A colon-associated cystic mass occurring in conjunction with cecal dilatation in a Holstein cow

Abstract

A 7-year-old Holstein cow was presented for reduced appetite and decreased milk production. Based on physical examination, cecal dilatation was the primary differential diagnosis and was confirmed at surgery. However, in addition to the dilated cecum, 2 large cystic masses were found firmly attached to the proximal loop of the ascending colon.

A 7-year-old, fourth lactation, Holstein dairy cow was presented to the University of Illinois Veterinary Teaching Hospital with a 2-day history of decreased milk production and reduced appetite. The cow was from a herd of approximately 200 milking cows housed in confinement and fed a total mixed ration (TMR). The cow calved without complication 16 days prior to admission. Fourteen months prior to presentation, in the previous lactation, the cow was diagnosed with a left displaced abomasum which was corrected with an omentopexy. Milk yield at 14 days in milk was 38.5 kg/d which decreased to 13.2 kg/d by the day of admission.

Case description

At presentation, the cow weighed 680 kg, had a rectal temperature of 39.2°C, a heart rate of 80 beats/min, and a respiratory rate of 32 breaths/min. The cow had 3 rumen contractions in 2 min, was negative for urine ketones, had a packed cell volume of 30%, and a plasma total protein of 70 g/L. She was estimated to be 5% dehydrated. Auscultation and percussion of the abdomen revealed a large area of high-pitched resonance in the dorsal half of the right abdomen extending from the paralumbar fossa to the 10th intercostal space. Rectal palpation revealed a uterus with a right horn of approximately 8 cm diameter which, when manipulated, yielded a mucopurulent vaginal discharge. There was also a large, dilated structure in the right, caudal abdomen presumed to be the cecum. The cow passed a small quantity of loose manure during the examination.

Based on history and physical examination findings, a presumptive diagnosis of cecal dilatation was made and a standing, right-flank, exploratory surgery was pursued to arrive at a definitive diagnosis and treatment. The right paralumbar fossa was clipped and aseptically prepared for surgery. Regional anesthesia was accomplished with a distal paravertebral block using 2% lidocaine. Beginning 8 cm ventral to the transverse processes of the lumbar vertebrae and 10 cm caudal to the last rib, a 30-cm incision was made in the paralumbar fossa. Upon entering the abdomen, a large, gas-dilated cecum was immediately evident. The cecum was exteriorized and found to be hyperemic due to the significant distension but there was no torsion of the cecum and the tissue appeared healthy. A typhlotomy was performed and a large quantity of gas and approximately 30 L of ingesta were removed from the cecum.

The exploration was continued beginning with the cranial abdomen and the previous omentopexy was found to be intact. During exploration of the caudal abdomen, a 10 cm × 22 cm, firm, oblong mass was discovered firmly associated with the colon. The mass was exteriorized and a second, globoid, thin-walled, fluid-filled mass with a diameter of approximately 20 cm was also identified in close association with the first mass (Figures 1 and 2). Surgical exposure of the cysts and the associated colon was accomplished with minimal effort and little tension on the intestines. There was no evidence of discomfort in the cow when the cysts were exteriorized. With both cystic structures exteriorized, the fluid in the thin-walled sac was aspirated and it resembled peritoneal fluid. The thin-walled mass was incised and approximately 4 L of fluid were drained from the sac to facilitate manipulation of the other mass. The large mass was positioned such that the junction of the cyst and the colon was external to the body and easily accessible for manipulations. Blunt dissection was used to separate the larger mass from surrounding tissue. The mass was firmly attached to the proximal loop of the ascending colon and could not be dissected free from the colon without entering the lumen of the colon. To remove the mass, an intestinal clamp was placed on the colonic side of the attachment and a Carmalt forceps was placed adjacent towards the mass and the connection of the mass to the colon was sharply incised with a scalpel. The resulting defect in the colon was closed with 1 chromic gut in a Parker-Kerr pattern which was oversewn with 1 chromic gut in a Lembert pattern. The abdominal wall was closed routinely. After surgery, the cow was given flunixin meglumine (FlunixiJect; Butler Schein Animal Health, Dublin Ohio, USA), 1.1 mg/kg body weight (BW) IV, ampicillin (Polyflex; Fort Dodge Animal Health, Fort Dodge, Iowa, USA), 10 mg/kg BW, IM, erythromycin lactobionate (Erythrocin lactobionate 500 mg vial; Hospira, Lake Forest, Illinois, USA), 1.5 mg/kg BW, IV and 8 L of mineral oil mixed with 60 L of water per os.

