Lafeber Company I Two Generations of Veterinarians Caring & Working for the Health of Animals ™
10 Tips to Keep Your Senior Chickens Happy
Your backyard chickens are your pride and joy. You raised them from chicks to adulthood, and now the Golden Years have arrived for Henrietta, Red, Goldie, and Ginger. What can you expect and how can you help your little flock live happily through their “retirement”?
What Is A Senior Chicken?
The first step is to recognize when you’re dealing with senior backyard chickens. The average chicken usually lives for 7 or 8 years. Smaller breeds often live a bit longer than larger breeds, but exceptions occur. The world’s oldest chicken was confirmed by Guinness World Records in March 2023. Her name is Peanut, and she is a bantam breed.
A chicken’s peak years are about 3 or 4, with breed, health conditions, and other factors affecting this. So a 5- or 6-year-old chicken is not only older but likely a senior. Some chickens become seniors sooner than others and vice versa. Signs your backyard chickens are on that path include: not moving as fast, staying closer to the coop, lying down more frequently, change in egg laying for layers, increased health issues, “tattered feathers,” etc.
Enhance The Life Of Your Senior Backyard Chickens
Once you know you have senior chickens in the flock, here’s how you can help them maintain a good quality life.
- Provide the right food. If you were offering layer feed,it’sno longer needed because egg production has slowed greatly or stopped. The added calcium could be harmful at this life stage. Protein percentage should be at 16%, and definitely not more than 25%.
- Provide supplements. Lafeber’s Booster Berries Senior is formulated to aid senior chickens with ingredients to improve mobility and overall health. Arthritis is a major concern aschickensage, and glucosamine and chondroitin can help.
- Adjust the environment. Move roosts, food containers, waterers, etc. within easy reach for ahen suffering mobility issuesdue to arthritis. Add more bedding to senior nest boxes if their feathers seem sparser.
- Monitor senior backyard chickens closely. Check for signs of health concerns, such as overgrown nails, pressure sores on the feet, a chronically soiled vent, parasites like mites, tumors, breathing difficulty, etc. Help your chickens out by regularly trimming nails, providing more bedding or alternate places to roost or lie down, cleaning the vent area gently with warm water, using parasite preventives, and alerting your vet if you suspect a health issue.
- Examine the living area for hazards to seniors. Is there anything in the coop or run that a senior chicken might trip on if feetaren’tlifting as high? Anything else that might harm a senior?
- Determineif your senior needs a place of her own (with her best buddy or two!). As chickens age their needs can change. Observe how your seniors interact with the flock. Is it possible the seniors would do better in their own area with only a few younger hens?
- Consult your veterinarian. He or she can offer advice on minimizing health issues or adjusting the environment.
- Keep pests away. Stay on top of using preventives for both internal and external parasites. Mites, fleas, and other parasites could find easy prey in yourelderchickens. Carefully inspect your seniors daily so you can treat as soon as possible, because they have fewer defenses and reserves against them than younger chickens.
- Occasionally add apple cider vinegar to water in a plastic or glass dish (mix at 1 tablespoon per gallon) to promote good health. Do not use a water container with any metal components, as the vinegar corrodes those. Consult your veterinarian about the proper dose for your seniors. Always have fresh water available thatdoesn’thave added apple cider vinegar.
- Enjoy your senior backyardchickens! Age happens, and your older chickens have a lot to offer, whether through teaching the younger chickens, continuing bug patrol, adding a calm presence, and more.
https://lafeber.com/backyard-chickens/senior-chicken-care/?cmid=987c7e5f-5567-4477-a3a2-751b1407e5f4
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DVM 360 News | FDA approves generic pergolide tablets for equine Cushing disease
Author(s)Abi Bautista-Alejandre, Assistant Editor
January 5, 2026
Zygolide by Dechra offers a generic, bioequivalent option for managing pituitary pars intermedia dysfunction in horses.
