Kryptokisme

[Amazing Ferret]

Jeg tænkte på om der er nogen som har nogle "holdbare" facts om kryptokisme hos ildere.....

Jeg har nu læst jeg ved ikke hvor mange forskellige meninger om det, men som regel er de ikke bygget på ilder, men hund og kat

[Julie]

aner ikke rigtig noget om det, men ved at min fritz var kryptokid inden jeg fik ham..

[tzari]

Kikkede rundt i fænomenet og sætter lige de rting ved forskelige arter der kommer frem:

mennesker http://www.dr.dk/DR1/laegen/Programmer/2005/050929/20051130102510.htm

Risiko for testikelkræft?

Drenge, som mangler sten i pungen, har øget risiko for at udvikle testikelkræft.

Risikoen er især forhøjet, hvis stenene sidder i bughulen.

En tidlig operation nedsætter sandsynligvis risikoen for senere udvikling af testikelkræft.

Så ved mennesker er det vigtigt at få det bragt i orden hurtigst muligt pga testikel kræft riisko.

Hvad skyldes kryptorkisme?

Testiklerne dannes i bughulen, og herfra bevæger de sig normalt ned i pungen inden fødslen. 

Denne bevægelse styres bl.a. af hormoner.

Man ved ikke med sikkerhed, hvad kryptorkisme skyldes.

Det kan skyldes en nedsat hormonproduktion, eller det kan være arveligt betinget.

I nogle tilfælde kan det skyldes, at moderen er storryger under graviditeten.

Ved mennesker er det altså enten arveligt(men nedarvning er ikke skrevet) eller homonelle problemer

http://www.dr.dk/DR1/laegen/Programmer/2005/050929/Spørgsmål/20051111114038.htm

Vedrørende arvelighed af kryptorkisme må man regne med at din kommende søn
vil have 8 – 10% risiko for også at få kryptorkisme.

Dette tyder på mig til at være polygenetisk eller ressisiv når det kun er 8-10 % efter en der har defekten.

Heste
http://www.netdyredoktor.dk/sw9573.asp

Hvad kan du gøre for at nedbringe risikoen for, at din hest får kryptorkisme / klaphingst?
Da kryptorkisme skyldes arv, bør der ikke avles på hverken hopper eller hingste, som har fået afkom med erkendt kryptorkisme.

Dette indikere for mig at folk mener det er ressisivt eller polygenetisk ved heste eller ville man kunne fraskrive en af forældrene (f.eks hannen med begge kugler på plads eller hoppen der har lavet en rask hingst)

Hunde
http://www.netdyredoktor.dk/sw7421.asp

Hvad er fremtiden for din hund, hvis den er kryptorkid?
Hvis du lader din kryptorkide hund kastrere, har den på lang sigt ikke andre gener end andre kastrerede hunde, f.eks. overvægt og pelsforandringer.

Hvis du lader være med at kastrere din kryptorkide hund, er der risiko for:

Testikelkræft. Risikoen er op til 13 gange så høj for en testikel i bughulen, som for en  normalt placeret testikel.
Det væv, en testikel i bughulen sidder fast i, kan sno sig, så blodforsyningen bliver afsnørret. Det giver voldsomme smerter og kræver en akut operation.

Der er ulemper forbundet med at købe en hund, som er kryptorkid:

Udgift til kastration
Hunden bør ikke bruges i avlen

Hos hunde har de altså også risiko for testikel kræft og andre ubehagligheder hvis de ikke hurttigt kastreres.

I de allerfleste tilfælde er årsagen til kryptorkisme arvelig. Lidelsen kan dog godt dukke op med generationers mellemrum

Det tyder igen på ressisv og polygenetisk. Lyder så mest polygenetisk når det springer generationer over.

I nogle få tilfælde er årsagen til, at testiklen ikke kan komme på plads i pungen, ikke en medfødt tendens. En hvalp, der bliver bidt, kan godt danne noget arvæv i og omkring lyskekanalen, der forhindrer testiklen i at komme på plads.

