Euthanasia in horses refers to the process of humanely ending the life of a horse to alleviate suffering or when the quality of life is deemed unsustainable. This practice is considered in cases of severe illness, injury, or chronic pain where recovery is not possible. The decision-making process involves veterinarians, horse owners, and sometimes ethical and welfare considerations. Various methods are employed, with the primary aim of ensuring a painless and stress-free experience for the animal. This page compiles peer-reviewed research studies and scholarly articles that explore the ethical considerations, methods, decision-making processes, and impacts on equine welfare related to euthanasia.
Howard RD, McIlwraith CW, Trotter GW, Powers BE, McFadden PR, Harwood FL, Amiel D.Bilateral osteochondral defects (10 mm2 x 3 mm deep) were created on the distal articular surface of the radial carpal bone of ten, 2- to 3-year-old horses. One defect of each horse was repaired, using a sternal cartilage autograft (treated), and the other was left untreated (control). The horses were exercised on a high-speed treadmill at incrementally increased speed and duration over the course of 12 months. Horses were evaluated arthroscopically at 6 to 7 weeks, and clinical examinations were conducted weekly at exercise. Twelve months after surgery, carpuses of each horse were radiographe...
Valentine BA, Rousselle SD, Sams AE, Edwards RB 3drd .Three horses with fibrotic myopathy were examined for neuromuscular disease. In 2 horses, concentric needle electromyography was performed. Dense spontaneous activity suggestive of denervation, was found in multiple thigh muscles of 1 of the 2 horses. All 3 horses were euthanatized. Histochemical and histologic examination of tissue specimens was performed. All horses had degenerative lesions in peripheral and intramuscular nerves. Angular atrophy of type-1 and type-2 muscle fibers, indicative of denervation atrophy, was seen in multiple muscle specimens from all 3 horses. One horse was found ...
Freeman DE, Donawick WJ, Klein LV.The effect of a single ligature on back pressure in the internal carotid artery was studied in nine horses. In six anesthetized horses, one internal carotid artery was catheterized 2 cm from its origin and blood pressure was recorded continuously. Then the artery was ligated, pressure was recorded again, and the horses were euthanatized. In another three anesthetized horses, indwelling catheters were placed in both internal carotid arteries and a loose ligature was placed proximal to one catheter. After horses recovered from anesthesia, the ligature was tied and blood pressure was recorded in ...
Messer NT, Johnson PJ.Acute hepatic disease was diagnosed in 16 horses during the study period. Twelve of those cases were characterized as idiopathic acute hepatic disease (IAHD). In 9 of the 12 (75%) cases of IAHD, the horses were female, and 7 of the 9 females were lactating and had been treated with tetanus antitoxin at parturition. Diagnosis of IAHD was based on anamnesis, clinical signs, and results of serum biochemical analyses, hepatic biopsy, and postmortem examination. Within 1 year of the illness, 75% (9/12) of the horses had died or had been euthanatized. Not all horses had the typical fulminant signs a...
Zamos DT, Hunt RJ, Allen D.Fractures of the distal radius in two horses were repaired by open reduction and interfragmentary compression using screws placed in a lag fashion. One horse had a complete oblique fracture of the medial aspect of the epiphysis of the distal radius and was sound for riding 32 months after surgery. The other horse had an open spiral comminuted fracture with medial displacement of the distal radial fragment. Laminitis developed in the contralateral limb and this horse was euthanatized 5 weeks after surgery.
Knottenbelt DC, Jones RS, Brazil TJ, Proudman CJ, Edwards SR, Harrison LJ.One hundred and-two horses requiring to be euthanased for a variety of reasons were killed by the intravenous injection of a mixture of quinalbarbitone sodium (400 mg/ml) and cinchocaine hydrochloride (25 mg/ml). The dose rates used were 1 ml/10, 15, 20 and 30 kg bodyweight, and the time of injection was varied between 5 and 25 seconds. The average time to collapse from the start of the injection was 34 seconds and the average time to clinical death was 230 seconds. Slow injection (particularly of the low dose rates) and premedication with detomidine resulted in a longer time to collapse (medi...