The FDA has approved pergolide tablets (Zygolide; Dechra) for controlling clinical signs associated with pituitary pars intermedia dysfunction (PPID) in horses, also known as equine Cushing disease. According to Dechra, the medication is a generic, bioequivalent option for horses suffering from the condition.
PPID, an age-related endocrine disorder, is characterized by the degeneration of neurons that affect the production and regulation of hormones, including adrenocorticotrophic hormone (ACTH). Common clinical signs include a long, curly hair coat, delayed shedding, muscle loss, polydipsia, polyuria, lethargy, and laminitis. Some horses may also exhibit a rounded abdomen, exercise intolerance, abnormal sweating, and fat deposits above the eyes and on the top of the neck and tailhead.2 Additionally, affected horses face higher risk of chronic infection and abscesses. These equines also have decreased wound healing and higher parasite burdens.2
In a news release announcing the approval, Dechra said pergolide tablets is an essential therapy, whose FDA approval expands access for one of the most common endocrine disorders in older horses.1 Researchers estimate that approximately 20 to 33% of all horses develop PPID by the age of 20.3 According to the UC Davis Center School of Veterinary Medicine’s Center for Equine Health, the condition typically occurs in horses older than 15 years.2 Still, cases of PPID have been documented in horses as young as 7 years of age.2
According to Dechra, their pergolide tablets come in a peppermint flavor and are scored around the entire tablet for splitting ease. Beginning this month, the therapy was made available to veterinarians at major online pharmacies across the United States. Currently, the medication is only available in the US.
The medication has not been evaluated in breeding, pregnant, or lactating horses. Adverse effects include loss of appetite, weight loss, lack of energy, and behavioral changes. According to Dechra, most cases of appetite loss are mild, though a temporary reduction in dose may be necessary in severe cases. Pergolide tablets is contraindicated in horses with hypersensitivity to pergolide mesylate or other ergot derivatives, said Dechra.1
“The FDA approval of Zygolide brings to market a high-quality, cost-effective option to help make the management of PPID more accessible,” Greg Schmid, DVM, equine medical affairs lead of Dechra, said in the company news release.1 “This therapy provides another option for horses living with the condition, including a pill structure with 360-degree scoring on all sides and a peppermint flavor profile, helping to reduce stress for both horses and their caretakers.”
https://www.dvm360.com/view/fda-approves-generic-pergolide-tablets-for-equine-cushing-disease
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AVMA News I Wildlife likely spread H5N1 to Wisconsin dairy herd
Finding underscores ongoing spillover risk from wildlife as migratory seasons continue
By R. Scott Nolen
Published on December 31, 2025
The recent detection of highly pathogenic avian influenza (type A H5N1) in a Wisconsin dairy herd has resulted from a new wildlife-to-cattle transmission distinct from earlier outbreaks, according to a genetic analysis by the U.S. Department of Agriculture (USDA).
The virus confirmed as H5N1 clade 2.3.4.4b genotype D1.1 was detected in a herd of approximately 500 cows in Dodge County through the National Milk Testing Strategy (NMTS), according to a December 19 statement from the USDA’s National Veterinary Services Laboratories.
The USDA believes there is no reason for concern about the safety of the commercial milk supply or consumer health because products are pasteurized prior to entering the market. Moreover, the Centers for Disease Control and Prevention considers the human health risk for this virus to be low.
H5N1 trends
More than 1,000 infections in dairy cattle in 19 U.S. states have been confirmed, according to the USDA’s Animal and Plant Health Inspection Service.
Officials believe the Wisconsin dairy herd was infected during a spillover event caused by wildlife, according to Dr. Keith Poulsen, director of the Wisconsin Veterinary Diagnostic Laboratory. He explained that no cattle were moved on or off the affected farm. Also, no other H5N1 cases have been detected through the NMTS, cow movement testing, or other required testing for exhibition or sale within the state. And finally, no clinical signs were noted in the herd.
