Glossitis and tongue trauma subsequent to administration of an oral medication, using an udder infusion cannula, in a horse

Abstract

A 10-year-old gelding was presented with a tongue that had swelled immediately after oral administration of oxfendazole, using an udder infusion cannula. The tongue appeared to have been punctured inadvertently. The horse recovered after treatment with intravenous fluid, antibiotics, and anti-inflammatory drugs. Administering oral medication by this method should be discouraged.

A 10-year-old quarter horse gelding, 531 kg, was referred to the Large Animal Clinic, Atlantic Veterinary College, University of Prince Edward Island. The horse had a history of swelling of the tongue within 20 min of an oral administration of a liquid preparation of oxfendazole (Benzelmin; Wyeth Animal Health, Guelph, Ontario), using a 4-inch udder infusion cannula, 4 d prior to presentation. Initial treatments by the attending veterinarian and the owner included flunixin meglumine (flunazine; Vetoquinol, Lavaltrie, Quebec), 1 mg/kg bodyweight (BW), IV, q12h for 4 d, and procaine penicillin G (Procillin; Vetoquinol), 15 000 IU/kg BW, IM, q12h for the 3 d. On the 4th d, the horse was treated with ceftiofur sodium (Excenel; Pharmacia Animal Health, Orangeville, Ontario), 1.9 mg/kg BW, IV, q12h; 1 dose of trimethoprim sulfadoxine (Trivetrin; Schering-Plough Animal Health, Pointe Claire, Quebec), 22 mg/kg BW, IV; followed by trimethoprim sulfa-methoxazole (Novo-Trimel DS; Novopharm, Toronto, Ontario), 25 mg/kg BW, PO, q12h and 1 dose of flumethasone (Flucort; Wyeth Animal Health, Guelph, Ontario), 0.007 mg/kg BW, IV. Tetanus toxoid had been administered 6 mo previously. The horse became dehydrated and was unable to eat or drink, so his systemic condition had deteriorated.

Case description

On presentation, the horse was depressed and had a tucked abdomen. He was estimated to be 8% to 10% dehydrated, febrile (rectal temperature of 39.3°C), and tachycardic (heart rate of 60 beats/min). The tongue was blue, markedly swollen, ulcerated (buccal surfaces), and protruding from the mouth (Figure 1). Copious amounts of saliva were drooling from the mouth and the intermandibular space was swollen, warm, and painful to the touch. A thorough oral examination was difficult to perform because of the swollen tongue. The horse resented glossal palpation and manipulation, even after he was sedated with xylazine (Rompun; Bayer, Toronto, Ontario), 0.4 mg/kg BW, IV, and butorphanol, (Torbugesic; Wyeth Animal Health), 0.02 mg/kg BW, IV. Beside the possibility that the hypoglossal nerve was involved in the lack of tongue function, examination of the rest of the cranial nerves revealed no abnormal findings.

Figure 1.

A swollen tongue that is protruding from the mouth of a horse after an oral administration of a liquid preparation of oxfendazole, using an udder infusion cannula.

A complete blood (cell) count (CBC) revealed an inflammatory leukogram; mild leukocytosis, neutrophilia with slight left shift and toxic changes, and lymphopenia (Table 1). The serum biochemical analysis revealed mild hyponatremia, hypokalemia, hypochloremia, mild hypophosphatemia and hypomagnesemia, and mild azotemia (Table 1); these changes were consistent with the prolonged history of an inability to eat or drink, drooling saliva and dehydration.

Table 1.

A complete blood (cell) count (CBC) and serum biochemical analysis in a horse with glossitis and tongue trauma subsequent to oral administration of a liquid preparation of oxfendazole, using an udder infusion cannula

	Day 1	Day 4	Reference range
Hematocrit (L/L)	0.40	0.31	0.32–0.52
WBC (×109/L)	12.8	10.0	5.5–12.5
Neutrophils (mature) (×109/L)	10.75	7.80	2.7–6.7
Neutrophils (band cells) (×109/L)	0.38 (slight toxic changes)	0	0.0–0.1
Sodium (mmol/L)	133	138	135–148
Potassium (mmol/L)	2.6	2.9	3.0–5.0
Chloride (mmol/L)	93	96	98–110
Phosphorus (mmol/L)	0.97	1.14	1.0–1.8
Magnesium (mmol/L)	0.62	0.68	0.74–1.02
Urea (mmol/L)	13.3	5.2	3.5–7.0
Creatinine (μmol/L)	156	138	78–143

