Re:GAS BUBBLE IN POUCH

Dear Cherie:

You’re very welcome! Congratulations on performing a successful needle aspiration and restoring your male to normal again. It’s great to hear that he is swimming and eating like his old self once more. You did a fine job!

Keep a close eye on him for the next several days, though, Cherie. Problems with positive buoyancy and pouch gas sometimes tend to recur as more gas is secreted into the marsupium by various mechanisms. If the same problem comes back again, you may need to treat the seahorse for recurring pouch emphysema (PE) rather than simply evacuating the gas that builds up within his pouch. The treatment protocol I recommend in such cases is as follows:

First Treatment: Manually Evacuating Gas from the Pouch

At the first sign of a bloated pouch accompanied by any indications of positive buoyancy, the pouch should be "burped" or the trapped gas should be evacuated using a fine catheter or a needle and syringe. That will provide the affected seahorse with immediate relief, and if this simple first-aid measure resolves the issue, all is well and good.

In that case, the problem was no doubt due to simple pouch bloat, a harmless sort of gas build up that is entirely unrelated to chronic pouch emphysema. Pouch bloat can be caused by gas produced by the decay of embryonic material and the remains of placental tissue or other organic matter (possibly even stillborn young) within the brood pouch, if the male is unable to flush it out and cleanse it properly by pumping water in and out during its pouch displays (Cozzi-Schmarr, per. com.). And in some isolated cases, it’s possible that a bacterial infection of the pouch may also be involved (Cozzi-Schmarr, 2003). But it is far more common for pouch bloat to result from air bubbles trapped in the pouch during courtship displays, especially if the male chooses to display in the bubble stream produced by an airstone or bubble wand or bubble curtain (Strawn, 1954).

However, hobbyists should be aware that even a case of simple pouch bloat can contribute to recurring pouch emphysema, a much more serious problem, if it is not handled properly. The simple act of of struggling against the positive buoyancy that results from pouch bloat can alter the seahorse’s blood chemistry, and result in full-blown PE via acidosis of the blood if the problem is not relieved promptly.

The first indication of pouch bloat (or pouch emphysema) is a loss of equilibrium. The seahorse’s center of gravity shifts as the gas accumulates in its pouch, and it will have increasing difficulty swimming and maintaining its normal posture, especially if it encounters any current. It will become apparent that the seahorse has to work hard to stay submerged, as it is forced to abandon its usual upright swimming posture and swim with its body tilted forward or even horizontally in order to use its dorsal fin to counteract the tendency to rise.

The uncharacteristically hard work it must do while swimming means the hard-pressed seahorse builds up an oxygen debt in its muscles, and the lactic acid that builds up as a result of anaerobic metabolism further disrupts its blood chemistry and worsens the situation. It will struggle mightily in a losing battle against its increasing buoyancy until finally it can no longer swim at all, bobbing helplessly at the surface like a cork whenever it releases its grip on its hitching post. At this point, its pouch will be obviously swollen and bloated.

It is imperative that the gas be evacuated and neutral buoyancy restored long before that happens in order to assure that the affected seahorse is subjected to the least possible stress and does not have to overexert itself for an extended period. The longer it must fight against positive buoyancy, the greater the chances its blood will be acidified in the process and the more likely it becomes that a case of basic pouch bloat can progress into recurring pouch emphysema.

Breeding males are often especially susceptible to chronic pouch emphysema and GBS in general because of the placenta-like changes that occur in the lining of the pouch during pregnancy. Spongelike, its tissues expand as the capillaries and blood vessels swell and multiply. A film of tissue then forms around each embedded egg, providing it with a separate compartment (alveolus) of its own. The thickening of the wall of the marsupium and elaboration of pouch structures around the implanted eggs result in a dramatic increase in vascularization, and this increased blood supply (hence increased concentration of carbonic anhydrase) transports more dissolved gases to the pouch, increasing the risk of GBS accordingly.

Ideally, the air should be evacuated from the male’s pouch at the first sign of positive buoyancy. If this simple procedure does not cure the problem, then it is appropriate to move on to stronger measures once the problem recurs, as described below.

Second Treatment: Flushing the Pouch combined with administering Acetazolmide orally.

In my experience, acetazolmide (brand name Diamox) is much more effective in treating PE when it is ingested rather than administered as a pouch flush or a series of baths. Therefore, if pouch gas recurs a second time, I recommend treating it more aggressively with antibiotic/antifungal pouch washes while feeding the affected seahorse Diamox-injected shrimp (or Diamox bioencapsulated in live shrimp, depending on how badly handicapped the buoyant male happens to be when it comes to feeding).