“Together, these points are very similar to new spillover events that we recorded in Arizona and Nevada in early 2025,” Dr. Poulsen said, adding that the Wisconsin outbreak appears to be contained to a single farm.
Dr. Poulsen explained that the B3.13 clade is still the predominant H5N1 strain affecting dairy cattle in Arizona, California, Idaho, Nebraska, and Texas, according to the USDA, and is the result of a single spillover event in the Texas panhandle in late 2023.
The biggest risk factor for interstate movement is movement of lactating cows, he said.
“We have yet to work out the pathophysiology of H5N1 in dairy cattle, likely because we cannot replicate natural infection in experimental settings. B3.13 also causes significant morbidity, especially the first time a farm is affected. We do not see this with D1 clade infections, but there are far fewer instances of D1 infections, so we need more data to be 100% confident,” Dr. Poulsen added.
Future considerations
He added that the D1 clade has been the predominant variant in North American flyways for over two years.
“Before the second week of December 2025, we thought that spillover risk was limited to desert areas where migratory birds may share water and feed sources. Midwestern dairies typically do not have waterfowl flying around the free stall barns and there is plenty of food and water in the natural waterways.
“Having a D1 pop up in the upper Midwest, even if it is a one-off event, gives us pause, and we may need to rethink long-term management strategies. As long as HPAI is in global migratory flyways, we are going to have to think about spillover to dairy cows and domestic poultry,” he said.
The affected farm in Dodge County, located in southeastern Wisconsin, remains under quarantine while the Wisconsin Department of Agriculture, Trade and Consumer Protection conducts an epidemiological traceback to ensure no further spread has occurred.
Dr. Poulsen said Wisconsin will return to monthly surveillance for the NMTS, a federal order implemented in December 2024 requiring raw milk sampling from silos nationwide.
“The question we all are asking ourselves now is to what end?” he said. “Migration season runs February to June and September to December, but it isn’t sustainable to maintain surveillance forever.”
Dr. Poulsen strongly supports the biosecurity recommendations from the National Milk Producers Federation because they distill the Secure Milk Supply guidelines to focus on H5N1.
“Biosecurity is not a magic bullet for protection,” he said, “but it will reduce the time the herd is affected and in quarantine, increase the time to infection, and have fewer negative health effects for the herd.”
https://www.avma.org/news/wildlife-likely-spread-h5n1-wisconsin-dairy-herd
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TVP – October 3, 2025 | Issue: Mixed Animal Practice Edition 2025
Equine Medicine
Common Causes of Colic in Horses
Colic is associated with multiple causes and successful outcomes depend on timely recognition, proper medical management, and early referral when indicated.
Myriah Albrecht, DVM
Nimet Browne, DVM, MS, DACVIM (LAIM)
Abstract
Colic remains one of the most common and potentially life-threatening conditions of the horse; favorable outcomes require prompt recognition, accurate diagnosis, and timely intervention. Colic is associated with a plethora of etiologies, and distinguishing between gastrointestinal and extragastrointestinal origins is essential. Gastrointestinal causes of colic include impactions, gas accumulation, displacement, inflammation, and parasitism. History-taking, physical examination, and diagnostic evaluation should follow a methodical approach, and diagnostics may include transrectal palpation, nasogastric intubation, abdominal ultrasonography, blood work, and abdominocentesis. In addition, recognizing when referral is indicated improves long-term outcomes. Advancements in technology, such as wearable biosensors and camera monitoring systems for early detection and monitoring of colic, can be especially useful during unsupervised hours and have led to improved outcomes.
Take-Home Points
Colic is a general term used to describe abdominal pain and is among the most frequently encountered medical issues of horses.
Appropriately diagnosing etiologies requires a thorough history, systematic approach to physical examination and diagnostic workup, and recognition of the common causes of colic.
