Ferret-abdominal Surgical Procedures Part I

Vol. 21, No. 9 September 1999

CE

V

20TH ANNIVERSARY

Refereed Peer Review

FOCAL POINT ★ With some variation, the surgical procedures involved in treating adrenal gland neoplasia, paraurethral or prostatic cysts, and pancreatic beta-cell tumors in ferrets are similar to the procedures routinely performed in other small animals.

KEY FACTS ■ Any abdominal surgery for neoplasia in ferrets should include evaluation of the lymph nodes and all abdominal organs for concurrent neoplasia or metastasis. ■ Paraurethral or prostatic cysts generally occur secondary to adrenal gland neoplasia. ■ During partial pancreatectomy, leakage of small amounts of pancreatic enzymes may not be associated with pancreatitis. ■ Surgical removal of pancreatic beta-cell tumors is frequently considered a debulking procedure because metastasis and local recurrence are common.

Ferret Abdominal Surgical Procedures. Part I. Adrenal Gland and Pancreatic Beta-Cell Tumors University of Florida

Jason Wheeler, DVM R. Avery Bennett, DVM, MS ABSTRACT: With the increasing popularity of ferrets as pets, veterinarians are being asked to perform surgical procedures on these animals that they have previously performed only on dogs and cats. This two-part article discusses common problems in ferrets that require abdominal surgery and the proper surgical management of these conditions. Variations in ferret anatomy and pertinent disease pathophysiology are also described. Part I covers adrenal gland disease, paraurethral and prostatic cysts, and pancreatic beta-cell tumors. Part II will discuss surgical techniques related to treatment of gastrointestinal foreign bodies, splenomegaly, liver biopsy, cystotomy, and ovariohysterectomy.

T

he popularity of ferrets as pets has been steadily increasing. As a result, veterinarians are being asked to perform surgical procedures with which they have had little experience in ferrets. In general, ferret abdominal surgery is analogous to similar procedures routinely performed in dogs, cats, and other small animals. With a more thorough understanding of the surgical conditions most frequently encountered, the slight variations in anatomy, and the pathophysiology of the disease in question, ferret abdominal surgery can be performed in most general practice situations. Because ferrets have a high incidence of tumors and clinical signs are often nonspecific, abdominal exploratory surgery provides an opportunity to examine all abdominal structures. This two-part article provides an overview of the most commonly encountered conditions requiring abdominal surgical intervention in ferrets. Part I discusses adrenal gland diseases, paraurethral and prostatic cysts, and pancreatic beta-cell tumors (insulinomas). Part II will address surgical techniques related to treatment of gastrointestinal foreign bodies, splenomegaly, liver biopsy, cystotomy, and ovariohysterectomy.

ADRENAL DISEASES At least 95% of generalized alopecia in neutered ferrets 3 years of age or older is caused by neoplasia or hyperplasia of the adrenal glands.1 This syndrome is strictly an adrenal disease—the pituitary gland is not involved, which makes use

