Anatomy and Physiology of the Ferret:
A Brief Overview of How the Domestic Ferret’s Body Is Designed to Eat and Digest Raw and Whole Prey Foods:
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Ferret Teeth:The domestic ferret is equipped with teeth and jaws which are built to efficiently kill prey. The ferret has a total of thirty-four permanent (adult) teeth (incisors, canines, premolars, and molars).[1] Each of these teeth plays a specific role in helping the ferret to catch and consume its prey. The canines, the large fangs located at the front of the mouth, are used to puncture and grip prey.[2] The upper third pre-molar and lower first molar, found near the back of the mouth, in front of the non-carnassial molars, are the carnassial (or sectoral) teeth. The purpose of these teeth is to shear through tissue and bone, much like scissors cut through paper.[3] The non-carnassial molars at the rear of the mouth can be used to crush invertebrates.[4] Incisors are used to help scrape meat off the bone, but it appears that ferrets can continue to eat food with little hindrance if these are lost or damaged.[4] Each of the ferret’s 34 teeth serve a specific purpose and allow for the efficient consumption of raw and whole prey foods.
Ferret Mouth:The ferret has a total of five pairs of salivary glands, the mandibular, parotid, sublingual, zygomatic, and molar.[5] In most creatures digestion begins in the mouth, with enzymes (such as amylase) in the salvia (which is produced by the salivary glands) beginning to break down components in food.[6] Mammalian carnivores, however, (including the domestic ferret) do not begin to digest food in the mouth in the way that humans and herbivores do. Carnivorous animals do not have enzymes for digestion present in their saliva, in fact if a carnivore did have proteolytic (protein digesting) enzymes in their saliva, the oral cavity (mouth) could be damaged by auto digestion (self digestion), instead a ferret’s digestive process begins in the stomach.[7] Food is cut into manageable pieces by the carnassial teeth and then swallowed whole (not chewed).[8] A carnivore does produce saliva, which is acidic and produced in large amounts, but the primary function is to provide lubrication for the esophagus as food is swallowed and transported to the stomach.[8 ]
According the James G. Fox, author of “The Biology and Diseases of the Ferret”:
“Because ferrets tend to ingest their food quickly, it is unlikely that salivary enzymes play a significant role in digestion, as evidenced by demonstration that parotid and submandibular saliva lack amylase* activity (91). For the ferret, it is probable that the lubricant function of the saliva is most important, particularly when the animals are fed a pelleted diet in the laboratory or as pets.”
*Note: Amylase is an enzyme that breaks down starches into sugars. The ferret is an obligate carnivore, and because there is no reason they should be consuming carbohydrates, they have no such need for this enzyme, thus it is not present in their saliva.
Ferret Jaw: The ferret’s jaw, as was previously mentioned, is adapted to killing and shearing prey. The jaw of the ferret has only a vertical motion, its jaw can not move side to side (laterally) and masticate (grind) its food.[8] The structure of the jaw only allows for slicing and shearing motions. The jaw of the ferret is designed in such a way that it does not dislocate when it is opened wide (such as when biting onto a prey animal for the kill).[9] The musculature of the ferret’s jaw gives it a very powerful bite. The masseter is responsible for adducting (closing) the lower jaw.[10] The temporalis also adducts the lower jaw.[11] Lastly, the lateral and medial pterygoids assist the masseter and the temporalis in closing the jaw. [11] In short, the ferret’s powerful jaws are highly adapted to killing and consuming prey.
