Синдром эпизодического падения у кавалеров

Синдром Эпизодического Падения (далее EFS) у кавалер кинг чарльз спаниелей
 Описание симптомов

Обзор

 В то время как этот набор симптомов может показаться сложным, один ветеринар сказал, что EFS выглядит «не похожим ни на что другое».
 EFS — это нарушения, связанные с гипертонусом, вызванным физической нагрузкой, подразумевающим увеличение мышечного тонуса и неспособность мышечного расслабления, эпизоды будут в ответ на возбуждение, физические упражнения, или разочарование, за исключением тяжелых случаев — когда симптомы могут быть хроническими, или происходить без видимой причины.
EFS состоит из множества признаков и его не так легко описать. У каждой собаки будет свое собственное проявление  приступа. Частота, тип и/или серьезность эпизодов могут увеличиваться, уменьшаться или изменяться с возрастом. Таким образом, нет никакого единого шаблона прогрессирования EFS.
Если у кавалера был один эпизод, даже умеренный, возможно предположить, что собака больна и, в таком случае она имеет прямые показания для проведения ДНК-теста.
По продолжительности приступы EFS бывают от сиюминутных до очень продолжительных в зависимости от самой собаки и степени выраженности стрессов, вызывающих приступ. В редких случаях собаки были не в состоянии выйти из приступа. Правильный диагноз важен, что бы помочь облегчить симптомы, если это возможно. Обычно первичные симптомы возникают в возрасте пяти месяцев и старше, но так же могут возникать и в более раннем возрасте (в любом).  EFS равнозначно проявляется в любом окрасе и у представителей обоих полов.
Ваша собака может быть обследована ветеринаром на другие заболевания. Некоторые симптомы могут быть похожими на Сирингомиелию, эпилепсию, портокавальный шунт печени и некоторые другие заболевания. Однако, если существует подозрение на EFS, то для постановки точного диагноза менее дорогостоящий вариант, по сравнению с неврологическим, или любым другим обследованием, является (на сегодняшний день) ДНК-тестирование. Достоверно не известно, связан ли «синдром ловли мух» с EFS, но он может наблюдаться у кавалеров больных EFS.
Описание Симптомов
Во время приступов собака находится в сознании и иногда способна реагировать на внешние раздражители. Жизненные функции сохранены.
Во время приступа может наблюдаться один симптом, или любая комбинация из нижеперечисленных симптомов:
·         Замирание на мгновение
·         Замирание или ходьба с головой находящейся в положении вниз и набок
·         Скованность задних конечностей
·         Явное отсутствие координации в передних и задних конечностях
·         Заячья прыгающая походка
·         Выгнутая (горбатая) спина с судорогами задних конечностей (может быть признаком травмы спины)
·         Временная потеря контроля над задними конечностями
·         Попытка подняться приводящая к падению
·         Катания или кувыркания
·         Собака лежит на одном боку, задние конечности втянуты, передние и задние лапы могут подергиваться
·         Очевидный (видимый) спазм
·         Слюнотечение
·         Ретракция (отведение конечности по отношению к туловищу) передних конечностей, иногда над головой
·         Напряжение мышц вокруг рта с невозможностью открыть пасть
·         Ощущения выпирания глаз из-за напряжения мышц лицевого черепа
·         «поза охотника на оленя» когда передние конечности сжаты, а задние одеревенели
·         В крайних случаях может присутствовать хроническая повышенная тактильная чувствительность и скованность
EFS, по-видимому, не влияет (и не затрагивает) на темперамент.
В любом случае, если вы считаете что у вашей собаки был приступ EFS, либо она перенесла продолжительный приступ, или тяжелые частые приступы, немедленно обратитесь к ветеринарному врачу.
 

Подготовка материала для форума — Ломохова Елена («Брайтлайт Оф Москоу»)

Episodic Falling Syndrome (Muscle Hypertonicity):
Cavaliers Collapse Suddenly After Exercise

https://cavalierhealth.org/episodic_falling.htm

Episodic falling syndrome (EFS) is a unique genetic disorder in the cavalier King Charles spaniel. It has been recognized in the breed since the 1960s. No other breed is known to suffer from it.

EFS is a non-progressive disorder that tends to improve with therapy, and the life spans of affected dogs do not appear to be shortened by the disease.

Veterinarians may refer to it as hyperexplexia or muscle hypertonicity (and medically known as «paroxysmal exercise-induced dystonia or dyskinesia»). However, recent research (November 2010, July 2011, and January 2012) has established that EFS is not a muscular condition, but is due to a single recessive gene associated with brain function, a mutation of the BCAN gene. As a result, affected puppies are more likely to be found in cases of line breeding or inbreeding on carrier bloodlines.

