Fact Sheet Guinea Pig Satin syndrome, Osteodystrophy

 3. Affected guinea pig breeds

Satin guinea pigs are guinea pigs that have a specific hair structure due to a genetic defect. All breeds can be affected, so breed-specific classification is not possible.

4. Ocurrence in other animal species

The genetic defect that leads to the skeletal disease osteodystrophia fibrosa in guinea pigs due to the altered structure of the hair follicle has not yet been described in other domestic animals. The defect associated with the hair structure, the so-called „satin factor“, is specific to guinea pigs, even though other domestic animals (e.g. rabbits) do have coat types that are referred to as satin due to their sheen, but without any genetic similarity with regard to a defect such as „satin syndrome“ (e.g. dwarf satin rabbits, satin dwarf rams). However, the animals show severe and progressive dental disease at an early age. Cases of dentally healthy satin rabbits are very rare. The aetiology of these diseases is still unknown, although a genetic predisposition is considered likely. In other species, osteodystrophia fibrosa is usually caused by other diseases such as hyperparathyroidism, osteoporosis, osteomalacia, chronic kidney disease or tumors.

5. Problems/syndromes potentially associated with this trait

Satin syndrome includes changes in hair structures, hyperparathyroidism and changes in bones and joints due to osteodystrophia fibrosa. It is based on metabolic disorders, particularly due to malabsorption of calcium. This can result in anorexia, lameness and behavioral changes in the affected animals. There may be an increased mortality rate among young animals and the altered hair structure can make affected animals more susceptible to infectious skin diseases.

6.  Symptoms and clinical significance of the above-mentioned defects: Significance/effects of the defect on the physical/psychological well-being (burden) of the individual animal and classification into a burden category

*Individual breeding-related defects are assigned to different burden categories (BC) depending on their severity. The overall burden category is determined by the most severe defect identified in the individual animal. The BC system, which was developed based on the Swiss model, is still under development and is intended for guidance only. Therefore, the BC values listed here should be considered provisional. This is primarily because the German Animal Welfare Act does not provide a legally enforceable basis for classification into burden categories. Unlike in Switzerland, German legal standards do not quantify pain, suffering, or harm, nor do they assess their nature; rather, they are taken into account only if they impair the animal more than insignificantly.

The burdens that may result from defective breeding traits are divided into four categories (Art. 3 TSchZV, Switzerland). The overall assessment of an animal’s suitability for breeding is determined by the category of the trait or symptom that causes the animal the greatest burden (Art. 4 TSchZV, Switzerland).

Category 0 (no burden): These animals may be used for breeding.

Category 1 (mild burden): A mild burden exists when the adverse effects of traits and symptoms in companion and farm animals can be compensated for through appropriate care, housing, or feeding—without interventions on the animal and without regular medical care.

Category 2 (moderate burden): These animals may be used for breeding only if the breeding goal* ensures that the burden on the offspring is less than that of the parent animals.

Category 3 (severe burden): These animals must not be used for breeding.

*However, for an assessment in the guidelines, it is assumed that a breeding goal can actually be achieved through appropriate breeding programs without breeding-related defects being expected in the intermediate generations that could cause suffering, pain, or harm (see also the expert opinion by Prof. Cirsovius).

Physical:
The hair structure and hair density of satin guinea pigs is altered. The silky shimmer („shimmer coat“]) of the hair is caused by the fact that the hair is hollow on the inside. This means that incident light is reflected differently. The hair is more sensitive and brittle than in non-satin guinea pigs. Long-haired guinea pigs in particular therefore break off more quickly. At the same time, however, satin guinea pigs have significantly more hair than non-satin animals.

Affected animals may be smaller than guinea pigs without satin factor and show mild motor dysfunction. The animals can become ill at the age of a few months, but usually between one and five years of age. Both satin guinea pigs and guinea pigs that are only carriers of the satin gene(s) may have reduced fitness compared to non-satin guinea pigs and are more likely to develop hyperparathyroidism and associated osteodystrophy. Osteodystrophia fibrosa, which occurs in satin guinea pigs, is caused by secondary hyperparathyroidism. Affected animals are significantly more likely to develop progressive degenerative kidney disease (renal secondary hyperparathyroidism). Osteodystrophy is caused by a continuous progressive remodeling of the bone tissue (replacement of solid bone tissue by fibrous tissue and formation of bone cysts), which is attributed to changes in the kidney (renal osteodystrophy) or in the thyroid gland (e.g. fibrous osteodystrophy). Both the altered bones and the joints that have been altered to the point of complete destruction are painful.

