• Information
  • Article by Dr Kooistra
  • DNA-test

A lot of thanx to Mijke van Heyningen for the english translation.  


Information about Saarlooswolfhonden, Pituitary Dwarfism and the Genetic test

What is pituitary dwarfism:
Dwarfism is a horrible incurable disorder which you don’t wish to any dog. A dwarf has a badly developed pituitary , which means that certain hormones (such as growth hormones) are not produced. Due to the shortage of the production of the thyroid stimulating hormone, they have a slow functioning thyroid. Besides the fact that these dogs stay small, they are also haunted by various horrible side effects (e.g. baldness, itching, inflammations, malfunctioning of the liver and kidneys, slow behaviour) when they are not treated with medicines on a daily basis.


SWH dwarf pup


Recognising and existence of dwarfism in a breed:
Dwarfism is not always recognised by a breeder! Many dwarfs die in the uterus or die during the birth.
And moreover 90% of the living born dwarfs die in the first week.

Pups behind in growth are often not recognised as dwarfs. After (4 weeks or later) people see that a pup is different in comparison with the other pups. Dwarfism is known in the breeds German Shepherd,  Karelische Bearsdog, Saarlooswolfhond and the Czechoslovakian Wolfdog. 

If just 1 percent of the dogs is a dwarf in a population, then 18 percent of the population will be carriers of this gen mutation. This means that the number of carriers will be much higher than might be expected.



                                          SWH Dwarf and litter mates on day 1 and 1, 2 and  3 weeks old


The genetic test:
The university in Utrecht (NL) has developed in 2008 a genetic test, after years of investigation, which can determine the mutation of the gene that is responsible for pituitary dwarfism.

With the development of the dwarfism test it has become possible to prevent further dwarfs being born within

the Saarlooswolfhond and German shepherd breed!

With this test it is possible to see if a dog is a carrier of this mutated gen. And with good breeding policy no dogs have to be refused for breeding. The only thing is not to make combinations anymore with carrier x carrier. So it is very important to screen the whole SWH population .


How can a SWH owner do this genetic test with his SWH:

Because not all veterinarians know a lot about Pituitary dwarfism and the test, it is useful to give them the article of Dr. H. Kooistra:

Pituitary dwarfism in German shepherd dogs and Saarloos wolfhounds -Availability of a genetic test-

  • The owner can fill in all the info about himself and the dog in the form: ”Blood DNA research Pituitary Dwarfism”  and sign it.
  • Then the owner can go to his own veterinarian with his SWH,  the form and the pedigree of the dog.
  • The vet has to check the chip number, fill in the info and has to sign the form.
  • Then he can collect 4ml EDTA blood sample.
  • The 4 ml blood sample (collected in an EDTA containing tube) can together with the signed form and the copy of the pedigree send to:

Dr. H.S. Kooistra (H.S.Kooistra@uu.nl)                                                              

Department of Clinical Sciences of Companion Animals                        

Faculty of Veterinary Medicine, Utrecht University                                                       

Yalelaan 108                                                  

3584 CM Utrecht                                                                                               

The Netherlands

  • After the test the university will send a bill to the owner.
  • The costs of the genetic screening for the mutation that causes pituitary dwarfism in German shepherd dogs and Saarloos wolfhounds are about Euro 100 (excl. VAT).
  • When the university has received the paying of the owner, they will send him a certificate with the test result.



SWH litter with a SWH dwarf 4 wk

The results from already tested dogs is often published in the database which you find here.