Many cases of colic can be resolved by a combination of treatments (e.g., oral and/or intravenous fluids, enteral laxatives, pain management, antispasmodic medications, temporary feed restriction).
Successful outcomes depend on timely recognition of colic, proper medical management, and early referral when indicated.
Any condition causing abdominal pain in the horse is referred to as colic, which remains among the most common medical conditions affecting equids. Because of the prevalence of colic and its complexity and potential for severe complications or even death, prompt recognition, appropriate treatment, and early referral when necessary (TABLE 1) are key to successful outcomes.
Causes of colic can broadly be classified as gastrointestinal or extragastrointestinal. The equine digestive tract is extremely complex and can be affected by a wide range of issues.
Common gastrointestinal causes can be separated by location (e.g., gastric, small intestine, large intestine) and include impactions, gas or tympany (e.g., obstruction), displacements or torsions, inflammation (e.g., diarrhea, colitis), and parasitism.
Extragastrointestinal causes of colic may involve reproductive tract disorders (e.g., uterine or testicular torsion, ovarian disorders such as large granulosa theca cell tumors, ovarian cysts, estrus during routine heat cycles), urinary tract conditions (e.g., stones, infection, bladder rupture, urethral obstruction), liver or splenic conditions (e.g., organ failure, enlargement, rupture, abscessation, neoplasia, infarction), and peritoneal or abdominal wall issues (e.g., neoplasia, peritonitis, adhesions, hernia, trauma).
Signs of musculoskeletal disorders such as laminitis or rhabdomyolysis (tying-up) may resemble signs of colic and are commonly misclassified due to overlapping clinical signs such as restlessness, sweating, and reluctance to move.
Colic Workup History
In working up a routine colic case, obtaining a thorough history from the owner or caretaker is critical and should be completed first. A detailed history can help distinguish the severity of the pain as well as the duration and progression of the colic episode. Information that can provide context for the physical examination and diagnostic findings as well as identifying the specific cause of colic includes any predisposing factors (e.g., diet changes, recent deworming, administration of medications such as NSAIDs), previous or current health issues, recurrent colic episodes, activity level or routine exercise practices and discipline, recent transport or stressful event, and changes in manure output or consistency.
Physical Examination
After a detailed history is obtained, a physical examination should then be performed efficiently and systematically. All physical examinations should begin with simply observing the horse and its surroundings. Note the horse’s attitude, behavior, and posture to identify any signs of discomfort or agitation (e.g., up-and-down behavior, inability to stand quietly [depending on the horse’s natural behavior], pawing, flank watching, flehmen response, sweating, muscle fasciculations or tremors, abrasions on distal extremities or bony prominences along the face or body, abnormal abdominal contour, fecal staining along the rear or tail). In addition, the surrounding environment and housing area should be examined for things such as disruption of bedding secondary to rolling or thrashing, manure output and consistency, uneaten feed, and quality of feed or hay.
For the hands-on portion of the physical examination, clinicians should develop their own systematic process and ensure that all components are addressed during each examination. Interpretation of vital parameters can indicate severity of the colic episode as well as potential for systemic compromise.
Auscultation of the heart and lungs, aside from just obtaining heart and respiratory rates, is a crucial part of the colic workup and is often overlooked when the focus is on the abdomen. Auscultation of these areas can provide vital information about both extragastrointestinal causes of colic and overall systemic status. Abdominal auscultation should include assessment of borborygmi as absent, hypomotile, normal, or hypermotile, as well as any pinging sounds.
Every physical examination of a horse should include obtaining rectal temperature, regardless of the nature of the visit (i.e., healthy/preventive or sick). In addition, asking the client whether temperatures are routinely taken on the farm can be useful for identifying any trends or differentiating between possible infectious or systemic disease.
Bounding digital pulses, weight shifting, or reluctance to lift feet or walk when asked may suggest laminitis, and these signs in addition to stiff or sore muscles may indicate rhabdomyolysis, both of which are frequently confused for episodes of colic.
