P R A C T I C E - AEMV

Exotic Pet 

P R A C T I C E 

VOLUME 5 • ISSUE 2 • FEBRUARY 2000 

Over the years, many of our readers have requested that an issue of Exotic Pet Practice be solely devoted to one 

species. This issue on ferrets is the first of two planned for the year 2000. Let us know what you think about this 

changed format. Please send your correspondence to Susan Sibiski, 526 Cole Ln, Baltimore, MD 21220, or send 

e-mail to ssibiski@home.com. 

SCIENTIFIC ARTICLE 

Heart Disease in Ferrets 

Michael A. Dutton, DVM, Dipl ABVP–Companion Animal Practice 

Heart disease is common in ferrets. Currently the two most common causes 

of heart disease are heartworm and dilated cardiomyopathy. Other causes 

include hypertrophic cardiomyopathy, myocarditis, and valvular disease. 

Diagnostics 

Initial diagnosis is based on history, radiology, and physical examination. It 

has been recommended that ferrets have annual thoracic radiographs starting 

at the age of 5 years to detect signs of heart disease. Historically, the symptomatic 

ferret may exhibit signs of lethargy, raspy breathing, rear leg weakness, 

or intolerance of prolonged activity. Many other ferret diseases can give similar 

symptoms, so it is important to follow up with testing. Physical examination 

may reveal moist rales, gallop rhythms, or tachypnea on auscultation. 

Abdominal ascites, hepatomegaly, or splenomegaly are also possible. Because 

of the similarity between the symptoms of heart disease and other common 

ferret diseases, a complete blood count (CBC), biochemical profile, and occult 

heartworm test should be considered to allow for an accurate diagnosis. 

Radiographically, signs of heart disease include generalized cardiomegaly, 

pulmonary edema, pleural effusion, and pulmonary vein enlargement. 

Practitioners can also have a “whole body” radiographic test done to check 

abdominal structures. Abdominal abnormalities with heart disease can 

include ascites, hepatomegaly, splenomegaly. Additional cardiac-specific tests 

include electrocardiography (ECG) and ultrasonography. If fluid is present, 

abdominocentesis or thoracentesis with fluid analysis may be performed. 

Dilated Cardiomyopathy 

Dilated cardiomyopathy (DCM) is a common finding in mature ferrets. In 

a practice that uses thoracic radiographs as a screening tool, many cases are 

symptom free. In symptomatic ferrets, signs include lethargy, dyspnea, 

weight loss, or lack of appetite. On radiographs, DCM has similar signs as in 

other species; these signs include cardiomegaly, pleural effusion, increased 

interstitial pattern to lungs, and abdominal changes mentioned above. ECG 

changes may be noted, as in other species. 

If possible, ultrasound should be performed to determine whether digoxin 

should be administered at this time. One set of data has a normal fractional 

shortening of 42%. 1 Values less than this warrant the administration of 

digoxin. Therapy is based on test results and the clinical condition of the ferret. 

Mild cases of DCM coupled with normal ultrasound results may only be 

managed with a diuretic agent. 

More severe cases may need 

digoxin added along with 

angiotensin-converting enzyme 

(ACE) inhibitors. Ferrets experiencing 

respiratory distress may require 

thoracentesis if pleural effusion is 

present, in addition to oxygen therapy 

and use of nitroglycerin, digoxin, 

diuretics, and ACE inhibitors. 

Response to therapy requires 

repeated radiographic tests and 

ultrasonography at an appropriate 

time interval. 

Heartworm Disease 

In ferrets, heartworm disease 

causes cardiac and respiratory diseases 

such as lethargy, coughing, 

dyspnea, ascites, and, in a few 

cases, melena. Because of the low 

worm burdens seen in ferrets, diagcontinues 

on page 10 

ISSUE HIGHLIGHTS: 