Small Animal/Exotics

20TH ANNIVERSARY

Compendium September 1999

of the term Cushing’s disease inapprolargement is an indication for repriate.2,3 In some cases the histologic moval. If it appears that the adrenal diagnosis is adrenocortical hyperplasia, gland cannot be safely removed withwhereas adrenocortical adenoma or out damaging adjacent structures, cortical adenocarcinoma is diagnosed such as the caudal vena cava, it is best in others.4,5 Metastasis is uncommon to remove as much affected tissue as but has been reported1; however, some possible in order to obtain a biopsy tumors do show local invasion into the specimen and debulk the mass. vena cava, liver, and adjacent abdomiThe left adrenal gland is located nal viscera.4,5 within the sublumbar fat just cranial The primary clinical sign associated and medial to the cranial pole of the with adrenal neoplasia is bilaterally left kidney (Figure 2).11,12 It is deep within the lumbar fat in the retroperisymmetric, pruritic or nonpruritic alotoneal space. In general, only the venpecia, usually beginning at the hindtral surface of the gland can be visualquarters and progressing cranially along ized through the peritoneum. In some the body.2 Spayed female ferrets frequently have vulvar enlargement, with animals, the surface may appear grossor without alopecia (Figure 1). Male ly normal with the abnormal portion ferrets with adrenal neoplasia occasiondeeper and not readily visible. It is imally have prostatic or paraurethral portant to open the peritoneum, discysts, with or without alopecia. 5 Figure 1A sect through the fat, and explore the Splenic enlargement, pancreatic betaentire gland using blunt dissection becell tumors, and cardiomyopathy are fore declaring it normal. also common in ferrets with adrenal It is generally easy to remove the left neoplasia.2,5 adrenal gland. The adrenolumbar Adrenal disease is suspected based (phrenicoabdominal) vein courses over on the physical examination, history, the ventral surface of the left adrenal and signalment. The diagnosis is fregland and must be ligated on each side quently confirmed via ultrasound evalof the gland before removal.12 Large 1,6 tumors may be receiving blood from uation of the adrenal glands. An adrenal steroid panel to evaluate circuother large vessels that might require lating levels of hormone precursors in ligation or cauterization. Hemostatic ferrets and dogs is available through clips are very valuable in controlling the University of Tennessee (Clinical hemorrhage from these vessels. After Endocrinology Laboratory, Departthe vessels have been ligated, the ment of Comparative Medicine, 423adrenal gland is removed using sharp 974-5638; $60 for ferret test, $120 for or blunt dissection. Some large tumors canine test).7 invade the caudal vena cava, presumSurgery is currently considered the ably migrating through the adrenotreatment of choice for adrenal neolumbar vein. Once inside the vena plasia.8,9 Because adrenal neoplasia frecava, they tend to grow cranially withquently occurs coincidentally with Figure 1B in the lumen but are not attached to pancreatic beta-cell tumor and lym- Figure 1—A ferret with (A) alopecia the vessel wall. Removal requires temphoma, the lymph nodes, liver, spleen, and (B) vulvar enlargement typical of porary occlusion of the caudal vena and pancreas must be evaluated.10 In those seen with adrenal gland disease. cava, venotomy, and closure of the female ferrets, it is also important to venotomy as described below. Some evaluate the ovarian and uterine stumps and the mesentumors are large enough to invade or compromise the tery for any evidence of ectopic or residual ovarian tisleft kidney, thereby necessitating nephrectomy. sue that might cause similar clinical signs. The right adrenal gland is found by elevating the The adrenal glands are evaluated for size, color, and caudalmost pole of the caudate lobe of the liver, which shape. They should be 2 to 3 mm wide, 6 to 8 mm overlies the cranial pole of the right kidney (Figure 2).10 1,6,10 The presence A thin membrane (hepatorenal ligament) extends from long, light pink, and homogeneous. of lumps, firm areas, discolorations, cysts, or gross enthe caudal tip of this liver lobe toward the kidney and is CLINICAL SIGNS ■ DIAGNOSIS ■ PHRENICOABDOMINAL VEIN

Compendium September 1999

Small Animal/Exotics

Atlas of Breed-Related Canine Ocular Disorders the ultimate visual diagnostic guide Atlas of

Breed-Related Canine Ocular Disorders

Kerry L. Ketring Mary B. Glaze

85 $95*

140 pages, gloss-coated cover and pages, all color, fall 1998

$

Kerry L. Ketring

Figure 2—Diagram of the anatomic relationship between the

adrenal glands and the caudal vena cava (VC). The left adrenal gland (LA), located a short distance from the caudal VC, is easily removed. The right adrenal gland (RA) is attached to the caudal VC along the dorsal surface of the vein and can be visualized from both the right and left aspects of the caudal VC. The hepatorenal ligament (H) is transected and held with forceps (F) to elevate the caudate lobe of the liver (L), providing exposure to the right portion of the right adrenal gland. The kidneys (K) are shown for orientation (A = adrenolumbar vein).

incised sharply to elevate the liver lobe. The hepatorenal ligament can then be used to retract the liver ventrally, allowing exposure of the right adrenal gland, which is visualized on the dorsal aspect of and tightly attached to the caudal vena cava. Its location is actually more dorsal rather than strictly on the right side of the vena cava; thus the adrenal gland must be evaluated from both the right and left sides of the caudal vena cava for abnormalities. Because of its intimate association with the vena cava, removal of the right adrenal gland is significantly more difficult than is removal of the left. Vascular clamps are almost essential in performing a complete right adrenalectomy in ferrets. These clamps are designed to occlude veins with minimal trauma to the vessel wall. Clamps are placed on the caudal vena cava, cranially and caudally to the mass, isolating the portion of the vena cava that contains the adrenal mass. We have occluded the caudal vena cava for up to 1 hour in ferrets with adrenal tumors without causing overt clinical effects. The right adrenal gland is dissected from both the right and left sides of the caudal vena ANATOMY ■ RIGHT ADRENALECTOMY

A

•

Mary B. Glaze

10% off!

