Veterinarian comments about dog licensing, pit bulls, & street dog parasites

From ANIMAL PEOPLE,  April 2013:

Your January/February 2013 editorial “Pi,  Dorothy,  and the qualities of humane leadership” gave me stuff to ponder that I hadn’t seriously considered before,  such as the emphasis on adopting one’s way out of shelter euthanasias versus the likely better bang for the buck approach of focusing even more than currently on spaying and castrating. I would enthusiastically support stronger spay/castration laws and regulations if I thought that they would be effectively enforceable and enforced.  Current spay/castration laws are neither effectively enforceable nor effectively enforced,  so I am doubtful that tougher ones would have more of an effect. The biggest block to the success of breeding and licensing laws and regulations is establishing the fact of ownership.  I can’t imagine the latter being accomplished except via a volunteer army going door to door to ask questions in the service of the state.  Or,  perhaps,  by making it a capital offense to keep an unfixed or unlicensed companion animal. The second highest obstacle to success is increasing the 70% figure that you cite (for all U.S. pet dogs) to 90%-plus.  That remaining 20%-30% of companion animal caregivers are the hard core.  Changing the behavior of any hard core person is always especially challenging,  if not impossible,  no matter what the subject. Assuming that potentially useful and practical laws or regulations could be written,  I would be a vocal advocate of such,  especially to stem shelter killing of pit bulls.  However,  I have seen and read how shelter dog demographics change from era to era.  Today it’s pit bulls and Chihuahuas.  Yesterday it was Rottweilers.  The day before yesterday,  it was German shepherds.  Before that,  cocker spaniels and Dobermans,  and on and on.  So it makes no sense to me to limit improved and increased breeding and licensing strictures to pit bulls,  if one’s goal is to reduce shelter killing for good. On another subject,  in your January/February 2013 edition,  under “New record number of dog attack fatalities,”  you wrote “ANIMAL PEOPLE recorded 47 fatal dog attacks in 2012,  33 by pit bulls.”  But in one of your book reviews in that same edition,  you wrote “The 2012 toll of 38 people killed by dog bites, including 24 killed by pit bulls,  broke the previous record––now broken three times in four years.”  The contradictory numbers don’t affect your claims and assertions and point of view,  but do give me a chuckle. Finally,  in response to my letter “Veterinarian comments on canine perceptions of life & death,  and the requirements of a good doggy diet,”  you wrote of street dogs,  “The dogs would not be successfully reproducing without an adequate food supply.  The critical issue for street dogs,  worldwide,  is lack of parasite control.” In Mexico and throughout West Africa,  where I have lived and traveled,  I don’t recall ever seeing a single litter of street puppies or young juveniles,  or even just one puppy or young juvenile,  trotting along behind their street dog dam.  (Though I must admit to never having visited any waste dump sites.)  There are multiple reasons for my not having had this observation,  only one of which is that any mammal who is chronically and significantly malnourished and/or heavily parasitized is unlikely to be very fertile or fecund.  In the absence of adequate animal control,  street dog populations do indeed tend to maintain despite high mortality.  But the reason is almost certainly replacement by other juvenile or young adult dogs,  not by successful street dog reproduction. I would love to read a published study that produced evidence which supports your assertion that sickly,  thin street dogs are that way because of heavy internal parasitism rather than because of inadequate diet.  The #1 suspect in severe gastrointestinal parasitism in street dogs,  as in all dogs,  would be the common dog roundworm,  Toxocara canis.  And many,  if not most,  dogs become immune or relatively immune to Toxocara canis at about one year of age,  and do not harbor any roundworms.  So your claim about the primary significance of parasitism on street dog ill-health is rather extraordinary. ––Bruce Max-Feldman, DVM Berkeley,  California

Merritt Clifton responds:

From the top,  it is true,  as ANIMAL PEOPLE has often pointed out,  that dog sterilization requirements meant to be enforced through licensing laws have never been effective in the U.S.,  and have had limited success only in Calgary,  Alberta,  Canada,  some of the most affluent cities in Asia,  and parts of western Europe.  

Encouraging sterilization via charging higher license fees for unaltered dogs helped considerably to introduce dog sterilization as the U.S. societal norm.  In Los Angeles,  for instance,  which was among the first communities to try differential licensing,  only 5% of the licensed dogs were sterilized as of 1970,  but 54% were sterilized by 1979.  A national study done a decade later found that a sampling of 86 pounds and shelters located in areas without differential licensing handled approximately the same number of dogs each year from 1980 to 1985.  By comparison,  61 pounds and shelters in areas that had differential licensing handled an average of 12.3% fewer dogs. 

Unfortunately,  differential licensing  has not visibly helped much in the 20-odd years since the rate of dog sterilization rose to three or four times the rate of dog licensing.

However,  at least two other approaches to dog sterilization have proved eminently successful.   Since California mandated sterilization of shelter dogs before adoption in 1998,  the numbers of dogs killed in California shelters has fallen by 22%,  even though pit bull intake and killing over the same years more than doubled.

San Francisco in 2006 mandated sterilization of pit bulls,  enforceable on observation that a dog is a pit bull.  Introducing this requirement brought declines in pit bull impoundment of 50%,  81%,  and 26% in the next three fiscal years,  even as pit bull impoundment soared in other California cities.

Concerning the alleged “contradiction” in the pit bull attack data reported in the January/February edition of ANIMAL PEOPLE,  there is no contradiction if one reads the complete items.  The DogsBite.orgdata reported in “New record number of dog attack fatalities,”  also mentioned in the book review in question,  pertained exclusively to fatalities caused by dog bites.   