Medical Treatment of Ferret 

Adrenal Disease 

ROUNDTABLE 

page 11 

Cystic Prostatic Disease in a 

Ferret 

FROM THE LITERATURE 

page 13 

Fine-Needle Aspiration of 

Adrenal Glands 

CASE REPORT 

page 15

EXOTIC PET PRACTICE 


Editor in Chief 

Shawn Messonnier, DVM 

Paws and Claws Animal Hospital 

Plano, Texas 

Editorial Board 

Terry W. Campbell, DVM, PhD 

Department of Clinical Science 

Colorado State University 

Fort Collins, Colorado 

Cathy A. Johnson-Delaney, DVM 

Senior Veterinarian, Primate Medicine 

Washington Regional Primate Research 

Center 

University of Washington 

Seattle, Washington 

James K. Morrisey, DVM, 

Diplomate ABVP–Avian Specialist 

Avian and Exotic Animal Medicine and 

Surgery Service 

Animal Medical Center 

New York, New York 

Wm. Kirk Suedmeyer, DVM 

Senior Staff Veterinarian 

Kansas City Zoological Gardens 

Adjunct Assistant Professor of 

Zoological Medicine 

UMC College of Veterinary Medicine 

Kansas City, Missouri 

Amy Beth Worell, BS, DVM, 

Diplomate ABVP–Avian Specialist 

All Pets Medical Centre 

West Hills, California 

Advisory Board 

Michael A. Dutton, DVM, 

Diplomate ABVP–Companion 

Animal Practice 

Weare Animal Hospital 

Weare, New Hampshire 

Gregory Rich, DVM 

West Esplande Veterinary Clinic & Bird 

Hospital 

Metairie, Louisiana 

ISSN 1086-4288 © February 2000 by Mosby, 

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10 


continues from page 9 

nosis can be difficult. Clinical signs, radiographs, and antigen testing are 

possible aids. Technical support for an antibody test (Assure FH, Synbiotics, 

San Diego, Calif) claims that the test is accurate for ferrets. 2 In my practice, 

four ferrets suspected of having heartworm disease (based on signs, CBC, 

and radiographs) tested positive on this antibody test. Other ferrets without 

heartworm symptoms tested negative. A competing product (Heska SoloStep 

FH, Fort Collins, Colo) does not make a claim that it is successful in testing 

ferrets. 

Treatment is difficult since thromboembolic episodes do occur and can be 

fatal. Currently, antithrombotic therapy is recommended to minimize this 

possibility. Heparin and aspirin have been used for this. Prednisone is thought 

to be superior in minimizing side effects associated with heartworm in ferrets. 

Thiacetarsemide 

Thiacetarsemide (Caparsolate, Merial, 2.2 mg/kg IV bid for 4 treatments) 

is administered via a cephalic catheter. Begin heparin therapy (100 units SQ 

q24h for ferrets weighing 0.45-1.35 kg) at the same time and continue for 

21 days. 3 Strictly confine the ferret during this time and treat it for any concurrent 

cardiac disease appropriately. After 3 weeks of heparin administration, 

discontinue its use and start with aspirin (22 mg/kg PO q24h) for 3 

months. Begin giving heartworm preventive medication 1 month after adulticide 

therapy is administered. Antigen or antibody testing every 3 months to 

check on progress of the disease is recommended. 

Melarsomine 

Melarsomine (Immiticide, Merial, 2.5 mg/kg deep epaxial IM) has been 

tried, and there are numerous anecdotal reports of its success. The advantage 

of melarsomine is its ability to stage the severity of heartworm disease 

and treat it the same as in dogs. Ferrets with mild to moderate heartworm 

disease can be given 2 injections 24 hours apart, whereas severe cases can 

have 1 injection right away and 2 injections (24 hours apart) after 1 month. 

The injections are given with the ferret sedated. Many practitioners use 

isoflurane for this. Concurrent use of corticosteroid is advised. 

Prednisone and Ivermectin 

As with heartworm disease in cats, an alternative to the elimination of 

adults is reducing the symptoms of heartworm by using corticosteroids until 

the Dirofilaria immitis worm (which causes heartworm disease) dies. A dose 

of 2 mg/kg q24h of a liquid prednisolone (Pediapred, Medeva Pharmaceuticals, 

Fort Worth, Tex) has been used successfully in my practice. Concurrent 

use of ivermectin on a monthly basis is recommended because ivermectin has 

a slow adulticide effect. 

Heartworm Preventive Medications 

Heartworm preventive medication should be given to animals in endemic 

areas. Many practices use the oral ivermectin, either in tablet form or in a 

liquid suspension. For tablets, one quarter of a 68 µg-tablet (Heartgard30, 

Merial) is sufficient. Due to the medicine’s instability when exposed to air, 

the rest of the tablet should be discarded. An oral suspension using a 1% 

injection for cattle (Ivomec 1% Injection for Cattle, Merial) can also be used 

after dilution with propylene glycol. Mixing 0.3 mL of Ivomec with 28 mL 

propylene glycol yields a suspension of 0.1 mg/mL. The ferret dose is 0.2 

mL/kg once monthly. The suspension is good for approximately 2 years if 

the owners keep the suspension in a dark place. 

Other Diseases 

As mentioned, other cardiovascular diseases have been reported in the literature 

that are beyond the scope of this article. You are advised to check 

continues on page 13


ROUNDTABLE 

Medical Treatment of Ferret Adrenal Disease 

For this special roundtable, we are pleased to welcome Charles Weiss, DVM, a wellknown 

veterinarian who is on the cutting-edge of ferret medicine. Dr Weiss treats 

an average of 5 to 10 ferrets a day in his practice at Potomac Animal Hospital in 

Potomac, Md (301 299-4142); www.ferretdoctor.com. In addition, he has lectured at 

veterinary conferences and has published articles on ferret medicine and surgery in 

peer-reviewed journals. He consults with veterinarians nationwide on a daily basis on 

topics related to ferret care. His recent work on medical treatment of adrenal tumors 

and hyperplasia has received worldwide attention. 