unique compilation of exceptional-quality, fullcolor photographs illustrating the full range of inherited ocular diseases recognized in the dog. A lifetime resource that will never go out of date by two noted experts, one university affiliated, the other in private referral practice! Serves as a companion to Ocular Disorders Presumed to be Inherited in Purebred Dogs, the report of the Genetics Committee of the American College of Veterinary Ophthalmology. FEATURES ■ Concise and well-organized by Appropriate anatomic feature for general ■ Over 350 color images enhanced practitioners, students/residents by arrows in training, and ■ Captions discuss history, signs, breeders evaluation, and case highlights ■ Separate index of all included Second in a series breeds by the authors of ■ High-gloss finish and spiral bindAtlas of Feline Ophthalmology ing—ideal for use as a diagnostic guide and client education tool ■ Extensive current bibliography for further information on treatment

CALL OR FAX TODAY TO ORDER 800-426-9119 • Fax: 800-556-3288 Price applies only within US, Canada, and the Caribbean. International prices upon request. Email: [email protected]

VLS

VE T E R I N A RY

BOOKS

L E A R N I NG

SYS T E M S

Small Animal/Exotics

20TH ANNIVERSARY

cava to isolate the tumor as much as possible before placing the clamps. The caudal vena cava is dissected free from surrounding fat, which allows clamps to be placed caudal and cranial to the mass. It is important to dissect as much tissue off the vena cava as possible in the event that suturing this vein is required. With the aid of magnifying loupes and microsurgical instruments, a plane of dissection between the adrenal gland and the vena cava is identified. Through this plane, dissection is continued until the adrenal gland is removed from the surface of the vena cava. The wall of the vena cava is inspected for defects. If an incision was created in the vena cava during dissection, it is closed with a simple continuous pattern of 8-0 nylon suture on an atraumatic needle. Small holes are sutured with 8-0 nylon in a mattress pattern. Generally, there are very small holes that go undetected even with inspection through a magnifying loupe. Before the clamp is released, a piece of oxidized regenerated cellulose (Surgicel™; Ethicon Inc., Somerville, NJ) is wrapped around the vena cava where the adrenal mass was removed; this will aid in hemostasis following clamp removal. When the clamp is removed, hemorrhage will be noted from the small holes in the wall of the vena cava; gentle pressure is applied for approximately 5 minutes to allow clots to form and seal the holes. The oxidized regenerated cellulose is left in place and not disturbed during closure. The pressure in the vena cava is low, which makes postoperative hemorrhage less problematic. Tumors of the right or left adrenal gland may invade the caudal vena cava. These may be removed through a venotomy (more likely with left adrenal tumors) or by resecting and anastomosing the caudal vena cava (more likely with right adrenal tumors because of their more diffuse attachment to the caudal vena cava). For the venotomy, the caudal vena cava is occluded using vascular clamps as described. The venotomy should be just large enough to remove the tumor from the lumen of the vein. It is best to close the longitudinal incision transversely to prevent attenuation of the luminal diameter. It is generally easiest to place a few interrupted sutures to provide apposition and then close with a simple continuous pattern, which will provide a better seal. In some cases a portion of the caudal vena cava must be removed to completely resect an adrenal tumor. We have removed up to 1 cm of vena cava and still been able to create a tension-free anastomosis. Vena cava ligation cannot be recommended in ferrets until appropriate research into its effects has been conducted. A technique described for partial excision of the right adrenal gland involves the use of hemostatic clips.13 Once the gland is freed from surrounding tissues, hemostatic clips are applied between the gland and the vena

Compendium September 1999

cava. The tissue is then transected along the clips, which provide hemostasis of vessels between the adrenal and the vena cava. Using this technique, more of the adrenal tissue remains in the ferret, which increases the chance that tumor will recur. Abdominal closure is routine. A postoperative dose of dexamethasone (1 mg/kg) may be administered. After 24 hours, prednisone (0.1 mg/kg orally once daily for 3 days) is administered.8 Although postoperative steroids may not be necessary, it appears that many ferrets suffer less depression and have a more rapid return to their normal state when glucocorticoids are administered for a short time (i.e., 3 days). Patients are returned to a normal diet within 6 to 12 hours of surgery. Following adequate removal of the adrenal neoplasia, a swollen vulva will generally return to normal within 2 weeks and hair loss will begin to resolve in 1 to 4 months. Following bilateral adrenalectomy, ferrets often require glucocorticoid therapy for longer periods. Mineralocorticoid supplementation is required as well in some ferrets with bilateral adrenalectomy. In a study in which bilateral adrenalectomies were performed in normal ferrets, no abnormalities were identified12; however, this study did not evaluate steroid levels. Ferrets were given 0.9% saline for drinking water, but electrolyte levels were not determined either.