Differentiating Between Gastrointestinal and Extragastrointestinal Cause
Differentiating between gastrointestinal and extragastrointestinal causes of colic may require further diagnostics. Although each case is unique and may necessitate alternative diagnostics, a routine colic diagnostic workup may include transrectal palpation, nasogastric intubation, ultrasonography, blood work, and abdominocentesis. Although all of these diagnostics together will provide a comprehensive evaluation of the horse, the ability to perform them depends on patient compliance, case presentation, availability of supplies, financial considerations, and clinician preference.
Transrectal Palpation
Transrectal palpation can often yield a diagnosis and is also useful for determining the degree of bowel distention, although inadequate restraint or lack of amenability of the horse can preclude the ability to perform.1 In addition, the diagnostic usefulness of transrectal palpation is limited to evaluation of the caudal one-third of the abdomen; therefore, more cranial abnormalities may be missed.
Nasogastric Intubation
Nasogastric intubation can be both diagnostic and therapeutic, depending on the underlying cause. Assessment of the amount, consistency, contents, and odor of the reflux may be useful. Abnormal findings include > 2 L of reflux for an average-sized adult horse, foul- or fetid-smelling reflux, excessive feed quantity or volume of gas, hemorrhagic reflux, or overall difficulty with advancing the nasogastric tube. Portable meters for measuring L-lactate and serum amyloid A have also become more accessible and can provide beneficial information during a colic examination and be used to help determine if referral is needed.
Ultrasonography
Abdominal ultrasonography is less invasive and can yield a plethora of information. Ultrasonography equipment is becoming more accessible in ambulatory settings, although inadequate user comfort and experience may deter clinician use. During ultrasonography, examining the abdomen as well as the caudal thoracic area may aid in identifying conditions such as pleuropneumonia, diaphragmatic hernias, or other thoracic pathologies that may mimic or complicate abdominal disorders.
Abdominocentesis
Abdominocentesis is a sensitive way to evaluate pathology in the abdomen because the composition of peritoneal fluid changes rapidly in response to pathophysiologic changes.1 Fluid samples can be collected with a needle, teat cannula, or bitch catheter, and collection is performed in a standard manner with few associated complications. Evaluation of peritoneal fluid (FIGURE 2) can also be useful for deciding whether to refer the case.
Causes of Colic
Given the large size of horses as well as the limitations of diagnostic modalities available, a definitive diagnosis may or may not be reached. However, understanding the common causes of colic and their pathophysiology are essential for guiding a focused and efficient workup and implementing appropriate treatment plans.
Recognizing causes that are most likely given the horse’s scenario will help tailor clinical evaluation, improve efficiency during evaluation, improve communication with clients, and guide therapies or timely referral. The most frequently encountered causes of colic are impaction colic, gas colic, and displacements.
Impaction Colic
Risk for development of an impaction is increased for horses that consume coarse hay or low-quality forage or have poor dentition, reduced exercise or activity levels, and/or abrupt changes in water availability or intake.
Impactions can occur in all parts of the gastrointestinal tract. Gastric impactions are rare and account for < 5% of causes of colic in horses.2 Small intestine impactions are more commonly associated with ingestion of coastal Bermuda grass hay, accumulation of dead ascarid worms after deworming therapy, or inflammatory bowel disease. The most frequently encountered location for impaction is the large colon, which accounts for the main cause of colic in horses.2 The most common location for large colon impactions is the pelvic flexure due to its anatomic design, which includes a hairpin turn as well as decreased lumen size. Impactions can also occur in the small colon, although similar to gastric impactions, they are less likely. Small intestine impactions may be appreciated during abdominal ultrasonography, and a history of diet or recent deworming may be useful to support the diagnosis.