Ferret Skull: The elongated, flat-topped skull of the ferret is another feature which points to its carnivorous nature. The reason for the skull’s shape is twofold. First, the flat surface of the skull allows for the muscles of the cheeks and jaw to attach efficiently to the top of the head.[12] The bite of the ferret is quite powerful, being driven by strong muscles attached to the jaw. The skull of the ferret is also adapted in another unique way: it is elongated, putting the teeth right out in front; perfect for a ferret running through narrow tunnels and burrows. This is an evolutionary method of both defense and offense. The ferret has its powerful jaws leading through the tunnels in case of a frontal assault, but the ferret can also use this design to catch prey in the same environment.[13]
Ferret Skeletal Structure:The ferret’s vertebrae are slightly longer than those of some other familiar carnivores such as dogs and cats. This gives the ferret its long, unique, streamlined shape. It has a long back, short legs, and elongated neck. This unique combination of body parts allows the ferret to effectively carry its prey through tunnels and burrows without the prey getting caught underfoot and tripping the ferret. [13]
Ferret Digestive Tract:The ferret is an obligate carnivore, and like other carnivores it has a very short digestive tract (relative to humans). A carnivore (such as a ferret) has a digestive tract that is three to four times the length of its body, while an herbivore (such as a cow) has a digestive tract that is greater then ten times the length of its body. [7] Specifically, in the domestic ferret food only takes about three to four hours to digest. [14] Compared to a human’s digestive time of twenty-four to seventy-two hours (depending on what is ingested), this time is minute. [15] This short transit time helps to prevent food-borne bacteria (such as salmonella and E. coli) from affecting the ferret.
Bacteria needs a certain period of to multiply and flourish (incubate) in the gut before it affects the animal, causing it to become ill. For example, for Salmonella bacteria the minimum incubation time is six hours and for E.Coli the minimum incubation time is twelve hours. [16] [17] In most cases, the food has already passed through the system of the ferret before the bacteria has a chance to incubate and multiply to appreciable levels. The reason humans can get salmonella and E. coli has to do with time. Humans have a much longer digestive tract then carnivores and coupled with the extra time it takes humans to digest meat (relative to fruits and vegetables), it is easy to see why humans are such good hosts for such bacteria. While ferrets may be resistant to food borne bacteria, they are not immnue to it. Ferrets can still become infected by salmonella, e. coil, and other food borne bacteria, although the risk is rather minimal.
As for the harder fragments, such as bone, teeth, and claws, the acidity of the stomach helps to wear down any sharp fragments that are ingested; this helps to keep the fragments from perforating the lining of the intestines. [8] The pH of a carnivore’s stomach (even with food present) is usually about 1-2. [17] The pH of the stomach of a fasted ferret is between 1.5-3.5. [18] The pH of a human’s stomach is usually around 2-4.[19] In addition, carnivores have approximately ten times more hydrochloric acid in their stomachs then the human stomach. [8]
These special digestive features help the ferret to efficiently digest raw and whole prey foods without great risk of illness or injury. This does not mean it is impossible for a ferret to sustain internal injury, such as blockages or perforations from ingested bone, teeth, claw, etc (accidents can and sometimes do, occur) it simply means the risks are rather low.
Another way that the ferret’s digestive tract is specifically suited to digest raw and whole prey foods is the way that they derive glucose from the foods they consume. Glucose is a crystalline monosaccharide used by the cells of the body as a source of energy and a metabolic intermediate.[20] It is believed by Elizabeth Hodgkins, DVM, and others (such as Holistic Ferret) that ferrets, and other obligate carnivores, obtain their glucose through a process known as gluconeogenesis (pronounced gloo-coh-nee-oh-jen-a-sis). [21] This is the conversion of amino acids (found in protein) and fat into glucose. [22] Humans obtain their glucose though the breaking down of ingested carbohydrates, which is done through the use of various enzymes. [23] Unlike the liver of the ferret (which is constantly performing gluconeogenesis) the only time a omnivore’s body performs gluconeogenesis is in periods of starvation where the creature’s own muscle protein is broken down and converted into glucose. [24]
A ferret is fully capable of obtaining glucose solely from amino acids and fats and unless the ferret is insulinomic (see here) they have no need for the ingestion of carbohydrates. [21] In fact, excess ingested carbohydrates in the diet of the domestic ferret might cause or contribute to the pancreatic disease, insulinoma (see here).