Until 2010, EFS appeared to be a life-long condition of the cavaliers affected by it. However, research that year found that milder cases of EFS are more of a common condition in the CKCS, which tend to stabilize by age one year. EFS rarely is life-threatening. A July 2011 UK/US study found that, «carriers are extremely common (12.9%).» In a May 2012 report of DNA testing of 2,811 cavaliers, only 3.7% were affected with EFS, but another 21.52% were carriers of the EFS gene, which is nearly double the percentage predicted in the July 2011 study.

In a June 2012 report of DNA testing of 280 cavaliers, the UK’s Animal Health Trust researchers estimate that 19.1% of CKCSs are carriers of EFS, 35% of wholecolors (rubies and black-and-tans) are carriers, 0.3% of particolors (Blenheims and tri-colors) are affected with EFS, and 5.1% of wholecolors are affected.

Some researchers have suggested that EFS in cavaliers may be associated with another disorder unique to the breed, called «idiopathic asymptomatic thrombocytopenia», an abnormally low number of blood platelets. Drs. Jens Häggström and Clarence Kvart of Sweden have noted in a 1997 article that thromboembolic events in the cerebral circulation of blood may be involved in EFS. See Blood Platelets for more information.

UK’s Animal Health Trust offers a DNA swab test to detect the mutations causing episodic falling syndrome in the CKCS. UK’s LABOKLIN also offers a detection test, as a result of the UK/US July 2011 study.

Symptoms

Symptoms of EFS vary, but they all are attributed to the dog’s muscles being unable to relax. Typical signs include the cavalier engaged in exercise or being excited or stressed, and then suddenly develop a rigid gait in Diane Shelton CKCS Patient Ruby Leethe rear limbs, extending and retracting in an exaggerated, stiff manner, like that of a hopping rabbit. The dog’s back may be arched, and the dog often yelps. One or more limbs may also protract excessively. (See the photo at left of a ruby cavalier in the throes of arched protraction.) The dog may lose its footing while running. It usually loses all coordination and collapses on its side or on its face. When the cavalier collapses, it may hold its forelegs over its head. In some instances, the cavalier’s symptoms follow a “deer-stalking” behavior, with its head held close to the ground and its rear high in the air, as if stalking game. In the most severe cases, the dog may hold its head so low that its hind quarters somersault over its head. The affected cavalier may exhibit these symptoms only when excited or stressed, but in some cases, the behaviors have not been stress-induced. The dog may also overheat during an episode, possibly due to an inability to pant.

Cavaliers with episodic falling on YouTubeSee videoed examples of EFS episodes on YouTube here.

https://www.youtube.com/results?search_query=cava … falling&aq=0&oq=cavalier epis

The cavalier does not lose consciousness during the episodes, and mentally, it remains normal. Technically, the collapse is not a seizure, although it may be appear as one. The CKCS appears to know what is happening to it, and sees clearly, but loses control of its body. Afterwards, in most instances the dog recovers relatively quickly; it stands up and acts as if nothing unusual had occurred. However, if the cavalier exercises again immediately after recovery, it may induce another episode.

Also, some severely affected cavaliers have been known to lapse into repeated, lengthy episodes of the syndrome, and may even suffer permanent neurological injuries and not be able to recover from the attacks. At least a few CKCSs are known to have been euthanized to avoid continued suffering from the disorder.

It is to be distinguished from presyncope, another disorder to which cavalier King Charles spaniels are predisposed, which has some of the same symptoms. Syncope in cavaliers is associated with late stages of mitral valve disease. For more information on syncope and presyncope in CKCSs, see Mitral Valve Disease and Syncope.

Diagnosis

10 month old CKCS in EFS, courtesy, Dr. Boaz LevitinEpisodic falling syndrome is the result of a single recessive gene mutation associated with neurological function. Until 2010, EFS had been believed to be a type of metabolic muscle disorder. The ages of cavaliers studied with EFS have varied from two months to four years. Both male and female CKCSs are affected. (The CKCS at right experiencing EFS is a ten-month-old. Courtesy, Dr. Boaz Levitin.)

The dogs are neurologically normal between episodes. Electromyographic evaluation detects the muscles at rest and engaged in no abnormal spontaneous activity. There is no evidence of heart or respiratory problems during the episode or the collapse. Blood tests, spinal fluid analysis, muscle biopsies, and magnetic resonance imaging (MRI) of the brain have not proved to be helpful in diagnosing the syndrome. Diagnosis, therefore, has been based solely upon the symptoms of the episode.