The pathognomonic hobbling or tripping gait (attempt to relieve all limbs) is caused by the painfulness and the relieving posture. The osteodystrophic changes due to a disturbed calcium metabolism can begin either in the head skeleton or in the pelvic bones. Due to changes in the jaw bones, affected animals show disturbances in feed intake despite starvation (and also the development of malocclusion due to lack of feed intake as a result of persistent tooth growth), they are anorectic and emaciated [4,6,8]. They are often more hectic and anxious and behave more aggressively in groups. As the disease progresses, the animals withdraw, isolate themselves from their conspecifics and become calmer. Later, osteopenia, osteosclerosis and spontaneous fractures can also develop.

Satin syndrome is also associated with an increased mortality rate among young animals. Due to their hair structure, satin guinea pigs are also more susceptible to infestation with ectoparasites (hair lice, mites) and skin fungus.

Psychological:

Satin syndrome leads to painful bone and joint changes. This chronic pain leads to refusal to eat despite hunger and to restricted mobility. Presumably due to the chronic pain, affected animals behave more aggressively in the group than unaffected conspecifics. Fights can lead to fractures.  Severely affected animals can be excluded from the group. In this respect, the genetic disease not only leads to massive pain, suffering and damage to the animal itself, but also impairs the species-appropriate group dynamics of these social animals.

Burden category: 3

7. Heredity, genetics, and known genetic tests, if applicable

The satin factor can occur in all guinea pig breeds, both short-haired and long-haired breeds. It can also occur in guinea pigs that do not have the typical satin sheen on the outside. The monogenic defect is inherited in an autosomal recessive manner. Although the satin factor can also occur in other animal species such as mice and hamsters, it only relates to the phenotypic hair structure and cannot be related to the osteodystrophic changes that occur in satin guinea pigs due to the completely different genetic background.

 8.  Diagnosis –further investigations

The changes in the animal resulting from the symptoms can be determined by a veterinarian as part of the usual clinical diagnostics (general examination, laboratory/blood diagnostics, X-ray and anamnesis). The very shiny coat of satin guinea pigs is usually already noticeable on inspection – in short-haired breeds with reddish colors, however, more so than in long-haired breeds. Sometimes crossbreeding with satin guinea pigs can be narrowed down anamnestically if guinea pig breeders provide information about this. However, a diagnosis of the satin factor based solely on an inspection of the coat should be rejected. In addition to inspection (very shiny coat, weight loss, age), the diagnosis of satin factor includes clinical examination (movement, deformities, fractures, pain, etc.), imaging procedures/x-rays (assessment of bone texture, fractures) and blood laboratory diagnostics (determination of alkaline phosphatase/AP, calcium, phosphate). In affected younger animals, the AP is higher than in unaffected guinea pigs of the same age group. As the disease progresses, the AP values increase with hypocalcemia and simultaneous normo- or hyperphosphatemia. The AP value, like the adspection and other clinical examinations, can only accompany the imaging diagnosis. Without clinical reference, they are not sufficiently meaningful. In principle, a reliable diagnosis can only be made by radiographic examination in two planes (ideally of the skull and long bones), as this allows the bone structure to be assessed.

It is difficult to prove the prevalence of the satin factor in animals that do not have a particularly shiny coat because non-shiny phenotypes are not usually associated with the satin factor genetic defect.

9. Necessary or Possible Measures from an Animal Welfare Perspective

Decisions on breeding or show bans should be made in connection with the exposure category (BK). Depending on the severity and findings, the decisive factor for a breeding ban may be the most severe finding, i.e. the finding that most affects the animal and its classification in one of the burden categories (BC), or also the correlation assessment if there are many individual breeding-related defects.

a) Orders that appear necessary 

Breeding ban (according to § 11b supported order according to § 16a (1) p.1), as it is a defect characteristic of burden category 3.

 b) Possible Orders

Complete elimination of satin guinea pigs from breeding. It is also not possible to use satin carriers for breeding, as it is not possible to predict the extent to which phenotypic expression will occur again in subsequent generations. In addition, there is still no certainty as to whether carriers of the satin factor can also develop clinical or subclinical satin syndrome.

Please note:

Measures taken by the competent authority must be recognizably suitable to prevent future damage to the affected animal and/or its offspring. With regard to the type and depth of processing of orders and breeding bans, decisions are always made on a case-by-case basis at the discretion of the competent authority, taking into account the circumstances found on site.

10.  General Assessment Under Animal Welfare Law

a) Germany

From an animal welfare perspective, guinea pigs with the defect/syndrome described above are to be classified as torture breeding in Germany in accordance with Section 11b TierSchG.