The pouch flush solution I prefer is a combination of nifurpirinol and neomycin sulfate, since that combo works together synergistically to forms a wide spectrum antibiotic with potent antifungal as well as antibacterial properties (Basleer, 2000). Nifurpirinol (Furanase) and neomycin sulfate (Neosulfex) are the active ingredients in two different commercial products designed for aquarium use, and both of them used to be readily available at your local fish store. Neosulfex has since been discontinued, I believe, but neomycin sulfate is still found in many aquarium medications and is also available online from the National Fish Pharmacy.

Because it is so difficult to distinguish chronic pouch emphysema (PE) from ordinary pouch bloat, which has virtually identical symptoms, many seahorse keepers delay treatment too long when their prize ponies are experiencing buoyancy problems. They will often continue to evacuate the air from the pouch repeatedly in the forlorn hope that their stallion has not developed a life-threatening form of GBS but merely trapped a little air during his pouch displays. Very often this is wishful thinking, which only delays the inevitable and subjects the seahorse to ongoing stress needlessly, while making successful treatment more difficult by increasing the risk that gas emboli will form elsewhere and cause more damage in the meantime. In many cases, all you accomplish by waiting and hoping for the best is to allow the PE to become more advanced, more entrenched, and more severe in the interim.

To avoid this sort of needless delay, I suggest flushing the pouch thoroughly with antibiotics at the first sign of pouch gas and positive buoyancy should your initial attempt to evacuate the air fail to cure the problem (Garrick-Maidment, pers. com.). The affected seahorse must be handled in order to "burp" its pouch or evacuate the air via pouch massage anyway, so I recommend administering an antibiotic pouch wash at the same time.

Not only is repeatedly evacuating the air from the male’s pouch counterproductive in most cases, the constant manipulation can be hard on the tissue of the pouch, aggravating the dermal layers of the marsupium and leaving them vulnerable to secondary infections. (The male marsupium is far more complex than most hobbyists realize, consisting of four separate layers of epithelial and connective tissue, with the innermost layers being heavily vascularized.) [That’s one advantage that needle aspiration staff, Cherie — they are easier on the seahorse on its delicate pouch been massaging or burping the pouch is.]

The skin or integument of the pouch is of course its first line of defense against disease. It contains mucus glands, and the slime covering the skin acts as a barrier to ectoparasites and infection. The protective slime may even contain antibodies and antibacterial substances (Evans, 1998). Marine fish are always in danger of dehydration because the seawater they live in is saltier than their blood and internal body fluids (Kollman, 1998). As a result, they are constantly losing water by diffusion through their gills and the surface of their skin, as well as in their urine (Kollman, 1998). The mucus layer also acts as a barrier against this, waterproofing the skin and reducing the amount of water that can diffuse through its surface (Kollman, 1998).

Repeatedly burping or massaging the pouch removes this protective barrier, and the shearing pressures that are involved may aggravate the underlying tissue, resulting in secondary infections of the outer marsupium that can further complicate the picture.

Progressing directly to flushing the pouch plus oral Diamox after the first pouch evacuation helps minimize these repeated insults to the delicate marsupium.

Third Treatment:

If all goes well, as it usually does when the proper measures are performed in a timely fashion, a third round of treatments is normally not necessary. In fact, some experts report a 100% cure rate for pouch emphysema when such pouch flushes are properly administered during the early stages of the condition (Garrick-Maidment, per. com.).

However, if the pouch flushes and an oral Diamox should fail to resolve the problem, the recompression-decompression cure would be your next recourse. Paul Groves found pressurization to be an effective cure for pouch emphysema, as well as the other forms of GBS, while he was conducting his extensive series of trials with gas bubble syndrome.

And if they happen to have the necessary equipment already on hand, some hobbyists prefer to treat PE with recompression-decompression as their second form of treatment, skipping over the Diamox and pouch flushes altogether. I have not tried the latter personally, however.

So that’s the rundown on pouch gas and pouch emphysema, Cherie. That is the progression of treatments I normally recommend for this problem. You did a great job with the first step — using a needle aspiration to evacuate the gas from your male’s pouch. In your case, I would suggest that you obtain the necessary apparatus and medications to perform a pouch flush and keep them on hand in case that should become necessary. It’s always best to be prepared…

In the meantime, I am a little concerned about the thinness of your seahorses. Can you please tell me what you have been feeding them and how often? Are you providing them with a staple diet of frozen Mysis, Cherie? If so, what brand of Mysis are you using? Do you enrich the frozen Mysis and, if so, what enrichment product do you use to fortify their food? If you can provide me with a little more information about your present feeding regimen, perhaps I can offer some suggestions that may help you to fatten them up a bit.

Best of luck with your children, Cherie!

Happy Trails!
Pete Giwojna