Hikkui - possible cause and remdies

Spike Cover's picture
Submitted by Spike Cover on Fri, 02/10/2017 - 15:01

By: Spike Cover

February, 2017

Hikkui is the bane of keepers of high-grade Koi.  It seems to be much more prevalent on fish that are over 3 (and usually over 4) years old and it almost always occurs on the red (hi or beni) but has been seen by the author as occurring on white and black of a showa on which the disease was very prevalent and advanced. 

It should be noted that no one knows for sure what causes hikkui.  The best guess, based on the disease symptoms and limited histopathology, is that its cause is viral. 

This view seems to be supported by the fact that most treatments reported to have had some success all involve removal and/or killing the infected tissue (much like the treatments for warts).  Another way to put this is: we treat the symptoms w/o knowing the etiology.

Again, it is widely reported by those who have dealt with it that the best way to rid the infected fish of hikkui is to completely remove the infected tissue.  This can be done by a number of means:

  1. Surgery – physical removal of the infected tissue
  2. Chemical cautery – chemically degrading the infected tissue with chemicals.  Using a cauterizing chemical in conjunction with surgery can help to ensure that any non-obviously infected tissue will be killed (and later sloughed off) if the surgery is less than completely effective in removing all infected tissue.
  3. Freezing – killing the infected tissue with cold causing it to die and slough off. Note: extending the freeze-zone slightly past that of the infected tissue and into non-infected tissue can provide a margin of safety making sure that all infected tissue is frozen and killed.

Surgery is typically done with a sharp blade that can be used to cut the tissue away or, if the tissue presents as a typical soft gelatinous mass, the blade may be used to scrape (non-cutting, i.e., sideways) away the tissue.  Used together with cautery paste, Orahesive and Friar’s balsam, this is the only method that has been tried and proven successful by the author.

Chemical cautery can be performed with caustic chemicals like potassium permanganate paste; silver nitrate sticks (solid silver nitrate on the end of a small stick similar to a Q-tip/cotton bud where the silver nitrate is in place of the cotton – typically used in vet medicine to stop bleeding from dog toenails clipped into the quick) or purpose-made cautery paste.  Note: silver nitrate can result in tattooing if blackened tissue and/or residual silver nitrate is subsequently covered by healing tissue.  Additionally, care should be taken to burn or freeze as little healthy tissue as practical and the fish should be totally sedated during the procedure.

Freezing (cryo-therapy) can be accomplished by using commercially available devices/preparations that dispense sub-freezing, <-50°F, gas or liquid directly onto the infected tissue.  Freezing compounds include:      

  • Super Cold™ (see Figure to right) and other canned preparations;
  • Liquid CO2, high pressure cylinders;
  • Liquid Nitrogen – available only to special customers

It has also been reported (but much more scarcely) that keeping infected fish in pristine water and/or feeding a specific high-grade Koi food has resulted in instances of spontaneous remission.  The feeding “treatment” was tried by the author and found not to work in his pond/situation.

Heat cautery has not been used by the author and is not recommended due to potential scarring and loss of color.  It is best to catch hikkui early and treat it such that the red pigmented skin is disturbed or eroded as little as is practical while still removing the infected tissue.


References:
Groff, J, circa 2004. Personal communications with the author.  Examination of hikkui infected tissue showed spindle-cell tumors which is indicative of a viral infection.
Martin, S, circa 2005. Personal communications with the author.  Examination of hikkui infected tissue showed spindle-cell tumors which is indicative of a viral infection
Okamoto, M, circa 2005.  Personal communication with the author re: spelling of hikkui
Saint-Erne, N, 2007.  Lecture at AKCA convention in Phoenix, AZ, reported that hikkui infected tissue was sent to U. GA where Brand Ritchie, et al found evidence of what appeared to be a herpesvirus infection of the tissue.
Sirri, R et al, 2016. Hikui disease in nine koi carp (Cyprins carpio): first description of a cutaneous perivascular wall tumour. Vet Dermatology; 27: 301-e74


Hikkui infected Doitsu sanke:

Video showing the treatment of the above fish is available at: https://www.youtube.com/watch?v=DZKhgF88YJM
Kohaku with several hikkui lesions on head:

A treatment for Hikkui was developed by Duncan Griffiths and may be found on his website at: http://www.koiquest.co.uk/Hikui.htm

The author treated the sanke pictured below using Duncan’s method.  It took a year to heal, i.e., so that the spot was no longer visibly different from the surrounding tissue.  Before and during treatment pictures are show below:

Note: this case was caught and treated early.  Treatment of advanced cases have not faired nearly so well.

