The client should be instructed to telephone in advance to book an examination of a ferret. In this way a brief history can be taken in order to determine the type of problem and its urgency as well as to give advice on any fasting that may be necessary. If it is thought that blood tests or sedation will be required, a fasting period of about 4 hours is advised, but no longer than 6 hours because if the animal has an insulinoma a severe hypoglycaemic crisis could occur. If it is thought that the animal might need to be admitted, it can also be suggested that the ferret is brought to the clinic in its cage (if this is not too large), rather than a carry box, with a small supply of its favourite food. For routine appointments, the ferret can be safely transported in a carry box for cats. If accustomed to living together, more than one ferret can be left together in the carry box or cage. Clients coming for the first time should be asked to bring some packs of the commercial food that they give to their ferret in order to check the composition and determine whether the food is suitable.
RESTRAINT
Ferrets are normally docile and used to being handled; however, they do have the defect of biting without any warning. Because of their sharp canines, they can inflict extremely painful and tenacious bites. Although it can be useful to ask the animal’s owner in advance about the ferret’s character (e.g. whether it tends to bite), for prudence, a ferret should never be approached with an outstretched hand, but rather the animal should be allowed to come out of the carry box spontaneously and should then be grasped from above, surrounding the shoulder girdle with one hand (Fig. 1).
Placed in a new environment, ferrets are not usually intimidated; indeed, they are curious and try to explore it. Consequently, when put on an examination table, they do not stay still for more than a few seconds. Most ferrets will let themselves be handled tamely, but do not tolerate being restrained; for this reason it is better not to use rigid constraint, but rather delicate handling, perhaps passing the animal from one hand to another, indulging its movements.
In the case of aggressive subjects, effective, safe restraint that is safe for both the animal and the handler requires a certain practice. If the animal is grasped firmly with one hand around its neck and the shoulder girdle, it cannot twist round and bite, but in practice it is difficult to examine the animal thoroughly and in this case brief sedation, achieved with a gaseous anaesthesia administered via a face mask, may be more productive.
The technique for lifting a ferret is to surround the chest with one hand and support the hind limbs with the other (Fig. 2). As with kittens, lifting a ferret by the scruff of the neck immobilises it temporarily, which allows brief, non-painful manipulations. The offer of very tasty food (for example, vitamin preparations for ferrets, flavoured laxative pastes for cats) sometimes distracts the animal for sufficient time to perform injections or brief, short-lasting manipulations. Ferrets do not usually support the introduction of an otoscope into their ears; even when a ferret is sedated it tends to shake its head vigorously during this examination.
If necessary, anaesthesia with isoflurane, which is well tolerated, can be used for disturbing or painful clinical procedures (e.g. sampling and biopsies) or to examine rebellious animals. Induction via a mask is fast, as is the subsequent awakening. Since the haematocrit starts to fall within a few minutes of starting anaesthesia (because of splenic sequestration), any blood samples must be taken as the first procedure.
HISTORY
As for all species, the history should always be taken in detail and systematically in order to collect the important information.
Age
Many pathologies are more frequent in certain age ranges (e.g. ingestion of foreign bodies in the young, onset of adrenal disease after 3-4 years).
Origin
Ferrets imported from intensive breeding facilities in foreign countries (e.g., USA, the Netherlands, New Zealand) are sterilised early and are more susceptible to endocrine disorders; they are usually marked with a tattoo (e.g. two dots on the ear of American Marshall ferrets).
Gender and reproductive state
Sexually intact females are subject to hyperoestrogenism during oestrus; spayed females may have residual ovarian tissue.
Vaccination history
Ferrets must be vaccinated regularly against distemper throughout their life.
Prevention of heartworm disease
In endemic regions, the prevention of filariasis is essential also in ferrets. The owner must be asked which product has been used and it should be checked that it has been used regularly for the whole period necessary.
Cage
Size: check that the cage is sufficiently spacious.
Type of furniture: are there dangerous objects inside the cage?
Home environment
How much time does the animal spend outside the cage? Ferrets need to be left free for a few hours. Have the surroundings been made safe and is the ferret watched while it is free? The environment outside the cage is a source of many dangers, in particular toxic substances, foreign bodies, falls from heights and being crushed.