But as the very next paragraph of  “New record number of dog attack fatalities” explained,  “ counts only fatalities resulting from bite wounds.  Counting also deaths resulting from heart failures suffered during dog attacks,  injuries suffered in trying to escape from dog attacks,  and infections resulting from dog bites,  and covering Canada as well as the U.S.,  ANIMAL PEOPLE recorded 47 fatal dog attacks in 2012,  33 by pit bulls.”

Street dog replenishment The suggestion that the reason for street dog replenishment “is almost certainly replacement by other juvenile or young adult dogs,  not by successful street dog reproduction” begs the question of where “other juvenile or young adult dogs” might be coming from in regions where dogs are relatively rarely kept in homes,  even when routinely fed by one particular household whose courtyard,  back alley,  or doorway is the dog’s usual habitat.  To varying degree,  this includes the entirety of the Islamic world,  Asia except in some affluent cities in recent years,  the formerly Communist nations of eastern Europe,  where most people live in small apartments,  and most of Africa and Latin America,  where even dogs claimed as pets often roam without restraint.  In some of these regions there is a pronounced tendency for dogs in homes to be “breed dogs.”  Sometimes unaltered “breed dogs” produce mongrel offspring,  who are dumped at large and add to the street dog population;  but the prevalence among street dogs of mongrels without distinctive breed characteristics suggests that their last ancestors who had homes were more than one generation back.  

“A mark-resight survey method to estimate the roaming dog population in three cities in Rajasthan, India,”  by six co-authors including Lex and Elly Hiby and Jack Reese,  published in BMC Veterinary Research 2011,  found that up to a third of all unaltered female dogs were lactating in Jaipur,  Jodhpur and Jaisalmer before the introduction of local Animal Birth Control programs.

Parasites The recent study which most directly examined the relationship between parasitic infection and poor body condition among street dogs may have been “Stray dog population health in Jodhpur, India in the wake of an animal birth control (ABC) program,” published in the February 2011 edition of Preventive Veterinary Medicine.  Reported the five co-authors,  “A prevalence survey of 323 sexually intact stray dogs caught from the streets of Jodhpur from September to November 2005 indicated that low body condition score (70%), skin conditions (69%) and tick infestation (68%) were the most common health problems in this population. An observational study of 888 stray dogs on the streets of Jodhpur from March to April, 2006 revealed that sterilized dogs were more likely to have a higher body condition score than sexually intact dogs when controlling for age,”  even though “the current parasite control protocol at the kennel/shelter facility was inadequate to treat mange.”

Among other studies relevant to the Toxocara canis burden among street dogs and other dogs found at large,  as compared to domestic pets,  are these three pertaining to dogs in hot parts of the world: “Gastrointestinal and ectoparasites from urban stray dogs in Fortaleza (Brazil),”  published in the August 2010 edition of Parasitology Research,  found that among the carcasses of 46 street dogs,  38 had intestinal parasites;  83% had dog hookworm (A. caninum),  while 9% had Toxocara canis.  Either parasite can significantly lower body scores.

“Prevalence of Toxocara Canis infection in dogs and its effects on various blood parameters in Lahore (Pakistan),”  published in 2009 by the Journal of Animal & Plant Sciences,   found that among samples of 100 street dogs and 100 pet dogs,  49% of the street dogs were infected,  compared to 30% of the pets. “Prevalence of Toxocara canis in stray dogs,  northern Iran,”  published in the July 2009 edition of the Pakistan Journal of Biological Sciences,  found that among 27 adult dogs and 23 puppies shot by animal control in the city of Sari,  41% of the adults and 83% of the puppies were infected with Toxocara canis. Also of note are these two studies pertaining to dogs in cold climates:

“Prevalence of Toxocara canis infection in dogs in the Warszawa area,”  published in the Polish journal Wiad Parazytol in 2000,   found that among a sample of 500,  Toxocara canis was found in 3.4% and 8.8% of the dogs at two shelters,  but in only 0.4% of the dogs who had homes.

“The prevalence of intestinal parasites in dogs and cats in Calgary,  Alberta,”  published in the December 2011 edition of Canadian Veterinary Journal,  found that “The overall parasite prevalence was 21.1% in shelter-sourced dogs and 15.5% in currently homed dogs… We found an overall prevalence of Toxocara canis of 2.9%,”  but “Toxocara canis infection was much higher in shelter-sourced animals of all ages (9% in all ages; 19% in those younger than one year.”  This study also produced comparative findings for giardia:  “9.2% in currently homed dogs compared to 4.2% for shelter-sourced dogs.”

Other internal parasites Two other studies relevant to the internal parasite burden of street dogs compared to pet dogs: “Occurrence of Neospora caninum antibodies in sera from dogs of the city of São Paulo,  Brazil,”  by seven co-authors,  published in the June 2002 edition of Veterinary Parasitology,  reported that “Sera from 500 owned dogs and from over 600 feral street dogs from the city of São Paulo,  Brazil were assayed for anti- bodies to Neospora caninum…Antibodies to Neospora caninum were found in nearly 10% of owned dogs and in 25% of stray dogs.”

“A survey for infection with Dirofilaria immitis,  Ehrlichia canis,  Borrelia burgdorferi, and Babesia canis in feral and client-owned dogs in the Turks and Caicos Islands, British West Indies,”  by three co-authors, published in the June 2008 edition of Canadian Veterinary Journal,  found that  “Feral dogs were 14.8 and 11.2 times more likely to be seropositive to Dirofilaria immitis and Ehrlichia canis,  respectively,  than were client-owned dogs.”

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