Non-accidental injuries found in necropsies of domestic cats: a review of 191 cases

Abstract

Animal cruelty is defined as a deliberate action that causes pain and suffering to an animal. In Brazil, legislation known as the Environmental Crimes Law states that cruelty toward all animal species is criminal in nature. From 644 domestic cats necropsied between January 1998 and December 2009, 191 (29.66%) presented lesions highly suggestive of animal cruelty. The main necroscopic finding was exogenous carbamate poisoning (75.39%) followed by blunt-force trauma (21.99%). Cats from 7 months to 2 years of age were the most affected (50.79%). In Brazil, violence is a public health problem and there is a high prevalence of domestic violence. Therefore, even if laws provide for animal welfare and protection, animals are common targets for violent acts. Within a context of social violence, cruelty toward animals is an important parameter to be considered, and the non-accidental lesions that were found are evidence of malicious actions.

Introduction

Animal cruelty is defined as a deliberate action that causes pain and suffering to an animal.^1,2 In Brazil, legislation known as the Environmental Crimes Law (Law 9605, 12 February 1998) states that cruelty toward all animal species is criminal in nature. These crimes are under-reported; therefore, there are no official statistics illustrating the real depth of the problem.

Among the animals received for necropsy by the Department of Pathology at the School of Veterinary Medicine and Animal Sciences at the University of Sao Paulo, Brazil (FMVZ/USP), there are cases highly suggestive of cruelty. Such cases are often submitted by the owner, usually without an elucidative anamnesis, or the animals are sent by the Police Enforcement with a police report. The lesions vary from those caused by chemical agents, such as poisons, to those caused by such mechanical forces, such as blunt-force traumas and puncture wounds.^3–5 According to police reports, as well as owners’ reports, the main motivations for inflicting non-accidental injuries upon animals are issues in interpersonal relationships involving neighbours and family members, or even dislike for the animals.

Intentional poisoning is a public health problem that affects both humans and animals. In Brazil, one of the main agents used for this purpose is aldicarb, a highly toxic carbamate pesticide known as ‘chumbinho’.^6–8 Although this pesticide is legally authorized as a pesticide used in agriculture, it is illegally traded for the extermination of rodents and companion animals.^7,8

Blunt-force injuries are caused by the impact of a hard object against a body without perforation and can result from accidental or non-accidental actions. These lesions can be produced by humans in aggressive actions, such as punching and kicking, by the bites of other animals — most frequently dogs — or even accidentally, as in hit-by-car cases and falls.^9–11 Blunt force injuries may result in the rupture of internal organs and/or blood vessels, bruising, lacerations of muscles and broken bones throughout the entire body.^9–13 These injuries can affect the head, thorax, abdomen and limbs. Depending on the force applied against the body wall, blunt-force injuries can also lead to lacerations, ruptures, hemorrhage and avulsion. ¹¹

Non-accidental injuries were initially characterized in victims of child abuse. There are reports that describe a high correlation between child abuse and animal cruelty; therefore, this characterization can be extended to animals.^14,15

Animal cruelty is an element of the complex family network of domestic violence ¹⁴ and when children and teenagers witness animal abuse they may develop personality disorders, ultimately leading to violence against humans.^16,17 In other cases, children torture their pets as a result of frustration because of an inability to deal with parental abuse, bullying in their school or even because they find enjoyment, due to psychopathology, in such cruel acts.^18,19 The history of cruelty towards animal reported by serial killers supports this theory.^17,20,21 Adults who were cruel to animals in childhood and/or adolescence tend to be more in favour of corporal punishment, such as spanking a child or slapping a spouse. ²²

In Brazil, cats are thought to be the main targets for acts of cruelty, although there are few studies focused specifically on this topic. In the analysis of the causes of death of dogs and cats in Sao Paulo, Brazil, 11% of the canine deaths were attributed to cruelty, whereas this percentage increased to 34% for cats. ³ According to a study conducted with 84 prisoners in two high security prison facilities, most of the prisoners had committed abuse against cats and approximately 33 patterns of cruelty were described, mainly involving burning and breaking bones. This abuse against cats was attributed to their physical and behavioral characteristics, making them targets for those who are likely to practice acts of violence against humans. ²³ Therefore, it has been demonstrated that detecting, prosecuting and punishing cruelty towards animals is of important concern to society.^2,3

Discovery of animal cruelty can cause an ethical dilemma for veterinarians because reporting the abuse may interfere with the relationship between the owner and pet, and may betray professional confidentiality. ¹⁴ The veterinarian may suspect non-accidental injuries during the clinical examination, mainly based on medical records, anamnesis and the observation of the relationship between the animal, its owner and other family members.^9,14 A forensic necroscopic examination should be performed to evaluate whether the lesions present accidental or non-accidental patterns.^24,25

The aims of this study are to describe the characteristics and the frequency of death by non-accidental injuries found in domestic cats during necropsy and to analyze the possible causes and characteristics of these deaths.