WBC — white blood cells

Based on the history and physical examination, tentative diagnoses included glossitis as a sequela to fracture of the hyoid apparatus, a penetrating oropharyngeal foreign body, or a drug reaction to oxfendazole (1,2). Strangles was also considered because of the swollen intermandibular space, but it was considered less likely, based on history, sequence of events, and the course of the condition. In addition, the swelling in the intermandibular area appeared to be due to the swollen base of the tongue.

Initial treatment was aimed at correcting the dehydration, treating the inflammation and associated edema of the tongue, and providing enteral nutrition. A 16-G catheter was placed in the right jugular vein and lactated Ringer’s solution was administered at a rate of 10 mL/kg BW/h for the first 6 h. The rate of infusion was reduced to 4 mL/kg BW/h for the next 18 h and then to a maintenance rate of 2 mL/kg BW/h, for the next 48 h, at which time the horse was able to maintain his hydration status by the oral route. Sodium penicillin G (Penicillin G Sodium for Injection; Novopharm, Toronto, Ontario), 22 000 IU/kg BW, IV, q6h, and gentamicin sulphate (GentaMax 100; Phoenix Pharmaceutical, St. Joseph, Missouri, USA), 6.6 mg/kg BW, IV, q24h, were adminstered for 6 d. Dexamethasone sodium phosphate (Dexamethasone 2; Vetoquinol), 0.1 mg/kg BW, IV, was administered, followed 12 h later by flunixin meglumine, 1.1 mg/kg, IV, q12h for 3 d. He was fed 1 kg of complete pellets mixed in 5 L of water, q6h, PO, for 2 d, via a nasogastric tube.

Ventrodorsal, lateromedial, and lateromedial oblique radiographs of the skull revealed a generalized soft tissue swelling at the at the level of the tongue and an intact hyoid apparatus, but no foreign body. Endoscopic examination of the upper respiratory tract and guttural pouches revealed ventral collapse of the pharyngeal roof. It is likely that the pharyngeal collapse was due to enlarged retropharyngeal lymph nodes, secondary to the inflammation of the glossal tissue.

On Day 2, the horse became brighter, his vital signs returned to normal, and he was not dehydrated. Oral examination revealed reduced tongue swelling and a puncture wound (2–3 mm in diameter) in the right ventrolateral aspect of the tongue, from which purulent material was draining (Figure 2). This was consistent with the side and location of the mouth where the udder infusion cannula had been inserted to administer the oxfendazole. Ultrasonographs of the intermandibular space revealed a large delineated soft tissue swelling (8 cm × 15 cm [3.2 in × 6 in]), containing multiple hypoechoic loculated areas, consistent with small abscesses, 1 of which was superficial.

Figure 2.

A puncture wound in the right ventrolateral aspect of the tongue that was caused by the inadvertent intralingual injection of oxfendazole in a horse.

The intermandibular area was clipped and sterilely prepared in a routine manner. The superficial abscess was aspirated by using an 18-G needle; 3 mL of yellow purulent material was collected and submitted for routine culture (aerobic and anaerobic) and sensitivity testing. The abscess was lanced at the most dependent area and gently flushed with 500 mL of saline every 12 h for 7 d. Bacterial culture of the aspirate revealed the presence of mixed aerobic and anaerobic bacteria, a significant number of isolates of which were sensitive to the antibiotics that were being used. Streptococcus equi was not isolated.

On Day 3, the horse continued to improve as the glossal and intermadibular swelling resolved and he was introduced to a moistened pelleted ration (Horse Chow Checkers; Purina, Truro, Nova Scotia). On Day 4, the flunixin meglumine was changed to phenylbutazone (Phenylbutazone; Univet Pharmaceuticals, Milton, Ontario), 2.2 mg/kg BW, IV, q24h. Results of the complete blood (cell) count (CBC) and serum biochemical analysis had improved significantly (Table 1). By Day 5, the tongue was no longer protruding from the mouth, and the horse was regaining some glossal mobility. He was reintroduced to a fine stem hay diet over the next 2 d and his consumption gradually increased. On Day 7, the antibiotic was changed to ceftiofur sodium (Excenal; Pharmacia Animal Health), 2.2 mg/kg BW, IM, q24h for 4 d, and the anti-inflammatory drug to phenylbutazone (Phenylbutazone Tablets; Dominion Veterinary Laboratories, Winnipeg, Manitoba), 2.2 mg/kg BW, PO, q24h for 7 d. The horse was discharged on Day 8, when he was consuming 4 flakes (20 lb/9 kg) of hay per day.