Q. What are and how common are 

adrenal tumors and hyperplasia in the 

ferret? 

Dr Johnson-Delaney: The pathologists 

report the adrenal gland tissue 

submitted shows hyperplasia, adenoma, 

adenocarcinoma, or, occasionally, 

pheochromocytoma. Some reports 

have mixes of more than one type of 

neoplastic process, ie, “predominantly 

adenoma with sections resembling 

pheochromocytoma.” I believe this 

condition is very common and would 

estimate that one quarter of the ferrets 

we see over the age of 3 years 

may be affected. 

Dr Dutton: Adrenal disease, in a 

majority of cases, is in the form of a 

benign hyperplastic or adenomatous 

change to one or both of the adrenal 

glands. These changes result in the 

hypersecretion of a variety of 

steroidal compounds and hormones. 

Depending on which substances are 

secreted, certain symptoms develop. 

Adrenal disease is the most common 

endocrinopathy in the older ferret. 

Dr Morrisey: Adrenal disease is common 

in the ferret. The hyperplasia or 

neoplasia of the adrenal gland produces 

androgens and estrogens and 

causes signs associated with excesses 

of these hormones. There is probably 

a continuum from hyperplasia to 

adenoma to adenocarcinoma based 

on the duration of the disease. 

Dr Weiss: Adrenal tumors and 

hyperplasia are the most common 

tumors we see in our practice, seeing 

2 to 5 cases of this disorder a week 

almost without exception. The 

affected adrenal gland produces an 

excess of androgens and estrogens, 

resulting in the clinical signs common 

in this condition. The classic clinical 

signs almost diagnostic of this condition 

include bilaterally symmetrical 

alopecia, return to male sexual 

behavior in the neutered male ferret, 

and a swollen vulva in the female 

spayed ferret. Other common clinical 

signs include lethargy, muscle loss, 

pruritis, aggression, and strangury. 

Q. What is the treatment of choice for 

an adrenal tumor or hyperplasia in the 

ferret? Many clients decline treatment 

in their alopecic, but otherwise “normal,” 

ferrets. Should adrenal disease 

always be treated, since many ferrets 

can live for years with hyperplasia 

without overt illness? 

Dr Johnson-Delaney: The gold standard 

for treatment is surgical removal 

of the diseased adrenal tissue. Medical 

treatment aimed at blocking the 

hormones is just beginning—the 

pharmacokinetic and drug metabolism 

studies have yet to be done. A 

controlled study being done out of 

the University of Tennessee is comparing 

a unilateral adrenalectomy and 

subsequent hormone levels with the 

use of a leuprolide acetate depot 30- 

day formulation. Other clinical uses 

of this formulation and other antihormonal 

medications are giving 

clinical remission, but again, the controlled 

studies have not been performed. 

We do not know on a sustained 

basis what the sex steroid levels 

do following unilateral or bilateral 

adrenalectomy over time. The 

University of Tennessee study is 

planned to answer some of these 

questions. 

Should the disease be treated? I am 

convinced, having had my own ferrets 

with this disease, that it should be 

treated, as they are not feeling 100% 

when the sex steroids are elevated. 

Owners who have brought their balding 

animals to us want the ferrets to 

be treated. I have seen ferrets who 

were not treated brought in for 

euthanasia. They don’t feel well. The 

type of treatment depends on the 

physical examination, hormonal 

panel, age of the animal, concurrent 

diseases (such as cardiac, islet cell neoplasia, 

lymphoma, etc), results of the 


ultrasound examination, and a discussion 

with the owner about options. 

Dr Dutton: Surgical intervention is 

the treatment of choice for ferrets. 

Over 90% of ferrets can be cured by 

surgery. Whether to treat surgically 

or not depends on the symptoms of 

the ferret, their age, and owner commitment. 

Alopecic ferrets with no 

other symptoms do fine for years 

without therapy. Most other symptoms 

that occur will require management. 

Vulvar enlargement can lead 

to recurrent vaginitis. On the same 

note, elevated estrogen levels can 

lead to aplastic anemia. Intense skin 

pruritis that can lead to ulceration 

will develop in one third of the ferrets. 

In males, benign prostatic 

enlargement can develop and cause 

urethral obstruction. Overall, treating 

the disease early avoids these 

possible complications. 

Dr Morrisey: The treatment of 

choice, at present, is surgical removal 

of the adrenal gland. This treatment 

is most likely to cure the disease by 

removing the affected gland. It is 

possible that the disease may develop 

in the other gland or recur if the 

entire gland is not removed. I recommend 

treating the disease in ferrets 

under 6 years of age if there are few 

or no concurrent diseases. 