Type of games
Soft, rubber toys are usually ripped apart and eaten, which can cause intestinal obstruction.
Diet
Type of food (including snacks and various rewards) and the frequency of its administration. It is worth controlling the label of the food administered, to check its composition and percentage fibre content. Unsuitable food can predispose to bowel disorders (inflammatory disease, diarrhoea), urinary tract stones and insulinoma. The type of any snacks given is important: all food of vegetal origin and any containing carbohydrates are contraindicated.
Other ferrets present and their state of health
A disorder that appears soon after the introduction of a new ferret raises the possibility of an infectious condition.
Other animals and their state of health
The main disorders that a ferret can catch from dogs and cats are distemper, dermatophytosis (rare) and pulicosis (common).
Contact with humans with influenza
The ferret is susceptible to human influenza virus.
Past medical history and treatments
Investigate the time of onset, symptoms and course of any past medical problems, their treatments and the results of the treatments.
History of the current health problem
When the problem appeared and with what signs, how these have changed over time, any treatment and its results. It should be remembered that ferrets, particularly elderly ones, may have several important disorders concomitantly.
- Specific questions
- level of activity, exercise tolerance
- change in appetite or thirst
- change in state of nutrition
- presence of drooling or vomiting
- appearance and consistency of the faeces, presence of melaena, blood or mucus
- frequency of bowel movements
- tenesmus
- presence of blood in the urine
- changes in the animal’s coat
- abnormal behaviours
Sialorrhoea may appear in the case of nausea (also in the case of insulinoma), ulcers, injuries or inflammation of the oral cavity, oral foreign bodies and reactions to the taste of drugs or gaseous anaesthesia.
Vomiting may develop in the case of gastroenteritis, foreign bodies, hypoglycaemia, megaoesophagus (in which case, it is actually regurgitation), renal failure and poisoning.
Diarrhoea can appear in the case of gastroenteritis, foreign bodies, parasites, neoplasms, Aleutian disease and inflammatory bowel disorders. In fasting animals the bile pigments become stronger giving the faeces a green colour, although this is not strictly specific to a pathological condition.
Melaena besides being a sign of infection and non-infectious gastrointestinal disorders, may be caused by the administration of non-steroidal anti-inflammatory drugs, poisoning, Aleutian disease, hyperuraemic ulcers and clotting disorders.
CLINICAL EXAMINATION
During the examination it is advisable to observe the ferret while it moves freely around the room to evaluate its state of attention, ambulation and sight. A ferret usually explores a new environment carefully and tries to squeeze into any opening. The animal normally has a well-arched back (Fig. 3). The ferret will often urinate and defecate in a corner, enabling a fresh specimen of faeces to be collected. An empty bladder makes it easier to palpate the abdomen. A frightened or excited ferret shows a characteristic piloerection of the fur on its tail (Fig. 4).
Having assessed the animal’s attitude and sensorium, the direct physical examination of the ferret is performed. Its weight, which should be recorded regularly, is a very useful datum for comparison with the animal’s previous condition (taking into account the physiological increase in weight during the cold season). The nutritional status is, however, evaluated by palpation of the muscle mass (in particular at the level of the shoulder and pelvic girdles and the vertebral column) and of the layer of adipose tissue (which may be especially abundant in the abdomen and groin) (Fig. 5). It is important not to confuse ascites with obesity. Elderly ferrets usually have less muscle mass. The state of hydration is not evaluated well from a skin fold because the skin of the ferret is less elastic than that of the dog or cat; hydration in the ferret is better assessed from the moisture of the mucosal membranes, which should be pink.
The nasal planum (Fig. 6) must be clean and slightly moist, without discharges or crusts; a dry nasal planum may indicate dehydration and fever. Sialorrhoea, swellings and submandibular lymphadenopathy should not be present. The oral mucosae should be pinkish and slightly moist. The venous return time should be 1-2 seconds. Shock or anaemia (due to internal or external haemorrhages, blood clotting disorders, oestrogen toxicity) may cause pale mucosae.
