Anomalie Hépatique vasculaire

Hepatic vascular hereditary malformations in Westies, Scotties, Dandies, and Cairn terriers

Extrahepatic Portosystemic Shunt and Primary Portal Hypoplasia Without Hypertension are the two most common congenital hepatic disorders in these breeds.

Both diseases can coexist in the same dog.
According to Dr Center, both malformations share the same genetic origin.

Primary portal hypoplasia without hypertension may be 15 to 30 times more frequent than extrahepatic shunt in predisposed breeds, but is usually less serious and remains often undiagnosed.

SYMPTOMS

They usually appear in the first two years of life (severe cases appear earlier, sometimes at weaning, but mild cases can remain asymptomatic throughout the dog's life).
Up to 10-20% of dogs affected by a liver shunt are asymptomatic.

Symptoms are those with hepatic insufficiency, since the badly irrigated liver cannot fulfill its role in detoxifying the blood, or in producing proteins.

- Growth retardation, underweight
- Capricious appetite
- Gastrointestinal symptoms (diarrhea, vomiting)
- Behavioral and neurological symptoms (related to hepatic encephalopathy and hypoglycemia, fatigue, prostration and alternating agitation, aggression, vocalization, seizures, tremors, coma)
- Increased drinking and urine
- Urinary symptoms related to urinary stones (kidney and bladder)

Females are slightly more often affected because the porto-azygos shunt (one particular type of extrahepatic shunt) affects twice as many females than males.

Differences between the two anomalies:

The shunt is a blood vessel that bypasses the liver, which produces liver failure. Its gravity is proportional to the size and position of the vessel (the porto-cava shunts are more frequent and severe as the porto-azygos shunts)

Primary portal hypoplasia without hypertension affects portal vessels that supply the different liver lobes and produces more or less marked effects, depends on the hepatic lobes touched, leading to liver failure whose gravity is proportional to the number of affected lobes.
This is a primary decrease in blood flow through the portal vein, without atresia nor hypertension.

Hepatic vascularisation

Normal hepatic vessels Extra-hepatic Shunt ( porto-caval )

NORMAL PORTAL VEINS HYPOPLASTIC PORTAL VEINS

DIAGNOSTIC :

- Laboratory diagnosis of liver failure:

Determination of serum FASTING BILE ACID and POSTPRANDIAL (2:00 after a meal containing fat)

. Bile acids after 12 hours fasting are normally below 10 umol / l
This value is sometimes normal after prolonged fasting.
It is often normal for portal hypoplasia, and higher for shunts.

. Postprandial bile acids are normally below 30 umol / l
This value is always increased with hepatic vascular diseases

- Definitive diagnosis of a liver shunt extravascular:

-Ultrasound Fasting (first-line exam)
-IRM, Scintigraphy, portography, or Angio-Scan that has become the test of choice, able to confirm a shunt and locate it if ultrasound does not.

- Definitive diagnosis of primary portal hypoplasia:

It needs to eliminate the hypothesis of a shunt first,
then biopsies on several hepatic lobes (at least 3).

Clinical and biological differences between the two congenital vascular defects

The symptoms of liver shunt are generally more pronounced than those of primary portal hypoplasia

The modified biological analyzes are in favor of a liver shunt:

- Microcytosis (erythrocytes)

- Low levels of serum urea, creatinine and cholesterol

- Moderate hypoproteinemia and hypoalbuminemia

- Hypoglycemia (fickle)

- Low level of serum protein C, often less than 70%
(the lower the C protein is, the severest is the shunt)

TREATMENT

- Medical treatment of liver failure syndrome (Antibiotics, lactulose, enemas, antiemetics, dietary measures) and possible urinary complications (in case of urinary stones)

This treatment is sufficient in many cases, especially in mild symptomatic cases.

- Surgical treatment

It is conceivable in cases with obvious symptoms

. Ligature of the extrahepatic shunt.
According to the Dutch club's Cairn, 85% of liver shunt dogs were operated on at the University of Utrecht at the age of 3-4 months and successfully, at an approximate cost 1000 €.

. Lepatic lobectomy during portal hypoplasia.
This surgery is much more delicate and rarely implemented because the dogs affected with primary portal hypoplasia without hypertension can usually be managed medically.

DIETARY MEASURES

Protein should be limited but high quality. The best protein sources in this case are dairy products and soy. Red meat, fish and giblets should be avoided.
Probiotics are recommended (some yogurts)
Special dietary foods for liver insufficiency exist and are indicated.

GENETIC :

Dr. Center conducts research at Cornell University (USA) to identify the genetic causes for these two diseases.
She concluded that a possible polygenic inheritance and maybe the involvement of an autosomal dominant gene with incomplete penetrance and variable expressivity.

