GENETIC TEST NOW AVAILABLE FOR “NAKED FOAL” SYNDROME

Reference: “A nonsense variant in the ST14 gene in Akhal-Teke horses with naked foal syndrome,” G3: Genes| Genomes| Genetics, February 2017

susceptible to laminitis--prednisolone treatment did not increase laminitis incidence. “Within the prednisolone-treated group, horses with PPID or EMS had a higher incidence of laminitis overall but were not found to have a higher incidence during the period of prednisolone administration specifically,” says Jordan. “Hence, our findings suggest that while PPID and EMS are risk factors for laminitis in their own right, we found no evidence that prednisolone

Prednisolone did not increase laminitis incidence among horses with metabolic or endocrine disease.

treatment would further increase the risk.”

Jordan cautions that these findings may not apply to other glucocorticoids. “It’s difficult to say if the outcome would be similar,” she says. “Dexamethasone has a longer duration of action and is more commonly used as an injection or for short-term administration, compared to prednisolone, which is frequently prescribed for longer term use. As with prednisolone, the evidence of a link between dexamethasone administration and laminitis is limited to case reports, and we found no more in-depth studies during our literature search. This is definitely an area where further research is required.”

For now, Jordan says she hopes veterinarians feel more comfortable using prednisolone. “[It] is an extremely useful drug in equine medicine, and I would hope that our study would give veterinarians more confidence in their use of it,” she says. “Personally, I would still use the drug with caution in horses with a history of laminitis. I would also consider testing for endocrine diseases in animals showing clinical signs, particularly in at-risk breeds, and particularly if I was considering using the drug for a longer course of treatment. As with any drug of this nature, it would still be recommended to taper to the lowest effective dose and aim for the shortest duration of treatment achievable to minimize the risk of side effects.”

Reference: “Does oral prednisolone treatment increase the incidence of acute laminitis?” Equine Veterinary Journal, January 2017

Researchers have identified the gene responsible for a rare disease found primarily in Akhal-Teke horses, a breed native to Turkmenistan that is known for its glossy coat.

First described in 1938, “naked foal” syndrome (NFS) causes youngsters to be born nearly hairless. They typically die within weeks or months of birth, though the exact causes of death are still not fully understood.

Previous pedigree analysis revealed NFS to be an autosomal recessive trait, meaning a horse can carry a single copy of the gene without being affected, but when two such horses (called “carriers”) are mated, there is a 25 percent chance that the resulting foal will have the disease.

Seeking to develop a test to identify NFS carriers in the Akhal-Teke population, researchers at institutions across Europe, as well as at the University of California– Davis Veterinary Genetics Laboratory, worked together to analyze the genome of two affected horses, two carriers and 75 unaffected horses of other breeds.

Using the resulting data, the researchers identified a mutated gene on a

chromosome associated with NFS, which enabled them to develop a genetic test. The analysis can show a horse to be free of the mutated gene, a carrier or “affected,” meaning he has inherited both copies of the mutated gene.

Low doses of a common anticoagulant drug may help prevent a lifethreatening neurological complication of equine herpesvirus type 1 (EHV-1) infection.

Typically, EHV-1 causes only mild clinical signs, but in outbreak situations, an estimated 33 percent of infected horses may develop equine herpesvirus myeloencephalopathy (EHM),

By using this test, Akhal-Teke breeders will be able to avoid breeding NFS carriers and reduce the number of affected foals produced. The test is now available through the UC– Davis laboratory. which is characterized by damage of the blood vessels in the brain and spinal cord and ensuing neurological deficits.

Vaccines against EHV-1 infections are available, but they do not fully protect against the neurological form of the disease. “Some data are available on antiviral drugs, but mostly limited to the bioavailability of the compounds or on their effectiveness in cell culture,”

DRUG SHOWS PROMISE IN PREVENTING NEUROLOGICAL COMPLICATION

says Jasmin Walter, DVM, DECAR, of the University of Zurich in Switzerland. “Proper randomized clinical studies are almost impossible to perform under natural outbreak conditions, which makes it hard to obtain scientific evidence for EHM prevention options.” Treatment of EHM is limited to anti-inflammatory medication and supportive care.

Faced with these challenges during an outbreak of EHV-1 at a large breeding facility in southern Germany in the spring of 2009, researchers and clinicians there decided to see whether the drug heparin would prevent EHM.

“The idea of using heparin was brought up early during the outbreak by Kerstin Fey, DVM, DECEIM, an equine internal medicine specialist, and Klaus Osterrieder, DVM, PhD, who specializes on the virology side,” says Walter, who was the veterinarian in charge at the stud at the time.

Heparin is an anticoagulant used to treat diseases associated with abnormal or excessive blood-clotting, such as thrombosis, laminitis or endotoxic shock. “EHM has a thromboischemic pathomechanism---meaning it causes blood to clot---which may be inhibited by anticoagulant drugs like heparin,” explains Walter. Furthermore, in cell culture experiments, heparin and related substances are able to prevent virus entry into cells.

A total of 79 horses were kept in seven different barns at the German farm where the EHV-1 outbreak occurred, and 61 developed at least one clinical sign of infection---most often fever. In the early phase of the outbreak, 30 of the affected horses did not receive heparin, and these horses served as the control group. Thirty-one horses were given heparin as soon as signs of illness appeared.

“I decided to use a very tentative treatment regime with low doses for a short, defined period to avoid possible side effects,” says Walter. “Regular bloodwork in all the

horses was not possible to check for critical conditions like anemia 0 or thrombocytopenia 0 , which can arise under heparin medication.” Treated horses received subcutaneous injections of 25,000 IU of heparin twice daily for three days. Horses with only a fever were given no other treatment; those exhibiting neurological signs received anti-inflammatory drugs, as well as antibiotics when necessary to prevent bladder infection due to paralysis.

When the outbreak ended nearly a month later, the researchers reviewed the records of all the horses and found a distinct trend: Only one of the horses treated with heparin developed EHM, while seven of the horses in the control group came down with neurological disease. The researchers describe these results as “promising” and hope other clinicians try this approach when faced with an EHV-1 outbreak to collect more data.

“To my knowledge no one else has tried this, but I hope our paper will encourage equine clinicians and researchers to work on this topic,” says Walter.

Reference: “Prevention of equine herpesvirus myeloencephalopathy—Is heparin a novel option? A case report,” Tierärztliche Praxis Großtiere, October 2016