Since some of the symptoms of EFS are similar to other disorders, such as liver shunt, an epileptic seizure, or syringomyelia, the examining veterinarian may mis-diagnose the episodes and unnecessarily screen the dog for those other maladies. The primary differences between EFS and other disorders are that they usually are induced by exercise, excitement, stress, or apprehension; the EFS-affected dog remains conscious during the episodes; and the dog rarely will experience any continuing pain or discomfort.

Therefore, video recordings of the dog’s EFS episodes are helpful to the veterinarian in diagnosing the disorder. If a video device is not available, the owner should write a precise report of the Cavalier’s behaviors during the episode, to avoid mis-diagnosis, needless testing, and treatment with drugs which may inadvertently aggravate the condition.

In a brief July 2009 article, UK researchers Dr. Richard J Piercy and Gemma Walmsley disclosed that they had identified a genetic form of muscular dystrophy in the cavalier, with symptoms (weakness and exercise intolerance) similar to some of those of EFS. However, these other symptoms of this muscular dystrophy may clearly distinguish it from EFS: muscle atrophy, difficulty swallowing, and an enlarged tongue. Also, the researchers have found that only males are affected by this form of muscular dystrophy, and the females are only carriers of the mutation.

DNA Testing

DNAIn 2011, two UK research groups (see below) independently developed DNA swab tests for detecting a recessive gene associated with brain function, the BCAN gene, which, when mutated, is the cause of episodic falling disorder in the CKCS. EFS is inherited as a autosomal recessive trait. If a DNA-tested cavalier is found to not have the mutated BCAN gene, then it is «clear» of EFS. If the dog is found to have two of the mutated gene, then it is «affected» and has EFS, whether it shows symptoms or not. If the dog is found to have only one of the mutated gene, then it is not affected but is «a carrier».

The knowledge of whether a cavalier is clear, affected, or a carrier of EFS is important to the responsible breeder who wants to avoid passing EFS to future generations in her bloodline of cavaliers. See Breeders’ Responsibilities below for additional information about how to use the results of DNA testing to choose breeding partners.

• Animal Health Trust: The UK’s Animal Health Trust offers a DNA swab test for the gene mutations causing EFS, through the AHT’s online DNA testing webshop. The test was developed by Dr. Jacques Penderis (at the University of Glasgow) and a research team at the Animal Health Trust. The DNA test is available world-wide.

• LABOKLIN: Researchers led by Dr. Robert Harvey of the London School of Pharmacy, Dr. Leigh Anne Clark (Clemson) and Dr. Diane Shelton (Univ. Cal. at San Diego) (email gshelton@ucsd.edu) have identified the underlying genetic defect causing EFS in cavaliers. They found:

«Consistent with the unique clinical observed in affected dogs, we discovered that a homozygous microdeletion affecting BCAN is associated with EFS in CKCS dogs, confirming that this disorder is inherited in an autosomal recessive manner. This mutation was not detected in control DNA samples from 54 other dog breeds, confirming the unique nature of this genomic rearrangement. … Wider testing of a larger population of CKCS dogs without a history of EFS from the USA revealed that carriers are extremely common (12.9%). The development of molecular genetic tests for the EFS microdeletion will allow the implementation of directed breeding programs aimed at minimizing the number of animals with EFS and enable confirmatory diagnosis and pharmacotherapy of affected dogs.»
See report here for details. LABOKLIN’s website for ordering the test kit is here.

•PawPrint Genetics: Paw Print Genetics, a US company located in Spokane, Washington, offers test kits for identifying the genetic defect causing EFS in cavaliers. Pat Print Genetics’ website for ordering the test kit is here.

•VetGen: Veterinary Genetic Services (VetGen), a US company located in Ann Arbor, Michigan, which provides canine genetic disease detection services, offers test kits for identifying the genetic defect causing episodic falling syndrome in cavaliers. VetGen’s website for ordering the test kit is here.

The Animal Health Trust (AHT) reported that, as of May 15, 2012: 2,811 cavaliers had been DNA-tested for episodic falling syndrome, of which 104 (3.7%) were «affected» with two of the mutated EFS gene; 605 (21.52%) were «carriers» with only one of the mutated gene; and the rest, 2,102 (74.78%), were clear of the defective gene.

In a June 2012 report of DNA testing of 280 cavaliers, AHT researchers estimate that 19.1% of CKCSs are carriers of EFS, 35% of wholecolors (rubies and black-and-tans) are carriers, 0.3% of particolors (Blenheims and tri-colors) are affected with EFS, and 5.1% of wholecolors are affected.