Materials and methods

Data from necropsies of domestic cats were collected between January 1998 and December 2009 from the entry records and results of necroscopic examinations from the Department of Pathology – FMVZ/USP. Data chosen for this study were as follows: date of entry, age, gender, breed, colour of the coat, cause of death and necropsy findings. A database was developed using Excel software (Microsoft).

Owing to age differences, subjects were placed in age groups as established by the American Association of Feline Practioners and American Animal Hospital Association (AAFP–AAHA). These groups included kittens (from birth to 6 months of age), juniors (7 months to 2 years of age), prime (3–6 years of age), mature (7–10 years of age), senior (11–14 years of age) and geriatric (over 15 years of age). ²⁶ The breeds studied were mixed-breed, Siamese, Persian and British Shorthair.

To evaluate whether the lesions presented unintentional or intentional injuries, the parameters chosen were the analysis of the necropsy findings, including photos and the owner’s report, which detailed the animal’s access to the outdoors, its feeding habits, its behavior and, in the case of carbamate poisoning, whether this substance was found on the owner’s property. When available, which occurred in approximately 20% of the cases, the police reports were also analyzed.

Poisoning

During the necroscopic exam, gastric contents and liver fragments were collected for the toxicological examination to detect possible carbamate poisoning. Carbamate is a small, blackish, irregular granule (approximately 0.2 cm in diameter) interweaving the gastric contents. It may be present in smaller amounts in the distal portion of the esophagus and in the proximal portion of the duodenum. Macroscopic analysis was performed in all organs.

Blunt force trauma, puncture wounds and other lesions

Traumas were classified according to their locations (thoracic, abdominal, cephalic, lumbar and pelvic) and can result in injury to internal structures, such as ruptures in the liver, spleen, kidney, ureter, urinary bladder, stomach, diaphragm, lung and thoracic vessels. Trauma can cause hemorrhages and the rupture of central nervous system tissues. Puncture wounds were found in the lateral thorax, and other lesions — including cervical bruising and abdominal evisceration — were also found. The lesions were measured and dissected to evaluate their depth and the dimension of the muscle layers affected by the traumatic lesion. Any bone fractures were similarly measured.

Results

Out of 644 domestic cats that were examined by necropsy between January 1998 and December 2009 at the Department of Pathology – FMVZ-USP, 191 (29.66%) presented with lesions highly suggestive of animal cruelty. Among these cats, 88 were male (46.07%), 86 were female (45.03%) and gender was not specified for the remaining 17 animals (8.9%). Regarding age group, 29 (15.18%) were between the age of 1 and 6 months, 97 (50.79%) were between the age of 7 months and 2 years, 30 (15.71%) were aged 3–6 years, 15 (7.85%) were aged 7–10 years and two (1.05%) were aged 11–14 years; no information regarding age was available for the remaining 18 animals (9.42%). According to breed, 158 (82.72%) of the cats were mixed breed, 24 (12.57%) were Siamese, six (3.14%) were Persian and one (0.52%) was British Shorthair; the breed was unknown for two animals (1.05%). The frequency of patterns of non-accidental injuries is recorded in Table 1.

Table 1.

Frequency of patterns of non-accidental injuries

Non-accidental injury	n	%
Carbamate poisoning	144	75.4
Blunt force trauma	42	22.0
Puncture wounds	3	1.6
Cervical bruising	1	0.5
Abdominal evisceration	1	0.5
Total	191	100.0

Considering blunt force trauma, 23.81% (10/42) occurred in the abdomen, 16.67% (7/42) in the head, 11.90% (5/42) in the thorax, 7.14% (3/42) in the lumbar region, 4.76% (2/42) in the pelvis, 2.38% (1/42) in the limbs and 33.33% (14/42) in more than one site. All puncture lesions occurred on the thorax. One case of polytraumatism was characterised as sexual assault in a 9-month-old, female mixed-breed cat. The distribution of the patterns of non-accidental injuries by age group is demonstrated in Table 2.

Table 2.