Figure 1.

The larger, thick-walled cyst (A) and the thin-walled cyst (B) were both fluid-filled and were exteriorized from the abdomen while still attached to the colon.

Figure 2.

Attachment of the larger, thick-walled cyst (A) to the colon can be visualized (C) after the thin-walled cyst (B) was drained.

The cow passed manure of a normal volume and consistency when walking to a stall following surgery and post-operative treatments. Treatments with flunixin meglumine and ampicillin were repeated the morning after surgery. Within the next 12 h, the cow was eating TMR and hay and drinking water. Hydration status had returned to normal by the morning following surgery. The cow passed a significant volume of loose manure with mineral oil and frank blood evident in the stool during the first 18 h after surgery. The character of the manure was considered to be a result of a rapid increase in the rate of passage of ingesta due to resolution of the cecal dilatation, any possible obstruction associated with the cysts and the oral administration of mineral oil. The blood in the stool was assumed to be due to the enterotomy rather than an infectious enterocolitis or a significant surgical complication because it did not persist past 12 h after surgery and the cow’s appetite significantly improved after surgery.

The cow was discharged in the afternoon following surgery with instructions to continue ampicillin at 10 mg/kg BW, IM, q12h for 3 more days. After returning to the farm, the consistency of the cow’s manure returned to normal, her appetite improved steadily, and the cow recovered from surgery without complication. Milk yield increased after the cow returned to the farm, with peak production occurring at 56 days in milk at 43.5 kg/d. The cow’s last recorded DHI test day milk production was 31.2 kg/d at 178 days in milk. The cow was dried off at 289 days in milk and removed from the herd at 309 days in milk (293 d after surgery) due to the combination of age, health history, and failure to become pregnant.

The masses removed at surgery were submitted to the Veterinary Diagnostic Laboratory at the University of Illinois for further examination. The large, firm mass weighed 6 kg and was found to be a cystic structure. The interior of the cyst was filled with a network of fibrous tissue that created a dense honeycomb-like structure. The cyst contained straw-colored serous fluid. Dissection of the mass at the point at which it was excised revealed no communication with the colon. Histologic examination revealed that the wall of the cyst was composed of mature fibrous connective tissue at the periphery while the central portion of the wall of the cyst was composed of mature and immature granulation tissue and fibrin (Figure 3). Areas of coagulative necrosis with large fibrin thrombi and mineralization of the cyst wall were present. The tunica muscularis of the colon was hyperplastic and hypertrophied. The histologic structure of the thin-walled cyst was the same as described for the larger cyst; however, the lumen of the thin-walled cysts was lined by a single layer of flat, cuboidal to columnar cells that were not seen in the lumen of the larger structure. The thin-walled cyst and the larger cyst did not communicate. The fluid sample collected from the cyst during surgery was intended for culture; however, due to financial considerations, the owner declined to pursue testing beyond histology.

Figure 3.

Cellular composition of the cyst. The cyst wall is composed of mature and immature fibrous connective tissue (star) which is expanded by edema. The cyst is lined by non-ciliated, cuboidal to columnar cells (arrow). Hematoxylin & eosin.

Discussion

Cecal dilatation occurs most commonly in dairy cattle, with the Holstein breed being the most commonly affected (1,2). Cows aged 3 to 5 y have the highest frequency of diagnosis of cecal dilatation but the age range of cattle affected is from < 1 y to > 10 y (2). While cecal dilatation has been diagnosed at all stages of lactation, it most commonly occurs in the first 8 wk of lactation. Typical presenting complaints associated with cecal dilatation are anorexia, decreased milk production, and a change in quantity or character of manure. Cattle with cecal dilatation typically have a normal temperature, heart rate, and respiratory rate. Colic is an uncommon symptom. Upon auscultation and percussion, a high-pitched resonance in the right abdomen extending from the paralumbar fossa to the 10th intercostal space is highly suggestive of cecal dilatation. The dilated cecum can usually be palpated per rectum (1,2). The cow herein was slightly older than the average reported in the literature but typical in all other respects.