Dr Weiss: The treatment of choice of 

ferrets with adrenal gland tumors and 

hyperplasia involves surgery. Surgery 

utilizes a unilateral or subtotal bilateral 

(complete adrenalectomy of the 

larger gland and 50%-60% of the 

smaller gland) adrenalectomy for unilateral 

and bilateral disease, respectively. 

With this technique, glucocorticoid 

and mineralocorticoid replacement 

is rarely required postoperatively. 

Alternatively, complete adrenalectomy 

can be performed, which will 

decrease the incidence of postoperative 

recurrence. Although complete 

right adrenalectomy is technically very 

difficult, the advent of cryosurgery 

has made complete right adrenalectomy 

much easier with less risk to the 

patient. With bilateral, complete 

adrenalectomy, mineralocorticoid and 

glucocorticoid replacement are usually 

necessary (fludrocortisone acetate 

0.025 mg/kg bid and prednisolone 

0.25 mg/kg sid, then tapered). For ferrets 

that are not good surgical candidates, 

medical treatment is advisable. 

continues on page 12 

11






Treatment, in my opinion, is very 

important to help the patient attain 

the best possible quality of life. Most 

clients, upon initial presentation, 

think their ferret with this condition is 

not lethargic, but in up to 90% of the 

cases, after treatment the client feels 

the ferret is more active (spending 

more time up playing). In addition, 

25% of the ferrets have an adrenal 

carcinoma, which, although unlikely 

to spread, is usually locally aggressive. 

Q. What new and old medical treatments 

are available for ferrets with 

this condition? Discuss surgery versus 

medical therapy. Mention costs 

involved and success of treatment. 

Dr Johnson-Delaney: Older medical 

treatment is largely limited to using 

mitotane, which is an adrenolytic 

drug. In some cases this has worked, 

but we do not know if the drug is 

actually delivered to the adrenal tissue 

in the ferret, nor do we know the best 

dosage or delivery method. We have 

not done the pharmacologic work in 

the ferret with mitotane. In some ferrets, 

I have reduced the gross size of 

the adrenal tissue and decreased 

serum sex steroid levels using a 

dosage regimen of 50 mg/kg per os 

every 24 hours; the ferret may receive 

a dose for up to 4 consecutive days if 

it is not getting nauseated and having 

reduced energy, then the ferret should 

have at least 3 days off. Newer treatments 

are centering around the antigonadotropic 

drugs (leuprolide 

acetate, several different depot formulations 

with different dosages and 

diffusion rates; goserelin), anti-estrogen 

agents (tamoxifen citrate, anastrozole), 

anti-androgen agents (flutamide, 

finasteride, bicalutamide), and 

seasonal-light cycle associated agents 

(melatonin). Tamoxifen has been tried, 

and practitioners reported that the 

ferrets got extremely lethargic and 

nauseated and could not tolerate the 

drug. The anti-androgen agents are 

being tried as a way to decrease 

prostate swelling quickly in the affected 

males. It shows promise. (See 

Charlie Weiss for dosages.) 

These are not controlled pharmacologic 

studies, but clinical ones. 

12 

Leuprolide acetate depot is being 

used and seems to show great 

promise—it shuts down sex steroidogenesis 

at the pituitary level. 

Although I am having success using 

the 30-day depot formulation at 100 

to 200 µg/kg given every 4 to 6 weeks, 

Charlie Weiss is using the 4-month 

depot formulation at 3000 µg every 4 

months. Because the formulations are 

different and as the literature 

describes, it is difficult to compare 

dosages between the formulations. 

We are both having success. We need 

to do the controlled, pharmacologic, 

and drug metabolism studies with all 

of these drugs, as well as investigate 

LH and FSH receptor sites on the ferret 

adrenal glands and further investigate 

the pathogenesis of this disease. 

Leuprolide in any formulation is not 

cheap: a 3.75-mg 30-day single human 

dosage costs approximately $400—out 

of that I can get thirty-five to thirtyseven 

100-µg doses, which brings the 

cost down. Surgery is more expensive 

up front, but if the ferret does well on 

the medications, it seems to come out 

about the same over the course of 

long-term treatment. Although cost 

matters to most clients, that has not 

been the factor that has determined 

which course my clients decide on for 

their animals. We evaluate each ferret 

and try to determine how to deliver 

the best quality of life with a normal 

life span. 

Dr Dutton: The advantage of 

surgery is a long-term cure for the 

majority of ferrets. Medical therapy 

is lifelong, and with the newer medical 

therapies available, the cost can 

be more than surgery. Mitotane 

(Lysodren, Bristol-Myers Squibb, 

Princeton, NJ) has been used in ferrets 

with limited success. It works 

better for hyperplastic conditions 

than neoplastic ones. Leuprolide 

(Lupron, TAP Pharmaceuticals Inc, 

Deerfield, Ill) and anti-androgen and 

anti-estrogen medications are all 

being investigated. Leuprolide seems 

to be the best medical choice so far, 

but it can be cost-prohibitive unless 

you have a large patient group 

requiring this medication. 