Patterns of non-accidental injuries by age group (there are no geriatric cats, ie, older than 15 years of age)

Age group	Kitten *		Juniors †		Prime ‡		Mature §		Senior ¶		NA	Total
	n	%	n	%	n	%	n	%	n	%	n	%	n
Carbamate poisoning	14	9.7	80	55.6	24	16.7	11	7.6	2	1.4	13	9.0	144
Blunt force trauma	15	35.7	18	42.9	6	14.3	3	7.1	0	0.0	0	0.0	42
Puncture wounds	2	66.7	1	33.3	0	0.0	0	0.0	0	0.0	0	0.0	3
Cervical bruising	0	0.0	1	100.0	0	0.0	0	0.0	0	0.0	0	0.0	1
Abdominal evisceration	0	0.0	0	0.0	0	0.0	1	100.0	0	0.0	0	0.0	1
Total	31	16.2	100	52.4	30	15.7	15	7.9	2	1.0	13	6.8	191

^*Kittens: from birth to 6 months of age

^†Juniors: 7 months to 2 years of age

^‡Prime: 3 to 6 years of age

^§Mature: 7 to 10 years of age

^¶Senior: 11 to 14 years of age

NA = data not available

The distribution of non-accidental injuries by gender revealed that for cases of carbamate poisoning, there were 61 females (42.36%) and 67 males (46.53%); no gender information was available for 16 (11.11%) cats. Blunt-force trauma occurred in 25 females (59.52%) and 17 males (40.48%). The cases of puncture wounds (n = 3), cervical bruising and abdominal evisceration occurred in females.

The distribution of non-accidental injuries by gender revealed that for cases of carbamate poisoning, there were 61 females (42.36%) and 67 males (46.53%); no gender information was available for 16 (11.11%) cats. Blunt-force trauma occurred in 25 females (59.52%) and 17 males (40.48%). The cases of puncture wounds (n = 3), cervical bruising and abdominal evisceration occurred in females.

The analysis of breed distribution of non-accidental injuries revealed that for mixed-breed cats (n = 158), 80.38% (127/158) of the injuries were caused by carbamate poisoning, 17.72% (28/158) by blunt-force trauma and 1.9% (3/158) by puncture wounds. For Siamese cats (n = 24), 62.50% (15/24) of the injuries were caused by carbamate poisoning, 29.17% (7/24) were caused by blunt-force trauma, and cervical bruising and abdominal evisceration each constituted 4.17% (1/24) of the injuries. For Persian cats (n = 6), 83.33% of the injuries were caused by blunt-force trauma and 16.67% (1/6) were caused by carbamate poisoning. One British Shorthair was a victim of blunt-force trauma and, of the two cats of unspecified breed, one was poisoned by carbamate and one suffered blunt-force trauma. Distribution of the cause of death considering the necropsy findings is shown in Table 3.

Table 3.

Cause of death

Cause of death	CR		HS		Eut		NS		SS		Und		Total
	n	%	n	%	n	%	n	%	n	%	n	%	n
Carbamate poisoning	135	93,8	4	2.8	0	0.0	0	0.0	0	0.0	5	3.5	144
Blunt force trauma	6	14.3	23	54.8	4	9.5	3	7.1	1	2.4	5	11.9	42
Puncture wounds	0	0.0	3	100.0	0	0.0	0	0.0	0	0.0	0	0.0	3
Cervical bruising	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	1	100.0	1
Abdominal evisceration	0	0.0	1	100.0	0	0,0	0	0.0	0	0.0	0	0.0	1
Total	141	73.8	31	16.2	4	2.1	3	1.6	1	0.5	11	5.8	191

CR = cardiorespiratory collapse, HS = hypovolemic shock, Eut = euthanasia, NS = neurogenic shock, SS = septic shock, Und = undetermined

The main gross lesions found in cases of poisoning by carbamate were reddish areas in the pancreas and red–black areas distributed over the lung. The liver was reddish, and there were areas of hemorrhage in the brain. In the cases involving blunt-force injuries, reddish areas could be observed in all layers of the muscles, interspersed with hemorrhages and hematomas and, in certain cases, complete fractures of bones in the limbs, sternum, ribs and skull. The ruptures of viscera were accompanied by hematomas on the walls of the body.

