PG . 30
HORSE HEALTH NEWS - LIVER FAILURE
Pyrrolizidine alkaloids in plants such as Ragwort , Commonwealth Weed , Tarweed , Heliotrope , Paterson ’ s Curse ( or Salvation Jane ), panicum grasses , and clover ( alsike and red clover ) are most commonly implicated . Toxicity accumulates over the course of a horse ' s lifetime , and the consumption of two to five percent of a horse ' s body weight is required for liver damage . These alkaloids remain toxic in plants and grasses despite drying and may contaminate hay made from an area where the plants carrying the alkaloid occur .
Toxicity occurs in horses of all ages and breeds , but not all horses on a property will develop signs of liver dysfunction — so it is important to monitor horses on the same property as a known case . Clinical signs develop weeks to months following consumption of a sufficient quantity of the toxic plant and are consistent with chronic liver disease .
SIGNS OF LIVER DAMAGE :
Animals with confirmed liver disease can include symptoms such as : depression / lethargy ( 68 %), weight loss ( 50 %), anorexia ( 56 %), colic ( 50 %), photosensitisation – ‘ sunburned ’, crusty , painful skin lesions especially in white areas ( 16 %), diarrhoea , jaundice ( 42 %), blood clotting disorders ( 10 %), dermatitis , coronary band inflammation and neurological signs . About 10 % of healthy horses have slightly yellow whites of the eye and horses that are anorexic for any reason will develop slight jaundice , despite normal liver function . Neurologic abnormalities are typically associated with advanced liver disease , and range from subtle behavioural changes to head pressing and coma . Other signs of liver disease include diarrhoea , swelling along the ventral abdomen , excessive drinking , bilateral laryngeal paralysis ( which will cause difficulty breathing and a ’ roaring ‘ noise ), and red , congested mucous membranes .
Although reports exist of horses surviving , the prognosis is generally poor , especially when clinical signs are apparent . No specific treatment exists , but a horse ' s life may be prolonged by supportive care and nutrition . The best prevention for this disease is to remove all toxic plants from the pasture and ensure hay sources are free from toxic plants .
Clinical signs of liver disease are often vague and nonspecific . Evidence of liver disease is often first identified when animals are blood tested for a reason other than suspected liver disease — such as mild weight loss , malaise / lethargy , mild colic or poor performance . Sub-clinical disease ( when a disease is going on in the body , but it is as yet not severe enough to show signs ) is becoming more common , particularly in horses overgrazing poor quality , environmentally stressed pastures or being fed hay from such pastures .
LIVER FAILURE :
Horses with acute liver failure are more likely to have central nervous system signs such as yawning , blindness , disorientation , loss of body movement control , compulsive wandering , head-pressing , circling , gastric impaction and paralysis of the nerves and muscle in the throat . Horses with chronic liver disease commonly have weight loss and / or photosensitivity .
DIAGNOSIS :
If a horse demonstrates any of the clinical signs of liver disease , it should be evaluated by a veterinarian . In many cases , a cause for liver disease cannot be determined . Diagnosis of suspected liver disease requires all the pieces of the clinical jigsaw to be in place to obtain a clear picture . Veterinarians can perform diagnostic testing – for which history , physical examination , biochemical findings are critical , and ultrasound examination and liver biopsy if needed .
TREATMENT :
Therapy for liver disease is mainly aimed at supporting liver function and may be directed at an underlying cause , if known . Treatment may include intravenous fluids , anti-inflammatories , antibiotics , analgesics , drugs to reduce ammonia production , and diet .
There are numerous causes of the liver dysfunction and disease , but feeding recommendations are consistent for the vast majority of them . The goals should be to meet dietary energy needs , supply a high level of soluble carbohydrates , limit fat and salt and to meet but not exceed protein requirements . Feed multiple small meals with free access to good quality grass hay and / or pasture . If a horse can tolerate the protein ( ammonia in the blood may need to be monitored by a veterinarian ), lucerne can stimulate appetite and facilitate weight gain and is a good source of amino acids .
Regular monitoring by blood tests is important and knowing which plants can cause liver disease assists early diagnosis and improved outcomes .
The good news is that in many cases , regeneration of the liver and restoration of function is possible with careful management and timely veterinarian care .
* https :// brill . com / edcollchap / book / 9789086865239 / BP000004 . xmlhttps :// brill . com / edcollchap / book / 9789086865239 / BP000004 . xml
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