Abdominal Enlargement - Are There Any Tests That Will Help?

Abdominal enlargement is not an unusual occurrence. It can be due to a simple increase in intra abdominal fat due to weight gain but this is only one cause. There are many others. For example, redistribution of fat into the abdominal cavity may occur with Cushings disease (hyperadrenocorticism). This is not uncommon in dogs but is rare in cats as is hypothyroidism which can also result in abdominal enlargement in dogs. In the female, pregnancy should not be overlooked as a possible cause of abdominal enlargement. (See Information Sheet; Pregnancy Testing)

The abdominal enlargement can also be due to fluid accumulation in the abdominal cavity. This can be the result of liver disease, cardiac disease, abdominal tumours and, in cats, feline coronavirus disease (FCoV), causing feline infectious peritonitis (FIP).

Rapid onset abdominal enlargement in both dogs and cats can be the result of internal bleeding or leakage of urine into the abdominal cavity as a result of trauma from a fall or road traffic accident. Acute enlargement can be gas as well and should not be overlooked.

What is involved with diagnosis?

The first step is to take a thorough history and carry out a physical examination together with blood tests, including haematology and serum biochemistry which will give an indication regarding the functioning of the liver and kidneys. 

Urine analysis is also helpful since it gives an evaluation of the physical and chemical properties of the sample and association with the serum biochemistry results often points to the diagnosis.

Will additional tests be necessary?

This depends entirely upon the information obtained from the physical examination and the "general" tests undertaken. For example in the case of hyperadrenocorticism (Cushings disease) we may have to admit the animal for a few hours in order that special blood tests can be carried out. Hypothyroidism may be confirmed by determination of serum thyroxine (T4 tests) again involving blood samples.

If there are organ problems such as liver disease, specific tests such as serum bile acid determination may be required together with radiography, ultrasonography or even biopsies.

Sometimes in the case of abdominal enlargement due to fluid accumulation, tests involving fluid sampling via fine needle aspiration may be necessary. Depending on the results of these tests, biopsies may sometimes have to be obtained which may involve general anaesthesia and a surgical operation, although sometimes this can be avoided by the use of ultrasound guidance techniques.