The oral cavity is inspected to control the state of the teeth and the gums (Fig. 7). If the ferret does not cooperate, it can be induced to open its mouth by suspending it briefly by the scruff of the neck: in this situation it usually opens its mouth widely to yawn. A more thorough examination may require sedation. Broken canines, tartar (Fig. 8) and gingivitis are commonly seen, especially in older ferrets and those not fed correctly. Masses and ulcerations should not be present (e.g. a sublingual mass could be a ranula, while a gingival mass could be an epulis or other type of tumour).
The periocular region should be clean and without discharges (Fig. 9). The eyes of ferrets, which are relatively small, are not easy to examine carefully. The menace response is physiologically absent, but a strong light induces closure of the eyelids. Visual capacity is difficult to evaluate, in part because ferrets often brush objects when they move. The sclera should be white and the cornea clear, transparent and without vessels. Fluorescein can be used, if necessary, to assess whether corneal ulcers are present. Bacterial conjunctivitis is uncommon; mycobacterial forms of conjunctivitis are, however, possible and are manifested by a strong inflammation and thickening of the third eyelid (Fig. 10).
The pupils have a horizontal aperture; direct and consensual reflexes should be present. The normal intra-ocular pressure is 23 ± 5 mmHg. Retinal atrophy may be present in elderly animals. Immature and complete cataracts are common (Fig. 11).
The presence of even large amounts of brownish wax in the auditory canal can be normal (Fig. 12) and is not necessarily related to acariasis (which, moreover, is often asymptomatic in ferrets). The presence of parasites (Otodectes cynotis) can be confirmed by collecting the wax on a cotton bud and observing it under a microscope after having diluted it with paraffin wax.
The submandibular, pre-scapular, axillary and popliteal lymph nodes, which are not usually very evident, can become palpable. In obese subjects they can be surrounded by an adipose panniculus, which can give the false impression of enlarged lymph nodes. The main causes of lymphadenomegaly are lymphoma and malignant metastases.
The coat should be thick and shiny, without areas of hair loss, although alopecia of the tail in the cold season can be normal. The main cause of alopecia is adrenal disease (Fig. 13). Cutaneous lymphoma may present with alopecia (Fig. 14).
Pushing aside the hair enables close inspection of the skin, which should not have scabs, growths, petechiae or parasites. Intense pruritus can induce self-inflicted injuries; the most common cause of pruritus in the ferret is adrenal disease, whereas allergy to flea-bites is less common. Pyodermatitis in the ferret is rare, as is dermatophytosis.
Auscultation is performed with a paediatric stethoscope (with a small head), first with the ferret standing on all four legs and then with the animal suspended by the nape (which causes a marked decrease in heart rate through a vagal reflex). The heart, which is in a relatively caudal positition, is auscultated from both sides of the chest and at the level of the sternum. The normal heart rate is 180-250 beats per minute and it is, therefore, difficult to detect murmurs or arrhythmias. A marked respiratory arrhythmia is normal (increased heart rate during inspiration). Murmurs may be associated with cardiomyopathy, stenosis or regurgitation of valves, anaemia and heartworm disease.
The evaluation of respiration should be started by observing the characteristics of the animal’s breathing (rhythm and depth). Tachypnoea and dyspnoea may be caused by fear, pain, fever, pneumonia, pulmonary oedema, filariasis, pleural effusions due to cardiac, neoplastic or infectious problems, pneumothorax, thoracic or abdominal masses and diaphragmatic hernias.
The visual inspection is followed by chest auscultation. Normal respiratory sounds are usually very mild. Abnormal breath sounds may be due to pneumonia, respiratory allergies, heart disorders or heartworm disease.
The abdomen should be palpated, which is facilitated by the elongated shape of the ferret and made even easier if the animal is suspended vertically. The palpation should be performed gently in order not to rupture diseased organs or a full bladder. The stomach is not normally palpable because it is protected by the rib cage. The liver may be enlarged because of congestion, lipidosis or neoplasm; in this last case the increase in the organ’s size can by notable. Palpation of the bowel should not cause pain and the bowel should not give the sensation of being full of air or fluid. The intestinal loops, usually soft, may be thickened as a result of inflammation or neoplasms (e.g. lymphoma).