Hvad er risikoen for at din hund er kryptorkid?
1-10% af alle hanhunde er kryptorkide. Risikoen er størst for de små racer.

Hvilke racer er særligt udsatte for at være kryptorkide?
Chihuahua, puddel, pomeranier, schnauzer, shetlandsk sheepdog, terrier.

Anden viden om kryptorkisme:
Det er hyppigst kun den ene testikel, der ikke falder på plads.

Mange opdrættere tror, at de kan massere en testikel på plads, men det er ikke muligt, hvis hunden  virkelig er kryptorkid. Nogle hvalpe kan have en kraftig refleks i en muskel, der kan trække testiklerne op mod lyskekanalen. De kan derfor se kryptorkide ud uden at være det, og i disse tilfælde vil massagen få musklen til at slappe af, så testiklen falder på plads.

Kat http://www.netdyredoktor.dk/sw34865.asp

Nogle kattes testikler udvikler sig ikke normalt, men bliver siddende i bughulen eller i lyskekanalen fremfor at sidde i pungen. Dette kalder man kryptorkisme, og det er en arveligt betinget tilstand. Kryptorkisme kan være enkeltsidig eller dobbeltsidig. Den kaldes abdominal, hvis den berørte testikel befinder sig i bughulen, og inguinal, hvis testiklen sidder i lyskekanalen. Begge disse tilstande medfører en øget risiko for testikelkræft, og for en drejning af testiklen med en deraf følgende smertefuld snoning af sædstrengen. Hankatte, der lider af kryptorkisme bør kastreres, både for deres egen skyld, men også for at forhindre avl af kryptorkide katte.

Igen risiko for testikel kræft og snoning af sædstring og arveligt men arvegang er ikke diffineret

Ilder:http://www.faurholts-ildere.dk/side9.html

Genet for kryptochisme er et recessivt-gen, hvilket betyder det kan ligge skjult, og videre gives til såvel tæver som hanner. Hos hannerne er det tydeligt at se, da en eller begge testikler ikke kommer ned i pungen, hvorimod der hos tæver ikke er noget ydretegn. Der kan hos en tæve fra et kuld, hvor der er fundet kryptorkide være problemer med det ligitament (ophæng) som holder livmoder på plads. Det kan være svagt. Det kan derfor være dissideret farligt for en sådan tæve, at blive med hvalpe, da ophænget til livmoderen kan briste under den øgede vægt en drægtighed medfører. Når en sådan tæve skal neutraliseres, vil det være en rigtig god ide, at fortælle dyrlægen der er kryptorkide kuldsøskende.

Her fremføres en teori om det ved ildere er ressisivt. Dette betyder jo reelt set ikke ved om din ilder er bærer da det KUN kan ses på de dyr der er berørt. Eneste måde at SANDSYNLIG gøre en ressisiv lidelse ikke bæres af et dyr er at parre den med et dyr der har defekten udtrykt. MEN ressisiver dør aldrig og alt avl er statestik så man kan være (u)heldig at kuldet alligevel ikke får dobbelt ressisiv men at bæreren af raske gen gives til alle afkom og så vil ingen jo være syge men alle bærere.
Det med tæverne rammes er ret interessant og vil da se om jeg kan finde mere om dette.

[tzari]

ok en rotte opdrætter med 7 års erfaring sagde det var ressisivt ved rotter søger stadig efter mere info 

[Black Diamond]

Jeg har skrevet til en dyrlæge i dag og spurgt om nogle af de spørgsmål er er oppe om Kryptokisme i ilderverden lige nu. Jeg skriver ind her når jeg får et svar. Jeg syndes udover det er meget spændne at undersøge. Da vi jo ikke har haft en dyrlæge inden over før og mange af os kun ved om det man kan finde om Katte og Hunde. Håber vi kan får svar på det med ilderen,.
En af de ting jeg kan set klart når jeg læser om det. Er at der er stor forskælg på Kryptokisme på katte og hunde. Derfor må man formode at det er det samme med en ilder!