Jones DL.Medical records were reviewed for 11 horses with squamous cell carcinoma of the larynx and/or pharynx. The average age at presentation was 15.3 years. No breed or sex predilection was present. At presentation, 6 of 11 horses were dyspneic and 4 horses had inspiratory stridor. Endoscopy was performed in all cases and was more useful in demonstrating a mass in the laryngopharyngeal region than laryngeal or guttural pouch radiography. Surgical excision was attempted in 3 horses and in 1 horse alleviated clinical signs for 4 months. Ten horses were euthanatized and 1 horse died. Results of this st...
van der Kolk JH, Kalsbeek HC, van Garderen E, Wensing T, Breukink HJ.The records of 21 horses with an adenoma of the pars intermedia of the pituitary gland were reviewed. The animals comprised nine Dutch warmblood horses and 12 ponies. They ranged in age from 12 to 30 years (mean +/- sem 21 +/- 1.3 years) for 20 of the horses, and comprised 13 geldings and eight mares. All the animals showed hirsutism. In 1991, nine horses were diagnosed as having the adenoma, equivalent to 0.5 per cent of the horses examined in 1991. The mean +/- sem survival time of four of the horses (from discharge to the development of complications which required euthanasia) was 192 +/- 5...
Woods PR, Helman RG, Schmitz DG.A 5-year-old Quarter Horse mare was examined because of weight loss of 2 months' duration. The horse was anemic and in poor body condition, and had several areas of cutaneous ulceration, including areas on the muzzle and distal portion of the limbs. Histologic examination of a rectal mucosa biopsy specimen revealed a lymphoplasmacytic infiltrate in the lamina propria mucosa. Results of a glucose absorption test were suggestive of malabsorption. Histologic examination of a biopsy specimen from the cutaneous lesions revealed pronounced arteritis, and weak, patchy immunofluorescent staining for i...
Baxter GM, Jackman BR, Eades SC, Tyler DE.Intra-abdominal adhesions were created by localized serosal trauma in 11 adult ponies at three locations on the small intestine. Six ponies received verapamil hydrochloride (0.2 mg/kg) subcutaneously every eight hours for three days, and five ponies received an equal volume of saline solution at the same intervals. The investigators were not informed which treatments the ponies received. Systolic, diastolic, and mean carotid arterial pressures and heart rates were measured six hours before surgery, and then 0.5, 1, 1.5, and 8 hours after the first treatment on each day for three days. One pony...
Freeman DE, Staller GS, Maxson AD, Sweeney CR.A mare with hemorrhage caused by guttural pouch mycosis was treated by insertion of a balloon-tipped catheter into the left internal carotid artery. During recovery from general anesthesia, the mare had profuse epistaxis, and was anesthetized again to determine the site of hemorrhage. The affected guttural pouch was opened to confirm that hemorrhage was from the left internal carotid artery. The mare was euthanatized, and, at necropsy, the balloon catheter was found in an aberrant branch that arose from the internal carotid artery and joined the basilar artery. The mycotic plaque was on the le...
Johnson PJ, Goetz TE.A 10-month-old Standard-bred colt was examined because of weight loss, fever, and extensive subcutaneous edema of the ventral aspects of its trunk. Diagnosis of granulomatous enteritis was based on D-xylose malabsorption, hypoproteinemia, and rectal mucosal biopsy. Campylobacter fetus subsp fetus was cultured from jugular venous blood when the horse was admitted to the hospital and 24 hours later. Appropriate antimicrobial agents and glucocorticoids failed to effect clinical remission. After euthanasia, granulomatous enteritis was confirmed at necropsy but C fetus subsp fetus was not isolated ...
