Re:Need first aid!

Pete Giwojna

Dear Seagazer:

Thanks for the additional information — it really helps clarify the situation. If your seahorse’s tail is positively buoyant, then it seems pretty clear that this is a problem with Gas Bubble Disease (GBD).

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, and this 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 (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, Seagazer, venous bubbles appear to have have formed in the affected area of your seahorse’s tail and led to the growth and development of extravascular gas bubbles in the adjacent tissue, causing the tail to swell and become buoyant.

The etiology of GBD is still poorly understood, and there are many theories as to what causes the gas emboli or micronuclei in the first place. Nitrogen gas supersaturation of the water, the unique physiology of the male’s brood pouch, inefficient degassing of CO2 in small closed-system-aquaria, low pH in the aquarium resulting in acidosis of the blood, malfunctions of the pseudobranch or the gas gland of the swimbladder, stress-related changes in blood chemistry that affect the oxygen-carrying capacity of hemoglobin, infection with gas-producing bacteria — all have been advanced as mechanisms that could trigger the formation of the gas emboli. Very likely GBD has multiple causes, but most experts now believe it is due to physical conditions in the seahorse tank rather than a pathogen.

In other words, despite its name, GBD is not a disease seahorses contract. Seahorses do not arrive with GBD, but they often develop the condition when kept in a system that exposes them to gas supersaturation, inefficient degassing of carbon dioxide, stress (especially if due to poor water quality and/or low pH), inadequate water circulation, a bacteria-laden substrate or other environmental factors conducive to the formation of gas embolisms. Not too long ago there was really not much a hobbyist could do for seahorses with GBD, but now, for the first time, there is a very promising new cure hobbyists can easily administer.

In all its various forms, Gas Bubble Syndrome is probably the most common affliction among seahorses. Public aquaria, labs, and big institutions that display Syngnathids or work with seahorses are accustomed to dealing with it and have developed several cures for GBD over the years. This includes submerging the affected seahorses at depths great enough to recompress them (> 10 feet) and cause the gas to go back into solution; using hyperbaric chambers to accomplish the same thing (the same treatment used for divers with the bends); surgical removal of the pseudobranch; and injections with carbonic anhydrase inhibitors such as Acetazolamide and Ceftazadine. Note: carbonic anhydrase is simply a zinc-containing enzyme that catalyzes the following reversible reaction, which helps change carbon dioxide into bicarbonate ion, a form of CO2 that is more easily carried in the bloodstream, or vice versa:

CO2 + H2O <—–> H2CO3 <—–> HCO3- + H+
carbon dioxide….carbonic acid…. bicarbonate ion

As long as the body’s normal equilibrium is maintained, all is well, but when imbalances drive this reaction too far in either direction, gas emboli can result. For instance, an excess of CO2 in the system will drive this reaction to the right, resulting in the accumulation of carbonic acid. When the carbonic acid builds up sufficiently, it disrupts the body’s acid-base balance and lowers the pH of the blood, producing acidosis.

The decrease in blood pH reduces the oxygen carrying capacity of certain types of hemoglobin, resulting in the release of oxygen in the blood, which eventually causes gas emboli to form in the most vascular parts of the seahorse’s body. Low pH in the aquarium can also result in acidosis, with the same outcome. And chronic stress or prolonged exertion can also cause a decrease in the blood pH, producing emboli via the same mechanism.

Likewise, imbalances which favor the exchange of bicarbonate for carbonic acid can drive this reaction too far to the left, triggering physiologic processes which liberate C02, again causing gas emboli to form in the most vascular parts of the seahorse’s body which are richest in carbon anhydrase. In either case, inhibiting this enzyme seems to prevent the formation of such gas emboli and allows the body to restore its normal equilibrium.

Unfortunately, none of the methods developed by the professionals for treating GBD are available to the average hobbyist. But it has recently been found that Diamox, the tablet form of Acetazolamide, a potent carbonic anhydrase inhibitor, is nearly as effective as the injections for treating GBD, making it the first practical cure for hobbyists to combat this dread affliction.

The Diamox is used in different ways to treat the different forms of GBD. For instance, Diamox pouch flushes are effective for treating chronic recurring pouch emphysema. On the other hand, a series of Diamox baths works better for treating external GBD (tail bubbles), and Popeye. And administering the Diamox orally is often most effective for treating internal GBD or hyperinflation of the gas bladder.

If if your female is still able to eat while anchored to a hitching post despite his positive buoyancy, Seagazer, you might try administering the Diamox orally via injected shrimp. I have found that the Diamox is often more effective when it’s ingested and administering the medication orally allows you to treat the seahorse in the main tank where she is most comfortable and relaxed. Here are the directions for this method of treatment, if you think it might be feasible in your case:

If you can obtain a small syringe with a fine needle, the acetazolamide solution can simply be injected into feeder shrimp or even frozen Mysis. Mic Payne (Seahorse Sanctuary) used this method of administering Diamox successfully when he had recurring problems with GBD due to maintaining a population of Hippocampus subelongatus in shallow tanks only 16-inches (40 cm) deep:

"Seahorses maintained in this system are susceptible to gas bubble disease. Specimens with bubbles around the eyes or under the epidermis of the tail are readily treated with acetazolamide (Diamox tablets 250 mg). Mix a very small amount of crushed tablet with water and inject it into several glass shrimp that are then frozen. These are then fed to the target animal at the rate of two per day for four days. Bubbles disappear on the second day."