Dr Morrisey: Several medical treatments 

have been tried with little or 

no success, such as ketoconazole and 

o,p’-DDD. For this reason, I do not 

recommend or offer either treatment. 

More recent medical therapies, such 

as melatonin and leuprolide acetate, 

have shown promise in reducing or 

eliminating the clinical signs of the 

disease. Definitive studies on the 

effect of these drugs on the adrenal 

tumors themselves have not been 

published. Because we do not yet 

understand the full effect of these 

medical therapies on the adrenal 

gland and the long-term effects, I recommend 

surgical treatment on ferrets 

under the age of 6 years if there are 

few or no concurrent signs. The benefits 

of surgical treatment include the 

removal of the offending organ, ability 

to examine the abdomen for concurrent 

diseases, and the chance of no 

recurrence (a cure). The disadvantage 

is anesthetic risk (usually low), and a 

perceived higher cost. Medical therapies 

are beneficial in their perceived 

lower cost and the lack of risk associated 

with anesthesia. The disadvantages 

include life-long treatment 

(which may cost more than surgery 

over time), an unknown effect on the 

tumor itself, and possible lack of longterm 

compliance. Also, medical therapy 

is not likely to cure the problem, 

only control it or its clinical signs. I 

recommend medical therapy in older 

animals with concurrent diseases, such 

as heart disease, or in cases of owners 

reluctant to have surgery performed 

on their pet. 

Dr Weiss: Previously, medical treatment 

included mitotane, yielding fair 

to poor results. This drug results in a 

high incidence of side effects, despite 

glucocorticoid replacement therapy. 

New, very promising medical therapy 

includes new drugs used in humans 

with breast and prostate cancer, 

since they block and inhibit estrogen 

and testosterone. Although these 

drugs can be very effective to inhibit 

the hormones and completely 

resolve clinical signs associated with 

this disease, it is not known whether 

they change the pathology of the 

adrenal gland. As a result, surgery is 

still the treatment of choice for this 

condition, but medical therapy may 

be a valuable choice for the ferret 

that is not a good surgical candidate. 

Although these new medical therapies 

can be very effective, they are 

expensive, costing as much or more 

than surgery in a single year. 

continues on page 13





one of the many ferret references 

now available to the veterinarian. 

Medications 

Medications used for the treatment 

of heart disease include 

diuretics, digitalis, and vasodilators. 

Furosemide is a commonly used 

diuretic and is dosed at 1 to 4 

mg/kg 2 or 3 times per day, given 

by mouth, intravenously, or subcutaneously. 

Digoxin (Cardoxin LS, 

Evsco, Buena, NJ) is given at 

dosages between 0.01 mg/kg every 

24 hours and 0.01 mg/kg twice a 




Q. Are particular drugs indicated for 

particular adrenal disease syndromes? 

That is, if a ferret is primarily showing 

aggression, is the drug choice different 

from a patient with alopecia? 

Dr Johnson-Delaney: There are 

particular drugs for particular adrenal 

disease syndromes. The anti-androgen 

drugs as mentioned above seem 

to help shrink the prostate more 

day, per mouth. Starting ferrets on 

a once daily regimen first is recommended. 

Ferret serum digoxin levels 

should be between 0.8 and 2 

ng/mL. ACE inhibitors such as 

enalapril (Enacard, Merial) can be 

used, but ferrets are sensitive to the 

hypotensive effects and caution is 

advised. A recommended dosage for 

enalapril is 0.5 mg/kg by mouth 

every 48 hours. 4 The frequency can 

be increased if no side effects are 

seen. Nitroglycerin 2% can be used 

as a venous vasodilator at the dose 

of 1 ⁄8-inch applied to the skin every 

12 to 24 hours. 

quickly than if we use leuprolide 

alone. Based on their action and the 

theory that the prostate is enlarged 

due to the action of the hormones, 

then blocking the receptor sites on 

the prostate tissue should shrink the 

tissue. For ferrets showing aggression 

and others with alopecia, I use 

leuprolide. Before starting any medical 

treatment, we submit a serum 

hormone panel to Dr Jack Oliver at 

the University of Tennessee Clinical 

Endocrinology Laboratory. We use 

this hormone panel periodically to 

References 

1. Stamoulis ME: Cardiovascular diseases, 

in Hillyer EV, Quesenberry KE 

(eds): Ferrets, Rabbits, and Rodents: 

Clinical Medicine and Surgery. 

Philadelphia, WB Saunders, 1997, p 

66. 

2. Synbiotics technical support, San 

Diego, Calif: Personal communication, 

1998. 