[Julie]

Hvordan forholder det sig så med hensyn til kræft når en han er opereret/kastreret? Er der større risiko for kræft end hos ikke-kryptokide hanner, eller er det det samme?

[Malene]

Hvis det er mht. arvegangen du tænker på, så tror jeg slet ikke der findes fakta om det. Det gør der, så vidt jeg har læst, heller ikke ved andre dyrearter. Men teorien man er mest sikker på, er at det er arveligt og højst sandsynligt ressisivt (og polygenetisk) ved de fleste dyrearter. Dvs. det kan bæres af BÅDE hunner og hanner.

Men her er hvad jeg har kunne finde. Der er meget lidt om ildere og lidt meget (sorry) om hunde, men jeg orker ikke at sortere i det

Ildere
"Other genetic traits are more serious problems, such as congenital deafness, juvenile cataracts, kinked tails, obesity, coat condition, monorchism (one testicle retained in the body cavity), and cryptorchism (both testicles retained). Breeders who cannot be positive that instances of these disorders in their kits are not genetic in origin should have the parents of these ferrets neutered. In some cases, the lineage of seemingly unrelated ferrets with a common disorder can be traced to find a common ancestor. All breeder animals with this ancestor should be neutered."
Kilde: http://209.85.129.132/search?q=cache:1Uqc3QSH2hIJ:www.ferret.org/newsletter/1999/102genetics.pdf+retained+testes+ferrets+genetic&cd=4&hl=da&ct=clnk&gl=dk&client=firefox-a

"In some hobs one or both testicles fails to descend properly into
the scrotum at birth. This is thought to be largely a hereditary condition, and therefore affected animals should not be bred from (and cannot be shown). Retained testicles have a high risk of becoming cancerous and we therefore recommend that all monorchid and cryptorchid animals should be castrated."
Kilde: http://209.85.129.132/search?q=cache:7pqNNtgfhjEJ:www.willetthouse.co.uk/ferret-neutering.pdf+cryptorchidism%2Bheredity%2Bferrets&cd=3&hl=da&ct=clnk&gl=dk&client=firefox-a

"8.4.5.8 Congenital and Heritable Problems:
Anencephaly, neuroschisis, gastroschisis, Cryptorchidism, and Amelia, corneal dermoids, cataracts."
Kilde: http://compepid.tuskegee.edu/syllabi/pathobiology/pathology/labmed/chapter8.html


Sortfodede ildere
"In 2003, five cryptorchid animals were observed, and animals with heart and kidney defects have been observed sporadically since the commencement of captive breeding. These abnormalities mirror changes that have been seen in other carnivore species with low overall genetic diversity, including the Florida panther and giant panda. Causes for these changes are unknown but could include both genetic and environmental factors."
(sort fodede ildere)
Kilde: http://209.85.129.132/search?q=cache:E2r3qhG1PYgJ:www.cbsg.org/cbsg/workshopreports/23/blackfootedferret03_final_report.pdf+cryptorchidism%2Bpolecats&cd=7&hl=da&ct=clnk&gl=dk&client=firefox-a


Katte
"Genetisk sett er kryptorkisme en interessant defekt, fordi den er et eksempel på en kjønnsbegrenset opptreden, dvs. tilstanden begrenser seg til hannene (ike mange hunnkatter med testikler, nei...). Det bør skilles klart mellom uttrykkene "kjønnsbegrenset" og "kjønnsbundet", da det sistnevnte uttrykket betyr at ett gen bæres på et av kjønnskromosomene. Det er ingen ting som tyder på at kryptorkisme er forårsaket av kjønnsbundet arv."
Kilde: http://www.birmanett.no/genetikk/kryptorkisme.html