Diagnosis of gastric impactions requires endoscopy, although suspicion can follow nasogastric intubation, depending on the quantity and content of the reflux obtained. Transrectal palpations are often useful for diagnosing large and small colon impactions, although depending on the location, the impaction may not be within physical reach of the clinician. A history of reduced water intake, reduced manure output, or manure consistency that is dry or mucus-covered can be supportive.
Medical Management
Medical management of gastrointestinal impaction varies based on the site of the obstruction but focuses on relieving the impaction, controlling pain, and maintaining hydration. Gastric impactions are managed with repeated gastric decompression and lavage via nasogastric intubation, along with careful monitoring for rupture. Small intestinal impactions often require fluid therapy; anti-inflammatories; and, in some cases, gastric decompression, though surgical intervention is more common if the obstruction does not resolve. Large colon impactions are typically treated with enteral and intravenous fluids as well as laxatives. Small colon impactions may require enteral and intravenous fluids, laxatives, enemas, and careful monitoring for endotoxemia or salmonellosis. Across all sites, supportive care, analgesics, and close monitoring are essential. Referral for surgical management may be necessary.
Gas Colic
Gas colic, or tympany, is excessive gas accumulation and often results from dietary changes or grain overload. The excessive gas accumulation distends the gastrointestinal tract (FIGURE 3), leading to secondary pain. Fermentation in horses takes place in the hindgut, where an abundant microbial population breaks down carbohydrates and other components for energy. During the fermentation process, gas is produced and can accumulate if production is excessive or expelling is impeded. Common causes of increased production include rapid transition in feeding regimens or diets that are high in nonstructural carbohydrate content. Causes for inability to expel gas can include a physical obstruction that blocks the exit of gas or decreased motility from stress, illness, reduced exercise or physical movement, and/or pain.
Medical Management
Sufficient medical management may include antispasmodic therapies to relax the smooth muscles of the gastrointestinal tract, thereby reducing spasms and pain; exercise to improve gastrointestinal motility; analgesics; and feed restriction. However, additional therapies such as enteral fluids, intravenous fluids, and enteral laxatives may also be useful. Although gas colic is usually mild and responds well to medical management, if left unmanaged it can lead to more serious conditions.
Displacement
If severe enough, excessive gas buildup can lead to displacement or twisting of the gastrointestinal tract. Because some segments of the gastrointestinal tract are not attached to the body wall, a segment of the gastrointestinal tract may be physically moved from its natural location. Displacement occurs when a segment moves out of its normal anatomic position but does not twist, which in the horse typically involves the large colon and can result in left dorsal displacement of the large colon (also known as nephrosplenic entrapment) (FIGURE 4) or right dorsal displacement of the large colon (FIGURE 5). With left dorsal displacement, the left dorsal and ventral colon migrate dorsally and become trapped between the spleen and the left kidney within the nephrosplenic space. In right dorsal displacement, the left dorsal and ventral colon migrate across the abdomen toward the right side over or around the cecum.3 Diagnosis of large colon displacements are commonly appreciated during transrectal palpation, although abdominal ultrasonography can be useful as well.
Medical Management
For large colon displacements, medical management is often successful, although surgical correction and decompression may be necessary.
Phenylephrine, an α1 adrenergic receptor agonist, can be used to facilitate splenic contraction and correction of left dorsal displacement of the large colon.3 However, several adverse effects of this medication have been reported (e.g., hemorrhage, bradycardia, hypertension, arrhythmias) and may deter its use.3,4
Another mode of medical management that can cause splenic contraction and is a safer alternative is exercise. Rolling techniques while the patient is under general anesthesia have also been described. If desired, exercise and rolling techniques can be performed concurrently with phenylephrine administration.3
If surgical intervention is necessary, the approaches are laparoscopy and ventral midline celiotomy. Additional supportive therapies (e.g., enteral and/or intravenous fluids, enteral laxatives, analgesics, antispasmodic agents, feed restriction) are often beneficial.
