Hepatic microvascular dysplasia

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Hepatic microvascular dysplasia (HMD or MVD) or portal atresia is a disorder where mixing of venous blood and arterial blood in the liver occurs at the microscopic level. It occurs most commonly in certain dog breeds such as the Cairn and Yorkshire terriers although any dog breed may be at risk. [1] [2] [3]

Venous blood

Venous blood is deoxygenated blood which travels from the peripheral vessels, through the venous system into the right atrium of the heart. Deoxygenated blood is then pumped by the right ventricle to the lungs via the pulmonary artery which is divided in two branches, left and right to the left and right lungs respectively. Blood is oxygenated in the lungs and returns to the left atrium through the pulmonary veins.

Artery blood vessels that carry blood away from the heart

An artery is a blood vessel that takes blood away from the heart to all parts of the body. Most arteries carry oxygenated blood; the two exceptions are the pulmonary and the umbilical arteries, which carry deoxygenated blood to the organs that oxygenate it. The effective arterial blood volume is that extracellular fluid which fills the arterial system.

Liver vital organ in vertebrates and some other animals

The liver is an organ only found in vertebrates which detoxifies various metabolites, synthesizes proteins and produces biochemicals necessary for digestion. In humans, it is located in the right upper quadrant of the abdomen, below the diaphragm. Its other roles in metabolism include the regulation of glycogen storage, decomposition of red blood cells and the production of hormones.

This disease may also be found in cats.[ citation needed ]

HMD is sometimes misdiagnosed as Portosystemic vascular anomaly (PSVA) or a "Liver Shunt" (portosystemic shunt). HMD can be diagnosed with an MRI, using a tracing dye in the subject's blood, and observing the flow of blood through the subject's liver and surrounding areas (stomach, intestine) for anomalies. It can also be diagnosed using a bile-acid level test; or more accurately, a "fasting-blood ammonia levels" test. Symptoms include stunted growth in the first 6–9 months, vomiting, seizures, and hydro-encephalitic episodes (from ammonia concentrating in the blood).[ citation needed ] HMD is usually treated non-surgically with antibiotics (metronidazole) and stool-softeners (lactulose).[ citation needed ]

A portosystemic shunt or portasystemic shunt (PSS), also known as a liver shunt, is a bypass of the liver by the body's circulatory system. It can be either a congenital or acquired condition.

Metronidazole Antibiotic and antiprotozoal medication

Metronidazole, marketed under the brand name Flagyl among others, is an antibiotic and antiprotozoal medication. It is used either alone or with other antibiotics to treat pelvic inflammatory disease, endocarditis, and bacterial vaginosis. It is effective for dracunculiasis, giardiasis, trichomoniasis, and amebiasis. It is an option for a first episode of mild-to-moderate Clostridium difficile colitis if vancomycin or fidaxomicin is unavailable. Metronidazole is available by mouth, as a cream, and by injection into a vein.

Lactulose chemical compound

Lactulose is a non-absorbable sugar used in the treatment of constipation and hepatic encephalopathy. It is used by mouth for constipation and either by mouth or in the rectum for hepatic encephalopathy. It generally begins working after 8-12 hours, but may take up to 2 days to improve constipation.

Related Research Articles

Hepatology medical specialty

Hepatology is the branch of medicine that incorporates the study of liver, gallbladder, biliary tree, and pancreas as well as management of their disorders. Although traditionally considered a sub-specialty of gastroenterology, rapid expansion has led in some countries to doctors specializing solely on this area, who are called hepatologists.

Shetland Sheepdog Dog breed

The Shetland Sheepdog, often known as the Sheltie, is a breed of herding dog that originated in the Shetland Islands of Scotland. The original name was Shetland Collie, but this caused controversy among the Rough Collie breeders of the time, so the breed's name was formally changed. This hard-working small dog is intelligent, vocal, excitable and willing to please. They are incredibly loyal to their owners to the point where they are often referred to as "shadows" due to their attachment to family. This breed was formally recognized by The Kennel Club (UK) in 1909.

Ascites Abnormal buildup of fluid in the abdomen

Ascites is the abnormal buildup of fluid in the abdomen. Technically, it is more than 25 mL of fluid in the peritoneal cavity. Symptoms may include increased abdominal size, increased weight, abdominal discomfort, and shortness of breath. Complications can include spontaneous bacterial peritonitis.

Shunt (medical) hole or small passage which moves, or allows movement of, fluid from one part of the body to another

In medicine, a shunt is a hole or a small passage which moves, or allows movement of, fluid from one part of the body to another. The term may describe either congenital or acquired shunts; and acquired shunts may be either biological or mechanical.

Yorkshire Terrier Dog breed

The Yorkshire Terrier is a small dog breed of terrier type, developed during the 19th century in Yorkshire, England. Ideally its maximum size is 7 pounds (3.2 kg). A popular companion dog, the Yorkshire Terrier has also been part of the development of other breeds, such as the Silky Terrier. It has a grey, black and tan coat, and the breed's nickname is Yorkie.

Budd–Chiari syndrome Human disease

Budd–Chiari syndrome is a very rare condition, affecting one in a million adults. The condition is caused by occlusion of the hepatic veins that drain the liver. It presents with the classical triad of abdominal pain, ascites, and liver enlargement. The formation of a blood clot within the hepatic veins can lead to Budd–Chiari syndrome. The syndrome can be fulminant, acute, chronic, or asymptomatic. Subacute presentation is the most common form.