The liver of an obligate carnivore lacks the ability to down-regulate (slow down) the breakdown of amino acids through gluconeogenesis. As a result, the body has a high need for ingested protein. Without a high consumption of protein, the body begins to break down its own muscle protein, which results in muscle atrophy and nitrogen loss.[21]
The final digestive feature, or rather, lack there of, that points to the ferret’s carnivorous nature is the lack of a ceacum, an organ specifically designed for digesting plant fiber. [25] This organ is present in many animals, including carnivores such as cats and foxes, but the ferret is such a strict carnivore (even stricter then the cat, which is also an obligate carnivore) that it is not equipped with this organ. [25] Since plant fiber is not regularly ingested by the ferret; it has no need for such an organ.
Conclusion:It can be seen that the ferret is not only capable of capturing and digesting raw and whole prey foods, but they are specifically designed to subsist on a diet of ONLY animal products, thus reflective of their classification as an obligate carnivore. A ferret’s body has built in defense mechanisms to protect it (for the most part) from food borne bacteria, intestinal perforations, and more. Infection from food bourne bacteria, intestinal perforations from bone, and blockages can all occur, but due to the physiology of the ferret, the chances of this occurring are rather low.
Although domesticated for almost 2,500 years, the domestic ferret’s internal anatomy and physiology is identical to their wild relative(s). [26] The European polecat (one of the possible ancestors of the domestic ferret) and the domestic ferret bear a striking resemblance to each other, and even are close enough in DNA that they can successfully interbreed. [27] According to noted “ferret expert” Bob Church, ferrets are taxinomically, genetically, reproductively, and specifically very similar, if not identical, to the European polecat (one of the possible ancestors of the domestic ferret).[27]
Ferrets and polecats are so remarkably similar, because the purpose of domestication is to tame and breed animals for human use, and this can be done without altering the internal anatomy and physiology of the animal. [28] Due to the fact that the ferret’s internal anatomy and physiology is very similar, if not identical to that of the European polecat, the domestic ferret is still perfectly capable of consuming and thriving upon the same foods as their ancestors.
References1. James G. Fox, Biology and Diseases of the Ferret, 2nd ed. (Baltimore: Lippincott Williams and Wilkins, 1998), 36.
2. Jan Bellows D.V.M. DipAVDC, “Ferret Dentistry,” in VeterinaryPartner (June 27, 2002),
www.veterinarypartner.com/Content.plx?P=A&A=140&S=1&SourceID=1.
3. Webster’s New World College Dictionary, 3d ed, “carnassial”
4. Bob Church, “What About A Ferret’s Teeth?” in FerretCentral (February 27, 1998),
www.ferretcentral.org/faq/history.html#teeth.
5. John Henry Lewington, Ferret Husbandry, Medicine, and Surgery(Elsevier Health
Sciences, 2000), 16.
6. Webster’s New World College Dictionary, 3d ed, “saliva”
7. Milton R. Mills, MD. “The Comparative Anatomy of Eating,” in Ladet: Love Animals,
don’t eat them,
www.geocities.com/RainForest/2062/ana.HTML.
8. Wendy Volhard, “Feeding Your Dog for Optimum Health and Longevity,” in Know Better Petfood,
www.knowbetterdogfood.com/dogcare/health/nutrition.php.
9. James G. Fox, Biology and Diseases of the Ferret, 2nd ed. (Baltimore: Lippincott Williams and Wilkins, 1998), 21.
10. Victoria Clayton and Catherine Lenox, “Ferret facial and masticatory muscles,” Duke University, Duram, NC.
www.baa.duke.edu/companat/jaw%20facial%20mm/ferret/ferretface.htm.