Discussion

The oral route is commonly used for administering medication in equine practice. Some medications, such as anthelmintics, are already contained in tubes that have a blunt, ready-to-use end. Other medications that are in tablet or powder formulations need to be mixed with water, syrup, or molasses, and then administered either by a catheter tip syringe or a regular syringe with a cut tip. Udder infusion cannulas are metal and have a pointed tip that has the potential to puncture oral soft tissues if they are used to administer medication. They are not manufactured for this purpose, but, unfortunately, they are still being used to administer oral medication. Having witnessed the serious damage that can be caused using this method of administering oral medication, the owner was advised to discontinue this practice.

The important signalment was the initial sudden swelling and bluish discoloration of the tongue. The exact scenario of the injury and the subsequent events are unknown; however, we suspect that when the medication was administered, the metal cannula punctured an area of the tongue that contains a major blood vessel, possibly the sublingual vein, leading to the formation of the hematoma; this would explain the sudden enlargement and discoloration of the tongue. As a consequence to the trauma, the inoculation of oral microflora, and, possibly, a soft tissue reaction to the oxfendazole injection, an inflammatory cascade was initiated and an abscess formed.

Glossitis in the horse is commonly caused by tongue lacerations during mastication of rough forage, or wooden or metallic foreign bodies (3). Sharp teeth can lacerate the tongue, and this may result in glossitis. Occasionally, glossitis can result from penetrating foreign bodies (3,4). It is thought that in horses, glossal penetrating foreign bodies are acquired during mastication, compared with laryngopharyngeal foreign bodies, which are usually acquired during swallowing (3). The clinical signs associated with oropharyngeal foreign bodies usually depend on the size and location of the foreign body and the oropharyngeal structures that are involved and injured. Typically, clinical signs include dysphagia, ptyalism, and retropharyngeal swelling (3,4). Contrary to the presentation in this case, cases with oropharyngeal foreign body are rarely presented with depression, complete inability to eat or drink, and severe swelling of the tongue (4).

Penetrating foreign bodies often develop fistulous drainage tracts, which look grossly similar to the puncture wound in this case (3–6). In previous reports of penetrating foreign bodies of the tongue, the causative foreign bodies identified were hypodermic needles, wire, or wood (3,4).

Although rare in horses, Actinobacillus lignieresii infection of the tongue can result in an acute development of similar clinical signs, including an enlarged tongue, ptyalism, and dysphagia. However, in such cases, those signs develop over a longer period of time (7). Actinobacillus lignieresii was not isolated in the present case. A drug reaction to the oxfendazole injection was considered in this case because of the peracute nature of the clinical signs that developed following its administration. Oxfendazole is a benzimidazole anthelmintic that is used primarily in horses (8). However, no adverse reactions had been noted in horses receiving 10× the recommended dose during field trials (8). A hypersensitivity reaction in response to the rapid death of parasites is possible, but this has not yet been reported, and if it occurs, it should take more than 20 min to develop (8). Oxfendazole is not a sterile solution, and it is possible that the intralingual injection of oxfendazole contributed to the septic glossitis in addition to the oral microflora driven into the tongue through the puncture wound.

Another potential complication from the oral administration of medications, which may occur separately or concurrently with a puncture wound, is injury to hypoglossal nerve or fracture of the hyoid apparatus. The latter can occur from excessive traction of the tongue (9,10). Clinical signs are similar to the presented case and include dysphagia and a prolapsed tongue that is painful to manipulation, but they can also include regional cellulitis, if the fracture opens into the oropharynx (9,10). Radiographic examination may help in the diagnosis (10).

This report describes an unusual cause of glossitis in the horse. The use of an infusion cannula to administer medication, PO, should be discouraged by veterinarians. Oral administration in horses should be done using instruments that are not likely to cause injury. CVJ