Lerche E, Laverty S, Blais D, Sauvageau R, Cuvelliez S.An 18-month-old male Belgian horse was anesthetized and placed in dorsal recumbency for cryptorchidectomy. Xylazine was used for sedation and guaifenesin with thiamylal for induction of anesthesia. A surgical plane of anesthesia was maintained with halothane. During anesthesia, second-degree atrio-ventricular blocks, hypoventilation and a 1-minute duration rise of mean arterial pressure (80 to 130 mm Hg) occurred. Total anesthesia time was 1 hour. On recovery from anesthesia, the horse exhibited flaccid paralysis of the hind limbs and was only able to elevate himself to a dog sitting position....
Todhunter RJ, Freeman KP, Yeager AE, Lust G.This study assessed the effects of postoperative exercise and intra-articular polysulfated glycosaminoglycan (PSGAG) on the repair of osteochondral defects in the carpal joints of ponies. Eighteen ponies with normal carpi had osteochondral defects (mean dimensions 2.4 cm x 0.9 cm) created arthroscopically on the dorsal aspect of the distal articular surface of the radial carpal bone. The ponies were randomized (while balancing for age [range, 2 to 15 years; median, 5.0 years]) to two groups--nine ponies were exercised and nine were stall confined. Beginning at surgery, six ponies in each group...
Ricardi G, Dyson SJ.Eight horses had forelimb lameness which was considered unrelated to primary forelimb pain, but was associated with radiographic abnormalities of one or more cervical vertebrae. There was no evidence of ataxia or weakness. The degree and character of the forelimb lameness varied between horses. In 4 horses, selective local analgesic techniques were used to rule out lameness associated with pain in the forelimb. In the other 4 horses, radiographic examination of the cervical region was performed on the basis of forelimb lameness seen in conjunction with neck stiffness and/or neck pain. Three ho...
Ruggles AJ, Beech J, Gillette DM, Midla LT, Reef VB, Freeman DE.A 13-year-old Quarter Horse gelding was referred for evaluation of a draining tract and fracture of the right hemimandible of 4 weeks' duration. Two days prior to admission, the horse had developed pigmenturia. Radiography of the mandible revealed a fracture of the vertical ramus of the right hemimandible, loss of the right lower second premolar, and osteomyelitis involving an extensive portion of the hemimandible. Ultrasonography of the left kidney revealed loss of normal renal architecture. Histologic examination of tissue obtained from the right hemimandible revealed granulomatous osteomyel...
Greene EA, Smith KR, Pendergraft JS, Raub RH, Arns MJ.When the decision was made to euthanatize an acutely laminitic Thoroughbred broodmare, graduate students from the Department of Animal Sciences and Industry reconstructed the skeleton for use as a teaching tool. The reproductive and gastrointestinal tracts were removed and preserved in formalin. The hide, muscle, tendons, ligaments, and organs were removed, and the bones were boiled in water for > or = 48 h to remove all remaining tissue. After boiling, the bones were soaked in gasoline to remove fat from the marrow cavities and then soaked in a bleach/detergent mixture as a final cleaning ...
Fubini SL, Boatwright CE, Todhunter RJ, Lust G.Intra-articularly administered, long-acting corticosteroids are a beneficial treatment for many equine joint disorders because they alleviate inflammation and signs of pain, but they also exert detrimental effects on the biochemical composition and morphologic features of articular cartilage. Chondroprotective drugs have been shown to mitigate some of the deleterious effects of intra-articularly administered corticosteroids on articular cartilage of laboratory animals. Twenty-one ponies were assigned at random to receive 1 of 3 treatments in the right middle carpal joint. Group-1 ponies (n = 8...
Hubbell JA, Muir WW, Gaynor JS.Six horses scheduled for euthanasia were instrumented for the measurement of blood flow by thermodilution, pulmonary arterial, right atrial and arterial blood pressures and collection of arterial blood for pH and blood gas analysis. The horses were anaesthetised with intravenous (iv) thiamylal sodium (10 mg/kg) and placed in right lateral recumbency. After euthanasia with an overdose of pentobarbitone sodium (100 mg/kg, iv) and loss of the electrocardiogram and arterial pulse pressure, thoracic compression at rates of 40, 60 and 80 compressions/min was instituted. Thoracic compression was acco...