In Europe, it is in Nederland that Pr. Van Steenbeek and his team are conducting similar research on extrahepatic shunt. He concluded with polygenic inheritance and the likely involvement of two different genes.
Blood samples of the affected puppies are welcome at Utrecht University

PUPPIES SCREENING :

It is essential to test the puppies having a weight delays or other symptoms.
A simple determination of postprandial bile acids is sufficient according to Dr Center.

The rate is generally :

greater than 70 umol/l in the case of shunt

and less than 70 umol/l in the case of primary portal hypoplasia.

A rate higher than 100 signs almost certainly a shunt.

It should be done in all young West/Cairn/Scott in the first year (the earliest possible) in order:

- To remove from the reproduction affected dogs.
In practice this means that young whose bile acids rates are abnormal should be removed from the reproduction, even if it has no associated symptoms.

- To quickly know the hepatic status of individuals. It is important not to be in the situation later in their lives, to have to differentiate between a liver disease present at birth to an acquired liver disease, which would require multiple invasive and expensive examinations.

In practice, breeders can screen puppies from 6-8 weeks (when the puppy eats solid food) before they leave to ensure to the new owner/buyer of the puppy that he is free of any vascular congenital hepatic anomaly.

For the test to be valid and incontestable, the puppy should be perfectly dewormed and identified beforehand, he should not suffer from another disease at the time of sampling.

The test is cheap (16 euros per sample in France) and fast (results the day of reception of the sample). It allows the breeder to protect inexpensively from a sale of a puppy at risk of developing an inherited disease in his youth.

The bile acids test is part of the 8 basic health checks recommended by the Cairn Terrier Club of America before any reproduction.

The RALIE (French breed club for Irish Wolfhound and Deerhound) and liver shunt
(RALIE website excerpt)

"Since 1 January 2009, the club has set up a program for breeders who agree to follow the "Health + Standard" protocol recommended by the club.
These breeders will have their litters published in the "Litters A" part of the website.

4 points are required in this program:
1-Genetic identification of breeding animals;
2- Official Screening of DilatedCardioMyopathy before the mating (with result clear);
3-Screening puppies for portosystemic shunt they live the breeder;
4. etc. "

Extract from the Nederland Cairn Terrier Club (website)

"Conclusions :

For a large number of years, the Netherlands’ Cairn Terrier Club has pursued an intensive policy with respect to the assessment of liver shunt and to reduce the percentage of shunt sufferers in the breed. An increasing percentage of puppies is being tested. Meanwhile, 90% of the breeders, who are members of the NCTC, have their puppies tested. From 1991, more than 6000 puppies have been tested. The percentage of puppies diagnosed with a shunt has decreased from 3% until below 1% at the moment. Despite all measures taken and all attention paid to the problem, every now and then a puppy is born with a shunt, although from the combination of parent animals no higher risk could be expected. Ultimately, the results of the DNA research at Utrecht University will enable to guide breeding programmes further. In conclusion, we can put that the problem of liver shunt in Cairn Terrier breeding has been handled energetically. Much has been achieved in a limited number of years thanks to the major cooperation from breeders, the policy of the breed club, and the outstanding cooperation between Utrecht University and the Netherlands’ Cairn Terrier Club. In future, we need to be vigilant. Finalisation of the DNA research into shunts in Cairn Terriers should be the next important step forward."

Details of the screenings from 1990 to 2012:

From 1990 to 1993 the affected cairn puppies were 2.48%,

From 1994 to 2001 they were 0.96%.

Now the Cairn terrier puppies affected by a congenital liver shunt are less than 0.5% among the tested litters.

year	puppies tested	puppies no tested	shunts
2001	580	65	4
2002	604	87	1
2003	596	92	2
2004	Not published
2005	563	74	1
2006	454	49	1
2007	428	28	5
2008	386	38	1
2009	341	8	3
2010	360	7	0
2011	325	5	1
2012	393	0	3

Bibliography:

Dr Van Steenbeek and coll /Université d’Utrecht, ND (Distribution of extrahepatic congenital portosystemic shunt morphology in predisposed breeds)

Dr Shanon Center /Cornell University Ithaca, New York, USA (article du Merck veterinary Manual = Portosystemic Vascular Malformations in Small Animals)

Dr Avril Hamel Jolette and Dr Lyanne Fifle/centre vétérinaire DMV de Montréal Canada (Anomalies vasculaires hépatiques congénitales)

Dr Karen M. Tobias/ University of Tennessee, Knoxville,USA (Understanding common liver disorders in Yorkshire Terriers & other toy breeds (2013))