air in the tail?

Dear Sponger:

I am sorry to hear about the problems that your male seahorse has been having with Gas Bubble Syndrome (GBS). It sounds like the soft, air-filled bumps on his tail are subcutaneous emphysema, another form of GBS that is commonly known as "tail bubbles" by hobbyists for obvious reasons.

Gas Bubble Disease (GBD) is believed to be caused by gas emboli forming within the tissue of heavily vascularized portions of the seahorse’s anatomy — the placenta-like brood pouch of males, the eye, the muscular prehensile tail — and it can take several different forms depending on where the bubbles or emboli occur. When it occurs in the brood pouch of the male, chronic pouch emphysema or bloated pouch results, leading to positive buoyancy, which is by far the most common form of GBD. When it occurs in the capillary network behind the eye (choroid rete), Exopthalmus or Popeye results, and the eye(s) can become enormously swollen. When it affects the capillary network of the gas bladder (the rete mirabile), hyperinflation of the swimbladder occurs, resulting in positive buoyancy. When it affects the tail or snout, external gas bubbles form just beneath the skin and look like raised blisters. When intravascular emboli occur deep within the tissue and occlude blood flow, generalized edema results in the affected area. Or extravascular emboli may cause gas to build up within the coelom, often resulting in positive buoyancy and swelling or bloating of the abdominal cavity (internal GBD). If untreated, the gas bubbles worsen and the condition is fatal.

The prehensile tail of the seahorse is often affected when conditions are favorable for the formation of such gas emboli because it has a rich blood supply via the dorsal aorta and caudal vein (hence plenty of carbonic anhydrase to induce the formation of intravascular gas bubbles) and because the tail is the site where seahorses tend to store their limited fat reserves (the extravascular seed nuclei or emboli that trigger GBD form most readily in adipose tissue due to the higher solubility of certain gases in lipids than in aqueous tissues)..Intravascular bubbles are seen in both the arterial and venous circulation, with vastly greater numbers detected in venous flows (venous gas emboli). The far more numerous venous bubbles are believed to first form in lipid tissues draining the veins. Lipid tissue sites possess very few nerve endings, possibly masking critical insults at first, and veins, which are thinner than arteries, appear more susceptible to extravascular gas penetration.

In seahorses, oxygenated blood is delivered to the tail via the dorsal aorta, a major artery running the length of the body below the spine, and CO2-laden water is returned via the caudal vein which runs along the inside of the tail. In your case, Sponge or, venous bubbles appear to have formed at the most distal portion of the tail where the oxygen tension is lowest.

There is an effective treatment for this condition, sir. Subcutaneous emphysema or tail bubbles typically respond very well to treatment with Diamox (the tablet form of acetazolamide), as explained below:

The recommended dosage is 250 mg of Diamox per 10 gallons with a 100% water change daily, after which the treatment tank is retreated with the Diamox at the dosage indicated above (Dr. Martin Belli, pers. com.). Continue these daily treatments and water changes for up to 7-10 days for best results (Dr. Martin Belli, pers. com.).

The Diamox baths should be administered in a hospital ward or quarantine tank. Diamox does not appear to adversely affect biofiltration, but it should not be used in the main tank because it could be harmful to inhibit the enzymatic activity of healthy seahorses.

Using the tablet form of acetazolamide (250 mg), crush the required amount to a very fine powder and dissolve it thoroughly in a cup or two of saltwater. There will usually be a slight residue that will not dissolve in saltwater at the normal alkaline pH (8.0-8.4) of seawater (Warland, 2002). That’s perfectly normal. Just add the solution to your hospital tank, minus the residue, of course, at the recommended dosage:

Place the affected seahorse in the treatment tank as soon as first dose of medication has been added. After 24 hours, perform a 100% water change in the hospital tank using premixed water that you’ve carefully aerated and adjusted to be same temperature, pH and salinity. Add a second dose of newly mixed Diamox at the same dosage and reintroduce the ailing seahorse to the treatment tank. After a further 24 hours, do another 100% water change and repeat the entire procedure until a total of up to 7-10 treatments have been given. About 24 hours after the final dose of acetazolamide has been added to the newly changed saltwater, the medication will have lost its effectiveness and the patient can be returned directly to the main seahorse tank to speed its recovery along.

As with Diamox pouch flushes, one of the side affects of acetazolamide baths is loss of appetite. Try to keep the affected seahorse eating by plying it with its favorite live foods during and after treatment, until it has fully recovered.

There is usually noticed improvement within three days. Dr. Martin Belli reports they nearly 100% success rate when this treatment regimen is followed for 7-10 days, and most cases clear up in less than a week.

Best of luck obtaining the Diamox and resolving your case of subcutaneous emphysema, Sponger.

Respectfully,
Pete Giwojna