ECVO uitslagen = eye test results

HD uitslagen = HD röntgen results

Dwerggroei uitslagen = darfism tests results

Contact AVLS : Marianne Eggink (secretariat) secretaris@avls.nl



© 2009 - Mijke van Heyningen (mijke@wolfdog.org )


* With thanks to Audry for photo’s of SWH dwarf! (more info: ( http://saarlooswolfhond.web-log.nl )

English translation:  Mijke van Heyningen  Published with Dr Kooistra's permission

Pituitary dwarfism in German shepherd dogs and Saarloos wolfhounds

-Availability of a genetic test-



Annemarie Voorbij and Hans Kooistra

Department of Clinical Sciences of Companion Animals

Faculty of Veterinary Medicine, Utrecht University

Utrecht, The Netherlands

The pituitary is a hormone producing gland at the base of the brain. This pea-sized gland is composed of three parts: the anterior pituitary, the intermediate lobe and the posterior pituitary. The anterior pituitary synthesizes and secretes six hormones, which are essential for numerous body functions, such as growth, reproduction, lactation, metabolism and handling stress.

These 6 hormones are:

  • Growth hormone (GH), which is essential for growth.

  • Thyroid stimulating hormone (TSH), which regulates thyroid function.

  • Prolactin (PRL), which is essential for lactation.

  • Follicle stimulating hormone (FSH) andLuteinizing hormone (LH), which are essential for ovulation in female animals and sperm production in male animals

  • Adrenocorticotroph hormone (ACTH), which stimulates the adrenal cortex   

Any defect in the development of the pituitary gland may result in a form of isolated or combined pituitary hormone deficiency. In dogs, congenital GH deficiency or pituitary dwarfism is the most striking example of pituitary hormone deficiency. This recessive inherited disorder is encountered most often in German shepherd dogs, but it has, for example, also been reported in Saarloos wolfhounds. The genetic defect causing congenital GH deficiency in German shepherd dogs is also the cause of pituitary dwarfism in Saarloos wolfhounds, because the disorder in the latter breeds was first recognized after German shepherd dogs had been used in the breeding of Saarloos wolfhounds.

German shepherd and Saarloos wolfhound dwarfs have a combined deficiency of GH, TSH, PRL, and the gonadotropins. In contrast, ACTH secretion is preserved in these animals.

Dogs that are carriers of the mutated gene that causes pituitary dwarfism do not have any symptoms and look exactly the same as the dogs that aren’t carriers. Since pituitary dwarfism is a recessive disorder of a single gene, the birth of a dwarf indicates that both parents are carriers of the mutation.

Pituitary dwarfs are significantly smaller than their healthy littermate, but the dwarfs are in proportion. Another clinical manifestation of pituitary dwarfism is that the dwarfs have retained their puppy hair coat. In time, the hair coat will be largely lost and the animal will become alopecic (bald) (Figure 1).

The growth retardation and the abnormal hair coat are mostly noticed by 2 to 3 months of age. The hairs are easily epilated, and when the animal loses its hair coat, the skin can become squameous and hyperpigmented, making the skin darker in color. Furthermore, due to a lowered local immunity of the skin, dwarfs are prone to bacterial skin infections. 

However, the clinical signs are not limited to exterior appearances. The dwarfs suffer from a whole range of clinical manifestations far worse than skin and hair coat problems. For instance, GH deficiency also leads to underdevelopment of the kidneys, causing chronic renal failure. The deficiency of TSH will result in an underactive thyroid gland, causing the animals to be slow and dull. Furthermore, the insufficiency of the gonadotropins will result in failure of one or both testis to move, or "descend" into the scrotum (cryptorchidism) in male dwarfs. Female dwarfs do go into heat, but they do not ovulate. It can be concluded that pituitary dwarfism is a serious disorder. 

Although the physical features of pituitary dwarfism may seem obvious, the final diagnosis should be based on 'pituitary stimulation tests'. These tests can detect a deficiency of GH, TSH, prolactin, LH and FSH.

The most logical therapeutic option would be to treat the dwarfs with canine GH and thyroid hormone. Treating the animal with thyroid hormone is simple, but it is not possible to treat the dwarfs with canine GH, since it is not available for therapeutic use. However, research has demonstrated that porcine GH is identical to canine GH, making it a good alternative for treatment. 

