Re:air bubbles in the end of tail

#4818
Pete Giwojna
Guest

Dear Paul:

Your male seahorse has developed subcutaneous emphysema of the tail, a form of Gas Bubble Disease (GBD) that is commonly known as external GBD or simply "tail bubbles" by hobbyists for obvious reasons. In cases of subcutaneous emphysema the blisterlike gas bubbles tend to form in the soft tissue of the subcutis at the most distal portion of the tail end can be easily observed with the naked eye. When these are examined microscopically, they are often associated with gas-filled ‘pseudocysts’ lined with endothelial tissue that are suggestive of gas-dilatation of lymphatic vessels. Chronic cases often exhibit fibrosis or a thickening and toughening of the skin around the bubble, and these are the most stubborn cases that are the hardest to cure. But when the condition is detected early, it usually responds very well to treatment with Diamox, as we will discuss later in this e-mail.

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 (i.e., subcutaneous emphysema) 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).

Different parts of the body can thus be affected depending on how the
initial gas emboli or micronuclei form, grow and spread. During an
episode of GBD, bubbles may initially form in the blood
(intravascular) or outside the blood (extravascular). Either way,
once formed, a number of different critical insults are possible.
Intravascular bubbles may stop in closed circulatory vessels and
induce ischemia, blood sludging, edema, chemistry degradations, or
mechanical nerve deformation. Circulating gas emboli may occlude the
arterial flow or leave the circulation to lodge in tissue cites as
extravasular bubbles. Extravascular bubbles may remain locally in
tissue sites, assimilating gas by diffusion from adjacent
supersaturated tissue and growing until a nerve ending is deformed or
circulation in nearby capillaries and vessels is restricted. Or,
extravascular bubbles might enter the arterial or venous flows, at
which point they become intravascular bubbles. Extravascular bubbles
can thus become intravascular bubbles, and vice versa, via diffusion
and perfusion. This is important because it means that under certain
conditions extravascular seed bubbles or micronuclei can enter the
bloodstream and migrate from their birth site to other critical areas
as intravascular bubbles. 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 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, but 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 seahorses, venous bubbles often form at the most distal portion of the tail where the oxygen tension is lowest.

Fortunately, Paul, subcutaneous emphysema, the form of GBS your male seahorse has developed, responds extremely well to treatment with carbonic anhydrase inhibitors. The suggested treatment regimen is as follows:

Acetazolamide Baths

The recommended dosage is 250 mg of Diamox (the tablet form of acetazolamide) per 10 gallons with a 100% water change daily, after which the treatment tank is retreated with acetazolamide at the dosage indicated above (250 mg/10 gal) (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 acetazolamide baths should be administered in a hospital ward or quarantine tank. Acetazolamide does not appear to adversely affect biofiltration or invertebrates, 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 acetazolamide 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.

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.

The seahorse usually show improvement of the tail bubbles 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.

If you prefer, you can also administer the acetazolamide orally, which will allow you to treat the affected seahorse in the main tank amidst familiar surroundings and in the company of its tankmates where it is the most comfortable. You get the acetazolamide into the food by preparing a solution of the medication, as described below, and then injecting it into live feeder shrimp or even the large Piscine Energetics frozen Mysis relicta. The medication is deactivated fairly quickly once you prepare the solution for injecting, so you must prepare a new acetazolamide solution each day during the treatment period. Here’s how to proceed:

Administering Acetazolamide Orally

I have found that acetazolamide is often more effective when it’s ingested and administering the medication orally allows you to treat the seahorse in the main tank where he’s most comfortable and relaxed.

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 acetazolamide 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."

Hawaiian volcano shrimp or red feeder shrimp (Halocaridina rubra) 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 reports 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.

Unfortunately, Paul, obtaining Diamox (the tablet form of acetazolamide) can often be a Catch-22 situation for hobbyists. It is a prescription drug often used for treating glaucoma, hydrocephaly, epilepsy, congestive heart failure, and altitude sickness in humans so you have to get it from your Vet or perhaps your family doctor. Unfortunately, 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 and have Diamox on hand but it can sometimes be difficult to get your MD to jump that final hurdle and prescribe it for a pet. Either way, it can be tough to get the medication you need under these circumstances.