Leendertse IP.A three year old warm-blood gelding with severe colic was referred to a veterinary clinic. The history revealed that the horse was found early in the morning with severe colic, and laying in the pasture. On arrival the clinical examination showed a complete wet horse with a pulse rate of 92/min, a respiratory rate of 24/min., a pcv of 0.50 L.L.-1, a T. of 38.0 degrees C, and no gastric reflux. Rectal examination revealed a sticky rectal mucous membrane and a colonic impaction together with displacement of the large colon. A diagnostic laparotomy showed an impaction as is seen in horses with Gr...
van der Kolk JH, van Hoorn CJ, van Garderen E, van den Belt AJ.An eighteen-year-old pony gelding was referred to the Faculty of Veterinary Medicine because of colic, due to cecal tympany. His haircoat was dull with long wavy hair. After medical treatment of the colic it was sent home three days later. Just before it had been dismissed the morning plasma glucose concentration measured 10.2 mmol.l-1. The basal plasma cortisol concentration was high (180 nmol.l1) and basal plasma ACTH concentration was highly elevated (> 960 pg.ml1). An ACTH-stimulation test was performed by intravenous administering of 0.25 mg synthetic ACTH 1 24 at 9.00 hours showing ad...
Johnson CM, Cullen JM, Roberts MC.Ten ponies (160-250 kg, ages 17 months to 20 years) developed severe diarrhea within 24 hours of castor oil administration (2.5 ml/kg orally). The diarrhea was most severe between 24 and 48 hours post-dosing and subsided by 72 hours. Ponies were euthanatized at 24, 48, and 72 hours post-dosing and intestine was evaluated histologically and ultrastructurally. Twenty-four hours after dosing, the mucosa of the cecum and ventral colon had extensive superficial epithelial erosion and neutrophil infiltration. In the ileum, the epithelium of villous tips was separated from the lamina propria. Scannin...
Yvorchuk-St Jean KE, Debowes RM, Gift LJ, Kraft SL, Sinha AK, Kennedy GA.A 5-week-old belgian colt was examined for colic of 12 hours duration after several episodes of diarrhea. Physical examination revealed signs of abdominal pain, mild dehydration and normal auscultable borborygmi in all abdominal quadrants. Distention of the cecum, large colon and small intestinal was evident on abdominal radiographs. The foal was treated medically as the owners declined surgery. The colt was euthanized because of continued deterioration and failure to respond to medical therapy. Post-mortem exam revealed the presence of a trichophytobezoar obstructing the distal part of the tr...
Kollias-Baker CA, Pipers FS, Heard D, Seeherman H.Pulmonary edema associated with transient airway obstruction was detected in 3 horses. The cause of obstruction was different in each horse, but after relief of the obstruction, clinical signs and radiographic abnormalities were indicative of pulmonary edema. In 2 of the 3 horses, pink frothy fluid was evident in the airways. The horses were treated with furosemide, nasal insufflation of O2, anti-inflammatory agents, and anti-biotics. Of the 3 horses examined, 1 horse died acutely, 1 horse recovered fully, and 1 developed pleuritis and was subsequently euthanatized.
Smith KC, Tearle JP, Boyle MS, Gower SM, Mumford JA.Equid herpesvirus-1 (EHV-1; Ab4 isolate) was inoculated unilaterally into the cavum vaginale of four pony colts under general anaesthesia. The animals were monitored daily for evidence of scrotal or testicular swelling and euthanased electively on days 3, 4, 6 and 12 after infection. Detailed pathological examination of the male genital tract was carried out. In animals examined at days 3 and 4 after infection, replication of EHV-1 was detected bilaterally in mesothelial and endothelial cells of the parietal and visceral vaginal tunics. The mesothelial infection had resolved by day 12 after in...
