars Intermedia Dysfunction (PPID) is a common endocrine disorder affecting around 20% of horses over 20 years old, caused by the degeneration of dopamine-producing neurons in the brain.
- The condition leads to excessive production of pituitary hormones like ACTH, resulting in elevated cortisol levels, metabolic dysfunction, and often insulin resistance.
- Common symptoms include delayed coat shedding, muscle loss, fat redistribution, lethargy, immune suppression, and behavioral changes, with advanced cases showing increased infection risk.
- Veterinarians diagnose PPID through clinical evaluation and hormone testing, primarily the ACTH test, TRH stimulation test, and insulin sensitivity tests to identify concurrent insulin resistance.
- Pergolide mesylate (Prascend) is the gold-standard medication that replaces dopamine function, helping regulate hormone levels, improve symptoms, and reduce laminitis risk.
- Long-term management focuses on diet (low-carbohydrate if insulin resistant), supplements (antioxidants, minerals, chasteberry), and routine veterinary, dental, and hoof care to maintain comfort and prevent complications.
References
- McFarlane, D. Equine Pituitary Pars Intermedia Dysfunction. Veterinary Clinics of North America: Equine Practice. 2011. View Summary
- Dybdal N.O. et al. Diagnostic testing for pituitary pars intermedia dysfunction in horses. J Am Vet Med Assoc. 1994. View Summary
- Schott, H. et al. Recommendations for the Diagnosis and Treatment of Pituitary Pars Intermedia Dysfunction. Equine Endocrinology Group. 2021.
- Ireland, J.L., et. al. Comparison of owner-reported health problems with veterinary assessment of geriatric horses in the United Kingdom. In: Equine Veterinary Journal. 2011.View Summary
- McGowan TW et al. Prevalence, risk factors and clinical signs predictive for equine pituitary pars intermedia dysfunction in aged horses. Equine Vet J. 2013.View Summary
- McFarlane, D. et al. Neutrophil function in healthy aged horses and horses with pituitary dysfunction. Veterinary Immunology and Immunopathology. 2015. View Summary
- Frank, N. et al. Insulin dysregulation. Equine Veterinary Journal. 2013.View Summary
- Johnson PJ et al. Endocrinopathic laminitis in the horse. Clin Tech Eq Prac. 2004.
- Asplin KE et al. Induction of laminitis by prolonged hyperinsulinaemia in clinically normal ponies. Vet J. 2007. View Summary
- Spelta, C.W. Equine pituitary pars intermedia dysfunction: current perspectives on diagnosis and management. Veterinary medicine. 2015. View Summary
- McFarlane D et al. The role of dopaminergic neurodegeneration in equine pituitary pars intermedia dysfunction (equine Cushing’s disease). Proceedings of the 49th Annual Connvention of the American Association of Equine Practitioners. 2003.
- How to Diagnose Equine Pituitary Pars Intermedia Dysfunction. Beaufort Cottage Laboratories. 2014.
- McFarlane, D et al. Effects of season and sample handling on measurement of plasma ?-melanocyte-stimulating hormone concentrations in horses and ponies. Am J Vet Res. 2004. View Summary
- Schott II, H. et al. The Michigan Cushing's Project. Proc. Am. Ass. equine Practnrs. 2001.
- Beech, J. et al. Comparison of cortisol and ACTH responses after administration of thyrotropin releasing hormone in normal horses and those with pituitary pars intermedia dysfunction. J Vet Intern Med. 2011. View Summary
- Couëtil L et al. Plasma adrenocorticotropin concentration in healthy horses and in horses with clinical signs of hyperadrenocorticism. J Vet Intern Med. 1996. View Summary
- Mastro, L.M. et al. Pituitary pars intermedia dysfunction does not necessarily impair insulin sensitivity in old horses. Domest Anim Endocrinol. 2015. View Summary
- Miller, AB et al. Effects of pituitary pars intermedia dysfunction and Prascend (pergolide tablets) treatment on endocrine and immune function in horses. Domest Anim Endocrinol. 2021 View Summary
- Bradaric, Zrinjka et al. Use of the chasteberry preparation Corticosal for the treatment of pituitary pars intermedia dysfunction in horses. Pferdeheilkunde. 2013.
- Kaczmarek, K. et al. Insulin resistance in the horse: A review. Journal of Applied Animal Research. 2016.
- Spears, J.W. et al. Chromium propionate increases insulin sensitivity in horses following oral and intravenous carbohydrate administration. Journal of Animal Science. 2020. View Summary
- Stewart, Allison. Magnesium Disorders in Horses. Vet Clin Equine. 2011. View Summary
- Geor, R.J. Metabolic Predispositions to Laminitis in Horses and Ponies: Obesity, Insulin Resistance and Metabolic Syndromes. J Equine Vet Sci. 2008.
- Hofberger, S. et al. Suspensory ligament degeneration associated with pituitary pars intermedia dysfunction in horses. Vet J. 2015. View Summary