PARAURETHRAL OR PROSTATIC CYSTS Male ferrets with adrenal neoplasia may develop prostatic enlargement, prostatitis, paraprostatic cysts, or paraurethral cysts. It is likely that these problems are a result of excessive quantities of hormones produced by the adrenal tumor.5,10 Treatment is aimed at surgical removal of the affected adrenal gland(s). After the adrenal neoplasia has been removed, the prostate rapidly decreases in size, often within 1 or 2 days. In some ferrets with prostatic enlargement and paraprostatic cysts, the cystic structure may be as large as or larger than the urinary bladder. These cysts frequently contain a tenacious, green, often odoriferous material.1 The contents of the cyst are aspirated intraoperatively and submitted for culture and sensitivity testing. Biopsy of the affected prostate is recommended to rule out primary prostatic disease. Marsupialization of the cyst is not usually necessary. Omentalization may be indicated. A defect is created in the cyst, and omentum is sutured in place over this defect. The omentum will absorb fluid if the cyst continues to be productive postoperatively. After remov-al of the adrenal neoplasia, cystic structures tend to regress rapidly. PANCREATIC BETA-CELL TUMORS Hypoglycemia in ferrets is usually caused by pancre-

ABDOMINAL CLOSURE ■ GLUCOCORTICOID THERAPY ■ PROSTATE ■ HYPOGLYCEMIA

Small Animal/Exotics

atic beta-cell tumors (insulinomas). The disease occurs at approximately the same frequency as adrenal neoplasia; the two diseases commonly occur at the same time and affect both male and female ferrets 3 years of age or older.14 The tumor produces high levels of insulin, driving glucose out of circulation and into cells. Clinical signs associated with pancreatic beta-cell tumor are related to hypoglycemia and generally consist of weakness and depression. These signs may be subtle and short-lived and may resolve on their own early in the course of the disease. Frequently, ferrets salivate and paw at the mouth as if experiencing nausea. As the disease progresses, the periods of weakness and lethargy become more pronounced and persistent. 3,15,16 Although uncommon, some animals eventually develop seizures and coma and may die.3,16 Definitive diagnosis is frequently made based on a fasting (4 to 6 hour) blood glucose below 70 mg/dl (normal, 90 to 100 mg/dl).1 Determining the insulin:glucose ratio may be helpful in questionable cases. Pancreatic beta-cell tumors are generally too small to detect with ultrasonography.17 The recommended treatment for pancreatic beta-cell tumor is surgical excision.16 Patients with this tumor should receive either intravenous 2.5% dextrose and 0.45% NaCl or intravenous 5% dextrose in water instead of lactated Ringer’s solution during the procedure.1,10,16 As described for adrenal neoplasia, a complete exploratory celiotomy is performed to evaluate for the presence of concurrent disease. A pancreatic betacell tumor may metastasize to the liver, spleen, and regional lymph nodes, indicating the need to collect biopsy specimens from these tissues during the exploratory celiotomy.16–18 The pancreas has a right limb that is longer and larger than the left limb and is located within the mesoduodenum (Figure 3).19 At the caudal duodenal flexure, the right limb turns onto itself so that the entire right limb is to the right of the root of the mesentery. The left limb is shorter and thicker and lies within the deep leaf of the greater omentum. The pancreas is V-shaped, and the right and left limbs meet at the apex of the V, which is called the body of the pancreas and lies at the pyloroduodenal junction. In most ferrets, there is one duct within each limb of the pancreas; the two pancreatic ducts join to form the common pancreatic duct. The common pancreatic duct then joins the bile duct and empties into the duodenum as the major duodenal papilla, 2.8 cm caudal to the cranial duodenal flexure. An accessory pancreatic duct and minor duodenal papilla are present in a small percentage of ferrets. The cranial and caudal pancreaticoduodenal arteries are the major blood supply to the right limb of the pancreas, METASTASIS ■ COMMON PANCREATIC DUCT

Share Your Knowledge We invite you to impart your clinical knowledge by discussing your interesting cases, unusual presentations, or procedures for clinical solutions for the following features: E IC CHALLENG DIAGNOST

isoning rn on a Rat Po Unexpected Tu

DIAGNOSTIC CHALLENGE

A detailed account of a clinical dilemma takes readers from specific patient presentation through the steps leading to the ultimate diagnosis in 1000-1500 words.