Justification:

According to § 11b TierSchG, it is prohibited to breed vertebrates if breeding knowledge indicates that, as a result of breeding, the offspring or progeny will have, among other things

• body parts or organs for species-appropriate use are missing or unsuitable or deformed for hereditary reasons, resulting in pain, suffering or damage (Section 11b para. 1 no. 1 TierSchG) or
• hereditary behavioral disorders associated with suffering occur (§ 11b Para. 1 No. 2 a) TierSchG) or
• keeping the animal is only possible with pain or avoidable suffering or leads to damage (§ 11b Para. 1 No. 2 c) TierSchG).

Pain is defined in animals as an unpleasant sensory perception caused by actual or potential injury that triggers motor or vegetative reactions, results in learned avoidance behavior and can potentially change specific behaviors (Hirt/Maisack/Moritz/Felde, TierSchG, Kommentar 4th ed. 2023 § 1 para. 12 mwN; basically also Lorz/Metzger TierSchG 7th ed. § 1 para. 20).

Suffering is any impairment of well-being not already covered by the concept of pain, which goes beyond simple discomfort and lasts for a not insignificant period of time (Hirt/Maisack/Moritz/Felde Tierschutzgesetz Kommentar 4th ed. 2023 § 1 para. 19 mwN; Lorz/Metzger, TierSchG Komm. 7th ed. 2019 § 1 para. 33 mwN). Suffering can also be physically and mentally impairing; fear in particular is classified as suffering in the commentary and case law (Hirt/Maisack/Moritz/Felde Section 1 TierSchG para. 24 with further references; Lorz/Metzger Section 1 TierSchG para. 37).

Damage occurs when the physical or mental state of an animal is temporarily or permanently altered for the worse (Hirt/Maisack/Moritz/Felde TierSchG Komm. 4th ed. 2023 § 1 para. 27 mwN; Lorz/Metzger TierSchG Komm. 7th ed. 2019 § 1 para. 52 mwN), whereby completely minor impairments based on a physical or psychological basis are not taken into account. „The target condition of the animal is assessed on animals of the same species.

The premature death of an animal is to be assessed as maximum harm (Hirt/Maisack/Moritz/Felde TierSchG Komm. 4th ed. 2023 § 11b marginal no. 5 with further references)

The breeding of satin guinea pigs fulfills the definition of torturous breeding due to the individual or multiple harms, pain and suffering described in detail under points 5 and 6 as a result of

Reshaping of the coat and associated:

• Osteodystrophy with painful bone and joint diseases,
• degenerative kidney disease,
• behavioral impairments, including withdrawal of a social animal,
• shortened life expectancy.

Body parts or organs (e.g. bones) are deformed for species-appropriate use if one of the essential functions (vital function, self-construction, self-preservation, reproductive function) can no longer be adequately performed, manifests itself in morphological or physiological changes or behavioral disorders that are associated with pain, suffering or damage (Hirt/Maisack/Moritz/Felde TierSchG Komm. 4th edition2023 § 11b Rn. 4; Lorz/Metzger TierSchG Komm.72019 edition § 11b marginal no. 7).

b) Austria

Guinea pigs with the defects/syndromes described above are classified as torture breeding in Austria in accordance with Section 5 TSchG.

Section 5 of the Austrian Animal Welfare Act (TschG) is violated if „breeding is carried out which is foreseeable to be associated with pain, suffering, harm or fear for the animal or its offspring (torture breeding), so that as a result, in connection with genetic abnormalities, in particular one or more of the following clinical symptoms occur in the offspring not only temporarily with significant effects on their health or significantly impair physiological life courses or cause an increased risk of injury“.

Breeding with guinea pigs that suffer from the following defects and the associated problems or that are genetically predisposed to them is to be qualified as torture breeding.

Satin guinea pigs are exposed to an increased risk of injury due to osteodystrophy. The pain associated with the defect is to be regarded as a significant impairment of physiological life cycles. In addition, Section 5 (2) of the German Animal Welfare Act (TSchG) lists in particular*:

• movement abnormalities
• lameness
• Malformations of the teeth, jaw or beak, insofar as these malformations conflict with their physiological functions

*The word „in particular“ means that the list is not exhaustive but exemplary.

The legal framework in Austria is clear and excludes animals that show signs of torture breeding or externally recognizable torture breeding characteristics from sale, purchase or exhibition.

c) Switzerland

Anyone wishing to breed with an animal that exhibits a trait or symptom that may lead to moderate or severe burden in connection with the breeding objective must first have a burden assessment carried out. Only hereditary defects are taken into account in the burden assessment (see Art. 5 of the FSVO Ordinance on Animal Welfare in Breeding (TSchZV)). Animals with defects that can be assigned to burden category 3 are subject to a breeding ban in accordance with Art. 9 TSchZV. It is also prohibited to breed with animals if the breeding objective results in category 3 defects in the offspring. Animals in category 2 may be used for breeding if the breeding objective is for the offspring to be less affected than the parents (Art. 6 TSchZV). Annex 2 of the TSchZV lists characteristics and symptoms that can lead to moderate or severe burden in connection with the breeding objective. Skeletal deformities or malformations, such as movement anomalies or paralysis and degenerative joint changes, are explicitly mentioned. In addition, individual breeding forms are expressly prohibited in accordance with Art. 10 TSchZV. In other cases, however, a breeding ban is only imposed on a case-by-case basis. Animals that have been bred on the basis of impermissible breeding objectives may not be exhibited (Art. 30a para. 4 let. b TSchV).