Picture below shows the same fish shortly after being treated by scraping off the hikkui and applying cautery paste, Orahesive powder and (sprayed on) Friar’s balsam:

It should also be noted that, on some occasions, areas touched by the treatment (including the Friar’s balsam) have lost the red color.  It is speculated that this may be due to weak color but that is unsubstantiated.  It is also speculated that if it is due to weak color, then it’s likely that the color would fade or vanish over time anyway.  In any event, a fish with noticeable hikkui is ruined or substantially degraded (from an aesthetic and show point of view) so the fish’s owner may as well try to rid the fish of the problem as the down side is a damaged fish either way.

Potential sources for Treatment Products
note: these were available at the time of this writing (except as noted)

Orahesive Powder
From Laguna Koi: $14.95
http://www.lagunakoi.com/Wounds-and-Abrasions/Orahesive-Powder-p-179.html

Or from Chemist.net (25grams): £3.69
http://www.chemist.net/medicines-ostomy-care/convatec/orahesive-protecti...

Or from Kusuri online (25grams): £9.58
http://kusuri.co.uk/kusuri-products/kusuri-orahesive-sealer-powder/

Friar’s Balsam:
From Walmart:  $13.69
https://www.walmart.com/ip/Herb-Pharm-0619437-Friars-Balsam-Compound-Liq...

Or from Vitacost: $10.49
http://www.vitacost.com/herb-pharm-friars-balsam-compound-1-fl-oz?csrc=G...|pcrid|97670539693|product|090900000002&gclid=Cj0KEQiA_eXEBRDP8fnIlJDXxsIBEiQAAGfyod8fv6xQmKjiZtaWnGuDdc0T-iMDVcBeMMoSrdmlhVQaAnHe8P8HAQ 

Cauterizer (Paste)
From Lincolnshire Fish Health (Paula Reynolds in UK): £5.50
Home page: http://www.lincsfishhealth.co.uk/
Note: This product is no longer available from this source and no suitable substitute has been currently identified

Cauterizer (sticks)
From Ebay (10 sticks): $10.59
http://www.ebay.com/itm/like/162201475912?lpid=82&chn=ps&ul_noapp=true

From Mountainside Medical: $26.99
https://www.mountainside-medical.com/products/grafco-silver-nitrate-appl...

Super Cold™
From Amazon: $15.95
https://smile.amazon.com/gp/product/B005DNQXI2/ref=oh_aui_detailpage_o00...


References:
Griffiths, D. Website: http://www.koiquest.co.uk/ (2-7-17)
Groff, J, circa 2004. Personal communications with the author.  Examination of hikkui infected tissue showed spindle-cell tumors which is indicative of a viral infection.
Martin, S, circa 2005. Personal communications with the author.  Examination of hikkui infected tissue showed spindle-cell tumors which is indicative of a viral infection
Okamoto, M, circa 2005.  Personal communication with the author re: spelling of hikkui
Saint-Erne, N, 2007.  Lecture at AKCA convention in Phoenix, AZ, reported that hikkui infected tissue was sent to U. GA where Brand Ritchie, et al found evidence of what appeared to be a herpesvirus infection of the tumors
Sirri, R et al 2016. Hikui disease in nine koi carp (Cyprins carpio): first description of a cutaneous perivascular wall tumour. Vet Dermatology; 27: 301-e74

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Note:  Hikkui is a Japanese word that reportedly roughly translates to, “red eating worm.”  It has been spelled several ways including hikkui, hikui and hi-kui.  The following is from an email from Masaki Okamoto (native Japanese speaker) “…HIKUI, HI-Kui and HIKKUI are just ways to make pronunciation easier, they all refer to exactly the same thing”

 


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