Without proper treatment, the long term prognosis is poor. Many dwarfs will not live more than 4 to 5 years. However, some dogs do live longer, probably because in some cases the pituitary still produces a small amount of hormones. Although the prognosis improves significantly when dwarfs are properly treated, their prognosis still remains guarded.

It should be clear that the birth of dogs with this serious illness should be prevented. In order to do so, two carriers of this mutation should not be bred. The problem is that, as mentioned earlier, one cannot distinguish a carrier from a non carrier judged on its appearance. This would require a genetic test. After 15 years of intensive research at the Department of Clinical Sciences of Companion Animals of Utrecht University, this test is now available! If this test would be used for all breeding animals, pituitary dwarfism could be completely eradicated in German shepherd dogs and the Saarloos wolfhounds.

A genetic test may not seem to be of big importance, since the disorder seems to occur only occasionally. However, one should keep in mind that many dwarfs die in the uterus or shortly after birth. One should also be aware of the fact that if just 1 percent of the dog populations are dwarfs, then 18 percent of the population will be carriers of the mutation. This means that the number of carriers will be much higher than might be expected. When 2 of these carriers are mated, on average 25 percent of their offspring will be dwarfs and half of the siblings will be carriers of the mutation.

For the genetic test, 4 ml. of blood (collected in an EDTA containing tube) is needed. The blood sample has to be shipped to: 

Dr. H.S. Kooistra (H.S.Kooistra@uu.nl)

Department of Clinical Sciences of Companion Animals

Faculty of Veterinary Medicine, Utrecht University

Yalelaan 108

3584 CM Utrecht

The Netherlands 

The costs of the genetic screening for the mutation that causes pituitary dwarfism in German shepherd dogs and Saarloos wolfhounds are Euro 100 (excl. VAT).

In short, pituitary dwarfism is a serious, incurable illness of which the occurrence is highly underestimated! The good news is that there is now a genetic test with which carriers of the mutation can be identified. If all breeding animals were tested (only once), and a correct breeding policy would be implemented, this severe illness could be completely eradicated.

Figure 1. A 10-month-old German shepherd dwarf with lack of guard hairs and retention of puppy hairs. 

The DNA-test for dwarfism can be sent to the following laboratories.

Van haeringen group (also provide for the DM test)

The cost of the analysis is 107,50€

Fill out this form and send it + 4 ml blood (in an EDTA-tube) to:

Dr. H.S. Kooistra ( H.S.Kooistra@uu.nl )
Department of Clinical Sciences of Companion Animals
Faculty of Veterinary Medicine, Utrecht University
Yalelaan 108
3584 CM Utrecht
The Netherlands

The cost of the analysis is 100€ ( excl VAT )

LABOKLIN (also provide for the DM test)

Go to: "genetics" -- "genetic diseases"-- "dogs" -- "dwarfism"

Tests without central registration - Important information from SKK

The above test does not have central registration in SKK but it is important to remember that you are always obligated to take consideration to the test result, even if it didn’t came out the way you expected.


If you want to test your dog with a genetic test that does not have central registration you should use SSK’s general referral “Remiss DNA-test”. This referral is used to secure the dogs identification when blood sample is taken. The referral is absolutely necessary for a possible future registration of your dog’s results. If the DNA-test you wish to perform can be registered in the future, with the help of the referral you can register your dog’s result afterwards. If you are missing the SKK referral your dog’s result will not be accepted for central registration. On the referral you have to state what disease the test is for, what laboratory that perform the test, which veterinary that does the sampling, owner of the dog and all information about the dog. Your veterinary take the blood test and the blood test is sent by the veterinary to the laboratory. The referral together with a copy of the test result is sent to SKK. Sent in referrals will be saved at SKK without measure until decision about central registration possibly is taken. The dog owner is also encouraged to send a copy of the test result to the breed club. 

Referral DNA-test (pdf file)