I.M., ., Dipl. A.C.V. Brooks, D.V.M . By Marjory on, D.V.M and Jeff Jacobs

was examd male Beagle, r-old, neutere Conugsy, a four-yea n of the rat poison hour of ingestio l placement ined within one d of subconjunctiva treatment consiste peroxide to induce trac® . Initial oral hydrogen a large and 30 mL of , Mugsy vomited of apomorphine therapy this Addiresponse to the rat bait. vomiting. In identified as l by gaslue material green-b charcoa d of amount mL of activate nt included 200 neously (SC). tional treatme 2.5 mg/kg subcuta supply of and vitamin K1 with a 10-day tric intubation ed to his owners Mugsy was discharg hours orally. mg every 24 vitamin K1 50

M

ry blood chemist nation. All

SEALING NS BY LES ILLUSTRATIO

for PT determi PT at recheck hours later limits. The because corwithin normal d for 48 hours ted finding values were tion was schedule , an unexpec confirm K deficiency A recheck examina vitamin K regimen to was 65.9 seconds al PT due to vitamin initiating an ion of the owners reportrection of abnorm 48 hours of after complet Although his within 24 to and Mugsy coagulopathy. should resolve K1 as directed resolution of K1. of dose of vitamin persistent prolongation had given vitamin re to rat poison, clotting appropriate ed that they y the cause of al vitamin nity for reexposu was markedl To determine whether addition for more had no opportu time (PT) assay finding in the PT and prothrombin was sent : 9.5-12.5). This clotting time time in the sample a (normal prewas drawn was needed, 57 seconds that his early K therapy . Whole blood prolonged at it appeared ion analyses 3.8 percent prevented ted because detailed coagulat anticoagulant (one part was unexpec vomiting had ive howproduct citrate ged, and the Contrac, and centrifu directly into sentation with of rodenticide. to a vetpoison. parts blood) a toxic dose on cold packs a long-acting citrate to nine absorption of shipped iolone, K was 1 Coagulation vitamin s bromad plasma at the same supernatant (Comparative ever, contain e laboratory University, therefore resumed ory, Cornell erinary referenc Treatment was tic Laborat two weeks. completion Section, Diagnos dosage for another recheck, 48 hours after d ed and York). d of activate At Mugsy’s next was still markedly prolong Ithaca, New ion panel consiste thrombin sample. A , the PT The initial coagulattime (aPTT), PT, and of vitamin K1 g from the previous vitaplastin TCT screenin unchanged d, parenteral partial thrombo aPTT and essentially submitte The was were (TCT). ry profile owners clotting time blood chemist SC, and the 48 given 50 mg and recheck min K1 was vitamin K1 2000 oral August resume instructed to

ed Peer Review

Forum Veterinary

76

THERAPEUTIC CHALLENGE

THERAPEUTIC CHALLENGE

While the course of therapy is often clear-cut, some patients present true challenges to medical skills. In 1000-1500 words, these cases describe the steps that eventually lead to case resolution.

KAREN WILSON

1,4,14–17

Intussuscep tio In a Yearlin n g By Linnea Lentz, D.V.M.

B

eau, a 15-mont h-old colt, had been colicky for about when the owners four hours called the referring and no other veterinarian. The abnormalidescribed as mild, colic was ties. An initial and Beau was treated IV injection with 10 cc Banamin ® nixine) administe of xylazine appeared e (flured intravenously to (IV), 10 cc of control the pain approximately 1 dipyrone IV, and for only 20 ⁄2 gallon of mineral minutes before oil administered a second tube. Within the via nasogastric dose was necessary. hour, Beau was again colicky and Rectal University of Minneso was referred to the palpation revealed ta. many distended loops of small testine. After placemen inInitial Treatme t of a nasogastric nt on Referra l Clinical signs reflux were obtained. tube, 6-7 L of on presentation Abdominocenincluded profuse tesis results were sweating, numerous normal. attempts to lie Because of the down, and a distended severity of the abdomen. Physical colic, the small examination reintestinal distention vealed a pulse , and nasogastr of 84 beats per ic reflux, we minute, recomdecreased gastrointe mended explorato stinal motility ry laparotomy in all four quadrants to diagnose the cause , slightly toxic of the colt’s colic. mucous membran The owners quickly es, a capillary agreed, and prerefill time of 2.5 seconds operative antibiotic (normal: 1-2), and a normal potassium penicillin s, including temperature. 22,000 units/kg Blood work revealed IV and Gentocin a packed cell (gentamicin) 6.6 volume of 48 percent mg/kg IV, were (normal: 32-48), administered before total protein of 7.2 g/dL preparing the colt (normal: 5.7-7.9), for surgery. During surgery, a jejunocec al intussuscep-➔