Volcano shrimp or red feeder shrimp from Ocean Rider (iron horse feed) work great for this. If a fine enough needle is used, they will survive a short while after being injected — long enough for their twitching and leg movements to attract the interest of the seahorse and trigger a feeding response.

Leslie Leddo has cured seahorses with tail bubbles and pouch gas using this technique. She found that a 1/2 cc insulin syringe with a 26-gauge needle was ideal for injecting frozen Mysis or live red feeder shrimp. They plump up when injected and ~1/2 cc is about the most of the solution they can hold. There bodies will actually swell slightly as they are slowly injected and excess solution may start to leak out. The 26-gauge needle is fine enough that it does not kill the feeder shrimp outright; they survive long enough for the kicking of their legs and twitching to assure that they will be eaten. So if your Vet or family doctor will prescribe the Diamox for treating your seahorse, ask them also to provide a 1/2 cc insulin syringe with a 26-gauge needle.

If you are using 250-mg tablets, Leslie found that 1/8 of a tablet provides enough Diamox for several days’ worth of injections. In other words, 1/8 of a 250-mg Diamox tablet provides enough of the medication to inject two shrimp daily for about 5 days. So each day, I would take 1/8 of a tablet and shave off approximately 20%-25% of it to make the Diamox solution for that day’s injections. (NOTE: if you are using 125-mg Diamox tablets, adjust your dosage accordingly — that is, start with 1/4 of a tablet and then shave off 20%-25% of it to make the Diamox solution.) Then crush the Diamox you have shaved off and to a very fine powder and dissolve it in a very small quantity of water.

Use the result solution to inject a few of the live feeder shrimp and feed them to the affected seahorse immediately after injecting them. You don’t want the healthy seahorses to ingest the medicated shrimp, so target feed them to your female after the other seahorses have already eaten their fill, or offer them to your female will she is isolated in a critter keeper or fish net breeder trap in your main tank. In that case, leave for in the critter keeper or breeder net only long enough to eat the medicated shrimp and then release her back with her tankmates.

Diamox doesn’t dissolve especially well in water; there’s always a residue of undissolved material left behind. Try to avoid this residue when you draw up the medicated solution in your syringe, the particles can sometimes clog up the fine bore needle when you are trying to inject the shrimp.

Each day you will have to prepare fresh Diamox solution to inject the shrimp for that day’s treatment, so just repeat the steps above each day. If all goes well, she should show improvement rapidly, with 2-3 days. If not, after you have fed her injected shrimp for 3 straight days, give her a break from the Diamox for a few days and try again. (Diamox can suppress the appepitite, so feed her unmedicated/uninjected shrimp for a few days to keep her eating and help restore her appetite.) Then feed her Diamox-injected shrimp again at the rate of 2 per day for a total of 3 more days, but this time increase the dosage of Diamox slightly (shave off a bit more of the tablet each day when you mix the new Diamox solution).

Depending on how severe her problems with positive buoyancy are, you may need to handfeed the medicated shrimp to the seahorse. If you can place it right up to his mouth, or even directly in his jaws, that may trigger his feeding instinct and she’ll slurp it right up. If not — if his positive buoyancy is so severe she cannot perch and feed normally on her own, and she refuses to accept handfeeding — then you have to administer the Diamox in a hospital tank as a series of baths instead. Let me know if that happens Seagazer, and I will send you detailed instructions for administering the Diamox as a bath.

Diamox is a prescription med so you’ll have to get it from your Vet or perhaps your family doctor (it often used to treat glaucoma, altitude sickness and a number of other conditions in humans). Veterinarians are often unfamiliar with Diamox — it’s very much a people med and unless you find a Vet that works with fish regularly, he or she will probably never have heard of gas bubble disease or treating it with carbonic anhydrase inhibitors. Many pet owners are on very good terms with their Vets, who are accustomed to prescribing medications for animals, so it’s often best to approach your Vet first about obtaining Diamox despite the fact they may never have heard of it until you brought it to their attention. Your family doctor, of course, will be familiar with such medications but it can sometimes be difficult to get your MD to jump that final hurdle and prescribe it for a pet.

Go ahead and try your family doctor. If you can get him (or a local Veterinarian) to look at the information on GBD above it should make perfect sense to them and, hopefully, persuade them to prescribe it for you. If not, there are other options we can pursue.

Best of luck obtaining the Diamox and treating your female, Seagazer!

Pete Giwojna

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