Treatment for right dorsal displacements is similar, although administration of phenylephrine would not be indicated. Transabdominal or transrectal trocharization of the cecum or large colon have also been performed as adjunctive therapies for a low-cost method when surgical intervention is not feasible.2 If large colon displacement progresses, volvulus or twisting of the large colon can result in the need for immediate surgical intervention.
Inflammation
Inflammation or infection of the small intestine is known as enteritis; of the large intestine, colitis; and of both, enterocolitis.5 Most cases of enterocolitis are infectious, although some may be inflammatory, and either can contribute to signs of colic.
For infectious etiology, bacterial, viral, and parasitic causes can all be implicated. For infectious cases, many of the pathogens involved pose zoonotic risk and warrant appropriate biosecurity measures. Relying on a thorough history from the owner or caretaker in addition to watching for any signs of loose manure can be useful. In such cases, abdominal ultrasonography can help identify thickening of the small and/or large intestinal wall. In addition, fluid content within the lumen may also be noted. If appreciated, fecal diagnostic testing is suggested to appropriately implement therapy as well as guide herd-health recommendations and biosecurity protocols.
Medical Management
Medical management may include antimicrobial therapies, although therapy should be based on clinical appearance and fecal pathogen testing as use of antimicrobials is not indicated for every patient. Blood work including a CBC and chemistry profile can be useful for systemically evaluating the horse and guiding therapies. In addition, depending on the degree of fluid loss, fluids may be given enterally to account for such loss, although intravenous fluid administration is often needed depending on the circumstance or patient response. Enterocolitis cases may need to be referred due to the intensity of medical management required and the need for appropriate isolation facilities.
Parasitism
Control of gastrointestinal parasitism has become increasingly more difficult over time due to the development of anthelmintic resistance. Parasite control strategies have been poorly understood and inappropriately implemented, resulting in overtreatment and emergence of resistant parasites.
The most prevalent group of gastrointestinal parasites affecting horses are cyathostomins,7 nematodes that can infect all horses of all ages and do not elicit development of immunity in response to infection. Clinical signs can be absent or can result in colic signs, diarrhea, weight loss, or death secondary to acute larval cyathostominosis (mass synchronous excystment of larvae, resulting in generalized typhlocolitis).6,7
Large strongyles, most commonly Strongylus vulgaris, have largely been eliminated from clinical detection secondary to anthelmintic treatment, although cases have been intermittently reported and can lead to thromboembolism and peritonitis.
Anoplocephala perfoliata tapeworms can also lead to colic signs due to their predilection for the ileocecal region, resulting in mucosal erosions at the site of attachment, intussusceptions, or impactions.
Parascaris equorum roundworms more commonly affect younger horses (typically less than 6 to 8 months of age unless immunocompromised); in contrast to cyathostomins, they do elicit an immune response to mitigate future infections and can also lead to more severe clinical signs when worm burden is high.7 Colic episodes associated with roundworm infections most commonly occur in heavily parasitized foals that have been given a dewormer and resulted in a large worm die-off with secondary accumulation and impaction of dead worms within the intestinal lumen.8
Medical Management
Anthelmintic strategies should be tailored specifically to each farm based on population, pathogen burden, and fecal diagnostics. According to numerous studies, fecal egg counts for identifying parasite burden can be misleading. However, to avoid contribution to resistance and to estimate resistance within a particular population, a fecal egg count should be performed at least 1 to 2 times per year, before anthelmintic treatment, to stratify horses into low-, medium-, or high-shedder categories to reduce pasture contamination. To assess therapy effectiveness, a fecal egg count reduction test should be performed 10 to 14 days after anthelmintic treatment.