August 2000

Peer Reviewed

Veterinary Forum

73

MONTH CASE OF THE

CASE OF THE MONTH

Some case presentations are so confounding that both diagnosis and therapy are perplexing. Often, a patient may return again and again with continuously changing signs. Word count: 1000-2000.

is Canine Hemipares

, D.V.M. By Donivan Hudgins

had been normal, activity levels old, 29were current asmine, a four-yearand vaccinations Retrievhepatitis, lepkg, spayed Golden for distemper, nza, parto the clinic er, was presented tosporosis, parainflue irus, Lyme of lameness. for sudden onset vovirus, coronoav found a stray The owner had disease, and rabies. susand given Solu The patient was goat in the backyard ® (prednisolone) goat may have pected that the Delta Cortef presentaOn usly (IV) and butted Jasmine. 100 mg intraveno ry 2.5 cc inwas ambulato tion, the dog amoxicillin injectable nated, uncoordi The owner was but obviously tramuscularly. n revealed the provide cage rest and observatio instructed to and return deficit was in primary walking over the weekend dog’s condition the right rear leg. Monday if the ion re. Physical examinat had not improved week, Jasre of 101.6˚F, The following vealed a temperatu capiles, to improve, and pink mucous membran (normal: mine appeared she did have of 1 sec lary refill time whatever problems heart and Over the next 1-2 sec), normal seemed subtle. sign of pain. The weeks, her problungs, and no two to three but not as prodid knuckle over, right rear foot lems recurred the propriobefore, and indicating decreased indicatnounced as the dog that pinch ception, but toe owner reported were intact. to her deficits. ed sensory nerves seemed to adjust next few weeks, of the affected Temperatures Then, over the no different of coördination foot and leg were Jasmine’s lack other three feet than that of the seemed to worsen. and flexion 21, Jasmine On October and legs. Extension were examinajoints for hip of the stifle and was re-presented reflex on on a leash normal, but patellar tion. When followed appeared exaggerated, the right was in the lawn, Jasmine ated, with upper motor which suggested to be very uncoördin Appetite and neuron disease.

J

CORBIS

Compendium September 1999

August 2000

Peer Reviewed

66

Veterinary Forum

SEND YOUR ARTICLES TO:

Editor, Veterinary Forum 275 Phillips Blvd. Trenton, NJ 08618 Fax: (609) 882-6357 E-mail: [email protected]

Small Animal/Exotics

20TH ANNIVERSARY

Compendium September 1999

S
M’

scopic and nonpalpable to 2 cm3 but frequently can be visualized within the pancreas as small firm masses (0.5 to 2 mm).1,10 These small masses can generally be removed by blunt dissection. Hemorrhage is minimal and is typically controlled ENDIU MP using gentle digital pressure and a hemostatic agent (e.g., Gelfoam®, Pharmacia & UpANNIVERSARY john, Bridgewater, NJ, or Surgicel™). Small pancreatic ducts will generally seal; leakage of pancreatic enTwenty years ago, ferret zymes in small amounts is medicine and surgery were in not associated with pancretheir infancy. Little published atitis because enzyme activainformation was available, and tion has not occurred and ovariohysterectomy, castration, the peritoneum will absorb these enzymes.20 Pancreatic and anal sacculectomy were the wounds heal by fibrin depomost commonly performed sition and polymerization, surgical procedures. Over the fibrous protein synthesis, past two decades, our knowledge and reepithelialization. Panof ferret medicine and creatitis caused by rough tisphysiology has expanded, sue handling can occur but placing demands on our 17,20 is uncommon. surgical skills to be able to In some cases, multiple perform more intricate masses are observed, which procedures on these loving pets. is an indication for partial pancreatectomy. It has also We are now able to routinely been recommended that a perform such procedures as section of pancreas should removal of adrenal masses using be removed and submitted vascular clamps to provide for histologic examination temporary occlusion of the even if no masses are palpable; caudal vena cava. The degree of on occasion, these tumors difficulty in ferret surgery has are microscopic and diffuseexpanded with the widespread ly disseminated within the 1 use of magnifying loupe pancreas. There are two telescopes, microsurgical methods for performing partial pancreatectomy—dissecinstrumentation, and various tion and ligation of ductules hemostatic aids. Currently, and vessels, or suture fracnearly any surgical procedure ture technique.20 The suture that can be performed in dogs fracture technique requires and cats can be accomplished in less time but is associated pet ferrets as well. (Pictured: with more inflammation. Jason Wheeler [left] and R. The area of the lesion and Avery Bennett) distal to it are isolated by dissection, taking care not to disrupt the common pancreatic duct. The mesoduodenum or the deep leaf of the greater omentum is incised,
CO