"Katten er i regelen avlsdyktig når bare den ene testikkelen er på plass (monorkid), men da fejlen skyldes et arvelig anlæg bør en monorkid katt ikke brukes i avlen
...
Kuldsøstre til en mororkid/kryptorkid han vil i øvrig i visse tilfælde føre anleggene videre."
Kilde: Politikens Kattebog


Hunde
"Cryptorchidism is a common occurrence in dogs. Although the genetics are not fully understood, it is thought to be a recessive, and probably polygenetic, trait. Some have speculated that it is a sex-limited autosomal recessive trait, however, it is unlikely to be simple recessive."
Kilde: http://en.wikipedia.org/wiki/Cryptorchidism#Dogs

"Jo, det är såhär att en sjukdom eller defekt (eller andra egenskaper också för den delen) kan ligga som en s k recessiv gen.
...
Generna brukar skrivas t ex Tt, där den stora bokstaven står för det dominanta anlaget och den lilla för det recessiva. Enligt ärflighetsläran ser då en kombination mellan två hundar som bägge har Tt-uppsättning för tex kryptorchism ut som följer:

          T    t (pappan)
T (mamman)     TT   Tt

t         Tt   tt

Av valparna, som i det här fallet är fyra stycken, kommer en att överhuvudtaget inte bära på anlaget (TT), två stycken är anlagsbärare (Tt) men till synes helt friska och en (tt) blir kryptorchid.
...
Hälsningar Svenska Kennelklubben"
Kilde: http://web.telia.com/~u42121894/totte/kryptorkid.htm

"As mentioned in previous sections, cryptorchidism is a hereditary condition that can be passed on from affected sires and dams to their male and female young (only the male offspring can actually display the disorder because female offspring do not have testicles, however, affected female offspring can carry the genes through to the next generation thereby passing the disorder on).
...
What has been determined to some extent is the mode of inheritance in the dog. I use the words "to some extent" because even the mode of inheritance of canine cryptorchidism has been difficult to establish for certain. At the current time, cryptorchidism is thought to have an autosomal recessive mode of inheritance in the dog. The mode of inheritance has not been so well studied and determined in the cat, but is thought to be similar to the dog.
...
Keeping to this webpage's main topic, there is a gene or a number of genes responsible for making the testicle descend into its normal scrotal location in early life. This might be a gene with a role in testosterone production - after all, sufficient testosterone production is thought to assist normal testicular descent (hence the medical use of GnRH or hCG to try to correct cryptorchidism). Alternatively, it might even be a gene with a role in normal gubernaculum development (e.g. a gene responsible for making normal gubernaculum contractile proteins) - after all, a normally-regressing gubernaculum is required in order for the testicle to descend. Correct testicular descent could and is likely to be a combination of many different genes all working together.
...
Thus, it is not possible to detect whether or not an animal carries the cryptorchidism gene purely on the basis of whether it LOOKS cryptorchid or not: the animal could be a carrier of the defective gene and show no outward signs of the defect."
Kilde: http://www.pet-informed-veterinary-advice-online.com/cryptorchidism.html

"Cryptorchidism is a hereditary problem that can lead to testicular cancer. It is likely autosomal (meaning that both males and females can carry and pass on the gene)."
Kilde: http://www.lovableleo.com/breed.htm

"Den arvegangen som er best underbygd er en enkel recessiv arvegang med kjønnsbundet manifestasjon (bare hannhunder blir kryptorkide, mens tisper er bærere uten å vise defekten). Foreldrene til en kryptorkid hannhund er derfor begge bærere. Om tispen har genet i heterozygot (enkel) eller homozygot (dobbel) dose kan man ikke vite. Det hevdes også at flere enn ett enkelt gen er involvert."
Kilde: http://www.terjeviken.com/kryptorkisme.htm

"Generelt kan man si at man ikke bør kombinere to individer der lidelsen er kjent hos begge de potensielle foreldrenes nærmeste aner eller avkom.
Vennlig hilsen ~
Jon Snøfugl
Heimdal Dyreklinikk"
Kilde: http://www.bbstinywonders.com/health.html

"Du stopper ikke denne arvelige feilen ved å ta ut individer som har mangelen. Men du reduserer risikoen for kryptorkisme ved ikke å bruke kryptorkide hunder i avl, noe som heller ikke er tillatt.