Detailed legal assessments and/or expert opinions, if already available, can be made available to veterinary offices for official use on request.

11. Relevant jurisdiction

1. Germany: not known.
2. Austria: not known.
3. Switzerland: not known.

12. Order example available?

No.

Examples of orders are only made available to veterinary offices for official use on request.

13. Grants and Funding

14.  Bibliography/ References/ Links

Only a selection of sources on the defects described above and, where applicable, general literature on breeding-related defects on guinea-pigs is given here. More extensive literature lists on the scientific background will be sent exclusively to veterinary offices on request.

Note: The description of health problems associated with the trait, for which there is not yet sufficient scientific evidence, is based on the experience of experts from veterinary practice and/or university institutions, as well as publicly accessible databases or publications from animal insurance companies and therefore originates from different evidence classes.

As breeding and showing are international nowadays, the information does not usually only refer to the prevalence of defects or traits in individual associations, clubs or countries.

Sources:

Altmann, F. D. (2004). Guinea pigs. Ulmer.

Drescher, B., & Hamel, I. (Eds.). (2012). Guinea pigs: Pet and patient (3rd, completely revised and expanded edition). Enke Verlag. https://doi.org/10.1055/b-004-129941

Ewringmann, A., & Glöckner, B. (2005). Guiding symptoms in guinea pigs, chinchillas and degu: diagnostic guide and therapy ; 32 tables. Enke.

Ewringmann, A. (n.d.). Rabbit problem breeding [practice website]. Heimtierpraxis Berlin. https://heimtierpraxis-berlin.de/tierarten/kaninchen/problemzuchten/

Gallego, M. (2017). Case Report of a Satin Guinea Pig with Fibrous Osteodystrophy That Resembles Human Pseudohypoparathyroidism. Case Reports in Veterinary Medicine, 2017, 1321656. https://doi.org/10.1155/2017/1321656

Jordan, J. (2007). Investigations into osteodystrophia fibrosa in the domestic guinea pig (Cavia aperea f. porcellus) of the „satin“ breed: development of a radiographic score to validate the suspected diagnosis [dissertation, Mensch & Buch Verl]. https://refubium.fu-berlin.de/bitstream/handle/fub188/13512/00_dblim.pdf?sequence=1&isAllowed=y

Pelz, I. (2004). More about guinea pigs: Rassen – Haltung – Vererbung (3rd, revised ed.). Oertel und Spörer. https://www.zvab.com/Mehr-Meerschweinchen-Rassen-Haltung-Vererbung-Gebundene/5437015683/bd

Pignon, C., & Mayer, J. (2021). Guinea pigs. In Ferrets, Rabbits, and Rodents (pp. 270-297). Elsevier. https://doi.org/10.1016/B978-0-323-48435-0.00021-6

Prust, G. (1996). Guinea pigs: A book for beginners and advanced breeders. bede-Verl.

Quesenberry, K. E., Orcutt, C. J., Mans, C., & Carpenter, J. W. (Eds.). (2021). Ferrets, rabbits, and rodents: Clinical medicine and surgery (Fourth edition). Elsevier. http://ostochka.ru/gallery/Ferrets,%20Rabbits%20and%20Rodents,%204th%20Edition.pdf

Robinson, R., & Seaborne, S. (1988). Satin Coat in the Guinea Pig. Journal of Heredity, 79(3), 214-215. https://doi.org/10.1093/oxfordjournals.jhered.a110496

Schillinger, V. (2023). Which rabbit breed? Kaninchenwiese e.V. https://kaninchenwiese.de/anschaffung/welche-kaninchenrasse/

Schwarz, T., Störk, C. K., Megahy, I. W., Lawrie, A. M., Lochmüller, E.-M., & Johnston, P. E. J. (2001). Osteodystrophia fibrosa in two guinea pigs. Journal of the American Veterinary Medical Association, 219(1), 63-66. https://doi.org/10.2460/javma.2001.219.63

Stoffels-Adamowicz, E. (2014). The satin syndrome in guinea pigs-Nephropathy, hyperparathyroidism and bone disease of satin cavies [Master thesis, Ghent]. https://libstore.ugent.be/fulltxt/RUG01/002/165/467/RUG01-002165467_2014_0001_AC.pdf