Philadelphia, WB Saunders, 1997, pp 

69-70. 





Philadelphia, WB Saunders, 1997, p 67. 

monitor progress, to adjust therapy, 

etc. For the extremely pruritic ferret, 

I have used antihistamine therapy 

based on the theory that if some 

adrenal cells are becoming a 

pheochromocytoma, then systemic 

histamine levels may be elevated and 

contributing to the pruritis. This has 

helped some of these animals dramatically, 

even before we have gotten 

the sex steroid levels to come 

down. We do not have an assay for 

histamine in the ferret. 

continues on page 15 

HOW I . . . 

Collect Blood From Ferrets 


I routinely collect blood from 

ferrets using what is commonly 

called the vena cava approach. 

With the ferret in dorsal recumbency 

and the forelimbs pulled along 

the sides of the ferret, I extend the 

head and neck and palpate the sternal 

notch. The sternal notch is the 

junction between the sternum and 

the first rib. Being right-handed, I 

insert the needle through the skin at 

the sternal notch on the right side 

of the ferret, directing it to a point 

midway between the opposite 

shoulder and hip. Usually blood can 

be aspirated into a 23- to 25-gauge, 

5/8-inch (16-mm) needle before the 

hub touches the skin. At this 

depth, I am performing a jugular 

venipuncture and not entering the 

cranial vena cava. 

FROM THE LITERATURE 

Cystic Prostatic Disease in a Ferret 

A review of case material of prostatitis in domestic ferret materials at the Armed Forces Institute of Pathology indicated 

that 83% of the studied ferrets with prostatic disease had one or more cysts and 17% had paraprostatic cysts. 

Half of these ferrets had various degrees of prostatic squamous metaplasia. The inflammatory response ranged from 

subacute to chronic active or pyogranulomatous. All of the ferrets with prostatitis had concurrent or previous hyperplastic 

and/or neoplastic adrenocortical lesions. The ferrets exhibited clinical signs of bilateral truncal alopecia and 

dysuria. Grossly, the prostate was enlarged to up to twice the normal size by multiple thick-walled cysts that contain 

viscous white fluid. Adrenal lesions produce high levels of circulating estrogenic compounds that cause squamous 

metaplasia of glandular epithelium. The prostatic inflammation is associated with the presence of keratin, squames, 

and cellular debris. 

Coleman GD, Chavez MA, Williams BH: Cystic prostatic disease with adrenocortical lesions in the ferret (Mustela putorius furo). 

Vet Pathol 35:547-549, 1998. 

13



Client Teaching Guide 

Ferret 

CARE SHEET 


✔ 

✔ 

✔ 

✔ 

Hair Loss in Ferrets 

Hair loss (aka, alopecia) in ferrets can be a normal seasonal change in the haircoat, 

or it can be the result of a health problem. Ferrets have a thick haircoat that 

becomes thinner during the warm months. The increasing daylight hours and 

warmer temperatures stimulate the ferret to shed some of its hair (the pelting 

cycle). Abnormal hair loss occurs when lost hair, either in patches or over the 

entire body, remains unchanged throughout the year or progresses to baldness. 

Excessive scratching associated with hair loss is also abnormal. 

Adrenal Tumors: Adrenal tumors are common to older domestic ferrets in 

North America and result in progressive hair loss. Ferrets affected with these 

tumors are typically 5 years of age or older. Frequently, the hair becomes thinner 

than normal during the warmer months but returns to normal during the colder 

months. However, during the next pelting cycle, the hair loss becomes more 

severe, and not all of the hair returns during the next cold season. The hair loss 

pattern is typically equal on both sides of the ferret (bilaterally symmetrical) and 

frequently begins at the tail. This hair loss pattern is indicative of a hormonal 

imbalance associated with an adrenal tumor. Spayed females (jills) with adrenal 

tumors not only exhibit hair loss, but also frequently have a swollen vulva as if 

they are in heat. Detection of an adrenal tumor in ferrets involves a history of 

progressive hair loss typical of a hormonal imbalance, ultrasound examination of 

the abdomen, and exploratory surgery. Hormonal analysis of a blood sample may 

be useful in detecting ferrets with potential for adrenal tumor. 

Less Common Causes of Hair Loss: External parasites and fungal infections 

(eg, ringworm) can also cause hair loss in ferrets. In general, hair loss associated 

with fungal infections or flea and mite infestations appear in patches and 

cause the ferret to scratch. Although most ferrets with adrenal tumor–associated 

hair loss do not appear itchy, some ferrets will scratch excessively. Detection of 

fungal infections in the skin of ferrets often requires culture of hairs plucked from 

around the area of hair loss. Detection of mites usually requires examination of a 

skin scraping under a microscope. 

Trauma: Trauma can be another cause of hair loss in ferrets, especially associated 

with multiple-ferret households where aggressive behavior occurs between the 

ferrets. Often the owner of the ferrets is aware of the aggressive behavior, which 

simplifies the diagnosis. 