Hance SR, Schneider RK, Embertson RM, Bramlage LR, Wicks JR.Medical records and radiographs were reviewed from 20 foals with caudal femoral condylar lesions. Osseous lesions were classified radiographically into 3 categories. Type-I lesions were characterized by a discrete area of radiolucency within the subchondral bone of the caudal aspect of a femoral condyle and were associated with septic arthritis and osteomyelitis. Type-II lesions had localized, osseous irregularities involving < 50% of the femoral condyle. Type-III lesions had widespread irregularities involving a large area of the condyle, and in 5 foals with type-III lesions, there was a thin...
Kemper T, Spier S, Barratt-Boyes SM, Hoffman R.Five horses were admitted for treatment of smoke-inhalation injuries sustained in a barn fire. Three of the horses were mildly affected, with high respiratory rates (24 to 36 breaths/min) and normal to low arterial oxygen tensions (77.0 to 94.1 mm of Hg), and responded well to administration of diuretics, bronchodilators, corticosteroids, and antibiotics. The 2 remaining horses were severely affected. Both were in respiratory distress, with markedly low arterial oxygen tensions (50.4 and 57.1 mm of Hg) and cyanosis. These 2 horses required fluid resuscitation in addition to the treatments give...
Gift LJ, Gaughan EM, DeBowes RM, Pintchuk PA, Nickels FA, Foreman JH.Medical records of 11 adult horses with jejunal intussusception examined at 5 veterinary teaching hospitals between 1981 and 1991 were reviewed. Nine of 11 horses had signs of acute abdominal discomfort for < 24 hours, whereas 2 horses had a history of chronic signs. Five of 11 horses had an intraluminal or intramural mass associated with the jejunal intussusception. Two horses died or were euthanatized prior to surgery. Partial jejunal resection and jejunojejunal anastomosis were performed in 9 horses. One horse died during surgery and 2 were euthanatized prior to hospital discharge because o...
Smith KC, Whitwell KE, Mumford JA, Gower SM, Hannant D, Tearle JP.Twelve Welsh Mountain pony mares in late gestation were infected intranasally with EHV-1 (AB4 isolate) at dose rates from 10(3) to 10(7.3) TCID50. This resulted in 3 cases of paresis, at Days 9, 10 and 12 after inoculation, and 5 abortions, at Days 6, 9, 18, 19 and 20. Euthanasia was performed between Days 6 and 21, with collection of uterine specimens for histopathology, virus isolation and immunoperoxidase staining from the pregnant horn, non-pregnant horn and body. EHV-1 replication in endometrial vessels was detected as early as Day 6 and was maximal at Days 9-11, when widespread thrombois...
Hawkins JF, Schumacher JS, McClure SR, Light GS.Small intestinal incarceration through the lateral ligament of the urinary bladder was diagnosed in a 14-year-old, 569-kg, castrated Quarter Horse. The incarceration was corrected by ventral midline celiotomy. Approximately 70 cm of the middle portion of the jejunum was resected and end-to-end, single-layer anastomosis was performed. After surgery, the horse developed signs of adynamic ileus and lameness in the right forelimb. The horse developed laminitis in all 4 feet within 24 hours of surgery. The horse was euthanatized because of poor prognosis for survival. At necropsy, a 4.5-cm rent was...
Wilson DA.A 28-year-old Pinto mare was evaluated for multiple recurrences of a perianal squamous cell carcinoma. Clinical signs included lethargy, inappetence, weight loss, dyschezia, and hematochezia. The tumor involved the proximal portion of the vulvar labia, the perineum, and the anus, and there was a rectal fistula just left of the anus. Permanent end-on colostomy without further treatment of the carcinoma was the management option chosen. The colostomy functioned satisfactorily, and the mare's condition was stable for the next 14 months. Recurrence of lethargy and inappetence and development of we...
Boyd JS.A radio-opaque marker was injected intramuscularly at different levels and with needles of different lengths into the cervical musculature of a series of ponies and horses which were under profound anaesthesia prior to euthanasia. Subsequently the necks were sectioned and radiographed to determine the fate of the injected material. The results indicated that care was necessary in the selection of the level for injection in order to prevent deposition of material on to the periosteal surface of the cervical vertebrae or on to the ligamentum nuchae and fascial sheaths. The muscle mass over the t...
