Lecture 2 -- Small ferrets

What is the taxonomic classification class of ferrets?

Mammalia

What order do ferrets belong to?

Carnivora

What family do ferrets belong to?

Mustelidae

What term refers to female ferrets?

Jill

What term describes a neutered female ferret?

Sprite

What term refers to male ferrets?

Hob

What term refers to neutered male ferrets?

Gib

What term refers to baby ferrets?

Kitten or pup

What is the lifespan, weight and length of a ferret?

Lifespan: 6-9years

Weight: 0.6 -2kg

Length: 30-60cm

Describe the coat of a ferret

Fine dense undercoat with second layer of course guard hairs

What anatomical adaptation helps ferrets during mating and fighting?

Thick skin and hair over back of neck

→ Prevent against injuy during fighting and mating

Why are ferrets prone to heatstroke?

No sweat gland

What type of scent glands do ferrets have all over their body?

Sebaceous gland (Higher density around mouth and anus)

→ Secretion increased during breeding season → Coat becomes yellow

What changes occur in a ferret’s coat during the breeding season?

Sebaceous glands secretion increase → Cause the coat to become oily and yellow

What other scent glands do ferrets have? Where is it located? Where do the anal gland ducts open?

Anal glands

Located just inside the anus

Open at the 4 o’clock and 8 o’clock positions around the anus.

What do anal glands produce?

A serous, yellow liquid with a powerful odor.

What is an anal sacculectomy? Is anal sacculectomy legal in the UK?

Anal sacculectomy = Surgical removal of the anal glands

Ilegal (unless there is a medical reason)

Where does most of a ferret’s smell actually come from?

Primarily from sebaceous glands, not the anal glands

What spinal feature makes ferrets efficient hunters and able to escape through small spaces?

Long and flexible spine → Can squeeze through small space to get out of an cage

How many toes do ferrets have, and what is special about their claws?

Five toes per foot

Non-retractable claws → Require regular claw trimming if kept as pets to prevent overgrowth

What is the vertebral formula of a ferret?

C7 T15 L5 S3 Cd18

What is special about the ferret’s zygomatic bones and orbit?

The zygomatic arch is unclosed, forming an open orbit, similar to dogs.

Describe the relative size of the ferret’s jaw and cranium

Short jaw with a large cranium

How is the ferret jaw adapted for feeding?

Little to no lateral movement → Allow them to tear and shear 折斷 meat (Not chewing)

What type of vision do ferrets have? What advantage does this give?

Binocular vision = Eyes placed laterally

• Given good peripheral vision

What are the special features of a ferret’s eyes, and how are they adapted to its natural behavior?

Ferrets hunt mainly at night → Their eyes are well adapted for their nocturnal activity

• Sees well in dim light

• Sees movement rather than pictures

• Large domed 圓形拱頂 cornea

• Spherical 球形 lens

• Pupil slit is horizontal rather than vertical slit

• Have tapetum lucidum

• Well developed nicitiating membrane

What is the deciduous dental formula of ferrets?

Deciduous: 4/3, 1/1, 3/3, 0/0

What is the permanent dental formula of ferrets, and total number of teeth?

Permanent: 3/3, 1/1, 3/3, 1/2 → 17×2 = Total 34 teeth

What is special about ferret canines and premolars?

Canines: Long and curved

Upper 3rd premolar: Has three roots

Do all ferrets’ teeth have roots?

Yes

When do kittens teeth erupt in ferrets?

3-4weeks

Why can young ferret teeth cause issues while nursing?

Since kittens’ teeth erupt before they finish nursing, they can cause damage to the mother’s teats

When do permanent teeth erupt in ferrets?

50-74 days

What is the primary function of ferret saliva? Why?

Since ferrets are carnivores (Mainly eat meat), their saliva primarily functions to help lubricate food rather than digestion

How many paired salivary glands do ferrets have?

• Submandibular

• Parotid

• Sublingual

• Molar

• Zygomatic

Which ferret salivary glands have no amylase activity?

Parotid and submandibular glands

What type of muscle is found in the ferret oesophagus? Why?

Striated muscle throughout the entire length (Facilitate quick contraction for swallowing)

Does the ferret oesophagus resemble that of a dog or a cat?

Dog

• Cats: Striated muscles only in the proximal third

Apart from the jaw structure, what adaptations of the stomach allow ferrets to swallow food without chewing?

Stomach is capable of enormous distension → Allow gorging 狼吞虎嚥

Can ferrets vomit? Why?

Yes

• No true gastro-oesophageal sphincter

What are the nutritional requirements of ferrets?

• Obligate carnivores

• Lack the ability to digest fibre (>4% dietary fibre can cause issues)

  • 35-40% protein

  • 20% fat

  • <25% carbohydrate

  • Ca:Phos ratio ~1:1

Should ferrets be fasted before surgery? Why?

No

• Rapid intestinal transit time → Risk of hypoglycaemia

• Spontaneous secretion of HCl even when they are not fed

How should ferrets be fed before surgery?

Feed 2-3hours before surgery

What structures are absent in the ferret GI system?

1. Cecum

2. Appendix

3. Ileocolic junction/valve = No distinct separation between small and large intestine

What is the normal respiratory rate for ferrets?

30–40 breaths per minute

Are ferrets obligate nasal breathers?

No but they preferentially breathe through the nose

Why is placing an NG tube in ferret challenging? What would be a better choice instead?

• Small nostrils → Not much room to pass a NG tube

• Oesophagostomy tube is a better choice

How many lobes are in the left and right lung of a ferret?