Treatment: Ferrets with alopecia associated with adrenal tumors require surgical 

removal of the tumor. In most cases, the hair will return after several months. 

In some cases, especially those that have progressed to severe baldness, all of the 

hair may not return following surgery. Alopecia associated with fungal or parasitic 

disease can be treated medically. 

14 

Copy and use in partnership with your clients.



CASE REPORT 

Fine-Needle Aspiration of Adrenal Glands 

Michael A. Dutton, DVM, Dipl ABVP–Companion Animal Practice 

In cases of ferret hyperadrenocorticism 

(adrenal disease), a small 

percentage of ferrets will have both 

adrenal glands involved in hyperplastic 

or neoplastic processes. In 

many of these cases, it may be difficult 

to determine whether bilateral 

disease is present. 

I undertook an investigation to 

find out if fine-needle aspiration 

(FNA) is a diagnostic method for 

determining whether an adrenal 

gland has the characteristic changes 

seen in adrenal disease. If so, hopefully 

it could be adapted to clinical 

use as an intraoperative test for 

determining whether unilateral or 

bilateral adrenalectomy should be 

performed. A local veterinary 

pathologist laboratory was contacted 

and it was arranged that the 

pathologist reading the biopsy 

would be different from the pathologist 

reading the cytology. After 

final reports were obtained, the 

results were collated. 

Ten consecutive ferrets symptomatic 

for hyperadrenocorticism 

underwent an adrenalectomy. FNA 

was performed on the adrenal gland 

before it was excised using a 3-mL 

syringe with a 22-gauge needle. The 

contents of the aspirate were gently 

expressed onto a glass slide, and a 

standard squash prep was performed. 

The adrenal gland was then 

excised. Both the slide and formalin 

biopsy sample were sent to the veterinary 

pathologist laboratory. 

Of the 10 samples, 5 cytologies 

showed abnormalities suggestive of 

adrenal disease. Of those 5, 3 

cytologies correlated to the histopathologic 

findings (ie, adenomatous 

changes, hyperplastic changes, 

adenocarcinomatous changes) of 

the biopsy. The other 2 did not correlate 

(ie, the cytology showed 

benign changes while the biopsy 

showed adenocarcinoma). All 10 

biopsy samples had histopathologic 

changes consistent with adrenal disease, 

where only 5 of the cytologies 

did. 

It is not surprising that there was 

poor correlation between the cytology 

and biopsy sample, since many 

adrenal changes are of a mixed 

type. However, based on this limited 

case report, it cannot be recommended 

that FNA is a diagnostic 

tool for determining the presence of 

adrenal disease. 




Dr Morrisey: There is no difference 

in medical treatments of which I’m 

aware. The medical therapies involving 

regulation of gonadotropinreleasing 

hormone (GnRH) may be 

more useful in controlling hormonerelated 

aggression, but since I do not 

use any of the other treatments, I 

cannot comment on their effectiveness 

in this area. 

Dr Weiss: Here are the medications 

we have used in over 300 cases of 

adrenal tumors and hyperplasia in 

the ferret. Leuprolide acetate (the 4- 

month injectable depot form; not the 

1-month depot) 2 mg/kg subcutaneously, 

until clinical signs recur (4-6 

months); bicalutamide (5 mg/kg) orally 

once a day until clinical signs completely 

resolve then pulse therapy 

(once a day, 1 week on then 1 week 

off, etc); and anastrozole (0.1 mg/kg) 

once a day until clinical signs completely 

resolve then pulse therapy 

(once a day, 1 week on then 1 week 

off). Leuprolide acetate inhibits the 

production of androgens and estrogens 

and is therefore very effective in 

the resolution of clinical signs. 

Bicalutamide inhibits androgen 

receptors alone, and anastrozole 

inhibits the formation of estrogens. 

Although bicalutamide and anastrozole 

can be used effectively alone, 

they should not be used in combination. 

I recommend a trial on leuprolide 

as the first line of therapy; if it’s 

not effective or not available then 

bicalutamide, then finally anastrozole. 

In cases of aggression or return 

to male sexual behavior, both leuprolide 

and bicalutamide seem to work 

equally well. We are currently performing 

clinical trials with all of these 

drugs, and results will be submitted 

for publishing. Results of the clinical 

trials and future studies are necessary 

to determine the safety and efficacy 

of these treatments. Since these 

drugs are specific in their actions, side 

effects are expected to be minimal. I 

wanted to update the dosages for 

bicalutamide and anastrozole. I recommend 

giving either drug until all 

clinical signs are resolved, then as a 

pulse therapy (1 week on, 1 week 

off) at the same dosages. 