20th 9 9 9 9 - 1 1 9 7

A LookBack

Figure 3—Diagram of the anatomy of the ferret pancreas. The

thick black arrow indicates the major duodenal papilla (a = cranial pancreaticoduodenal vessels; B = common bile duct; b = splenic vessels; c = gastroepiploic vessels; D = duodenum; d = caudal pancreaticoduodenal vessels; L = liver; Lt = left limb; P = pancreas; PD = major [common] pancreatic duct; Rt = right limb; S = spleen; Sv = splenic vessels; St = stomach).

whereas the pancreatic branch of the splenic artery supplies the left limb. Analogous veins provide drainage. To evaluate the pancreas, the free border of the greater omentum is pulled out of the abdomen and wrapped in saline-moistened sponges. The proximal portion of the duodenum is exteriorized while the colon is retracted caudally. The left lobe of the pancreas is visualized in the deep leaf of the greater omentum. The right lobe is visualized within the mesoduodenum. The body of the pancreas is along the pyloroduodenal junction. By moving the duodenum toward the midline, the dorsal aspect of the right lobe can be seen; moving the duodenum laterally allows visualization of the ventral surface of the pancreas. These manipulations allow inspection of the lymph nodes as well. Pancreatic beta-cell tumors range in size from micro-

PARTIAL PANCREATECTOMY ■ SUTURE FRACTURE TECHNIQUE

Compendium September 1999

Small Animal/Exotics

providing access to the right or left lobe of the pancreas, respectively. After isolation, a ligature is passed around the portion of pancreas to be excised. As the suture is tightened, it crushes the parenchyma of the pancreas and ligates the vessels and ducts. The tissue distal to the ligature is excised. The defect in the mesentery or omentum is closed to prevent entrapment of viscera. In the dissection and ligation technique, the lobules are gently separated from adjacent tissue until the vessels and duct or ductules are exposed. These are ligated with hemostatic clips or fine, absorbable monofilament suture and then transected distal to the ligatures to allow removal of the tissue. During partial pancreatectomy, care must be taken to ensure that the blood supply to other structures has not been compromised. If the pancreaticoduodenal vessels are ligated when a portion of the right limb of the pancreas is removed, the blood supply to the proximal duodenum may be impaired. On the left side, ligation of the splenic vessels could occur, thereby restricting blood flow to the spleen. After partial pancreatectomy, the duodenum and spleen must be evaluated prior to closure to ensure patency of the blood supply. In dogs, removal of 80% to 90% of the pancreas will not alter exocrine or endocrine pancreatic function as long as the common duct is maintained intact to drain the remaining portion20; this has not been studied in ferrets. After surgery, an intravenous catheter should be maintained for 24 to 48 hours and the patient should receive 2.5% dextrose and 0.45% saline or 5% dextrose in water at 10% of body weight for 24 hours. On the first day after surgery, the patient is fed a bland diet in small but frequent meals and lactated Ringer’s solution is administered intravenously or subcutaneously at 10% of body weight per 24 hours. On the second day after surgery, the patient is returned to its normal diet and generally requires no additional medication. Blood glucose is monitored every 12 to 24 hours and may take 2 to 3 days to return to normal.1 Surgical removal of pancreatic beta-cell tumors is frequently considered a debulking procedure because these tumors have a high recurrence rate and metastatic potential.16,18 Surgery provides definitive identification of the tumor and temporary relief of clinical signs associated with hypoglycemia. Fasting blood glucose level should be evaluated 2 weeks postoperatively and then every 1 to 3 months to determine whether the pancreatic beta-cell tumor is recurring. Subsequent surgeries may be performed if the beta-cell tumor recurs.

REFERENCES 1. Brown SA: Ferrets: Common disorders, in Jenkins JR, Brown SA: A Practitioner’s Guide to Rabbits and Ferrets.

BLOOD SUPPLY ■ POSTSURGICAL CARE

Produce the ultimate in dental x-rays Atlas of Canine & Feline DENTAL RADIOGRAPHY Thomas W. Mulligan • Mary Suzanne Aller • Charles A. Williams

Mary Suzanne Aller, Editor 248 pages, 846 radiographs with arrow overlays to indicate notable features

RATED ★★★★★

$

$89

80

ff! First in the field o % 0 1 846 reference radiographs ■ Practical tips throughout ■ More than 840 real-case images with indicative arrows ■ State-of-the-art techniques for the beginning practitioner, technician, and specialist ■ Precise information on positioning, supplies and equipment, processing, safety, film handling, and more

VLS

VE T E R I N A RY

BOOKS

L E A R N I NG

SYS T E M S

CALL OR FAX TODAY TO ORDER 800-426-9119 • Fax: 800-556-3288 Price valid only in the US, Canada, Mexico, and the Caribbean. Request international pricing. Email: [email protected]

Small Animal/Exotics

2. 3. 4.