Denne feilen har ikke en direkte recessiv eller dominant arvegang, men er avhengig av flere gener. Derfor bør en unngå å pare sammen individer som begge har feilen i nærmeste slekt. Ikke bestandig så lett å finne ut.

For å gjøre det ytterlig vanskelig, er det ikke all kryptorkisme som er arvelig, det kan også være påført i fosterstadiet, f.eks. av forskjellige medikamenter til tispa."
Kilde: http://www.canis.no/innlegg.php?iid=806405

"Defekten kan være ensidig eller dobbeltsidig (en eller ingen testikler i pungen). Defekten er arvelig, men vi kjenner ikke arvegangen fullt ut. Det må vurderes om en skal avle videre på hunder som har gitt avkom med testikkelmangel. Kullsøsken av en hannhund med testikkelmangel bør vurderes nøye før de eventuelt settes i avl."
Kilde: http://www.vorsteh.no/main/?hoved=arkiv&arkiv=2005&arkiv_artikkel=535

"CRYPTORCHIDISM is attributed to a hereditary factor transmitted by the It appears to be dominant in the horse but recessive in most other species (pig, dog, sheep). Castration of breeding animals is advocated rather than medicinal or surgical treatment. In this way cryptorchidism would be more rapidly eliminated. H. A. ROBERTSON."
Kilde: http://www.cababstractsplus.org/abstracts/Abstract.aspx?AcNo=19490100821

"Cryptorchidism.
Phenotype in dog (Canis familiaris).
Summary
Failure of one (unilateral) or both (bilateral) testes to descend.

Genes
INSL3. insulin-like 3 (Leydig cell).
RXFP2. relaxin/insulin-like family peptide receptor 2. Also known as LGR8."
Kilde: http://www.ncbi.nlm.nih.gov/sites/entrez?Db=omia&Cmd=ShowDetailView&uid=475&log$=omiaadsomia

"This defect is considered hereditary in most breeds and is sex-linked, autosomal recessive trait."
Kilde: http://my-pet-medicine.com/2009/01/26/cryptorchidism-problem/

"Canine cryptorchidism is believed to be a sex-limited hereditary trait with transmission due to a single autosomal recessive gene. The genetic predisposition may be carried by males or females, although it will only be manifested in males."
Kilde: http://www.lowchensaustralia.com/breeding/crypt.htm

"Females, including dams and littermates of affected dogs, can be genetically affected and pass on the trait at the same frequency as affected males. The mode of inheritance of cryptorchidism has not been established. The fact that Chinook crosses also had a significantly high percentage of diagnoses may suggest a major dominant influence. Conversely, many experts feel that this may be a polygenic trait, where a threshold of genes must combine to produce the disorder."
Kilde: http://www.seppalas.org/chinookhealth.htm

"This is generally considered to be a hereditary problem in dogs.  In breeds that have been studied, it appears to be polygenetic (caused by more than one gene) and recessive (parents may not exhibit the problem, but can pass it on).
...
Careful consideration should also be given to continued breeding of parents of a cryptorchid, who do carry the defective gene(s), or breeding of siblings of a cryptorchid, who may carry the defective gene(s)."
Kilde: http://www.samoyedhealthfoundation.org/diseases/cryptorchidism

"Canine cryptorchidism is believed to be a sex-limited hereditary trait with transmission due to a single autosomal recessive gene. The genetic predisposition may be carried by males or females, although it will only be manifested in males."
Kilde: http://www.tc.umn.edu/~rootk001/Class_notes_Root_Kustritz.htm#cryptorchidism