Principal strategies for management should focus on eliminating pasture contamination to prevent the parasite from completing its life cycle within the host. The daily infective dose for grazing horses is increased by high stocking density, overgrazed pastures, presence of horses with high fecal egg counts, presence of younger horses, spreading manure on pastures, and warm damp weather.9
Surgical Management of Colic
Although most clients and clinicians prefer to medically manage colic episodes, surgical intervention may be warranted for some cases. Early referral for surgical intervention decreases postoperative morbidity and mortality as well as reduces cumulative cost for hospitalization.1 One of the biggest hurdles encountered when deciding whether to pursue colic surgery is the financial cost for the surgical procedure and in-hospital postoperative management as well as the costs associated with loss of use, stall rest, and at-home management.10 In a recent retrospective study evaluating long-term outcome after colic surgery, it was noted that 72.1% of horses that were athletically active before surgery continued their athletic activity after surgery. In addition, the decision to proceed for colic surgery was rated at 4/5 for overall satisfaction by the owners polled in the study.10 Although prognosis and survival vary according to the severity and underlying cause of the colic episode, many horses recover fully and return to their previous level of activity and lifestyle. Prompt diagnosis and appropriate referral are critical for improving outcome for patients with lesions requiring surgical correction.
Colic Detection Technology
To improve prompt recognition of colic, technology progression with the use of live-stream cameras and wearable devices that monitor vital parameters and activity have been useful. Such devices are especially valuable for monitoring overnight or during times without direct supervision when early signs of colic might otherwise go unnoticed for a prolonged time. As technology and our understanding of equine veterinary medicine advance, so too will the ability to improve therapies and outcomes for horses affected by colic.
Summary
Colic is associated with multiple causes, which are either gastrointestinal or extragastrointestinal. Diagnosis involves history-taking; physical examination; and any combination of transrectal palpation, nasogastric intubation, abdominal ultrasonography, blood work, and abdominocentesis. Successful outcomes depend on timely recognition, proper medical management, and early referral when indicated.
References
- Cook VL, Hassel DM. Evaluation of the colic in horses: decision for referral. Vet Clin North Am Equine Pract. 2014;30(2):383-398, viii. doi:10.1016/j.cveq.2014.04.001
- Barton MH, Hallowell GD. Current topics in medical colic. Vet Clin North Am Equine Pract. 2023;39(2):229-248. doi:10.1016/j.cveq.2023.03.008
- Albanese V, Caldwell FJ. Left dorsal displacement of the large colon in the horse. Equine Vet Educ. 2014;26(2):107-111. https://doi.org/10.1111/eve.12119
- Hardy J, Bednarski RM, Biller DS. Effect of phenylephrine on hemodynamics and splenic dimensions in horses. Am J Vet Res. 1994;55(11):1570-1578. https://doi.org/10.2460/ajvr.1994.55.11.1570
- Uzal FA, Arroyo LG, Navarro MA, Gomez DE, Asín J, Henderson E. Bacterial and viral enterocolitis in horses: a review. J Vet Diagn Invest. 2022;34(3):354-375. doi:10.1177/10406387211057469
- Internal parasite control guidelines. American Association of Equine Practitioners. May 31, 2024. Accessed June 15, 2025. https://aaep.org/resource/internal-parasite-control-guidelines
- von Samson-Himmelstjerna G. Anthelmintic resistance in equine parasites – detection, potential clinical relevance and implications for control. Vet Parasitol. 2012;185(1):2-8. doi:10.1016/j.vetpar.2011.10.010
- Nielsen MK. Evidence-based considerations for control of Parascaris spp. infections in horses. Equine Vet Educ. 2016;28(4):224-231. https://doi.org/10.1111/eve.12536
- Proudman C, Matthews J. Control of intestinal parasites in horses. In Practice. 2000;22(2):90-97. https://doi.org/10.1136/inpract.22.2.90
- Matthews LB, Sanz M, Sellon DC. Long-term outcome after colic surgery: retrospective study of 106 horses in the USA (2014-2021). Front Vet Sci. 2023;10:1235198. doi:10.3389/fvets.2023.1235198
https://todaysveterinarypractice.com/equine-medicine/common-causes-of-colic-in-horses/