HOLD THE STARCHY FOOD DURING ULCER TREATMENT
When starting a horse on medication for gastric ulcers, it’s important to reduce his starch intake at the same time. Those are the findings of a new study from Denmark.
Although a low-starch diet can be beneficial to horses with gastric ulcers, it’s not always part of treatment plans, says Nanna Luthersson, DVM, of the Hestedoktoren clinic in Kirke Eskilstrup. “Unfortunately, many veterinarians do not want to comment on nutrition. This could be based on lack of knowledge or very strong tradition of feeding practices, which is usually the case with Thoroughbred racehorses,” she says. “So I quite often come across horses with a diagnosis of ESGD (equine squamous gastric disease), diagnosed and treated from other clinics, without any adjustments of their diet.”
For their study, the researchers used 58 horses diagnosed as having gastric ulcers with endoscopy. First the horses were divided into two groups based on the severity of their gastric lesions: 24 horses were classified as having moderate ulcers, with lesions
graded a 1 or 2 out of 4, while 34 were determined to have severe ulceration, with lesions graded 3 or 4 out of 4. Within each group, the horses were matched into pairs based on similar management, workload, diet and feeding times.
At the start of the study period, the horses in the severe ulcer group were started on omeprazole, a medication that reduces acid production in the stomach, while those in the moderate group did not receive medication. In both groups, one horse in each matched pair was put on a low-starch feed, with the total ration divided among three meals per day instead of two.
After four weeks, the omeprazole treatment was stopped, but the assigned diets were continued and the researchers re-examined the horses with an endoscope and again graded their lesions. Six weeks later (10 weeks after the start of the study) the researchers once again examined the horses with an endoscope and graded any visible lesions.
The researchers found that all the horses with severe ulcers showed significant reductions in lesion severity between the start of the study and the four-week endoscopic exam, but only those receiving
the starch-restricted ration sustained those improvements through the 10-week endoscopic exam. Horses whose diets did not change returned to their original lesion scores by week 10, deriving no long-term benefit from the medication.
These findings underscore the importance of reducing a horse’s starch intake when he begins receiving medication to treat ulcers, says Luthersson. “Horses with ESGD should receive medication treatment according to their veterinarian but have their diets adjusted, with a maximum starch level of less than one gram of starch per kilogram of body weight per day and a maximum of .3 grams of starch per kilogram of body weight per meal.”
She adds that the role of diet in treating horses with gastric ulcers is both important and tricky. “I have often seen a significant improvement of ESGD just with diet change. But if the ulcers are more severe the diet change alone is not enough,” Luthersson says. “Also, diet change requires that a horse have a normal appetite. Often ulcers cause reduced appetite, and a diet change will not be beneficial if the horse will not eat.”
NEW GENETIC TEST FOR UVEITIS RISK
Testing for two specific genetic markers can help identify Appaloosa horses most likely to develop uveitis, according to new research from the University of California, Davis.
All Appaloosa coat patterning, including the leopard pattern, blanket pattern and varnish roan, are produced by the leopard complex spotting gene, referred to as LP. However, to have a specific leopard spotted coat pattern--body-wide, dark, circular, pigmented spots on a white background---a horse needs to have one copy of the LP mutation and have an additional genetic modifier known as PATN1. Previously, research into eye disorders in Appaloosas linked LP to equine recurrent uveitis (ERU), a chronic inflammatory condition that can eventually lead to blindness.
“Based on previous work, we determined that Appaloosas homozygous for the LP allele [meaning
they inherit two copies of the gene] are about five to six times more likely to develop ERU than those who are not,” says Rebecca Renee Bellone, PhD. “In our current study, we modeled disease risk based on several parameters and calculated the probability of having disease if we included both LP and PATN1 genotypes in the model. Using 98 animals, we found
that the mean probability of getting disease if a horse is homozygous for LP and PATN1 is 90 percent, while the mean probability of disease risk for horses that do not have either LP or PATN1 is 1 percent.”
The research does not establish a causal relationship between LP or PATN1 and uveitis, but simply shows that horses with those alleles are at higher risk for disease, explains Bellone. “Work is ongoing to determine if LP is the causal risk variant or is tagging the causal risk variant,” she says. “In other words, we are still trying to determine if LP is the cause or just being inherited on the same strand of DNA as the cause.”
The current research, however, is sufficient to allow identification through genetic testing of Appaloosas at increased risk of developing uveitis, a proactive step Bellone encourages so owners can be on alert for the disease.
“It is recommended that those horses who genotype homozygous for LP (LP/
LP) be examined more frequently by a veterinary ophthalmologist for earlier diagnosis and intervention,” she says. “Insidious uveitis, the subclinical manifestation typically seen in Appaloosas, often does not present as outwardly painful episodes and may go unnoticed until there is extensive damage.”
Bellone adds that “trained eyes can sometimes tell the genotype for LP by looking at a horse, but we recommend testing for LP to understand which horses are at highest risk so that they can be carefully monitored by clinicians for signs of ERU or disease progression.”
Finally, Bellone says that despite these findings, she does not advocate testing for these markers to make breeding decisions. “We are not recommending breeding away from LP,” she says. “However, careful considerations should be made concerning producing horses homozygous for LP, as these horses are also night blind and other management considerations are needed for these animals.”
Reference: “Genetic investigation of equine recurrent uveitis in Appaloosa horses,” Animal Genetics, December 2019
Research does not establish a causal relationship between the genetic markers and uveitis but simply shows that horses who carry them are at higher risk for the disease.