Treatment

CavalierHealth.org Copyright © 2004 Blenheim CompanyDuring and after an episode, consider trying to comfort the dog by holding it gently. Do not force the dog’s legs to assume any position. Keep the dog as cool as possible, and allow it to rest as much as it wishes after the episode.

Until recently, no medications appeared to remedy the condition, and there was no known effective treatment. Affected dogs have not been found to respond to anticholinesterases. Phenobarbital (Solfoton), a barbiturate, frequently is prescribed.

Some temporary improvement has been observed following treatment with a benzodiazepine drug called diazepam (Valium). In a study concluded in 2002, a group of affected cavaliers was treated with another benzodiazepine drug, clonazepam (Klonopin, Rivotril), which is a drug used to treat humans for hereditary hyperexplexia or hyperekplexia («startle disease»). Both diazepam and clonazepam enhance GABA neurotransmission. However, clonazepam is more potent than diazepam in equivalent doses, and clonazepam has more anti-convulsant effects. In the 2002 study, with clonazepam treatment (at 0.5 mg/kg tid), the episodes decreased in frequency from between 25 and 30 per week to as few as one every two to three months. After two years of treatment with clonazepam, dogs in the study were described as clinically normal. It has been reported that CKCSs tend to be less responsive to diazepam than other breeds, but that cavaliers can markedly improve with clonazepam.

Dr. Jacques PenderisDr. Jacques Penderis (at right) (formerly a senior research neurologist at the Animal Health Trust in the UK and now at the University of Glasgow) has found that although some cavaliers initially respond well to treatment with clonazepam or diazepam, the dogs tend to develop tolerance to the drugs after a while and the beneficial effect wears off. Dr. Penderis states that the current treatment options for CKCSs with episodic falling syndrome are extremely limited.

In cases that do not respond to clonazepam and where the episodes are not particularly severe or frequent, it may be best to accept the collapse episodes and try to identify and avoid events or stressors that may trigger the episodes. In severe cases, treatment can be tried with acetazolamide (Diamox), which is a carbonic anhydrase inhibitor which has shown some efficacy in autosomal dominant hyperkalemic periodic paralysis. Use of acetazolamide must only be done under careful veterinary supervision, and a number of dogs do not appear to tolerate the drug very well.

For more advice on treatment please contact Dr. Penderis. He may be contacted at Clinical Neurology / Neurosurgery Service, Faculty of Veterinary Medicine, University of Glasgow, Bearsden Road, Glasgow G61 1QH, Tel: +(44) 0141 330 5738 (office), Email: jacques.penderis@glasgow.ac.uk

Vitamin E and tryptophan reportedly may decrease the frequency and severity of episodes. However, tryptophan (tryptophan hydroxylase 1) can increase serotonin levels, and a high level of serotonin is a suspected cause of early-onset mitral valve disease in the CKCS.

Periodic chiropractic treatments may be able to minimize an affected dog’s symptoms of EFS.

Breeders’ Responsibilities

Breeders’ ResponsibilitiesUK’s Animal Health Trust offers a DNA swab test to detect the mutations causing episodic falling syndrome in the CKCS. UK’s LABOKLIN also offers a detection test, as a result of the UK/US July 2011 study. USA’s Paw Print Genetics also offers a detection test. See DNA Testing for more information about these DNA testing programs.

— breeding decisions using DNA results

• If two clear cavaliers are mated, all offspring likewise should be clear of EFS.

• If a clear cavalier is mated to a carrier, the odds are that half of the puppies in the resulting litter will be clear and half will be carriers.

• If two carriers are mated, the odds are that half of the litter will be carriers, a quarter will be affected, and a quarter will be clear.

• If a carrier and an affected are mated, half of the litter should be affected and half should be carriers.

• If two affecteds are mated, all puppies in the litter should be affected.

Obviously, it would be preferable to mate only clear cavaliers to each other. But if a cavalier breeder finds that one of her breeding stock is a carrier, she should mate that dog only to a clear cavalier. Then, once the litter is produced, the breeder should DNA-test the puppies to identify the half that are clear and half that are carriers, and remove the carriers from the breeding program.*

* Read the UK Animal Health Trust’s article on «Should We Breed Carriers?» by Dr. Cathryn Mellersh here.

Two carriers should not be mated to each other, and, of course, no affecteds should be mated at all.

If a breeder DNA-tests her breeding stock for the mutated gene causing EFS and then follows the above breeding protocol, she could eliminate all EFS-carriers from her bloodline within two generations.

As of February 2013, the Cavalier King Charles Spaniel Club, USA recommends that its members/breeders comply with this breeding protocol.

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