"Worse than the hazard of infertility in such a case is the hazard of introducing cryptorchidism into one's strain. Since cryptorchidism is a recognized genetic recessive factor, once introduced into the strain, there is always the probability that it will pair with another recessive of the same kind and consequently manifest itself in the phenotype."
Kilde: http://www.dogbreedpicture.org/dogbreedpicture10.php

"It appears that cryptorchidism is polygenetic (involves multiple genes), and therefore elimination of this condition from a gene pool is difficult. This condition occurs more often in some breeds of dog (Saint Bernards and German Shepherd Dogs) than in others, but can and does occur in all dog breeds. Cryptorchidism achieves its highest levels of occurrence in heavily line-bred animals."
Kilde: http://www.barkbytes.com/medical/med0062.htm

"The most recent studies on the subject of missing or hidden testicles indicate that there can be several genetic causes.
...
Bilateral cryptorchidism may also be genetically slightly different, since both testes are usually found in almost the same ovarian position as they are in the early fetal life of normal males. It seems that this phenomenon may be caused by two or more genes. Such may be the case in unilateral cases too, although there is reliable data to suggest the possibility of a simple Mendelian recessive in the case of classic unilateral cryptorchidism. If two normal-phenotype dogs actually carry the recessive, on an average one might expect 25 percent of the litter to show the condition. But since about half of each litter is female, the average would only be 12½ percent. With such breedings that produce one-apparent-testicle dogs not being often repeated, it's difficult to find meaningful statistics. I have observed that when unilateral cryptorchids are bred, there is a high probability of them siring both unilateral and bilateral cryptorchids.
...
As mentioned, unilateral cryptorchidism often seems as if it were a simple, recessive, one-gene Mendelian trait, though possibly it is not. If the problem of unilateral cryptorchidism is indeed simply recessive, the occurrence of bilateral cryptorchids might have to be explained by the action of other, modifying genes, and many geneticists today do not find that idea appealing.
...
I believe it is safe to say that cryptorchidism is genetic, that it is in some way recessive, and that there is some sort of connection between bilateral cryptorchids and unilateral ones. Perhaps there is also a connection between the pituitary and floating testicles.
...
Unless it is a trait on the X or Y chromosome (and this isn't), it matters not which parent has what genotype."
Kilde: http://siriusdog.com/article3.php?id=51

"In dogs, cryptorchidism is hereditary, and affected animals should not be bred. Both parents of affected individuals should be implicated as carriers."
Kilde: http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/181901.htm

"Although the condition is of course seen only in male dogs, both males and females can carry the gene for cryptorchidism. Heterozygous  males and females, and homozygous females, will be physically normal, but can pass the gene on to their offspring. Homozygous males are cryptorchid. Thus cryptorchidism is thought to be a sex-limited autosomal recessive trait"
Kilde: http://www.upei.ca/~cidd/Diseases/urogenital%20disorders/cryptorchidism.htm

"Twelve cases of cryptorchidism were found in a colony of Minature Schnauzer purebred and crossbred dogs. At least nine affected dogs were derived from the same sire directly or indirectly.
...
Degree of inbreeding was greater for bilateral cases than unilateral cases. High incidence of cryptorchidism in this colony provided good evidence for hereditary nature of the condition in the Miniature Schnauzer dog. Morphologic observations were suggestive of a multiple gene defect."
Kilde: http://www.ncbi.nlm.nih.gov/pubmed/31014?dopt=Abstract

"This is an inherited disorder, and is inherited as a recessive trait.
...
Based on the few pedigree studies in dogs and experimental studies in other
animals, testis descent in the dog is thought to be controlled by at least 3
genes, the identity of which are unknown. Recessive mutations in such genes
result in cryptorchidism. Delayed descent of the testes may be a similarly
inherited trait, as there is evidence in mice that mutations in 1 or 2 of
the genes controlling testis descent in that species can result in delayed
testis descent."
Kilde: http://www.bakalo.com/cryptorchidism.htm