• Left: 2 (Cranial and caudal lobes)

• RIght: 4 (Cranial, midddle, accessory and caudal)
  

What is the special feature of a ferret’s respiratory system in terms of lung volume and the thoracic cavity?

• Large volume of lungs

• Large narrow thoracic cavity

• Narrow thoracic inlet

Why is the narrow thoracic inlet clinically important in ferrets?

Any abnormality e.g. tumor or foreign body can quickly cause severe respiratory compromise.

What is the resting heart rate of a ferret?

180–250 bpm.

Where is the ferret heart best auscultated?

Around the 6th–8th rib, near the diaphragm

Is pulse pressure a reliable indicator of cardiac output in ferrets?

No, pulses are difficult to palpate and pulse pressure is unreliable

How can we indirectly assess cardiac output in ferrets?

By monitoring urine output

Less than 1 ml/kg/hr may indicate low cardiac output

What is the approximate blood volume in ferrets?

5–7% of body weight

How much of a ferret’s blood volume can be safely sampled over 28 days?

No more than 15% of total blood volume

What PCV can be normal in ferrets?

PCV in ferret is high → Up to 61% can be normal

Do ferrets require cross-matching before blood transfusion?

No, blood from another ferret can be used without cross-matching

What are the main sites for blood sampling in ferrets?

• Cephalic vein

• Jugular vein

Is the tail artery used for blood sampling in ferrets?

Yes but less common → May be used in laboratory animals

How do ferret kidneys compare anatomically to dogs and cats?

Similar anatomy to dog s and cats

→ Bean-shaped, sit close to the adrenal glands.

How does ferret serum chemistry compare to dogs and cats?

Ferret serum chemistry is different from that of dogs and cats

• Kidney disease in cats and dogs: Creatinine rises in parallel with urea

• Kidney disease n ferrets: Creatinine often excreted through other routes → Does not end up in blood → Creatinine does not rise in parallel with increased urea

What can cause urethral blockage in ferrets?

• Prostate enlargement (Often associated with adrenal disease)

• Urolithiasis = Urinary stones (Less common)

Why is catheterisation difficult in male ferrets?

Because of the J-shaped os penis

At what age do ferrets reach puberty?

6-9 months

What type of breeders are ferrets?

Seasonal breeder - monoestrus

Are ferrets spontaneous or reflex ovulators?

Reflex ovulators = Ovulation occurs after mating

What is the gestation period in ferrets?

42days

How many litters do ferrets have per year, and how many kits per litter?

1 litter per year, up to 6 kits per litter

How can we distinguish male and female ferrets?

• Males:

  • Larger size than females

  • Obvious testes and penis

  • Preputial 陰莖包皮 opening on abdomen, cranial to genital area

• Females:

  • Smaller size than males

  • Vulva under tail, cranial to anus

What type of uterus do ferrets have: bicornuate or duplex?

Bicornuate uterus = Y-shaped, with two uterine horns that join into a single cervix.

What are the key features of the male ferret’s reproductive anatomy?

Anatomy similar to the dog

Testes are small relative to body size

Major difference: J-shaped os penis

What happens if female ferret fail to mate?

Jills are reflex ovulators = Only ovulate after mating → Fails to mate → Stays in oestrus → Prolonged oestrogen secretion → Too much oestrogen causes bone marrow suppression → Anaemia → Death

Why is routine spaying of all female ferrets (jills) not always recommended if they are not intended for breeding? How should they be managed?

• Neutering removes negative feedback from LH and FSH → Increase GnRH production → Cause adrenal disease → Immunosuppression

• Management:

  • Female ferret must be mated

  • Sham-mated by vasectomised 輸精管切除術 hob 擱架

  • Chemical oestrus suppression drugs

Where are the adrenal glands located in ferrets?

• Near each kidney, embedded in fat and covered by peritoneum

What major vessel lies ventral to both adrenal glands in ferrets?

Ipsilateral 同側 adrenolumbar artery

What clinical signs may be seen with adrenal disease with ferrets?

• Alopecia = Hair loss

• Behavioural changes: Aggression

• Swollen vulva (Females)

• Increase sex hormone → Swollen prostate → Difficulty urinating (Males)

• Muscle loss

What are the major risk factor for adrenal disease in ferrets, and what is the mechanism?

• Neutering in both males and females

  • Loss of negative feedback → Increased GnRH production → Increase LH and FSH → LH stimulates adrenal cells → Immunosupression → Hyperplasia 前列腺變大 and neoplasia 腫瘤形成

• Abnormal photoperiod

  • Ferrets come into season in response to increasing daylength

  • Animals housed indoors subject to abnormally long periods of daylight → Decrease level of melatonin → Increase hypothalamic activity → Increase GnRH → Increase LH and FSH

Which adrenal zone is responsible for hormone overproduction in ferret adrenal disease?

Zona reticularis

Which hormones are overproduced in ferret adrenal disease?

• Estradiol

• Androsterone and testosterone

• 17-alpha hydroxyprogesterone

Are corticosteroids overproduced in ferret adrenal disease?

No as there is no association with pituitary gland

P.S. Pathology to adrenal disease in ferrets is different as in dogs → Overstimulation of pituitary gland in dogs might cause adrenal disease

How can adrenal disease in ferrets be prevented?

1. Keep entire jills with a vasectomised male → Induces ovulation

2. Use GnRH agonist injections → Prolong exposure of GnRH induce negative feedback Reduce release of LH → Reduce stimulation of the adrenals

3. Neuter only when sexually mature + Use a GnRH agonist in addition to surgical sterilisation