Discussion

Although cruelty to cats has been socially accepted in the past,^2,27 tolerance of such cruelty has diminished over the last few decades. ¹ Accordingly, specific laws have been created to protect animals worldwide. However, in societies with high rates of violence, animals are common targets for violent acts — even in the presence of animal welfare laws. In Brazil, violence is a public health problem and there is a high prevalence of domestic violence against children, adolescents, spouses and the elderly. ²⁸

In 2003, the distribution of Brazil’s human population mortality owing to specific external causes (n = 156,657) were as follows: 51,043 (40.3%) cases were attributed to aggression, whilst 258 cases (0.2%) were due to poisoning. ²⁹ Data from cases of traumatic death in the city of Sao Paulo have shown that trauma was responsible for 7603 deaths in 2005, of which 3209 (42.2%) were caused by homicides and 1579 (20.8%) by traffic accidents. ³⁰ In the analysis of the causes of death determined at necropsy of domestic cats from the Department of Pathology – FMVZ-USP between January 1998 and December 2009, non-accidental injuries represented 29.66% (191/644) of cases. This finding can be seen as an indication of the widespread violent behavior of humans against animals, especially cats, which can be corroborated by previous studies performed by our group. These results revealed that when comparing cases of cruelty between dogs and cats, the latter are targets for malicious acts, such as poisoning and blunt-force trauma,^3,6 which was confirmed by our study. Other studies focused on intentional pet poisoning have revealed that dogs are poisoned more often than cats, although the most common agents utilised were ethylene glycol and rodenticides.^31–33. However, in contrast to ethylene glycol, which is commonly used in residences and cars as antifreeze, and rodenticides — which are commonly used to kill rats — poisoning by carbamates is less likely to be accidental in urban areas because its utilization is forbidden and illegal outside of agriculture. Previous studies have described animal cruelty as part of the network of domestic violence; considered as such, animal cruelty may reveal patterns of violence inside the familial environment, particularly in the relationship between children and parents.^13,16–21 The high level of aggression in youngsters who injure pets may, in many cases, can be due to physical aggression that they may have been subjected to by a parent. ¹⁸ Cats may be chosen as the victims of animal cruelty, because of their typical behavioral and physical characteristics, for example their mysterious personality, their unpredictable behavior, their body’s flexibility and smoother lines. ¹⁸ Additionally, the black cat has been linked to witchcraft in ancient times. These animals still remain the victims of prejudice in many cultures and are utilized in rituals.^2,34 Another important factor is that those characteristics may evoke cruel and sadistic behavior in children.^18,35 Studies have shown that serial killers and other violent criminals often began their criminal activities by murdering pets — mainly cats and dogs. ²³

The macroscopic lesions found in non-accidental injuries were carefully analyzed and the cases of poisoning were confirmed by toxicological screening. However, in the case of blunt-force trauma, even if an owner reported that there was not an accident or high-rise syndrome, we could not dismiss such cases. It is difficult to differentiate accidental from non-accidental lesions without medical records or full anamnesis, even in children.^36,37 In the veterinary field, the forensic pathologist must rely on the medical evidence and the owner’s report.

Age appeared to be a more important risk factor than gender or breed. Cats younger than 2 years were the most frequent victims of abuse. One plausible explanation for non-accidental injuries is the habit of exploring commonly observed in this category of animals. ³⁸ An additional factor is that neonates and young kittens are fragile, are unable to escape and have not yet developed defense mechanisms, ³⁹ all of which can make them attractive targets for malicious wounding.^3,18,35 Similar results were found in a previous study, ³ which concluded that both children and pets are often targets of abuse at an early age. In animals, because of the presence of fur and skin pigmentation, it can be difficult to observe bruising, petechiae, cigarette burns and other non-accidental lesions. ¹⁰ In children, such patterns of lesions are considered non-accidental and are commonly found in areas such as hands, ears, neck, arms, posterior and medial faces of the thighs, and other areas, such as the gluteal and genital regions, which can indicate abuse. ⁴⁰

Unfortunately, these patterns cannot generally be observed in animals until the time of necropsy, when the skin is deflected and bruising is present in the subcutaneous tissue. Upon analysis, lesions caused by blunt force trauma were found most frequently on the abdomen, followed by the head and thorax. In the case of malicious actions, these lesions frequently occur when the animal is kicked, trampled, struck with hard objects or thrown against walls.^{9,10,19,22,23} In live animals, accurate clinical examination combined with a history of abuse, such as repetitive bone fractures and the observation of the animal’s behavior in the presence of its owner, is crucial to support a case of cruelty.^9,10

The role of the veterinary pathologist and the clinician in recognizing non-accidental injuries should be re-evaluated because it may provide crucial evidence in the prosecution of animal cruelty.

The present findings lead to the conclusion that within a context of social violence, cruelty toward animals is an important parameter to be considered. Non-accidental lesions found in this study were evidence of malicious actions. Furthermore, cases that present these patterns of lesions should be analyzed under the perspective of forensic veterinary medicine.