"Based on the few pedigree studies in dogs and experimental studies in other animals, testis descent in the dog could be regulated by at least 3 known genes, as well as others that are presently unknown. Mutations in such genes impair the ability of the testes to descend, resulting in cryptorchidism. Delayed descent of the testes may be a less severe form of cryptorchidism, as it shown in some mouse studies. It has been shown in other animals, such as pigs and goats, that the prevalence of cryptorchidism in herds can be reduced over time by selecting against this trait. That is, cryptorchid animals and male and female parents of cryptorchid animals were not used as breeding stock."
Kilde: http://bakerinstitute.vet.cornell.edu/faculty/page.php?id=206


Svin
"Two hypotheses were examined: first, that this trait is controlled by homozygosity of a recessive gene at a single locus; second, that it is controlled by homozygosity of recessive genes at two loci. The single-locus recessive hypothesis was rejected, but the two-locus model was not."
Kilde: http://jhered.oxfordjournals.org/cgi/content/abstract/79/4/313


Placentale pattedyr
"There are a large number of genes and gene products involved in regulation of testis descent (Basrur & Basrur 2004, Klonisch et al. 2004). Baumans et al.(1983) hypothesized that a low molecular weight molecule in aqueous extracts of pig testes stimulated gubernaculum development; it was 20 years until Insl3 was identified. It is now known, based on data for multiple species, that products of Insl3, Great, androgen receptor, and CGRP genes, and those involved in testosterone production, must be available during critical points in development.
...
Dogma is that cryptorchidism is a heritable condition, despite the lack of a strong basis for this thought. It is also possible that at least some cases of cryptorchidism in common animals result from fetal exposure to endocrine disruptor agent. Despite limited size of studies, there is no doubt that brother–sister matings of dogs or pigs over several generations increases incidence of cryptorchidism (Cox et al. 1978, Mikami & Fredeen 1979, McPhee & Buckley 1984). There also is anecdotal opinion that cryptorchidism is familial in some sire lines of horses and pigs.

There has been no recent breeding study to establish if cryptorchidism is a heritable condition. There probably are two reasons. First, mode of inheritance and penetrance are difficult to establish in planned studies, and essentially impossible to deduce accurately from retrospective analysis. Sire of a cryptorchid male can be assumed to be heterozygous for the genes causing the disease, but many matings would be needed to determine if a given dam was homozygous or heterozygous for each gene involved. Establishing that an animal is a non-carrier for each gene is even more difficult. Rehfeld (1971) estimated that >40 male offspring would have to be studied at >6 months of age to establish that a dam probably was a non-carrier. Second is economic importance; knowledge of the genetics of cryptorchidism would not alter conventional management practices."
Kilde: http://www.reproduction-online.org/cgi/content/full/133/3/541?ck=nck


Andre
"In stallions it is a hereditary due to a dominant factor. In goats, sheep and pigs it is considered an autosomal recessice trait. There are varying opinions as to the cause in dogs, but the two most common theories are that it is a multigene sexlimited recessive trait or that it is a dominant trait with incomplete penetrance."
Kilde: http://www.jstor.org/pss/20094806

"Cryptorchidism can be heritable and is
believed to result from a sex-limited au-
tosomal recessive, or in some species,
dominant gene (Rhoades and Foley, 1977)."
Kilde: http://209.85.129.132/search?q=cache:A3eqvRHCuCQJ:www.floridamarine.org/engine/download_redirection_process.asp%3Ffile%3D96dunbar_3407.pdf%26objid%3D47002%26dltype%3Dpublication+cryptorchidism%2Bheredity&cd=67&hl=da&ct=clnk&gl=dk&client=firefox-a