5. 6. 7. 8.

9. 10. 11. 12.

20TH ANNIVERSARY

Denver, American Animal Hospital Association, 1993, pp 65–90. Rosenthal KL: Adrenal gland disease in ferrets. Vet Clin North Am Small Anim Pract 27(2):401–418, 1997. Hillyer EV: Ferret endocrinology, in Kirk RW, Bonagura JD (eds): Current Veterinary Therapy XI. Philadelphia, WB Saunders Co, 1992, pp 1185–1189. Hillyer EV, Quesenberry KE: Endocrine diseases, in Hillyer EV, Quesenberry KE (eds): Ferrets, Rabbits, and Rodents Clinical Medicine and Surgery. Philadelphia, WB Saunders Co, 1997, pp 85–98. Weiss CA, Scott MV: Clinical aspects and surgical treatment of hyperadrenocorticism in the domestic ferret: 94 cases (1994–1996). JAAHA 33:487–493, 1997. Ackermann J, Carpenter JW, Godshalk CP, Harms CA: Ultrasonographic detection of adrenal gland tumors in two ferrets. JAVMA 205(7):1001–1003, 1994. Rosenthal KL, Peterson ME: Evaluation of plasma androgen and estrogen concentrations in ferrets with hyperadrenocorticism. JAVMA 209(6):1097–1102, 1996. Rosenthal KL, Peterson ME, Quesenberry KE, et al: Hyperadrenocorticism associated with adrenocortical tumor or nodular hyperplasia of the adrenal gland in ferrets: 50 cases (1987–1991). JAVMA 203(2):271–275, 1993. Lawrence HJ, Gould WJ, Flanders JA, et al: Unilateral adrenalectomy as a treatment for adrenocortical tumors in ferrets: Five cases (1990–1992). JAVMA 203(2):267–270, 1993. Mullen H: Soft tissue surgery, in Hillyer EV, Quesenberry KE (eds): Ferrets, Rabbits, and Rodents Clinical Medicine and Surgery. Philadelphia, WB Saunders Co, 1997, pp 131–144. Mullen HS, Scavelli TD, Quesenberry KE, Hillyer E: Gastrointestinal foreign body in ferrets: 25 cases (1986 to 1990). JAAHA 28:13–19, 1992. Filion DL, Hoar RM: Adrenalectomy in the ferret. Lab Anim Sci 35(3):294–295, 1985.

Compendium September 1999

13. Birchard SJ: Adrenalectomy, in Slatter D (ed): Textbook of Small Animal Surgery. Philadelphia, WB Saunders Co, 1993, pp 1510–1514. 14. Brown SA: Adrenal and pancreatic neoplasia. Proc North Am Vet Conf :725–727, 1993. 15. Ehrhart N, Withrow SJ, Ehrhart EJ, Wimsatt JH: Pancreatic beta cell tumors in ferrets: 20 cases (1986–1994). JAVMA 209 (10): 1737–1740, 1996. 16. Elie MS, Zerbe CA: Pancreatic beta cell tumor in dogs, cats, and ferrets. Compend Contin Educ Pract Vet 17(1):51–59, 1995. 17. Caplan ER, Peterson ME, Mullen HS, et al: Diagnosis and treatment of insulin-secreting pancreatic islet cell tumors in ferrets: 57 cases (1986–1995). JAVMA 209(10):1741–1745, 1996. 18. Rosenthal KL: How we treat a pancreatic beta cell tumor in the ferret. Proc North Am Vet Conf:822, 1994. 19. Evans HE, An NQ: Anatomy of the ferret, in Fox JG: Biology and Diseases of the Ferret. Baltimore, Williams & Wilkins, 1998, pp 19–69. 20. Harari J, Lincoln J: Surgery of the exocrine pancreas, in Slatter D (ed): Textbook of Small Animal Surgery. Philadelphia, WB Saunders Co, 1993, pp 678–691.

About the Author Drs. Wheeler and Bennett are affiliated with the Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida. Dr. Bennett is a Diplomate of the American College of Veterinary Surgeons.