This dose (2 mg/kg of the 4-month 

Lupron depot) is exactly equivalent 

to 500 µg/month of the monthly 

depot. I have talked to over 30 veterinarians 

where 100 µg/month did 

not resolve the clinical signs of this 

disease. 

Q. Do the new medical treatments 

cure the disease (ie, many times clinical 

signs completely resolve)? 

Dr Johnson-Delaney: Cure? We 

don’t know that yet because many of 

the ferrets being treated medically 

have not died. At necropsy, we need 

to look at the adrenal tissue as well 

as the pituitary. In the few that I have 

treated that died of other causes, the 

pathologist has reported back that 

the adrenal tissue showed no signs of 

hyperestrogenism or other changes. 

We have not had enough of them go 

to necropsy yet to know. Ones that 

have had prostate pathology have 

come back with reports of tissue normal 

for an older neutered male. 

These early reports, along with the 

clinical progress, are very encouraging. 

But we don’t know the answers 

yet as to whether or not we can ever 

completely discontinue leuprolide 

therapy. If our model is correct, we 

may be able to lengthen the dosage 

intervals, and possibly cease during 

the non-breeding season. 

Dr Dutton: The new medical therapies 

do not cure, but manage the 

disease. 

Dr Morrisey: The mechanisms of 

action of both melatonin and leuprocontinues 

on page 16 

15






lide acetate are poorly understood. 

I have been involved in (as yet) 

unpublished clinical trials using both 

melatonin and leuprolide. Melatonin 

does appear to help with the clinical 

signs, especially hair loss, by causing 

down-regulation of prolactin and 

GnRH levels, but it did not appear to 

affect tumor size. In fact, some of 

the tumors became more locally 

invasive while on the melatonin therapy. 

Leuprolide acetate is a GnRHagonist 

and is thought to initiate a 

negative feedback on the endogenous 

production of GnRH. It is very 

effective at reversing alopecia and 

gonadal swelling. The effect of 

leuprolide acetate on the adrenal 

glands remains to be seen. 

Dr Weiss: At this point it is unknown 

whether these treatments 

cure the disease. Even though I speculate 

that these treatments do not 

change the underlying adrenal gland 

pathology, since the majority of 

adrenal gland lesions are benign 

(75%), and the carcinomas are rare 

to metastasize, palliative treatment 

to reverse the clinical signs can be 

quite rewarding. 

Q. Which ferrets are considered poor 

surgical candidates? 

Dr Johnson-Delaney: I take into 

consideration the animal’s overall 

condition, the diet it has been on, 

and concurrent conditions. Many of 

the older ferrets have some degree of 

heart disease. Functional islet cell 

neoplasia is quite common as a concurrent 

condition. Ferrets who also 

have lymphoma may not be good 

candidates. Many of the ferrets I am 

now treating medically have had previous 

unilateral or bilateral adrenalectomies, 

but because there is remaining 

tissue, the disease returned. It is 

very difficult to completely adrenalectomize 

many ferrets because they 

have accessory adrenal tissue scattered 

throughout the abdominal cavity. 

There is a tremendous variability in 

locations and vasculature supplying 

the right and left adrenals in ferrets. 

Ultrasound before surgery helps to 

decrease anatomic surprises! 

Dr Dutton: I would consider medical 

therapy (as opposed to surgery) for 

very old ferrets (7-8 years old) and 

ferrets with significant heart disease 

and other significant concurrent disease. 

A majority of ferrets with adrenal 

disease have or will have an insulinoma. 

I think that patients with mild 

insulinoma or well-controlled insulinoma 

are candidates for surgery, but 

the owner needs to be apprized of 

the fact that we cannot cure insulinoma, 

and the ferret, on average, lives 

only 1.25 years after a diagnosis of 

insulinoma. Also, a concern is that the 

condition of a ferret with insulinoma 

may worsen after an adrenalectomy 

because of the removal of high 

endogenous steroidal production by 

the adrenal disease. 

Dr Morrisey: Ferrets with advanced 

age (>6 years old) or concurrent disease 

such as heart disease, lymphoma, 

or other debilitating illness are considered 

poor surgical candidates. 

Dr Weiss: Prior to the advent of 

these drugs for this condition in the 

ferret, I considered any ferret 7 years 

of age or younger (in good physical 

condition and with normal serum 

chemistries and CBC results) a good 

surgical candidate. Even the majority 

of ferrets with controlled cardiomyopathy 

recovered quite well from 

surgery. Now, with these new effective 

medical treatments, my vision of 

a poor surgical candidate is changing. 

I still recommend surgery for ferrets 

5 years of age or younger if they 

are otherwise in good physical condition. 

In some ferrets with advanced 

disease, we now recommend medical 

treatment for 2 to 4 weeks to resolve 

some of the clinical signs, then 

surgery when the ferret is stronger. 

With this technique, we are seeing a 

faster recovery postoperatively than 

in the past. 

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