Opinion

Portosystemic shunts and those runty pups

by
September 15, 2016

The blog this week has been written by Dr Kerryn. It’s a bit of a technical one as it relates to a condition where the liver doesn’t work properly. Being one of the (many) causes of small pups (often known as runts) we thought this was worth discussing.

WHAT ARE PORTOSYSTEMIC SHUNTS?

Portosystemic shunts (PSS) are abnormal vessels connecting the blood vessel which carries blood from places such as the stomach and intestines, straight to the rest of the body’s blood supply without the blood being ‘cleaned’ by the liver.

This ‘shunt’ which bypasses the liver will result in a build up of toxins in the body; which often results in the patient having slow growth or no growth at all (we often call these puppies runty shunty puppies).

Because the liver is also deprived of growth factors, there are lots of other issues throughout the body, often sadly leading to death.

If a PSS occurs in a puppy it is most likely congenital (the puppy is born with the problem).

It can be an acquired problem in adult dogs if they develop a liver problem later down the track.

The shunt can either be within the liver (intrahepatic shunt) or outside of the liver (extrahepatic shunt). Which shunt a dog has depends on its breed and size.

HISTORY:

We recently saw a puppy with an intrahepatic shunt.

He was drinking and weeing a lot, not growing properly, underweight and had brain signs.

The brain signs included sleeping 23 out of 24 hours a day.

He was quite lethargic and would become sleepy after eating food.

When he was awake he was quite vocal and would groan like he had a head ache

PHYSICAL EXAM:

When I checked him over, this puppy was very lethargic and just slept on the table for the whole consultation, even when he had blood taken for testing.

This was quite weird as most healthy puppies are very wriggly, especially when having blood collected.

He was quite sensitive to light and didn’t like lifting his head – something we might also see with a puppy which had meningitis (yes, that’s nasty too).

OTHER POSSIBILITIES:

Other things it could be besides a PSS could be: meningitis (caused by infection from bacteria, fungi or a virus), congenital brain issues, toxins, electrolyte imbalances etc

TESTING:

We usually start broader in our diagnostic tests and then narrow in. This way we are less likely to miss other disease processes.

1) Full blood panel to start which often shows low urea, creatinine, glucose, cholesterol, albumin and anaemia with different size red blood cells.

2) Bile acid stimulation test: this involves fasting a patient for 12 hours and then taking blood. Then feeding them a small fatty meal and taking blood two hours later. With puppies with a PSS the bile acids are a lot higher on both samples which gives us a strong indication of PSS.

3) Urine analysis and culture; we often see changes in urine with puppies with PSS

4) Coagulation (blood clotting) test: coagulation factors are made in the liver so it is wise to test that these are within normal limits especially if the patient is a candidate for surgery.

5) Next step is sending them off to a specialist for further diagnostics such as a CT scan or for an ultrasound. On a CT scan it was shown that our patient had an intrahepatic PSS.

Plan

Intrahepatic shunts are a bit harder to correct than extrahepatic shunts. Extrahepatic shunts are easier to access and slowly tie off. Intrahepatic shunts require the patient to be 8months of age for surgery (as this is when their major veins, in particular the caudal vena cava – large vein which goes back to the heart- have done most of their growing). A coil is inserted into the jugular (a large vein in the neck) and fed down to the shunt where the coil is released and causes the shunt to slowly close.

The success rate of surgery for these puppies ranges between: 75- 95% depending on a variety of factors

Cost: $7000-$10,000 including work up

In the mean time before surgery these patients are on the following:

1) Antibiotics: to reduce the neurological signs that are secondary to the shunt

2) Laxatives (eg lactulose): which also reduce the neurological signs that are secondary to the shunt

3) Special liver diet: such as Hill’s L/d which helps put less stress on the liver. Since this diet is lo wer in energy, which is not ideal for growing puppies, cottage cheese is added to increase the energy intake.

4) A month before surgery patients are schedule for a revisit with the specialist and more medications are added such as anti-seizure medication etc. This gives the patient the best possible chance of doing well post surgery.

All in all portosystemic shunts aren’t the end of the world if treated BUT they do require a huge financial and time commitment of the owner to follow the medical treatment and commit to the surgery.

If all of this is possible, then these puppies can go on to live happy lives after surgery.

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