Biliary atresia congenital disorder of digestive system investigation of choice of the disease is MRCP

Biliary atresia, also known as extrahepatic ductopenia and progressive obliterative cholangiopathy, is a childhood disease of the liver in which one or more bile ducts are abnormally narrow, blocked, or absent. It can be congenital or acquired. It has an incidence of one in 10,000–15,000 live births in the United States, and a prevalence of one in 16,700 in the British Isles. Biliary atresia is most common in East Asia, with a frequency of one in 5,000.

Portal hypertension hypertension in the hepatic portal system, which are the portal vein and its branches, which drain from most of the intestines to the liver

Portal hypertension is hypertension in the hepatic portal system – made up of the portal vein and its branches, that drain from most of the intestine to the liver. Portal hypertension is defined as a hepatic venous pressure gradient. Cirrhosis is the most common cause of portal hypertension; other, less frequent causes are therefore grouped as non-cirrhotic portal hypertension. When it becomes severe enough to cause symptoms or complications, treatment may be given to decrease portal hypertension itself or to manage its complications.

Tibetan spaniel Dog breed

The Tibetan Spaniel is a breed of assertive, small, intelligent dogs originating in Tibet. This breed is not a spaniel; in the original meaning of the term; its breeding and role differs from other spaniels and spaniels are gun dogs. The spaniel name may have been given due to its resemblance to the bred-down lapdog versions of the hunting spaniels, such as the Cavalier King Charles spaniel.

Hepatic encephalopathy brain disease that is characterized by loss of brain function, the occurrence of confusion, altered level of consciousness, and coma that results when the liver is unable to remove toxins from the blood

Hepatic encephalopathy (HE) is an altered level of consciousness as a result of liver failure. Its onset may be gradual or sudden. Other symptoms may include movement problems, changes in mood, or changes in personality. In the advanced stages it can result in a coma.

HMD may refer to:

Ductus venosus

In the fetus, the ductus venosus shunts a portion of umbilical vein blood flow directly to the inferior vena cava. Thus, it allows oxygenated blood from the placenta to bypass the liver. Compared to the 50% shunting of umbilical blood through the ductus venosus found in animal experiments, the degree of shunting in the human fetus under physiological conditions is considerably less, 30% at 20 weeks, which decreases to 18% at 32 weeks, suggesting a higher priority of the fetal liver than previously realized. In conjunction with the other fetal shunts, the foramen ovale and ductus arteriosus, it plays a critical role in preferentially shunting oxygenated blood to the fetal brain. It is a part of fetal circulation.

Cholestasis Human disease

Cholestasis is a condition where bile cannot flow from the liver to the duodenum. The two basic distinctions are an obstructive type of cholestasis where there is a mechanical blockage in the duct system that can occur from a gallstone or malignancy, and metabolic types of cholestasis which are disturbances in bile formation that can occur because of genetic defects or acquired as a side effect of many medications.

Transjugular intrahepatic portosystemic shunt

Transjugular intrahepatic portosystemic shunt is an artificial channel within the liver that establishes communication between the inflow portal vein and the outflow hepatic vein. It is used to treat portal hypertension which frequently leads to intestinal bleeding, life-threatening esophageal bleeding and the buildup of fluid within the abdomen (ascites).

A right-to-left shunt is a cardiac shunt which allows blood to flow from the right heart to the left heart. This terminology is used both for the abnormal state in humans and for normal physiological shunts in reptiles.

A portacaval shunt is a treatment for portal hypertension. A connection is made between the portal vein, which supplies 75% of the liver's blood, and the inferior vena cava, the vein that drains blood from the lower two-thirds of the body. The most common causes of liver disease resulting in portal hypertension are Budd–Chiari Syndrome or Cirrhosis. Budd–Chiari should not be mistaken for Cirrhosis.

Cirrhosis Chronic disease of the liver, characterized by fibrosis

Cirrhosis, also known as liver cirrhosis or hepatic cirrhosis, is a condition in which the liver does not function properly due to long-term damage. This damage is characterized by the replacement of normal liver tissue by scar tissue. Typically, the disease develops slowly over months or years. Early on, there are often no symptoms. As the disease worsens, a person may become tired, weak, itchy, have swelling in the lower legs, develop yellow skin, bruise easily, have fluid build up in the abdomen, or develop spider-like blood vessels on the skin. The fluid build-up in the abdomen may become spontaneously infected. Other serious complications include hepatic encephalopathy, bleeding from dilated veins in the esophagus or dilated stomach veins, and liver cancer. Hepatic encephalopathy results in confusion and may lead to unconsciousness.

Anorectal varices are the dilation of collateral submucosal vessels due to backflow in the veins of the rectum. Typically this occurs due to portal hypertension which shunts venous blood from the portal system through the portosystemic anastomosis present at this site into the systemic venous system. This can also occur in the esophagus, causing esophageal varices, and at the level of the umbilicus, causing caput medusae. Between 44% and 78% of patients with portal hypertension get anorectal varices.

Head pressing is a veterinary condition characterized by standing close to a wall or corner face-first without moving. This condition is seen in pets such as dogs and cats, and also other animals such as cows, horses, and goats. Head pressing is usually a sign of a neurological disorder, especially of the forebrain, or of toxicity due to liver damage, such as portosystemic shunt and hepatic encephalopathy.

References

  1. "Liver Disease in Dogs" . Retrieved 2007-10-17.
  2. "When the Liver Isn't Getting Enough Blood". Archived from the original on 2002-05-01. Retrieved 2007-10-17.
  3. "HEPATIC MICROVASCULAR DYSPLASIA OR PORTAL ATRESIA". Archived from the original on 2007-10-24. Retrieved 2007-10-17.