Anomalies that can be found during palpation are enlarged organs, foreign bodies in the bowel, enlarged lymph nodes and pain responses (due to gastroenteritis, foreign bodies, urinary tract stones, urethral obstruction, splenomegaly, peritonitis). An increase in the volume of the abdomen may be due to ascites, splenomegaly, neoplasms or gastric dilation.
The spleen is easily palpable on the left hand side of the body and can have a notable volume without this being of pathological significance. The spleen must be homogeneous and not contain masses. Splenomegaly may be secondary to many disorders and may be due to lymphoma, haemangioma, haematoma; furthermore it accompanies a vast range of pathologies, such as insulinoma, adrenal disease, respiratory tract infections and cardiomyopathies, but is also a frequent finding in clinically normal ferrets. In rare cases an enlarged spleen is due to hypersplenism.
The kidneys are easily identifiable by palpation, during which their size and symmetry should be determined; renal cysts, sometimes of considerable size, are found quite commonly. Other causes of kidney enlargement include hydronephrosis, lymphoma and other tumours. The kidneys can be surrounded by notable amounts of adipose tissue, which should not be confused for pathological growths. The adrenal glands can be identified by palpation, if greatly enlarged. The bladder is small even when full; in the case of urethral obstruction, it can expand greatly.
The external genitalia are inspected in order to determine or confirm the animal’s gender. In females it is important to check the vulva to assess any increase in volume. The vulva may be enlarged during normal oestrus in sexually intact jills (Fig. 15), because of the presence of residual ovarian tissue in incorrectly spayed sprites, or because of the development of adrenal disease. A vulvar discharge may be observed in cases of vaginitis or pyometra (Fig. 16).
In sexually intact males, the testicles are assessed (Fig. 17). The testicles vary in size greatly, depending on the season, and become very small during the cold season. Cryptorchidism or (more rarely) testicular tumours may be found. The prepuce is examined for the presence of masses or exudates. Anal sacs are not present in animals from industrial breeding facilities that have been sterilised at a young age. Infections or neoplasms of the anal sacs are found rarely
The anus is examined for the presence of lesions, inflammation, prolapse, traces of diarrhoea and melaena. Rectal prolapse may be secondary to coccidiosis, a proliferative bowel disease, infection by Campylobacter spp., neoplasms, distemper and urinary tract stones.
The tail can show various degrees of alopecia, which may be physiological, particularly in the cold season. However, this is the part of the body which most commonly shows the first signs of the alopecia induced by adrenal disease (Fig. 18). Abundant comedones are frequent. Typically roundish tumours, called chordomas, may develop on the tail, especially at its tip (Fig. 19).
Theoretically, the neurological examination is the same as that carried out in dogs and cats, with the exception that the menace response is weak or absent. The ferret is, however, difficult to assess precisely because it generally does not collaborate well with the various manipulations. The sensorium and movement (strength and symmetry) are assessed first and then the cranial nerves. Nystagmus is difficult to detect because the sclera are not visible.
Proprioception is evaluated by the animal’s jumping and postural reactions. The patellar and retraction reflexes are useful for determining whether a lesion should be attributed to a lower motor neurone disease, that is, a peripheral disorder (decreased or absent reflexes) or to an upper motor neurone disease (increased or normal reflexes). The perception of pain and reflex withdrawal of the limbs are also assessed. In normal conditions, touching the anus with a blunt instrument stimulates the anal reflex with constriction of the sphincter; contemporaneously the ferret turns to see what has touched it.
Primary neurological disorders are rare in ferrets, whereas weakness of the hindquarters, or even paraparesis, is a common sign of numerous disorders, not all of which are neurological: cerebral or spinal lesions, hypoglycaemia, heart failure, anaemia, intestinal disorders, urethral obstruction, poisoning, etc. Seizures may be secondary to hypoglycaemia (the most common cause), trauma, infections of the central nervous system, poisoning, tumours, liver or kidney failure, etc. Idiopathic epilepsy has never been reported in the ferret. Aleutian disease can cause ataxia, incoordination, paresis or paralysis.
Taking the temperature is a very irritating procedure for a ferret and is, therefore, carried out at the end of the examination. It should, however, be noted that if the animal is very agitated during the examination, its body temperature may be falsely high. It is preferable to use a digital thermometer with a flexible tip since glass thermometers can break if the ferret struggles during the measurement.