11. James G. Fox, Biology and Diseases of the Ferret, 2nd ed. (Baltimore: Lippincott Williams and Wilkins, 1998), 27.
12. James G. Fox, Biology and Diseases of the Ferret, 2nd ed. (Baltimore: Lippincott Williams and Wilkins, 1998), 20.
13. Bob Church, “What is a ferret’s skeletal structure like?” in FerretCentral, (February 27, 1998),
www.ferretcentral.org/faq/history.html#skeleton.
14. Cathy A. Johnson-Delaney, DVM, Dipl ABVP (Avian), “Anatomy and Physiology of the Gastrointestinal System of the Ferret and Selected Exotic Carnivores,” (AEMV proceedings, 2006), 29.
15. Michael Picco, MD., “Digestion: How long does it take?” in Mayoclinic (August 8, 2008),
www.mayoclinic.com/health/digestive-system/AN00896.
16. “Salmonellosis (Public Health Concerns for the Farm Family and Staff)”, ChronicleOnline, December 1, 1997.
www.news.cornell.edu/releases/Jan98/DT104facts.html. (Accessed August 26, 2008)
17. Calvin B Johnson, M.D., M.P.H., Secretary, “Communicable Diseases Fact Sheets: Escherichia colia O157:H7 (E. coli)” in Department of Health,
www.dsf.health.state.pa.us/health/cwp/view.asp?A=171&Q=230380.
18. James G. Fox, Biology and Diseases of the Ferret, 2nd ed. (Baltimore: Lippincott Williams and Wilkins, 1998), 116.
19. Barbara Fouge`re, BVSc, The Pet Lover’s Guide To Natural Healing for Cats and Dogs, (Saint Louis: Elviser Saunders, 2006), 65.
20. Webster’s New World College Dictionary, 3d ed, “glucose”
21. How do you cite a patent?
www.wipo.int/pctdb/en/wo.jsp?IA=US1999020171&DISPLAY=STATUS22. Charles E. Ophardt, Virtual Chembook (2003),
www.elmhurst.edu/~chm/vchembook/604glycogenesis.html.
23. how humans obtain glucose
24. Geoffrey Zubay, Biochemistry, (New York: Addison Wesley, 1993)
25. Victoria Clayton and Catherine Lenox, “Ferret digestive system,” Duke University, Duram, NC.
www.baa.duke.edu/companat/Digestive%20system/ferret/ferret%digestive%20system.htm.
26. Kevin Schargen, DVM, PC, “Gotta Eat Meat,” Ferrets USA 13 (2008): 37-42.
27. Bob Church, “What is the difference between a ferret and a polecat?,” in Ferret Central,
www.ferretcentral.org/faq/history.html.
28. Webster’s New World College Dictionary, 3d ed, “domesticate”
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For Additional Information On This Topic, Please Visit:1.) Anatomy of the Ferret: www.mfran.org/medical_information/Anatomy/Anatomy.htm2.) Bob Church’s Article on What Makes a Ferret a Carnivore www.ferretcentral.org/faq/history.html#carnivores
3.) Bob Church’s Article on the Ferret Skeleton www.ferretcentral.org/faq/history.html#skeleton4.) Bob Church’s Article on Ferret Teeth www.ferretcentral.org/faq/history.html#teeth5.) Bob Church’s Article on Polecats and Ferrets www.ferretcentral.org/faq/history.html6.) Musculature of the Ferret Face (photo and text) www.baa.duke.edu/companat/jaw%20and%20facial%20mm/ferret/ferretface.htm7.) Ferret Digestive System (photo and text)www.baa.duke.edu/companat/Digestive%20system/ferret/ferret%digestive%20system.htm8.) Feeding Your Dog for Optimum Health and Longevity (article is relevant to ferret anat/phys)
www.knowbetterdogfood.com/dogcare/health/nutrition.php9.) Biology and Diseases of the Ferret, (Chapter 2: Anatomy of the Ferret and Chapter 4: Physiology of the Ferret) By James G. Fox. www.amazon.com/Biology-Diseases-Ferret-James-Fox/dp/0683300342