The frequency of occurrence of cecal dilatation in North America has not been reported in the literature. In the author’s experience (Garrett), the condition is diagnosed sporadically and much less commonly than displacement of the abomasum. However, there is 1 report of a high frequency of occurrence on 1 farm in which 5 cases were diagnosed in a 9-day period (3). Although changes in volatile fatty acids (4), myolectric activity of the ileum, cecum and colon, (5) and serotonin receptors in the ileum cecum and colon (6) have been explored, the etiology of most cases of cecal dilatation is unknown. A trichobezoar lodged in the ascending colon was associated with the onset of cecal dilatation in a 7-year-old Brown Swiss cow (7). The case reported here is the first reported occurrence of a cystic mass external to the intestinal tract occurring in conjunction with cecal dilatation.

The contents of the thin-walled cyst were easily examined during surgery and found not to originate from the lumen of the bowel. The thick, firm, fibrous nature of the wall of the larger cyst limited the ability to characterize the contents; however, communication of the larger, thick-walled cyst with the colon was deemed plausible. Since there was concern that the cystic structures were impairing intestinal function because of their weight and close association with the colon, the decision was made to attempt complete excision and examine the contents after removal. Even though the etiology and the functional significance of the cysts were unknown during surgery, the perceived risk of an adverse outcome was thought to be lower with complete, en bloc removal of the cysts than with leaving the cyst, attempting to drain the cyst via needle aspiration, or partial ablation of the cyst. Leaving the cyst could have led to subsequent intestinal dysfunction. Simply draining the cyst, draining followed by chemical ablation and partial ablation were not considered because communication with the bowel was uncertain.

Correction of cecal dilatation in cattle is most often accomplished with typhlotomy via a standing right flank laparotomy. However, conservative medical management including oral administration of mineral oil and parenteral prokinetic drugs such as bethanecol and neostigmine are described (8). Erythromycin has been shown to increase the rate of abomasal emptying in suckling calves (9) and cows following surgical correction of left displaced abomasum (10); albeit at doses of 8.8 mg/kg BW and 10 mg/kg BW, respectively. Erythromycin lactobionate at 1 mg/kg BW did not affect motility of the cecum of cattle but was hypothesized to have had some effect on the small intestine (11). In the case reported here, medical management was included in addition to the surgical correction in an attempt to speed recovery and reduce the likelihood of recurrence. While the cow recovered quickly, the advantage of the treatments compared with surgery alone could not be determined. Since the direct effect of erythromycin on motility of the gastrointestinal tract of cattle is probably limited to the abomasum and perhaps the small intestine, one should assume little advantage of treatment with erythromycin over surgery alone in the treatment of cecal dilatation until controlled studies are available.

The cysts discovered at surgery were not of enteric origin because no smooth muscle was present in the walls of the cysts. A Meckel’s diverticulum (embryologic persistence of the omphalomesenteric duct) was ruled out based on the histologic appearance. The histologic structure of the cysts most closely resembled mesenteric or mesothelial cysts; however, these have not been reported in the veterinary literature.

The pathogenic mechanism leading to the development of the 2 cystic structures adhered to the colon could not be determined. The time required for the cysts to develop cannot be known, but based on size and histology, they likely developed over several weeks if not months. What precipitated the acute onset of clinical signs is not known but it is hypothesized that the mass of the structures was increasing over time and that the weight led to a displacement of or alteration in motility of the cecum and colon. A decrease in aborad transit of ingesta through the colon may have precipitated the cecal dilatation. No reports of similar intestine-associated cysts in cattle could be found. While likely to be an uncommon finding, an intestine-associated cyst should be recognized as an anomaly that could be associated with intestinal dysfunction in cattle. CVJ