However, I would exhaust those possibilities first before I considered an online source for the Diamox. Print out some of the detailed information that’s been posted regarding GBS and how it’s treated using Diamox and present that to your family veterinarian and/or your family practitioner. Bring photographs of your red seahorse showing the bubbles on its tail and be prepared to bring the seahorse in for a visit, if necessary. (Veterinarians are prohibited by law from prescribing medications to treat an animal they have not personally seen and examined. If you have had a close personal relationship with your vet over a period of years, they are often willing to bend that rule in the case of fish, but you may well have to bring the red seahorse in for a quick checkup to get the desired results.)

If not — if neither your Vet or family physician will prescribe Diamox — then there are places you can order Diamox online without a prescription, but save that for a last resort. (You can’t always be certain of the quality of the medications you receive from such sources; in some cases, you even need to be concerned about counterfeit drugs, although Diamox certainly shouldn’t fall into that category.) The medications will take a week or two to arrive, which is troublesome when your seahorse is ailing and needs help ASAP. And, as you know, customs officials can confiscate such shipments.

If you ultimately need to go that route, Paul, the following source is the one most seahorse keepers have found works best:

Click here: Inhouse Drugstore Diamox – online information
http://www.inhousedrugstore.com/neurological/diamox.html

They offer 100 tablets of Diamox (250 mg) for around $20 US, but they ship from Canada by mail, which usually takes a little under two weeks for delivery.

In your case, Paul, since the gas filled tail bubbles are so extensive that they are causing the seahorse to float upside down, you may also want to consider lancing the bubbles to relieve the positive buoyancy and speed the healing process. There are two schools of thought regarding lancing the tail bubbles, sir. Some of the pros highly recommend it while others maintain that it should never be done For example, in the case of external GBS or subcutaneous emphysema, Tracy Warland recommends that the external blisterlike bubbles be lanced prior to the first of the Diamox baths (Warland, 2002). Other experts feel that tail bubbles should never be lanced and deflated because it can increase the risk of secondary infections developing. I ordinarily recommend lancing the tail bubbles only when they are so large or numerous that they cause buoyancy problems (the tendency to float) for the seahorse and prevent it from eating properly. Struggling against positive buoyancy can aggravate GBD by acidifying the seahorse’s blood, and of course, keeping the seahorse eating properly is very important to help it make a full recovery. Since that is the case with your male, Paul, I feel lancing the tail bubbles is appropriate in your case.

The "Syngnathid Husbandry Manual for Public Aquariums" recommends aspirating the bubbles after anesthetizing the seahorse and then treating with acetazolamide (brand name Diamox): " Under MS-222, discrete gas bubbles or ‘pseudocysts’ are first aspirated with a 27 ga. needle. The carbonic anhydrase inhibitor, acetazolamide, is then administered…"

If you feel that lancing the tail bubbles to accelerate the healing process is warranted in your case and you don’t feel comfortable anesthetizing the seahorse first, then perform the treatments in a hospital tank and administer an antibiotic to safeguard against secondary infections, and proceed as follows:

Use a fine sterile needle for this and approach each bubble from the side at a very shallow angle, taking extreme care to pierce only the surface of the bubble, not the underlying muscle and tissue of the tail (Warland, 2002). Once the bubble surface has been pierced, apply gentle pressure to the bubble to deflate it and release any air or fluid inside.

Remember, Paul, it is now known that you can combine anitibiotic therapy with Diamox treatments with no risk of dangerous drug interactions. It is therefore advisable to administer a good broad-spectrum antibiotic while you are treating the seahorse in your quarantine tank in order to prevent secondary infections, especially if you lance the tail bubbles. I would recommend an aminoglycoside antibiotic such as kanamycin (e.g., kanamycin sulfate, Kanacin, Kanacyn, Kanaplex, etc.) or neomycin sulfate. But triple sulfa is a reasonable alternative if that’s all that you have on hand or can readily obtain. Redose the quarantine tank with the anitibiotic after you make the water change each day.

Best of luck obtaining the medication you need, Paul! Here’s hoping your male seahorse is feeling much better again real soon.

Respectfully,
Pete Giwojna


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