Alexander K, Simon E, Mama K, Rao S, Bass L.This study aims to assess intrathecal mepivacaine for euthanasia in anesthetized horses and compare it to a traditional euthanasia method using a single intravenous injection of pentobarbital in sedated horses. Methods: Client-owned horses and horses requiring euthanasia due to involvement in concurrent research projects were used. Horses were randomly assigned to 1 of 2 groups: intrathecal mepivacaine after anesthesia or intravenous pentobarbital after sedation. All horses had normal vital parameters and no signs of infectious disease at the time of euthanasia. Methods: The intrathecal mepiva...
Carmalt JL, Allen A.To investigate potential relationships between cheek tooth occlusal morphology, apparent feed digestibility, and the reduction in feed particle size that occurs during digestion in horses. Methods: Cross-sectional study. Methods: 17 horses of various ages and breeds and either sex. Methods: Horses were fed 1 of 3 hay-based diets ad libitum for 14 days prior to euthanasia; nutrient analysis was performed on samples of each of the 3 diets. At the time of postmortem examination, the head was disarticulated, photographs were taken of the occlusal surfaces of the maxillary and mandibular cheek toot...
Van Camp SD, Mahler J, Roberts MC, Tate LP, Whitacre MD.An ovarian adenocarcinoma with teratomatous elements was removed from a 9-year-old mare. Although no other lesions were detected at ovariectomy, multifocal metastatic masses led to cachexia and euthanasia 2 months later. This case reaffirms the need to exercise caution when removing ovarian masses to prevent seeding of the abdomen. This report includes discussion of the WHO system of classification of ovarian tumors.
Roumen MP, Borgsteede FH, Vos JH.In autumn 2002 and 2003, the Animal Health Service received several young horses for post mortem investigation that had died or had been euthanised. It was found that severe cyathostominosis was the cause of death. The aetiology, pathology and diagnosis of this infection is discussed. Advice is given for preventative measures and usage of anthelmintics.
Ogihara K, Ishihara A, Nagai M, Yamada K, Mizutani T, Harafuji M, Nishio H, Madarame H.A 23-year-old Falabella gelding kept in Tochigi, Japan, for more than 20 years presented with a recurrent mass of the glans penis that was first noticed about a year earlier. Partial phallectomy was performed with no adjunctive therapy for local regrowth of the mass. The horse was euthanized 3 months after surgery for urinary retention due to suspected regrowth. The resected mass affected the genital and urethral mucosa of the glans penis, and was diagnosed as equine sarcoid by histopathology and identification of bovine papillomavirus (BPV) DNA. Phylogenetic analysis of the BPV genome of the ...
Woods PR, Helman RG, Schmitz DG.A 5-year-old Quarter Horse mare was examined because of weight loss of 2 months' duration. The horse was anemic and in poor body condition, and had several areas of cutaneous ulceration, including areas on the muzzle and distal portion of the limbs. Histologic examination of a rectal mucosa biopsy specimen revealed a lymphoplasmacytic infiltrate in the lamina propria mucosa. Results of a glucose absorption test were suggestive of malabsorption. Histologic examination of a biopsy specimen from the cutaneous lesions revealed pronounced arteritis, and weak, patchy immunofluorescent staining for i...
Ball MA, Weldon AD.A 5-year-old Appaloosa gelding was presented with a history of intermittent multiple joint swelling, weight loss, and anemia. Physical examination and clinical pathology revealed a grade IV/VI holodiastolic murmur, louder on the left, and a marked hyperproteinemia. Echocardiography of the heart demonstrated a large vegetative lesion on one of the aortic valve cusps. Blood cultures did not elucidate the causative organism, and the disease was refractory to empiric antibiotic therapy. The horse was euthanized after approximately 2 months of therapy.